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31aee0d0c0
libpng/pngrtran.c
Glenn Randers-Pehrson 31aee0d0c0 [devel] 
Fixed point APIs are now supported throughout (no missing APIs).
  Internal fixed point arithmetic support exists for all internal floating
    point operations.
  sCAL validates the floating point strings it is passed.
  Safe, albeit rudimentary, Watcom support is provided by PNG_API_RULE==2
  Two new APIs exist to get the number of passes without turning on the
    PNG_INTERLACE transform and to get the number of rows in the current
    pass.
  A new test program, pngvalid.c, validates the gamma code.
  Errors in the 16 bit gamma correction (overflows) have been corrected.
  cHRM chunk testing is done consistently (previously the floating point
    API bypassed it, because the test really didn't work on FP, now the test
    is performed on the actual values to be stored in the PNG file so it
    works in the FP case too.)
  Most floating point APIs now simply call the fixed point APIs after
    converting the values to the fixed point form used in the PNG file.
  The standard headers no longer include zlib.h, which is currently only
    required for pngstruct.h and can therefore be internal.
  (Patches by John Bowler)
2010-07-29 17:39:14 -05:00

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/* pngrtran.c - transforms the data in a row for PNG readers
*
* Last changed in libpng 1.5.0 [July 29, 2010]
* Copyright (c) 1998-2010 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
*
* This code is released under the libpng license.
* For conditions of distribution and use, see the disclaimer
* and license in png.h
*
* This file contains functions optionally called by an application
* in order to tell libpng how to handle data when reading a PNG.
* Transformations that are used in both reading and writing are
* in pngtrans.c.
*/
#include "pngpriv.h"
#ifdef PNG_READ_SUPPORTED
/* Set the action on getting a CRC error for an ancillary or critical chunk. */
void PNGAPI
png_set_crc_action(png_structp png_ptr, int crit_action, int ancil_action)
{
png_debug(1, "in png_set_crc_action");
if (png_ptr == NULL)
return;
/* Tell libpng how we react to CRC errors in critical chunks */
switch (crit_action)
{
case PNG_CRC_NO_CHANGE: /* Leave setting as is */
break;
case PNG_CRC_WARN_USE: /* Warn/use data */
png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE;
break;
case PNG_CRC_QUIET_USE: /* Quiet/use data */
png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE |
PNG_FLAG_CRC_CRITICAL_IGNORE;
break;
case PNG_CRC_WARN_DISCARD: /* Not a valid action for critical data */
png_warning(png_ptr,
"Can't discard critical data on CRC error");
case PNG_CRC_ERROR_QUIT: /* Error/quit */
case PNG_CRC_DEFAULT:
default:
png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
break;
}
/* Tell libpng how we react to CRC errors in ancillary chunks */
switch (ancil_action)
{
case PNG_CRC_NO_CHANGE: /* Leave setting as is */
break;
case PNG_CRC_WARN_USE: /* Warn/use data */
png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE;
break;
case PNG_CRC_QUIET_USE: /* Quiet/use data */
png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE |
PNG_FLAG_CRC_ANCILLARY_NOWARN;
break;
case PNG_CRC_ERROR_QUIT: /* Error/quit */
png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_NOWARN;
break;
case PNG_CRC_WARN_DISCARD: /* Warn/discard data */
case PNG_CRC_DEFAULT:
default:
png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
break;
}
}
#ifdef PNG_READ_BACKGROUND_SUPPORTED
/* Handle alpha and tRNS via a background color */
void PNGFAPI
png_set_background_fixed(png_structp png_ptr,
png_color_16p background_color, int background_gamma_code,
int need_expand, png_fixed_point background_gamma)
{
png_debug(1, "in png_set_background_fixed");
if (png_ptr == NULL)
return;
if (background_gamma_code == PNG_BACKGROUND_GAMMA_UNKNOWN)
{
png_warning(png_ptr, "Application must supply a known background gamma");
return;
}
png_ptr->transformations |= PNG_BACKGROUND;
png_memcpy(&(png_ptr->background), background_color,
png_sizeof(png_color_16));
png_ptr->background_gamma = background_gamma;
png_ptr->background_gamma_type = (png_byte)(background_gamma_code);
png_ptr->transformations |= (need_expand ? PNG_BACKGROUND_EXPAND : 0);
}
# ifdef PNG_FLOATING_POINT_SUPPORTED
void PNGAPI
png_set_background(png_structp png_ptr,
png_color_16p background_color, int background_gamma_code,
int need_expand, double background_gamma)
{
png_set_background_fixed(png_ptr, background_color, background_gamma_code,
need_expand, png_fixed(png_ptr, background_gamma, "png_set_background"));
}
# endif /* FLOATING_POINT */
#endif /* READ_BACKGROUND */
#ifdef PNG_READ_16_TO_8_SUPPORTED
/* Strip 16 bit depth files to 8 bit depth */
void PNGAPI
png_set_strip_16(png_structp png_ptr)
{
png_debug(1, "in png_set_strip_16");
if (png_ptr == NULL)
return;
png_ptr->transformations |= PNG_16_TO_8;
}
#endif
#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
void PNGAPI
png_set_strip_alpha(png_structp png_ptr)
{
png_debug(1, "in png_set_strip_alpha");
if (png_ptr == NULL)
return;
png_ptr->flags |= PNG_FLAG_STRIP_ALPHA;
}
#endif
#ifdef PNG_READ_QUANTIZE_SUPPORTED
/* Dither file to 8 bit. Supply a palette, the current number
* of elements in the palette, the maximum number of elements
* allowed, and a histogram if possible. If the current number
* of colors is greater then the maximum number, the palette will be
* modified to fit in the maximum number. "full_quantize" indicates
* whether we need a quantizing cube set up for RGB images, or if we
* simply are reducing the number of colors in a paletted image.
*/
typedef struct png_dsort_struct
{
struct png_dsort_struct FAR * next;
png_byte left;
png_byte right;
} png_dsort;
typedef png_dsort FAR * png_dsortp;
typedef png_dsort FAR * FAR * png_dsortpp;
void PNGAPI
png_set_quantize(png_structp png_ptr, png_colorp palette,
int num_palette, int maximum_colors, png_uint_16p histogram,
int full_quantize)
{
png_debug(1, "in png_set_quantize");
if (png_ptr == NULL)
return;
png_ptr->transformations |= PNG_QUANTIZE;
if (!full_quantize)
{
int i;
png_ptr->quantize_index = (png_bytep)png_malloc(png_ptr,
(png_uint_32)(num_palette * png_sizeof(png_byte)));
for (i = 0; i < num_palette; i++)
png_ptr->quantize_index[i] = (png_byte)i;
}
if (num_palette > maximum_colors)
{
if (histogram != NULL)
{
/* This is easy enough, just throw out the least used colors.
* Perhaps not the best solution, but good enough.
*/
int i;
/* Initialize an array to sort colors */
png_ptr->quantize_sort = (png_bytep)png_malloc(png_ptr,
(png_uint_32)(num_palette * png_sizeof(png_byte)));
/* Initialize the quantize_sort array */
for (i = 0; i < num_palette; i++)
png_ptr->quantize_sort[i] = (png_byte)i;
/* Find the least used palette entries by starting a
* bubble sort, and running it until we have sorted
* out enough colors. Note that we don't care about
* sorting all the colors, just finding which are
* least used.
*/
for (i = num_palette - 1; i >= maximum_colors; i--)
{
int done; /* To stop early if the list is pre-sorted */
int j;
done = 1;
for (j = 0; j < i; j++)
{
if (histogram[png_ptr->quantize_sort[j]]
< histogram[png_ptr->quantize_sort[j + 1]])
{
png_byte t;
t = png_ptr->quantize_sort[j];
png_ptr->quantize_sort[j] = png_ptr->quantize_sort[j + 1];
png_ptr->quantize_sort[j + 1] = t;
done = 0;
}
}
if (done)
break;
}
/* Swap the palette around, and set up a table, if necessary */
if (full_quantize)
{
int j = num_palette;
/* Put all the useful colors within the max, but don't
* move the others.
*/
for (i = 0; i < maximum_colors; i++)
{
if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
{
do
j--;
while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
palette[i] = palette[j];
}
}
}
else
{
int j = num_palette;
/* Move all the used colors inside the max limit, and
* develop a translation table.
*/
for (i = 0; i < maximum_colors; i++)
{
/* Only move the colors we need to */
if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
{
png_color tmp_color;
do
j--;
while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
tmp_color = palette[j];
palette[j] = palette[i];
palette[i] = tmp_color;
/* Indicate where the color went */
png_ptr->quantize_index[j] = (png_byte)i;
png_ptr->quantize_index[i] = (png_byte)j;
}
}
/* Find closest color for those colors we are not using */
for (i = 0; i < num_palette; i++)
{
if ((int)png_ptr->quantize_index[i] >= maximum_colors)
{
int min_d, k, min_k, d_index;
/* Find the closest color to one we threw out */
d_index = png_ptr->quantize_index[i];
min_d = PNG_COLOR_DIST(palette[d_index], palette[0]);
for (k = 1, min_k = 0; k < maximum_colors; k++)
{
int d;
d = PNG_COLOR_DIST(palette[d_index], palette[k]);
if (d < min_d)
{
min_d = d;
min_k = k;
}
}
/* Point to closest color */
png_ptr->quantize_index[i] = (png_byte)min_k;
}
}
}
png_free(png_ptr, png_ptr->quantize_sort);
png_ptr->quantize_sort = NULL;
}
else
{
/* This is much harder to do simply (and quickly). Perhaps
* we need to go through a median cut routine, but those
* don't always behave themselves with only a few colors
* as input. So we will just find the closest two colors,
* and throw out one of them (chosen somewhat randomly).
* [We don't understand this at all, so if someone wants to
* work on improving it, be our guest - AED, GRP]
*/
int i;
int max_d;
int num_new_palette;
png_dsortp t;
png_dsortpp hash;
t = NULL;
/* Initialize palette index arrays */
png_ptr->index_to_palette = (png_bytep)png_malloc(png_ptr,
(png_uint_32)(num_palette * png_sizeof(png_byte)));
png_ptr->palette_to_index = (png_bytep)png_malloc(png_ptr,
(png_uint_32)(num_palette * png_sizeof(png_byte)));
/* Initialize the sort array */
for (i = 0; i < num_palette; i++)
{
png_ptr->index_to_palette[i] = (png_byte)i;
png_ptr->palette_to_index[i] = (png_byte)i;
}
hash = (png_dsortpp)png_calloc(png_ptr, (png_uint_32)(769 *
png_sizeof(png_dsortp)));
num_new_palette = num_palette;
/* Initial wild guess at how far apart the farthest pixel
* pair we will be eliminating will be. Larger
* numbers mean more areas will be allocated, Smaller
* numbers run the risk of not saving enough data, and
* having to do this all over again.
*
* I have not done extensive checking on this number.
*/
max_d = 96;
while (num_new_palette > maximum_colors)
{
for (i = 0; i < num_new_palette - 1; i++)
{
int j;
for (j = i + 1; j < num_new_palette; j++)
{
int d;
d = PNG_COLOR_DIST(palette[i], palette[j]);
if (d <= max_d)
{
t = (png_dsortp)png_malloc_warn(png_ptr,
(png_uint_32)(png_sizeof(png_dsort)));
if (t == NULL)
break;
t->next = hash[d];
t->left = (png_byte)i;
t->right = (png_byte)j;
hash[d] = t;
}
}
if (t == NULL)
break;
}
if (t != NULL)
for (i = 0; i <= max_d; i++)
{
if (hash[i] != NULL)
{
png_dsortp p;
for (p = hash[i]; p; p = p->next)
{
if ((int)png_ptr->index_to_palette[p->left]
< num_new_palette &&
(int)png_ptr->index_to_palette[p->right]
< num_new_palette)
{
int j, next_j;
if (num_new_palette & 0x01)
{
j = p->left;
next_j = p->right;
}
else
{
j = p->right;
next_j = p->left;
}
num_new_palette--;
palette[png_ptr->index_to_palette[j]]
= palette[num_new_palette];
if (!full_quantize)
{
int k;
for (k = 0; k < num_palette; k++)
{
if (png_ptr->quantize_index[k] ==
png_ptr->index_to_palette[j])
png_ptr->quantize_index[k] =
png_ptr->index_to_palette[next_j];
if ((int)png_ptr->quantize_index[k] ==
num_new_palette)
png_ptr->quantize_index[k] =
png_ptr->index_to_palette[j];
}
}
png_ptr->index_to_palette[png_ptr->palette_to_index
[num_new_palette]] = png_ptr->index_to_palette[j];
png_ptr->palette_to_index[png_ptr->index_to_palette[j]]
= png_ptr->palette_to_index[num_new_palette];
png_ptr->index_to_palette[j] =
(png_byte)num_new_palette;
png_ptr->palette_to_index[num_new_palette] =
(png_byte)j;
}
if (num_new_palette <= maximum_colors)
break;
}
if (num_new_palette <= maximum_colors)
break;
}
}
for (i = 0; i < 769; i++)
{
if (hash[i] != NULL)
{
png_dsortp p = hash[i];
while (p)
{
t = p->next;
png_free(png_ptr, p);
p = t;
}
}
hash[i] = 0;
}
max_d += 96;
}
png_free(png_ptr, hash);
png_free(png_ptr, png_ptr->palette_to_index);
png_free(png_ptr, png_ptr->index_to_palette);
png_ptr->palette_to_index = NULL;
png_ptr->index_to_palette = NULL;
}
num_palette = maximum_colors;
}
if (png_ptr->palette == NULL)
{
png_ptr->palette = palette;
}
png_ptr->num_palette = (png_uint_16)num_palette;
if (full_quantize)
{
int i;
png_bytep distance;
int total_bits = PNG_QUANTIZE_RED_BITS + PNG_QUANTIZE_GREEN_BITS +
PNG_QUANTIZE_BLUE_BITS;
int num_red = (1 << PNG_QUANTIZE_RED_BITS);
int num_green = (1 << PNG_QUANTIZE_GREEN_BITS);
int num_blue = (1 << PNG_QUANTIZE_BLUE_BITS);
png_size_t num_entries = ((png_size_t)1 << total_bits);
png_ptr->palette_lookup = (png_bytep )png_calloc(png_ptr,
(png_uint_32)(num_entries * png_sizeof(png_byte)));
distance = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_entries *
png_sizeof(png_byte)));
png_memset(distance, 0xff, num_entries * png_sizeof(png_byte));
for (i = 0; i < num_palette; i++)
{
int ir, ig, ib;
int r = (palette[i].red >> (8 - PNG_QUANTIZE_RED_BITS));
int g = (palette[i].green >> (8 - PNG_QUANTIZE_GREEN_BITS));
int b = (palette[i].blue >> (8 - PNG_QUANTIZE_BLUE_BITS));
for (ir = 0; ir < num_red; ir++)
{
/* int dr = abs(ir - r); */
int dr = ((ir > r) ? ir - r : r - ir);
int index_r = (ir << (PNG_QUANTIZE_BLUE_BITS +
PNG_QUANTIZE_GREEN_BITS));
for (ig = 0; ig < num_green; ig++)
{
/* int dg = abs(ig - g); */
int dg = ((ig > g) ? ig - g : g - ig);
int dt = dr + dg;
int dm = ((dr > dg) ? dr : dg);
int index_g = index_r | (ig << PNG_QUANTIZE_BLUE_BITS);
for (ib = 0; ib < num_blue; ib++)
{
int d_index = index_g | ib;
/* int db = abs(ib - b); */
int db = ((ib > b) ? ib - b : b - ib);
int dmax = ((dm > db) ? dm : db);
int d = dmax + dt + db;
if (d < (int)distance[d_index])
{
distance[d_index] = (png_byte)d;
png_ptr->palette_lookup[d_index] = (png_byte)i;
}
}
}
}
}
png_free(png_ptr, distance);
}
}
#endif /* PNG_READ_QUANTIZE_SUPPORTED */
#ifdef PNG_READ_GAMMA_SUPPORTED
/* Transform the image from the file_gamma to the screen_gamma. We
* only do transformations on images where the file_gamma and screen_gamma
* are not close reciprocals, otherwise it slows things down slightly, and
* also needlessly introduces small errors.
*
* We will turn off gamma transformation later if no semitransparent entries
* are present in the tRNS array for palette images. We can't do it here
* because we don't necessarily have the tRNS chunk yet.
*/
static int /* PRIVATE */
png_gamma_threshold(png_fixed_point scrn_gamma, png_fixed_point file_gamma)
{
/* PNG_GAMMA_THRESHOLD is the threshold for performing gamma
* correction as a difference of the overall transform from 1.0
*
* We want to compare the threshold with s*f - 1, if we get
* overflow here it is because of wacky gamma values so we
* turn on processing anyway.
*/
png_fixed_point gtest;
return !png_muldiv(&gtest, scrn_gamma, file_gamma, PNG_FP_1) ||
png_gamma_significant(gtest);
}
void PNGFAPI
png_set_gamma_fixed(png_structp png_ptr, png_fixed_point scrn_gamma,
png_fixed_point file_gamma)
{
png_debug(1, "in png_set_gamma_fixed");
if (png_ptr == NULL)
return;
if ((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) ||
(png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ||
png_gamma_threshold(scrn_gamma, file_gamma))
png_ptr->transformations |= PNG_GAMMA;
png_ptr->gamma = file_gamma;
png_ptr->screen_gamma = scrn_gamma;
}
# ifdef PNG_FLOATING_POINT_SUPPORTED
void PNGAPI
png_set_gamma(png_structp png_ptr, double scrn_gamma, double file_gamma)
{
png_set_gamma_fixed(png_ptr,
png_fixed(png_ptr, scrn_gamma, "png_set_gamma screen gamma"),
png_fixed(png_ptr, file_gamma, "png_set_gamma file gamma"));
}
# endif /* FLOATING_POINT_SUPPORTED */
#endif /* READ_GAMMA */
#ifdef PNG_READ_EXPAND_SUPPORTED
/* Expand paletted images to RGB, expand grayscale images of
* less than 8-bit depth to 8-bit depth, and expand tRNS chunks
* to alpha channels.
*/
void PNGAPI
png_set_expand(png_structp png_ptr)
{
png_debug(1, "in png_set_expand");
if (png_ptr == NULL)
return;
png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
}
/* GRR 19990627: the following three functions currently are identical
* to png_set_expand(). However, it is entirely reasonable that someone
* might wish to expand an indexed image to RGB but *not* expand a single,
* fully transparent palette entry to a full alpha channel--perhaps instead
* convert tRNS to the grayscale/RGB format (16-bit RGB value), or replace
* the transparent color with a particular RGB value, or drop tRNS entirely.
* IOW, a future version of the library may make the transformations flag
* a bit more fine-grained, with separate bits for each of these three
* functions.
*
* More to the point, these functions make it obvious what libpng will be
* doing, whereas "expand" can (and does) mean any number of things.
*
* GRP 20060307: In libpng-1.2.9, png_set_gray_1_2_4_to_8() was modified
* to expand only the sample depth but not to expand the tRNS to alpha
* and its name was changed to png_set_expand_gray_1_2_4_to_8().
*/
/* Expand paletted images to RGB. */
void PNGAPI
png_set_palette_to_rgb(png_structp png_ptr)
{
png_debug(1, "in png_set_palette_to_rgb");
if (png_ptr == NULL)
return;
png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
}
/* Expand grayscale images of less than 8-bit depth to 8 bits. */
void PNGAPI
png_set_expand_gray_1_2_4_to_8(png_structp png_ptr)
{
png_debug(1, "in png_set_expand_gray_1_2_4_to_8");
if (png_ptr == NULL)
return;
png_ptr->transformations |= PNG_EXPAND;
png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
}
/* Expand tRNS chunks to alpha channels. */
void PNGAPI
png_set_tRNS_to_alpha(png_structp png_ptr)
{
png_debug(1, "in png_set_tRNS_to_alpha");
png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
}
#endif /* defined(PNG_READ_EXPAND_SUPPORTED) */
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
void PNGAPI
png_set_gray_to_rgb(png_structp png_ptr)
{
png_debug(1, "in png_set_gray_to_rgb");
png_ptr->transformations |= PNG_GRAY_TO_RGB;
png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
}
#endif
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
void PNGFAPI
png_set_rgb_to_gray_fixed(png_structp png_ptr, int error_action,
png_fixed_point red, png_fixed_point green)
{
png_debug(1, "in png_set_rgb_to_gray");
if (png_ptr == NULL)
return;
switch(error_action)
{
case 1:
png_ptr->transformations |= PNG_RGB_TO_GRAY;
break;
case 2:
png_ptr->transformations |= PNG_RGB_TO_GRAY_WARN;
break;
case 3:
png_ptr->transformations |= PNG_RGB_TO_GRAY_ERR;
}
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
#ifdef PNG_READ_EXPAND_SUPPORTED
png_ptr->transformations |= PNG_EXPAND;
#else
{
png_warning(png_ptr,
"Cannot do RGB_TO_GRAY without EXPAND_SUPPORTED");
png_ptr->transformations &= ~PNG_RGB_TO_GRAY;
}
#endif
{
png_uint_16 red_int, green_int;
if (red < 0 || green < 0)
{
red_int = 6968; /* .212671 * 32768 + .5 */
green_int = 23434; /* .715160 * 32768 + .5 */
}
else if (red + green < 100000L)
{
red_int = (png_uint_16)(((png_uint_32)red*32768L)/100000L);
green_int = (png_uint_16)(((png_uint_32)green*32768L)/100000L);
}
else
{
png_warning(png_ptr, "ignoring out of range rgb_to_gray coefficients");
red_int = 6968;
green_int = 23434;
}
png_ptr->rgb_to_gray_red_coeff = red_int;
png_ptr->rgb_to_gray_green_coeff = green_int;
png_ptr->rgb_to_gray_blue_coeff =
(png_uint_16)(32768 - red_int - green_int);
}
}
#ifdef PNG_FLOATING_POINT_SUPPORTED
/* Convert a RGB image to a grayscale of the same width. This allows us,
* for example, to convert a 24 bpp RGB image into an 8 bpp grayscale image.
*/
void PNGAPI
png_set_rgb_to_gray(png_structp png_ptr, int error_action, double red,
double green)
{
if (png_ptr == NULL)
return;
png_set_rgb_to_gray_fixed(png_ptr, error_action,
png_fixed(png_ptr, red, "rgb to gray red coefficient"),
png_fixed(png_ptr, green, "rgb to gray green coefficient"));
}
#endif /* FLOATING POINT */
#endif
#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
void PNGAPI
png_set_read_user_transform_fn(png_structp png_ptr, png_user_transform_ptr
read_user_transform_fn)
{
png_debug(1, "in png_set_read_user_transform_fn");
if (png_ptr == NULL)
return;
#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
png_ptr->transformations |= PNG_USER_TRANSFORM;
png_ptr->read_user_transform_fn = read_user_transform_fn;
#endif
}
#endif
/* Initialize everything needed for the read. This includes modifying
* the palette.
*/
void /* PRIVATE */
png_init_read_transformations(png_structp png_ptr)
{
png_debug(1, "in png_init_read_transformations");
{
#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
defined(PNG_READ_SHIFT_SUPPORTED) || \
defined(PNG_READ_GAMMA_SUPPORTED)
int color_type = png_ptr->color_type;
#endif
#if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
/* Detect gray background and attempt to enable optimization
* for gray --> RGB case
*
* Note: if PNG_BACKGROUND_EXPAND is set and color_type is either RGB or
* RGB_ALPHA (in which case need_expand is superfluous anyway), the
* background color might actually be gray yet not be flagged as such.
* This is not a problem for the current code, which uses
* PNG_BACKGROUND_IS_GRAY only to decide when to do the
* png_do_gray_to_rgb() transformation.
*/
if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
!(color_type & PNG_COLOR_MASK_COLOR))
{
png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
}
else if ((png_ptr->transformations & PNG_BACKGROUND) &&
!(png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
(png_ptr->transformations & PNG_GRAY_TO_RGB) &&
png_ptr->background.red == png_ptr->background.green &&
png_ptr->background.red == png_ptr->background.blue)
{
png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
png_ptr->background.gray = png_ptr->background.red;
}
#endif
if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
(png_ptr->transformations & PNG_EXPAND))
{
if (!(color_type & PNG_COLOR_MASK_COLOR)) /* i.e., GRAY or GRAY_ALPHA */
{
/* Expand background and tRNS chunks */
switch (png_ptr->bit_depth)
{
case 1:
png_ptr->background.gray *= (png_uint_16)0xff;
png_ptr->background.red = png_ptr->background.green
= png_ptr->background.blue = png_ptr->background.gray;
if (!(png_ptr->transformations & PNG_EXPAND_tRNS))
{
png_ptr->trans_color.gray *= (png_uint_16)0xff;
png_ptr->trans_color.red = png_ptr->trans_color.green
= png_ptr->trans_color.blue = png_ptr->trans_color.gray;
}
break;
case 2:
png_ptr->background.gray *= (png_uint_16)0x55;
png_ptr->background.red = png_ptr->background.green
= png_ptr->background.blue = png_ptr->background.gray;
if (!(png_ptr->transformations & PNG_EXPAND_tRNS))
{
png_ptr->trans_color.gray *= (png_uint_16)0x55;
png_ptr->trans_color.red = png_ptr->trans_color.green
= png_ptr->trans_color.blue = png_ptr->trans_color.gray;
}
break;
case 4:
png_ptr->background.gray *= (png_uint_16)0x11;
png_ptr->background.red = png_ptr->background.green
= png_ptr->background.blue = png_ptr->background.gray;
if (!(png_ptr->transformations & PNG_EXPAND_tRNS))
{
png_ptr->trans_color.gray *= (png_uint_16)0x11;
png_ptr->trans_color.red = png_ptr->trans_color.green
= png_ptr->trans_color.blue = png_ptr->trans_color.gray;
}
break;
case 8:
case 16:
png_ptr->background.red = png_ptr->background.green
= png_ptr->background.blue = png_ptr->background.gray;
break;
}
}
else if (color_type == PNG_COLOR_TYPE_PALETTE)
{
png_ptr->background.red =
png_ptr->palette[png_ptr->background.index].red;
png_ptr->background.green =
png_ptr->palette[png_ptr->background.index].green;
png_ptr->background.blue =
png_ptr->palette[png_ptr->background.index].blue;
#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
if (png_ptr->transformations & PNG_INVERT_ALPHA)
{
#ifdef PNG_READ_EXPAND_SUPPORTED
if (!(png_ptr->transformations & PNG_EXPAND_tRNS))
#endif
{
/* Invert the alpha channel (in tRNS) unless the pixels are
* going to be expanded, in which case leave it for later
*/
int i, istop;
istop=(int)png_ptr->num_trans;
for (i=0; i<istop; i++)
png_ptr->trans_alpha[i] = (png_byte)(255 -
png_ptr->trans_alpha[i]);
}
}
#endif
}
}
#endif
#if defined(PNG_READ_BACKGROUND_SUPPORTED) && defined(PNG_READ_GAMMA_SUPPORTED)
png_ptr->background_1 = png_ptr->background;
#endif
#ifdef PNG_READ_GAMMA_SUPPORTED
if ((color_type == PNG_COLOR_TYPE_PALETTE && png_ptr->num_trans != 0)
&& png_gamma_threshold(png_ptr->screen_gamma, png_ptr->gamma))
{
int i, k;
k=0;
for (i=0; i<png_ptr->num_trans; i++)
{
if (png_ptr->trans_alpha[i] != 0 && png_ptr->trans_alpha[i] != 0xff)
k=1; /* Partial transparency is present */
}
if (k == 0)
png_ptr->transformations &= ~PNG_GAMMA;
}
if ((png_ptr->transformations & (PNG_GAMMA | PNG_RGB_TO_GRAY)) &&
png_ptr->gamma != 0)
{
png_build_gamma_table(png_ptr, png_ptr->bit_depth);
#ifdef PNG_READ_BACKGROUND_SUPPORTED
if (png_ptr->transformations & PNG_BACKGROUND)
{
if (color_type == PNG_COLOR_TYPE_PALETTE)
{
/* Could skip if no transparency */
png_color back, back_1;
png_colorp palette = png_ptr->palette;
int num_palette = png_ptr->num_palette;
int i;
if (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_FILE)
{
back.red = png_ptr->gamma_table[png_ptr->background.red];
back.green = png_ptr->gamma_table[png_ptr->background.green];
back.blue = png_ptr->gamma_table[png_ptr->background.blue];
back_1.red = png_ptr->gamma_to_1[png_ptr->background.red];
back_1.green = png_ptr->gamma_to_1[png_ptr->background.green];
back_1.blue = png_ptr->gamma_to_1[png_ptr->background.blue];
}
else
{
png_fixed_point g, gs;
switch (png_ptr->background_gamma_type)
{
case PNG_BACKGROUND_GAMMA_SCREEN:
g = (png_ptr->screen_gamma);
gs = PNG_FP_1;
break;
case PNG_BACKGROUND_GAMMA_FILE:
g = png_reciprocal(png_ptr->gamma);
gs = png_reciprocal2(png_ptr->gamma,
png_ptr->screen_gamma);
break;
case PNG_BACKGROUND_GAMMA_UNIQUE:
g = png_reciprocal(png_ptr->background_gamma);
gs = png_reciprocal2(png_ptr->background_gamma,
png_ptr->screen_gamma);
break;
default:
g = PNG_FP_1; /* back_1 */
gs = PNG_FP_1; /* back */
break;
}
if ( png_gamma_significant(gs) )
{
back.red = (png_byte)png_ptr->background.red;
back.green = (png_byte)png_ptr->background.green;
back.blue = (png_byte)png_ptr->background.blue;
}
else
{
back.red = png_gamma_8bit_correct(png_ptr->background.red,
gs);
back.green = png_gamma_8bit_correct(png_ptr->background.green,
gs);
back.blue = png_gamma_8bit_correct(png_ptr->background.blue,
gs);
}
back_1.red = png_gamma_8bit_correct(png_ptr->background.red, g);
back_1.green = png_gamma_8bit_correct(png_ptr->background.green,
g);
back_1.blue = png_gamma_8bit_correct(png_ptr->background.blue,
g);
}
for (i = 0; i < num_palette; i++)
{
if (i < (int)png_ptr->num_trans && png_ptr->trans_alpha[i] != 0xff)
{
if (png_ptr->trans_alpha[i] == 0)
{
palette[i] = back;
}
else /* if (png_ptr->trans_alpha[i] != 0xff) */
{
png_byte v, w;
v = png_ptr->gamma_to_1[palette[i].red];
png_composite(w, v, png_ptr->trans_alpha[i], back_1.red);
palette[i].red = png_ptr->gamma_from_1[w];
v = png_ptr->gamma_to_1[palette[i].green];
png_composite(w, v, png_ptr->trans_alpha[i], back_1.green);
palette[i].green = png_ptr->gamma_from_1[w];
v = png_ptr->gamma_to_1[palette[i].blue];
png_composite(w, v, png_ptr->trans_alpha[i], back_1.blue);
palette[i].blue = png_ptr->gamma_from_1[w];
}
}
else
{
palette[i].red = png_ptr->gamma_table[palette[i].red];
palette[i].green = png_ptr->gamma_table[palette[i].green];
palette[i].blue = png_ptr->gamma_table[palette[i].blue];
}
}
/* Prevent the transformations being done again, and make sure
* that the now spurious alpha channel is stripped - the code
* has just reduced background composition and gamma correction
* to a simple alpha channel strip.
*/
png_ptr->transformations &= ~PNG_BACKGROUND;
png_ptr->transformations &= ~PNG_GAMMA;
png_ptr->transformations |= PNG_STRIP_ALPHA;
}
/* if (png_ptr->background_gamma_type!=PNG_BACKGROUND_GAMMA_UNKNOWN) */
else
/* color_type != PNG_COLOR_TYPE_PALETTE */
{
png_fixed_point g = PNG_FP_1;
png_fixed_point gs = PNG_FP_1;
switch (png_ptr->background_gamma_type)
{
case PNG_BACKGROUND_GAMMA_SCREEN:
g = png_ptr->screen_gamma;
/* gs = PNG_FP_1; */
break;
case PNG_BACKGROUND_GAMMA_FILE:
g = png_reciprocal(png_ptr->gamma);
gs = png_reciprocal2(png_ptr->gamma, png_ptr->screen_gamma);
break;
case PNG_BACKGROUND_GAMMA_UNIQUE:
g = png_reciprocal(png_ptr->background_gamma);
gs = png_reciprocal2(png_ptr->background_gamma,
png_ptr->screen_gamma);
break;
}
png_ptr->background_1.gray = png_gamma_correct(png_ptr,
png_ptr->background.gray, g);
png_ptr->background.gray = png_gamma_correct(png_ptr,
png_ptr->background.gray, gs);
if ((png_ptr->background.red != png_ptr->background.green) ||
(png_ptr->background.red != png_ptr->background.blue) ||
(png_ptr->background.red != png_ptr->background.gray))
{
/* RGB or RGBA with color background */
png_ptr->background_1.red = png_gamma_correct(png_ptr,
png_ptr->background.red, g);
png_ptr->background_1.green = png_gamma_correct(png_ptr,
png_ptr->background.green, g);
png_ptr->background_1.blue = png_gamma_correct(png_ptr,
png_ptr->background.blue, g);
png_ptr->background.red = png_gamma_correct(png_ptr,
png_ptr->background.red, gs);
png_ptr->background.green = png_gamma_correct(png_ptr,
png_ptr->background.green, gs);
png_ptr->background.blue = png_gamma_correct(png_ptr,
png_ptr->background.blue, gs);
}
else
{
/* GRAY, GRAY ALPHA, RGB, or RGBA with gray background */
png_ptr->background_1.red = png_ptr->background_1.green
= png_ptr->background_1.blue = png_ptr->background_1.gray;
png_ptr->background.red = png_ptr->background.green
= png_ptr->background.blue = png_ptr->background.gray;
}
}
}
else
/* Transformation does not include PNG_BACKGROUND */
#endif /* PNG_READ_BACKGROUND_SUPPORTED */
if (color_type == PNG_COLOR_TYPE_PALETTE)
{
png_colorp palette = png_ptr->palette;
int num_palette = png_ptr->num_palette;
int i;
for (i = 0; i < num_palette; i++)
{
palette[i].red = png_ptr->gamma_table[palette[i].red];
palette[i].green = png_ptr->gamma_table[palette[i].green];
palette[i].blue = png_ptr->gamma_table[palette[i].blue];
}
/* Done the gamma correction. */
png_ptr->transformations &= ~PNG_GAMMA;
}
}
#ifdef PNG_READ_BACKGROUND_SUPPORTED
else
#endif
#endif /* PNG_READ_GAMMA_SUPPORTED */
#ifdef PNG_READ_BACKGROUND_SUPPORTED
/* No GAMMA transformation */
if ((png_ptr->transformations & PNG_BACKGROUND) &&
(color_type == PNG_COLOR_TYPE_PALETTE))
{
int i;
int istop = (int)png_ptr->num_trans;
png_color back;
png_colorp palette = png_ptr->palette;
back.red = (png_byte)png_ptr->background.red;
back.green = (png_byte)png_ptr->background.green;
back.blue = (png_byte)png_ptr->background.blue;
for (i = 0; i < istop; i++)
{
if (png_ptr->trans_alpha[i] == 0)
{
palette[i] = back;
}
else if (png_ptr->trans_alpha[i] != 0xff)
{
/* The png_composite() macro is defined in png.h */
png_composite(palette[i].red, palette[i].red,
png_ptr->trans_alpha[i], back.red);
png_composite(palette[i].green, palette[i].green,
png_ptr->trans_alpha[i], back.green);
png_composite(palette[i].blue, palette[i].blue,
png_ptr->trans_alpha[i], back.blue);
}
}
/* Handled alpha, still need to strip the channel. */
png_ptr->transformations &= ~PNG_BACKGROUND;
png_ptr->transformations |= PNG_STRIP_ALPHA;
}
#endif /* PNG_READ_BACKGROUND_SUPPORTED */
#ifdef PNG_READ_SHIFT_SUPPORTED
if ((png_ptr->transformations & PNG_SHIFT) &&
(color_type == PNG_COLOR_TYPE_PALETTE))
{
png_uint_16 i;
png_uint_16 istop = png_ptr->num_palette;
int sr = 8 - png_ptr->sig_bit.red;
int sg = 8 - png_ptr->sig_bit.green;
int sb = 8 - png_ptr->sig_bit.blue;
if (sr < 0 || sr > 8)
sr = 0;
if (sg < 0 || sg > 8)
sg = 0;
if (sb < 0 || sb > 8)
sb = 0;
for (i = 0; i < istop; i++)
{
png_ptr->palette[i].red >>= sr;
png_ptr->palette[i].green >>= sg;
png_ptr->palette[i].blue >>= sb;
}
}
#endif /* PNG_READ_SHIFT_SUPPORTED */
}
#if !defined(PNG_READ_GAMMA_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED) \
&& !defined(PNG_READ_BACKGROUND_SUPPORTED)
if (png_ptr)
return;
#endif
}
/* Modify the info structure to reflect the transformations. The
* info should be updated so a PNG file could be written with it,
* assuming the transformations result in valid PNG data.
*/
void /* PRIVATE */
png_read_transform_info(png_structp png_ptr, png_infop info_ptr)
{
png_debug(1, "in png_read_transform_info");
#ifdef PNG_READ_EXPAND_SUPPORTED
if (png_ptr->transformations & PNG_EXPAND)
{
if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
{
if (png_ptr->num_trans &&
(png_ptr->transformations & PNG_EXPAND_tRNS))
info_ptr->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
else
info_ptr->color_type = PNG_COLOR_TYPE_RGB;
info_ptr->bit_depth = 8;
info_ptr->num_trans = 0;
}
else
{
if (png_ptr->num_trans)
{
if (png_ptr->transformations & PNG_EXPAND_tRNS)
info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
}
if (info_ptr->bit_depth < 8)
info_ptr->bit_depth = 8;
info_ptr->num_trans = 0;
}
}
#endif
#ifdef PNG_READ_BACKGROUND_SUPPORTED
if (png_ptr->transformations & PNG_BACKGROUND)
{
info_ptr->color_type &= ~PNG_COLOR_MASK_ALPHA;
info_ptr->num_trans = 0;
info_ptr->background = png_ptr->background;
}
#endif
#ifdef PNG_READ_GAMMA_SUPPORTED
if (png_ptr->transformations & PNG_GAMMA)
{
info_ptr->gamma = png_ptr->gamma;
}
#endif
#ifdef PNG_READ_16_TO_8_SUPPORTED
if ((png_ptr->transformations & PNG_16_TO_8) && (info_ptr->bit_depth == 16))
info_ptr->bit_depth = 8;
#endif
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
if (png_ptr->transformations & PNG_GRAY_TO_RGB)
info_ptr->color_type |= PNG_COLOR_MASK_COLOR;
#endif
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
if (png_ptr->transformations & PNG_RGB_TO_GRAY)
info_ptr->color_type &= ~PNG_COLOR_MASK_COLOR;
#endif
#ifdef PNG_READ_QUANTIZE_SUPPORTED
if (png_ptr->transformations & PNG_QUANTIZE)
{
if (((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
(info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)) &&
png_ptr->palette_lookup && info_ptr->bit_depth == 8)
{
info_ptr->color_type = PNG_COLOR_TYPE_PALETTE;
}
}
#endif
#ifdef PNG_READ_PACK_SUPPORTED
if ((png_ptr->transformations & PNG_PACK) && (info_ptr->bit_depth < 8))
info_ptr->bit_depth = 8;
#endif
if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
info_ptr->channels = 1;
else if (info_ptr->color_type & PNG_COLOR_MASK_COLOR)
info_ptr->channels = 3;
else
info_ptr->channels = 1;
#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
if (png_ptr->flags & PNG_FLAG_STRIP_ALPHA)
info_ptr->color_type &= ~PNG_COLOR_MASK_ALPHA;
#endif
if (info_ptr->color_type & PNG_COLOR_MASK_ALPHA)
info_ptr->channels++;
#ifdef PNG_READ_FILLER_SUPPORTED
/* STRIP_ALPHA and FILLER allowed: MASK_ALPHA bit stripped above */
if ((png_ptr->transformations & PNG_FILLER) &&
((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
(info_ptr->color_type == PNG_COLOR_TYPE_GRAY)))
{
info_ptr->channels++;
/* If adding a true alpha channel not just filler */
if (png_ptr->transformations & PNG_ADD_ALPHA)
info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
}
#endif
#if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) && \
defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
if (png_ptr->transformations & PNG_USER_TRANSFORM)
{
if (info_ptr->bit_depth < png_ptr->user_transform_depth)
info_ptr->bit_depth = png_ptr->user_transform_depth;
if (info_ptr->channels < png_ptr->user_transform_channels)
info_ptr->channels = png_ptr->user_transform_channels;
}
#endif
info_ptr->pixel_depth = (png_byte)(info_ptr->channels *
info_ptr->bit_depth);
info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, info_ptr->width);
#ifndef PNG_READ_EXPAND_SUPPORTED
if (png_ptr)
return;
#endif
}
/* Transform the row. The order of transformations is significant,
* and is very touchy. If you add a transformation, take care to
* decide how it fits in with the other transformations here.
*/
void /* PRIVATE */
png_do_read_transformations(png_structp png_ptr)
{
png_debug(1, "in png_do_read_transformations");
if (png_ptr->row_buf == NULL)
{
#ifdef PNG_CONSOLE_IO_SUPPORTED
char msg[50];
png_snprintf2(msg, 50,
"NULL row buffer for row %ld, pass %d", (long)png_ptr->row_number,
png_ptr->pass);
png_error(png_ptr, msg);
#else
png_error(png_ptr, "NULL row buffer");
#endif
}
#ifdef PNG_WARN_UNINITIALIZED_ROW
if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
/* Application has failed to call either png_read_start_image()
* or png_read_update_info() after setting transforms that expand
* pixels. This check added to libpng-1.2.19
*/
#if (PNG_WARN_UNINITIALIZED_ROW==1)
png_error(png_ptr, "Uninitialized row");
#else
png_warning(png_ptr, "Uninitialized row");
#endif
#endif
#ifdef PNG_READ_EXPAND_SUPPORTED
if (png_ptr->transformations & PNG_EXPAND)
{
if (png_ptr->row_info.color_type == PNG_COLOR_TYPE_PALETTE)
{
png_do_expand_palette(&(png_ptr->row_info), png_ptr->row_buf + 1,
png_ptr->palette, png_ptr->trans_alpha, png_ptr->num_trans);
}
else
{
if (png_ptr->num_trans &&
(png_ptr->transformations & PNG_EXPAND_tRNS))
png_do_expand(&(png_ptr->row_info), png_ptr->row_buf + 1,
&(png_ptr->trans_color));
else
png_do_expand(&(png_ptr->row_info), png_ptr->row_buf + 1,
NULL);
}
}
#endif
#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
if (png_ptr->flags & PNG_FLAG_STRIP_ALPHA)
png_do_strip_filler(&(png_ptr->row_info), png_ptr->row_buf + 1,
PNG_FLAG_FILLER_AFTER | (png_ptr->flags & PNG_FLAG_STRIP_ALPHA));
#endif
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
if (png_ptr->transformations & PNG_RGB_TO_GRAY)
{
int rgb_error =
png_do_rgb_to_gray(png_ptr, &(png_ptr->row_info),
png_ptr->row_buf + 1);
if (rgb_error)
{
png_ptr->rgb_to_gray_status=1;
if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
PNG_RGB_TO_GRAY_WARN)
png_warning(png_ptr, "png_do_rgb_to_gray found nongray pixel");
if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
PNG_RGB_TO_GRAY_ERR)
png_error(png_ptr, "png_do_rgb_to_gray found nongray pixel");
}
}
#endif
/* From Andreas Dilger e-mail to png-implement, 26 March 1998:
*
* In most cases, the "simple transparency" should be done prior to doing
* gray-to-RGB, or you will have to test 3x as many bytes to check if a
* pixel is transparent. You would also need to make sure that the
* transparency information is upgraded to RGB.
*
* To summarize, the current flow is:
* - Gray + simple transparency -> compare 1 or 2 gray bytes and composite
* with background "in place" if transparent,
* convert to RGB if necessary
* - Gray + alpha -> composite with gray background and remove alpha bytes,
* convert to RGB if necessary
*
* To support RGB backgrounds for gray images we need:
* - Gray + simple transparency -> convert to RGB + simple transparency,
* compare 3 or 6 bytes and composite with
* background "in place" if transparent
* (3x compare/pixel compared to doing
* composite with gray bkgrnd)
* - Gray + alpha -> convert to RGB + alpha, composite with background and
* remove alpha bytes (3x float
* operations/pixel compared with composite
* on gray background)
*
* Greg's change will do this. The reason it wasn't done before is for
* performance, as this increases the per-pixel operations. If we would check
* in advance if the background was gray or RGB, and position the gray-to-RGB
* transform appropriately, then it would save a lot of work/time.
*/
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
/* If gray -> RGB, do so now only if background is non-gray; else do later
* for performance reasons
*/
if ((png_ptr->transformations & PNG_GRAY_TO_RGB) &&
!(png_ptr->mode & PNG_BACKGROUND_IS_GRAY))
png_do_gray_to_rgb(&(png_ptr->row_info), png_ptr->row_buf + 1);
#endif
#ifdef PNG_READ_BACKGROUND_SUPPORTED
if ((png_ptr->transformations & PNG_BACKGROUND) &&
((png_ptr->num_trans != 0 ) ||
(png_ptr->color_type & PNG_COLOR_MASK_ALPHA)))
png_do_background(&(png_ptr->row_info), png_ptr->row_buf + 1,
&(png_ptr->trans_color), &(png_ptr->background)
#ifdef PNG_READ_GAMMA_SUPPORTED
, &(png_ptr->background_1),
png_ptr->gamma_table, png_ptr->gamma_from_1,
png_ptr->gamma_to_1, png_ptr->gamma_16_table,
png_ptr->gamma_16_from_1, png_ptr->gamma_16_to_1,
png_ptr->gamma_shift
#endif
);
#endif
#ifdef PNG_READ_GAMMA_SUPPORTED
if ((png_ptr->transformations & PNG_GAMMA) &&
#ifdef PNG_READ_BACKGROUND_SUPPORTED
!((png_ptr->transformations & PNG_BACKGROUND) &&
((png_ptr->num_trans != 0) ||
(png_ptr->color_type & PNG_COLOR_MASK_ALPHA))) &&
#endif
(png_ptr->color_type != PNG_COLOR_TYPE_PALETTE))
png_do_gamma(&(png_ptr->row_info), png_ptr->row_buf + 1,
png_ptr->gamma_table, png_ptr->gamma_16_table,
png_ptr->gamma_shift);
#endif
#ifdef PNG_READ_16_TO_8_SUPPORTED
if (png_ptr->transformations & PNG_16_TO_8)
png_do_chop(&(png_ptr->row_info), png_ptr->row_buf + 1);
#endif
#ifdef PNG_READ_QUANTIZE_SUPPORTED
if (png_ptr->transformations & PNG_QUANTIZE)
{
png_do_quantize((png_row_infop)&(png_ptr->row_info), png_ptr->row_buf + 1,
png_ptr->palette_lookup, png_ptr->quantize_index);
if (png_ptr->row_info.rowbytes == (png_uint_32)0)
png_error(png_ptr, "png_do_quantize returned rowbytes=0");
}
#endif /* PNG_READ_QUANTIZE_SUPPORTED */
#ifdef PNG_READ_INVERT_SUPPORTED
if (png_ptr->transformations & PNG_INVERT_MONO)
png_do_invert(&(png_ptr->row_info), png_ptr->row_buf + 1);
#endif
#ifdef PNG_READ_SHIFT_SUPPORTED
if (png_ptr->transformations & PNG_SHIFT)
png_do_unshift(&(png_ptr->row_info), png_ptr->row_buf + 1,
&(png_ptr->shift));
#endif
#ifdef PNG_READ_PACK_SUPPORTED
if (png_ptr->transformations & PNG_PACK)
png_do_unpack(&(png_ptr->row_info), png_ptr->row_buf + 1);
#endif
#ifdef PNG_READ_BGR_SUPPORTED
if (png_ptr->transformations & PNG_BGR)
png_do_bgr(&(png_ptr->row_info), png_ptr->row_buf + 1);
#endif
#ifdef PNG_READ_PACKSWAP_SUPPORTED
if (png_ptr->transformations & PNG_PACKSWAP)
png_do_packswap(&(png_ptr->row_info), png_ptr->row_buf + 1);
#endif
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
/* If gray -> RGB, do so now only if we did not do so above */
if ((png_ptr->transformations & PNG_GRAY_TO_RGB) &&
(png_ptr->mode & PNG_BACKGROUND_IS_GRAY))
png_do_gray_to_rgb(&(png_ptr->row_info), png_ptr->row_buf + 1);
#endif
#ifdef PNG_READ_FILLER_SUPPORTED
if (png_ptr->transformations & PNG_FILLER)
png_do_read_filler(&(png_ptr->row_info), png_ptr->row_buf + 1,
(png_uint_32)png_ptr->filler, png_ptr->flags);
#endif
#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
if (png_ptr->transformations & PNG_INVERT_ALPHA)
png_do_read_invert_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
#endif
#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
if (png_ptr->transformations & PNG_SWAP_ALPHA)
png_do_read_swap_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
#endif
#ifdef PNG_READ_SWAP_SUPPORTED
if (png_ptr->transformations & PNG_SWAP_BYTES)
png_do_swap(&(png_ptr->row_info), png_ptr->row_buf + 1);
#endif
#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
if (png_ptr->transformations & PNG_USER_TRANSFORM)
{
if (png_ptr->read_user_transform_fn != NULL)
(*(png_ptr->read_user_transform_fn)) /* User read transform function */
(png_ptr, /* png_ptr */
&(png_ptr->row_info), /* row_info: */
/* png_uint_32 width; width of row */
/* png_uint_32 rowbytes; number of bytes in row */
/* png_byte color_type; color type of pixels */
/* png_byte bit_depth; bit depth of samples */
/* png_byte channels; number of channels (1-4) */
/* png_byte pixel_depth; bits per pixel (depth*channels) */
png_ptr->row_buf + 1); /* start of pixel data for row */
#ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
if (png_ptr->user_transform_depth)
png_ptr->row_info.bit_depth = png_ptr->user_transform_depth;
if (png_ptr->user_transform_channels)
png_ptr->row_info.channels = png_ptr->user_transform_channels;
#endif
png_ptr->row_info.pixel_depth = (png_byte)(png_ptr->row_info.bit_depth *
png_ptr->row_info.channels);
png_ptr->row_info.rowbytes = PNG_ROWBYTES(png_ptr->row_info.pixel_depth,
png_ptr->row_info.width);
}
#endif
}
#ifdef PNG_READ_PACK_SUPPORTED
/* Unpack pixels of 1, 2, or 4 bits per pixel into 1 byte per pixel,
* without changing the actual values. Thus, if you had a row with
* a bit depth of 1, you would end up with bytes that only contained
* the numbers 0 or 1. If you would rather they contain 0 and 255, use
* png_do_shift() after this.
*/
void /* PRIVATE */
png_do_unpack(png_row_infop row_info, png_bytep row)
{
png_debug(1, "in png_do_unpack");
if (row_info->bit_depth < 8)
{
png_uint_32 i;
png_uint_32 row_width=row_info->width;
switch (row_info->bit_depth)
{
case 1:
{
png_bytep sp = row + (png_size_t)((row_width - 1) >> 3);
png_bytep dp = row + (png_size_t)row_width - 1;
png_uint_32 shift = 7 - (int)((row_width + 7) & 0x07);
for (i = 0; i < row_width; i++)
{
*dp = (png_byte)((*sp >> shift) & 0x01);
if (shift == 7)
{
shift = 0;
sp--;
}
else
shift++;
dp--;
}
break;
}
case 2:
{
png_bytep sp = row + (png_size_t)((row_width - 1) >> 2);
png_bytep dp = row + (png_size_t)row_width - 1;
png_uint_32 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
for (i = 0; i < row_width; i++)
{
*dp = (png_byte)((*sp >> shift) & 0x03);
if (shift == 6)
{
shift = 0;
sp--;
}
else
shift += 2;
dp--;
}
break;
}
case 4:
{
png_bytep sp = row + (png_size_t)((row_width - 1) >> 1);
png_bytep dp = row + (png_size_t)row_width - 1;
png_uint_32 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
for (i = 0; i < row_width; i++)
{
*dp = (png_byte)((*sp >> shift) & 0x0f);
if (shift == 4)
{
shift = 0;
sp--;
}
else
shift = 4;
dp--;
}
break;
}
}
row_info->bit_depth = 8;
row_info->pixel_depth = (png_byte)(8 * row_info->channels);
row_info->rowbytes = row_width * row_info->channels;
}
}
#endif
#ifdef PNG_READ_SHIFT_SUPPORTED
/* Reverse the effects of png_do_shift. This routine merely shifts the
* pixels back to their significant bits values. Thus, if you have
* a row of bit depth 8, but only 5 are significant, this will shift
* the values back to 0 through 31.
*/
void /* PRIVATE */
png_do_unshift(png_row_infop row_info, png_bytep row, png_color_8p sig_bits)
{
png_debug(1, "in png_do_unshift");
if (
row_info->color_type != PNG_COLOR_TYPE_PALETTE)
{
int shift[4];
int channels = 0;
int c;
png_uint_16 value = 0;
png_uint_32 row_width = row_info->width;
if (row_info->color_type & PNG_COLOR_MASK_COLOR)
{
shift[channels++] = row_info->bit_depth - sig_bits->red;
shift[channels++] = row_info->bit_depth - sig_bits->green;
shift[channels++] = row_info->bit_depth - sig_bits->blue;
}
else
{
shift[channels++] = row_info->bit_depth - sig_bits->gray;
}
if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
{
shift[channels++] = row_info->bit_depth - sig_bits->alpha;
}
for (c = 0; c < channels; c++)
{
if (shift[c] <= 0)
shift[c] = 0;
else
value = 1;
}
if (!value)
return;
switch (row_info->bit_depth)
{
case 2:
{
png_bytep bp;
png_uint_32 i;
png_uint_32 istop = row_info->rowbytes;
for (bp = row, i = 0; i < istop; i++)
{
*bp >>= 1;
*bp++ &= 0x55;
}
break;
}
case 4:
{
png_bytep bp = row;
png_uint_32 i;
png_uint_32 istop = row_info->rowbytes;
png_byte mask = (png_byte)((((int)0xf0 >> shift[0]) & (int)0xf0) |
(png_byte)((int)0xf >> shift[0]));
for (i = 0; i < istop; i++)
{
*bp >>= shift[0];
*bp++ &= mask;
}
break;
}
case 8:
{
png_bytep bp = row;
png_uint_32 i;
png_uint_32 istop = row_width * channels;
for (i = 0; i < istop; i++)
{
*bp++ >>= shift[i%channels];
}
break;
}
case 16:
{
png_bytep bp = row;
png_uint_32 i;
png_uint_32 istop = channels * row_width;
for (i = 0; i < istop; i++)
{
value = (png_uint_16)((*bp << 8) + *(bp + 1));
value >>= shift[i%channels];
*bp++ = (png_byte)(value >> 8);
*bp++ = (png_byte)(value & 0xff);
}
break;
}
}
}
}
#endif
#ifdef PNG_READ_16_TO_8_SUPPORTED
/* Chop rows of bit depth 16 down to 8 */
void /* PRIVATE */
png_do_chop(png_row_infop row_info, png_bytep row)
{
png_debug(1, "in png_do_chop");
if (row_info->bit_depth == 16)
{
png_bytep sp = row;
png_bytep dp = row;
png_uint_32 i;
png_uint_32 istop = row_info->width * row_info->channels;
for (i = 0; i<istop; i++, sp += 2, dp++)
{
#ifdef PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
/* This does a more accurate scaling of the 16-bit color
* value, rather than a simple low-byte truncation.
*
* What the ideal calculation should be:
* *dp = (((((png_uint_32)(*sp) << 8) |
* (png_uint_32)(*(sp + 1))) * 255 + 127)
* / (png_uint_32)65535L;
*
* GRR: no, I think this is what it really should be:
* *dp = (((((png_uint_32)(*sp) << 8) |
* (png_uint_32)(*(sp + 1))) + 128L)
* / (png_uint_32)257L;
*
* GRR: here's the exact calculation with shifts:
* temp = (((png_uint_32)(*sp) << 8) |
* (png_uint_32)(*(sp + 1))) + 128L;
* *dp = (temp - (temp >> 8)) >> 8;
*
* Approximate calculation with shift/add instead of multiply/divide:
* *dp = ((((png_uint_32)(*sp) << 8) |
* (png_uint_32)((int)(*(sp + 1)) - *sp)) + 128) >> 8;
*
* What we actually do to avoid extra shifting and conversion:
*/
*dp = *sp + ((((int)(*(sp + 1)) - *sp) > 128) ? 1 : 0);
#else
/* Simply discard the low order byte */
*dp = *sp;
#endif
}
row_info->bit_depth = 8;
row_info->pixel_depth = (png_byte)(8 * row_info->channels);
row_info->rowbytes = row_info->width * row_info->channels;
}
}
#endif
#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
void /* PRIVATE */
png_do_read_swap_alpha(png_row_infop row_info, png_bytep row)
{
png_debug(1, "in png_do_read_swap_alpha");
{
png_uint_32 row_width = row_info->width;
if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
{
/* This converts from RGBA to ARGB */
if (row_info->bit_depth == 8)
{
png_bytep sp = row + row_info->rowbytes;
png_bytep dp = sp;
png_byte save;
png_uint_32 i;
for (i = 0; i < row_width; i++)
{
save = *(--sp);
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = save;
}
}
/* This converts from RRGGBBAA to AARRGGBB */
else
{
png_bytep sp = row + row_info->rowbytes;
png_bytep dp = sp;
png_byte save[2];
png_uint_32 i;
for (i = 0; i < row_width; i++)
{
save[0] = *(--sp);
save[1] = *(--sp);
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = save[0];
*(--dp) = save[1];
}
}
}
else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
{
/* This converts from GA to AG */
if (row_info->bit_depth == 8)
{
png_bytep sp = row + row_info->rowbytes;
png_bytep dp = sp;
png_byte save;
png_uint_32 i;
for (i = 0; i < row_width; i++)
{
save = *(--sp);
*(--dp) = *(--sp);
*(--dp) = save;
}
}
/* This converts from GGAA to AAGG */
else
{
png_bytep sp = row + row_info->rowbytes;
png_bytep dp = sp;
png_byte save[2];
png_uint_32 i;
for (i = 0; i < row_width; i++)
{
save[0] = *(--sp);
save[1] = *(--sp);
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = save[0];
*(--dp) = save[1];
}
}
}
}
}
#endif
#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
void /* PRIVATE */
png_do_read_invert_alpha(png_row_infop row_info, png_bytep row)
{
png_uint_32 row_width;
png_debug(1, "in png_do_read_invert_alpha");
row_width = row_info->width;
if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
{
if (row_info->bit_depth == 8)
{
/* This inverts the alpha channel in RGBA */
png_bytep sp = row + row_info->rowbytes;
png_bytep dp = sp;
png_uint_32 i;
for (i = 0; i < row_width; i++)
{
*(--dp) = (png_byte)(255 - *(--sp));
/* This does nothing:
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = *(--sp);
We can replace it with:
*/
sp-=3;
dp=sp;
}
}
/* This inverts the alpha channel in RRGGBBAA */
else
{
png_bytep sp = row + row_info->rowbytes;
png_bytep dp = sp;
png_uint_32 i;
for (i = 0; i < row_width; i++)
{
*(--dp) = (png_byte)(255 - *(--sp));
*(--dp) = (png_byte)(255 - *(--sp));
/* This does nothing:
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = *(--sp);
We can replace it with:
*/
sp-=6;
dp=sp;
}
}
}
else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
{
if (row_info->bit_depth == 8)
{
/* This inverts the alpha channel in GA */
png_bytep sp = row + row_info->rowbytes;
png_bytep dp = sp;
png_uint_32 i;
for (i = 0; i < row_width; i++)
{
*(--dp) = (png_byte)(255 - *(--sp));
*(--dp) = *(--sp);
}
}
else
{
/* This inverts the alpha channel in GGAA */
png_bytep sp = row + row_info->rowbytes;
png_bytep dp = sp;
png_uint_32 i;
for (i = 0; i < row_width; i++)
{
*(--dp) = (png_byte)(255 - *(--sp));
*(--dp) = (png_byte)(255 - *(--sp));
/*
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*/
sp-=2;
dp=sp;
}
}
}
}
#endif
#ifdef PNG_READ_FILLER_SUPPORTED
/* Add filler channel if we have RGB color */
void /* PRIVATE */
png_do_read_filler(png_row_infop row_info, png_bytep row,
png_uint_32 filler, png_uint_32 flags)
{
png_uint_32 i;
png_uint_32 row_width = row_info->width;
png_byte hi_filler = (png_byte)((filler>>8) & 0xff);
png_byte lo_filler = (png_byte)(filler & 0xff);
png_debug(1, "in png_do_read_filler");
if (
row_info->color_type == PNG_COLOR_TYPE_GRAY)
{
if (row_info->bit_depth == 8)
{
if (flags & PNG_FLAG_FILLER_AFTER)
{
/* This changes the data from G to GX */
png_bytep sp = row + (png_size_t)row_width;
png_bytep dp = sp + (png_size_t)row_width;
for (i = 1; i < row_width; i++)
{
*(--dp) = lo_filler;
*(--dp) = *(--sp);
}
*(--dp) = lo_filler;
row_info->channels = 2;
row_info->pixel_depth = 16;
row_info->rowbytes = row_width * 2;
}
else
{
/* This changes the data from G to XG */
png_bytep sp = row + (png_size_t)row_width;
png_bytep dp = sp + (png_size_t)row_width;
for (i = 0; i < row_width; i++)
{
*(--dp) = *(--sp);
*(--dp) = lo_filler;
}
row_info->channels = 2;
row_info->pixel_depth = 16;
row_info->rowbytes = row_width * 2;
}
}
else if (row_info->bit_depth == 16)
{
if (flags & PNG_FLAG_FILLER_AFTER)
{
/* This changes the data from GG to GGXX */
png_bytep sp = row + (png_size_t)row_width * 2;
png_bytep dp = sp + (png_size_t)row_width * 2;
for (i = 1; i < row_width; i++)
{
*(--dp) = hi_filler;
*(--dp) = lo_filler;
*(--dp) = *(--sp);
*(--dp) = *(--sp);
}
*(--dp) = hi_filler;
*(--dp) = lo_filler;
row_info->channels = 2;
row_info->pixel_depth = 32;
row_info->rowbytes = row_width * 4;
}
else
{
/* This changes the data from GG to XXGG */
png_bytep sp = row + (png_size_t)row_width * 2;
png_bytep dp = sp + (png_size_t)row_width * 2;
for (i = 0; i < row_width; i++)
{
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = hi_filler;
*(--dp) = lo_filler;
}
row_info->channels = 2;
row_info->pixel_depth = 32;
row_info->rowbytes = row_width * 4;
}
}
} /* COLOR_TYPE == GRAY */
else if (row_info->color_type == PNG_COLOR_TYPE_RGB)
{
if (row_info->bit_depth == 8)
{
if (flags & PNG_FLAG_FILLER_AFTER)
{
/* This changes the data from RGB to RGBX */
png_bytep sp = row + (png_size_t)row_width * 3;
png_bytep dp = sp + (png_size_t)row_width;
for (i = 1; i < row_width; i++)
{
*(--dp) = lo_filler;
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = *(--sp);
}
*(--dp) = lo_filler;
row_info->channels = 4;
row_info->pixel_depth = 32;
row_info->rowbytes = row_width * 4;
}
else
{
/* This changes the data from RGB to XRGB */
png_bytep sp = row + (png_size_t)row_width * 3;
png_bytep dp = sp + (png_size_t)row_width;
for (i = 0; i < row_width; i++)
{
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = lo_filler;
}
row_info->channels = 4;
row_info->pixel_depth = 32;
row_info->rowbytes = row_width * 4;
}
}
else if (row_info->bit_depth == 16)
{
if (flags & PNG_FLAG_FILLER_AFTER)
{
/* This changes the data from RRGGBB to RRGGBBXX */
png_bytep sp = row + (png_size_t)row_width * 6;
png_bytep dp = sp + (png_size_t)row_width * 2;
for (i = 1; i < row_width; i++)
{
*(--dp) = hi_filler;
*(--dp) = lo_filler;
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = *(--sp);
}
*(--dp) = hi_filler;
*(--dp) = lo_filler;
row_info->channels = 4;
row_info->pixel_depth = 64;
row_info->rowbytes = row_width * 8;
}
else
{
/* This changes the data from RRGGBB to XXRRGGBB */
png_bytep sp = row + (png_size_t)row_width * 6;
png_bytep dp = sp + (png_size_t)row_width * 2;
for (i = 0; i < row_width; i++)
{
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = *(--sp);
*(--dp) = hi_filler;
*(--dp) = lo_filler;
}
row_info->channels = 4;
row_info->pixel_depth = 64;
row_info->rowbytes = row_width * 8;
}
}
} /* COLOR_TYPE == RGB */
}
#endif
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
/* Expand grayscale files to RGB, with or without alpha */
void /* PRIVATE */
png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
{
png_uint_32 i;
png_uint_32 row_width = row_info->width;
png_debug(1, "in png_do_gray_to_rgb");
if (row_info->bit_depth >= 8 &&
!(row_info->color_type & PNG_COLOR_MASK_COLOR))
{
if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
{
if (row_info->bit_depth == 8)
{
/* This changes G to RGB */
png_bytep sp = row + (png_size_t)row_width - 1;
png_bytep dp = sp + (png_size_t)row_width * 2;
for (i = 0; i < row_width; i++)
{
*(dp--) = *sp;
*(dp--) = *sp;
*(dp--) = *(sp--);
}
}
else
{
/* This changes GG to RRGGBB */
png_bytep sp = row + (png_size_t)row_width * 2 - 1;
png_bytep dp = sp + (png_size_t)row_width * 4;
for (i = 0; i < row_width; i++)
{
*(dp--) = *sp;
*(dp--) = *(sp - 1);
*(dp--) = *sp;
*(dp--) = *(sp - 1);
*(dp--) = *(sp--);
*(dp--) = *(sp--);
}
}
}
else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
{
if (row_info->bit_depth == 8)
{
/* This changes GA to RGBA */
png_bytep sp = row + (png_size_t)row_width * 2 - 1;
png_bytep dp = sp + (png_size_t)row_width * 2;
for (i = 0; i < row_width; i++)
{
*(dp--) = *(sp--);
*(dp--) = *sp;
*(dp--) = *sp;
*(dp--) = *(sp--);
}
}
else
{
/* This changes GGAA to RRGGBBAA */
png_bytep sp = row + (png_size_t)row_width * 4 - 1;
png_bytep dp = sp + (png_size_t)row_width * 4;
for (i = 0; i < row_width; i++)
{
*(dp--) = *(sp--);
*(dp--) = *(sp--);
*(dp--) = *sp;
*(dp--) = *(sp - 1);
*(dp--) = *sp;
*(dp--) = *(sp - 1);
*(dp--) = *(sp--);
*(dp--) = *(sp--);
}
}
}
row_info->channels += (png_byte)2;
row_info->color_type |= PNG_COLOR_MASK_COLOR;
row_info->pixel_depth = (png_byte)(row_info->channels *
row_info->bit_depth);
row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
}
}
#endif
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
/* Reduce RGB files to grayscale, with or without alpha
* using the equation given in Poynton's ColorFAQ at
* <http://www.inforamp.net/~poynton/> (THIS LINK IS DEAD June 2008)
* New link:
* <http://www.poynton.com/notes/colour_and_gamma/>
* Charles Poynton poynton at poynton.com
*
* Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
*
* We approximate this with
*
* Y = 0.21268 * R + 0.7151 * G + 0.07217 * B
*
* which can be expressed with integers as
*
* Y = (6969 * R + 23434 * G + 2365 * B)/32768
*
* The calculation is to be done in a linear colorspace.
*
* Other integer coefficents can be used via png_set_rgb_to_gray().
*/
int /* PRIVATE */
png_do_rgb_to_gray(png_structp png_ptr, png_row_infop row_info, png_bytep row)
{
png_uint_32 i;
png_uint_32 row_width = row_info->width;
int rgb_error = 0;
png_debug(1, "in png_do_rgb_to_gray");
if (
(row_info->color_type & PNG_COLOR_MASK_COLOR))
{
png_uint_32 rc = png_ptr->rgb_to_gray_red_coeff;
png_uint_32 gc = png_ptr->rgb_to_gray_green_coeff;
png_uint_32 bc = png_ptr->rgb_to_gray_blue_coeff;
if (row_info->color_type == PNG_COLOR_TYPE_RGB)
{
if (row_info->bit_depth == 8)
{
#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
if (png_ptr->gamma_from_1 != NULL && png_ptr->gamma_to_1 != NULL)
{
png_bytep sp = row;
png_bytep dp = row;
for (i = 0; i < row_width; i++)
{
png_byte red = png_ptr->gamma_to_1[*(sp++)];
png_byte green = png_ptr->gamma_to_1[*(sp++)];
png_byte blue = png_ptr->gamma_to_1[*(sp++)];
if (red != green || red != blue)
{
rgb_error |= 1;
*(dp++) = png_ptr->gamma_from_1[
(rc*red + gc*green + bc*blue)>>15];
}
else
*(dp++) = *(sp - 1);
}
}
else
#endif
{
png_bytep sp = row;
png_bytep dp = row;
for (i = 0; i < row_width; i++)
{
png_byte red = *(sp++);
png_byte green = *(sp++);
png_byte blue = *(sp++);
if (red != green || red != blue)
{
rgb_error |= 1;
*(dp++) = (png_byte)((rc*red + gc*green + bc*blue)>>15);
}
else
*(dp++) = *(sp - 1);
}
}
}
else /* RGB bit_depth == 16 */
{
#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
if (png_ptr->gamma_16_to_1 != NULL &&
png_ptr->gamma_16_from_1 != NULL)
{
png_bytep sp = row;
png_bytep dp = row;
for (i = 0; i < row_width; i++)
{
png_uint_16 red, green, blue, w;
red = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
green = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
blue = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
if (red == green && red == blue)
w = red;
else
{
png_uint_16 red_1 = png_ptr->gamma_16_to_1[(red&0xff)
>> png_ptr->gamma_shift][red>>8];
png_uint_16 green_1 =
png_ptr->gamma_16_to_1[(green&0xff) >>
png_ptr->gamma_shift][green>>8];
png_uint_16 blue_1 = png_ptr->gamma_16_to_1[(blue&0xff)
>> png_ptr->gamma_shift][blue>>8];
png_uint_16 gray16 = (png_uint_16)((rc*red_1 + gc*green_1
+ bc*blue_1)>>15);
w = png_ptr->gamma_16_from_1[(gray16&0xff) >>
png_ptr->gamma_shift][gray16 >> 8];
rgb_error |= 1;
}
*(dp++) = (png_byte)((w>>8) & 0xff);
*(dp++) = (png_byte)(w & 0xff);
}
}
else
#endif
{
png_bytep sp = row;
png_bytep dp = row;
for (i = 0; i < row_width; i++)
{
png_uint_16 red, green, blue, gray16;
red = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
green = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
blue = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
if (red != green || red != blue)
rgb_error |= 1;
gray16 = (png_uint_16)((rc*red + gc*green + bc*blue)>>15);
*(dp++) = (png_byte)((gray16>>8) & 0xff);
*(dp++) = (png_byte)(gray16 & 0xff);
}
}
}
}
if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
{
if (row_info->bit_depth == 8)
{
#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
if (png_ptr->gamma_from_1 != NULL && png_ptr->gamma_to_1 != NULL)
{
png_bytep sp = row;
png_bytep dp = row;
for (i = 0; i < row_width; i++)
{
png_byte red = png_ptr->gamma_to_1[*(sp++)];
png_byte green = png_ptr->gamma_to_1[*(sp++)];
png_byte blue = png_ptr->gamma_to_1[*(sp++)];
if (red != green || red != blue)
rgb_error |= 1;
*(dp++) = png_ptr->gamma_from_1
[(rc*red + gc*green + bc*blue)>>15];
*(dp++) = *(sp++); /* alpha */
}
}
else
#endif
{
png_bytep sp = row;
png_bytep dp = row;
for (i = 0; i < row_width; i++)
{
png_byte red = *(sp++);
png_byte green = *(sp++);
png_byte blue = *(sp++);
if (red != green || red != blue)
rgb_error |= 1;
*(dp++) = (png_byte)((rc*red + gc*green + bc*blue)>>15);
*(dp++) = *(sp++); /* alpha */
}
}
}
else /* RGBA bit_depth == 16 */
{
#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
if (png_ptr->gamma_16_to_1 != NULL &&
png_ptr->gamma_16_from_1 != NULL)
{
png_bytep sp = row;
png_bytep dp = row;
for (i = 0; i < row_width; i++)
{
png_uint_16 red, green, blue, w;
red = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
green = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
blue = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
if (red == green && red == blue)
w = red;
else
{
png_uint_16 red_1 = png_ptr->gamma_16_to_1[(red&0xff) >>
png_ptr->gamma_shift][red>>8];
png_uint_16 green_1 =
png_ptr->gamma_16_to_1[(green&0xff) >>
png_ptr->gamma_shift][green>>8];
png_uint_16 blue_1 = png_ptr->gamma_16_to_1[(blue&0xff) >>
png_ptr->gamma_shift][blue>>8];
png_uint_16 gray16 = (png_uint_16)((rc * red_1
+ gc * green_1 + bc * blue_1)>>15);
w = png_ptr->gamma_16_from_1[(gray16&0xff) >>
png_ptr->gamma_shift][gray16 >> 8];
rgb_error |= 1;
}
*(dp++) = (png_byte)((w>>8) & 0xff);
*(dp++) = (png_byte)(w & 0xff);
*(dp++) = *(sp++); /* alpha */
*(dp++) = *(sp++);
}
}
else
#endif
{
png_bytep sp = row;
png_bytep dp = row;
for (i = 0; i < row_width; i++)
{
png_uint_16 red, green, blue, gray16;
red = (png_uint_16)((*(sp)<<8) | *(sp + 1)); sp += 2;
green = (png_uint_16)((*(sp)<<8) | *(sp + 1)); sp += 2;
blue = (png_uint_16)((*(sp)<<8) | *(sp + 1)); sp += 2;
if (red != green || red != blue)
rgb_error |= 1;
gray16 = (png_uint_16)((rc*red + gc*green + bc*blue)>>15);
*(dp++) = (png_byte)((gray16>>8) & 0xff);
*(dp++) = (png_byte)(gray16 & 0xff);
*(dp++) = *(sp++); /* alpha */
*(dp++) = *(sp++);
}
}
}
}
row_info->channels -= (png_byte)2;
row_info->color_type &= ~PNG_COLOR_MASK_COLOR;
row_info->pixel_depth = (png_byte)(row_info->channels *
row_info->bit_depth);
row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
}
return rgb_error;
}
#endif
/* Build a grayscale palette. Palette is assumed to be 1 << bit_depth
* large of png_color. This lets grayscale images be treated as
* paletted. Most useful for gamma correction and simplification
* of code.
*/
void PNGAPI
png_build_grayscale_palette(int bit_depth, png_colorp palette)
{
int num_palette;
int color_inc;
int i;
int v;
png_debug(1, "in png_do_build_grayscale_palette");
if (palette == NULL)
return;
switch (bit_depth)
{
case 1:
num_palette = 2;
color_inc = 0xff;
break;
case 2:
num_palette = 4;
color_inc = 0x55;
break;
case 4:
num_palette = 16;
color_inc = 0x11;
break;
case 8:
num_palette = 256;
color_inc = 1;
break;
default:
num_palette = 0;
color_inc = 0;
break;
}
for (i = 0, v = 0; i < num_palette; i++, v += color_inc)
{
palette[i].red = (png_byte)v;
palette[i].green = (png_byte)v;
palette[i].blue = (png_byte)v;
}
}
#ifdef PNG_READ_BACKGROUND_SUPPORTED
/* Replace any alpha or transparency with the supplied background color.
* "background" is already in the screen gamma, while "background_1" is
* at a gamma of 1.0. Paletted files have already been taken care of.
*/
void /* PRIVATE */
png_do_background(png_row_infop row_info, png_bytep row,
png_color_16p trans_color, png_color_16p background
#ifdef PNG_READ_GAMMA_SUPPORTED
, png_color_16p background_1,
png_bytep gamma_table, png_bytep gamma_from_1, png_bytep gamma_to_1,
png_uint_16pp gamma_16, png_uint_16pp gamma_16_from_1,
png_uint_16pp gamma_16_to_1, int gamma_shift
#endif
)
{
png_bytep sp, dp;
png_uint_32 i;
png_uint_32 row_width = row_info->width;
int shift;
png_debug(1, "in png_do_background");
if (background != NULL &&
(!(row_info->color_type & PNG_COLOR_MASK_ALPHA) ||
(row_info->color_type != PNG_COLOR_TYPE_PALETTE && trans_color)))
{
switch (row_info->color_type)
{
case PNG_COLOR_TYPE_GRAY:
{
switch (row_info->bit_depth)
{
case 1:
{
sp = row;
shift = 7;
for (i = 0; i < row_width; i++)
{
if ((png_uint_16)((*sp >> shift) & 0x01)
== trans_color->gray)
{
*sp &= (png_byte)((0x7f7f >> (7 - shift)) & 0xff);
*sp |= (png_byte)(background->gray << shift);
}
if (!shift)
{
shift = 7;
sp++;
}
else
shift--;
}
break;
}
case 2:
{
#ifdef PNG_READ_GAMMA_SUPPORTED
if (gamma_table != NULL)
{
sp = row;
shift = 6;
for (i = 0; i < row_width; i++)
{
if ((png_uint_16)((*sp >> shift) & 0x03)
== trans_color->gray)
{
*sp &= (png_byte)((0x3f3f >> (6 - shift)) & 0xff);
*sp |= (png_byte)(background->gray << shift);
}
else
{
png_byte p = (png_byte)((*sp >> shift) & 0x03);
png_byte g = (png_byte)((gamma_table [p | (p << 2) |
(p << 4) | (p << 6)] >> 6) & 0x03);
*sp &= (png_byte)((0x3f3f >> (6 - shift)) & 0xff);
*sp |= (png_byte)(g << shift);
}
if (!shift)
{
shift = 6;
sp++;
}
else
shift -= 2;
}
}
else
#endif
{
sp = row;
shift = 6;
for (i = 0; i < row_width; i++)
{
if ((png_uint_16)((*sp >> shift) & 0x03)
== trans_color->gray)
{
*sp &= (png_byte)((0x3f3f >> (6 - shift)) & 0xff);
*sp |= (png_byte)(background->gray << shift);
}
if (!shift)
{
shift = 6;
sp++;
}
else
shift -= 2;
}
}
break;
}
case 4:
{
#ifdef PNG_READ_GAMMA_SUPPORTED
if (gamma_table != NULL)
{
sp = row;
shift = 4;
for (i = 0; i < row_width; i++)
{
if ((png_uint_16)((*sp >> shift) & 0x0f)
== trans_color->gray)
{
*sp &= (png_byte)((0xf0f >> (4 - shift)) & 0xff);
*sp |= (png_byte)(background->gray << shift);
}
else
{
png_byte p = (png_byte)((*sp >> shift) & 0x0f);
png_byte g = (png_byte)((gamma_table[p |
(p << 4)] >> 4) & 0x0f);
*sp &= (png_byte)((0xf0f >> (4 - shift)) & 0xff);
*sp |= (png_byte)(g << shift);
}
if (!shift)
{
shift = 4;
sp++;
}
else
shift -= 4;
}
}
else
#endif
{
sp = row;
shift = 4;
for (i = 0; i < row_width; i++)
{
if ((png_uint_16)((*sp >> shift) & 0x0f)
== trans_color->gray)
{
*sp &= (png_byte)((0xf0f >> (4 - shift)) & 0xff);
*sp |= (png_byte)(background->gray << shift);
}
if (!shift)
{
shift = 4;
sp++;
}
else
shift -= 4;
}
}
break;
}
case 8:
{
#ifdef PNG_READ_GAMMA_SUPPORTED
if (gamma_table != NULL)
{
sp = row;
for (i = 0; i < row_width; i++, sp++)
{
if (*sp == trans_color->gray)
*sp = (png_byte)background->gray;
else
*sp = gamma_table[*sp];
}
}
else
#endif
{
sp = row;
for (i = 0; i < row_width; i++, sp++)
{
if (*sp == trans_color->gray)
*sp = (png_byte)background->gray;
}
}
break;
}
case 16:
{
#ifdef PNG_READ_GAMMA_SUPPORTED
if (gamma_16 != NULL)
{
sp = row;
for (i = 0; i < row_width; i++, sp += 2)
{
png_uint_16 v;
v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
if (v == trans_color->gray)
{
/* Background is already in screen gamma */
*sp = (png_byte)((background->gray >> 8) & 0xff);
*(sp + 1) = (png_byte)(background->gray & 0xff);
}
else
{
v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
*sp = (png_byte)((v >> 8) & 0xff);
*(sp + 1) = (png_byte)(v & 0xff);
}
}
}
else
#endif
{
sp = row;
for (i = 0; i < row_width; i++, sp += 2)
{
png_uint_16 v;
v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
if (v == trans_color->gray)
{
*sp = (png_byte)((background->gray >> 8) & 0xff);
*(sp + 1) = (png_byte)(background->gray & 0xff);
}
}
}
break;
}
}
break;
}
case PNG_COLOR_TYPE_RGB:
{
if (row_info->bit_depth == 8)
{
#ifdef PNG_READ_GAMMA_SUPPORTED
if (gamma_table != NULL)
{
sp = row;
for (i = 0; i < row_width; i++, sp += 3)
{
if (*sp == trans_color->red &&
*(sp + 1) == trans_color->green &&
*(sp + 2) == trans_color->blue)
{
*sp = (png_byte)background->red;
*(sp + 1) = (png_byte)background->green;
*(sp + 2) = (png_byte)background->blue;
}
else
{
*sp = gamma_table[*sp];
*(sp + 1) = gamma_table[*(sp + 1)];
*(sp + 2) = gamma_table[*(sp + 2)];
}
}
}
else
#endif
{
sp = row;
for (i = 0; i < row_width; i++, sp += 3)
{
if (*sp == trans_color->red &&
*(sp + 1) == trans_color->green &&
*(sp + 2) == trans_color->blue)
{
*sp = (png_byte)background->red;
*(sp + 1) = (png_byte)background->green;
*(sp + 2) = (png_byte)background->blue;
}
}
}
}
else /* if (row_info->bit_depth == 16) */
{
#ifdef PNG_READ_GAMMA_SUPPORTED
if (gamma_16 != NULL)
{
sp = row;
for (i = 0; i < row_width; i++, sp += 6)
{
png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
+ *(sp + 3));
png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
+ *(sp + 5));
if (r == trans_color->red && g == trans_color->green &&
b == trans_color->blue)
{
/* Background is already in screen gamma */
*sp = (png_byte)((background->red >> 8) & 0xff);
*(sp + 1) = (png_byte)(background->red & 0xff);
*(sp + 2) = (png_byte)((background->green >> 8) & 0xff);
*(sp + 3) = (png_byte)(background->green & 0xff);
*(sp + 4) = (png_byte)((background->blue >> 8) & 0xff);
*(sp + 5) = (png_byte)(background->blue & 0xff);
}
else
{
png_uint_16 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
*sp = (png_byte)((v >> 8) & 0xff);
*(sp + 1) = (png_byte)(v & 0xff);
v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
*(sp + 2) = (png_byte)((v >> 8) & 0xff);
*(sp + 3) = (png_byte)(v & 0xff);
v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
*(sp + 4) = (png_byte)((v >> 8) & 0xff);
*(sp + 5) = (png_byte)(v & 0xff);
}
}
}
else
#endif
{
sp = row;
for (i = 0; i < row_width; i++, sp += 6)
{
png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
+ *(sp + 3));
png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
+ *(sp + 5));
if (r == trans_color->red && g == trans_color->green &&
b == trans_color->blue)
{
*sp = (png_byte)((background->red >> 8) & 0xff);
*(sp + 1) = (png_byte)(background->red & 0xff);
*(sp + 2) = (png_byte)((background->green >> 8) & 0xff);
*(sp + 3) = (png_byte)(background->green & 0xff);
*(sp + 4) = (png_byte)((background->blue >> 8) & 0xff);
*(sp + 5) = (png_byte)(background->blue & 0xff);
}
}
}
}
break;
}
case PNG_COLOR_TYPE_GRAY_ALPHA:
{
if (row_info->bit_depth == 8)
{
#ifdef PNG_READ_GAMMA_SUPPORTED
if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
gamma_table != NULL)
{
sp = row;
dp = row;
for (i = 0; i < row_width; i++, sp += 2, dp++)
{
png_uint_16 a = *(sp + 1);
if (a == 0xff)
*dp = gamma_table[*sp];
else if (a == 0)
{
/* Background is already in screen gamma */
*dp = (png_byte)background->gray;
}
else
{
png_byte v, w;
v = gamma_to_1[*sp];
png_composite(w, v, a, background_1->gray);
*dp = gamma_from_1[w];
}
}
}
else
#endif
{
sp = row;
dp = row;
for (i = 0; i < row_width; i++, sp += 2, dp++)
{
png_byte a = *(sp + 1);
if (a == 0xff)
*dp = *sp;
#ifdef PNG_READ_GAMMA_SUPPORTED
else if (a == 0)
*dp = (png_byte)background->gray;
else
png_composite(*dp, *sp, a, background_1->gray);
#else
*dp = (png_byte)background->gray;
#endif
}
}
}
else /* if (png_ptr->bit_depth == 16) */
{
#ifdef PNG_READ_GAMMA_SUPPORTED
if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
gamma_16_to_1 != NULL)
{
sp = row;
dp = row;
for (i = 0; i < row_width; i++, sp += 4, dp += 2)
{
png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
+ *(sp + 3));
if (a == (png_uint_16)0xffff)
{
png_uint_16 v;
v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
*dp = (png_byte)((v >> 8) & 0xff);
*(dp + 1) = (png_byte)(v & 0xff);
}
#ifdef PNG_READ_GAMMA_SUPPORTED
else if (a == 0)
#else
else
#endif
{
/* Background is already in screen gamma */
*dp = (png_byte)((background->gray >> 8) & 0xff);
*(dp + 1) = (png_byte)(background->gray & 0xff);
}
#ifdef PNG_READ_GAMMA_SUPPORTED
else
{
png_uint_16 g, v, w;
g = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
png_composite_16(v, g, a, background_1->gray);
w = gamma_16_from_1[(v&0xff) >> gamma_shift][v >> 8];
*dp = (png_byte)((w >> 8) & 0xff);
*(dp + 1) = (png_byte)(w & 0xff);
}
#endif
}
}
else
#endif
{
sp = row;
dp = row;
for (i = 0; i < row_width; i++, sp += 4, dp += 2)
{
png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
+ *(sp + 3));
if (a == (png_uint_16)0xffff)
png_memcpy(dp, sp, 2);
#ifdef PNG_READ_GAMMA_SUPPORTED
else if (a == 0)
#else
else
#endif
{
*dp = (png_byte)((background->gray >> 8) & 0xff);
*(dp + 1) = (png_byte)(background->gray & 0xff);
}
#ifdef PNG_READ_GAMMA_SUPPORTED
else
{
png_uint_16 g, v;
g = (png_uint_16)(((*sp) << 8) + *(sp + 1));
png_composite_16(v, g, a, background_1->gray);
*dp = (png_byte)((v >> 8) & 0xff);
*(dp + 1) = (png_byte)(v & 0xff);
}
#endif
}
}
}
break;
}
case PNG_COLOR_TYPE_RGB_ALPHA:
{
if (row_info->bit_depth == 8)
{
#ifdef PNG_READ_GAMMA_SUPPORTED
if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
gamma_table != NULL)
{
sp = row;
dp = row;
for (i = 0; i < row_width; i++, sp += 4, dp += 3)
{
png_byte a = *(sp + 3);
if (a == 0xff)
{
*dp = gamma_table[*sp];
*(dp + 1) = gamma_table[*(sp + 1)];
*(dp + 2) = gamma_table[*(sp + 2)];
}
else if (a == 0)
{
/* Background is already in screen gamma */
*dp = (png_byte)background->red;
*(dp + 1) = (png_byte)background->green;
*(dp + 2) = (png_byte)background->blue;
}
else
{
png_byte v, w;
v = gamma_to_1[*sp];
png_composite(w, v, a, background_1->red);
*dp = gamma_from_1[w];
v = gamma_to_1[*(sp + 1)];
png_composite(w, v, a, background_1->green);
*(dp + 1) = gamma_from_1[w];
v = gamma_to_1[*(sp + 2)];
png_composite(w, v, a, background_1->blue);
*(dp + 2) = gamma_from_1[w];
}
}
}
else
#endif
{
sp = row;
dp = row;
for (i = 0; i < row_width; i++, sp += 4, dp += 3)
{
png_byte a = *(sp + 3);
if (a == 0xff)
{
*dp = *sp;
*(dp + 1) = *(sp + 1);
*(dp + 2) = *(sp + 2);
}
else if (a == 0)
{
*dp = (png_byte)background->red;
*(dp + 1) = (png_byte)background->green;
*(dp + 2) = (png_byte)background->blue;
}
else
{
png_composite(*dp, *sp, a, background->red);
png_composite(*(dp + 1), *(sp + 1), a,
background->green);
png_composite(*(dp + 2), *(sp + 2), a,
background->blue);
}
}
}
}
else /* if (row_info->bit_depth == 16) */
{
#ifdef PNG_READ_GAMMA_SUPPORTED
if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
gamma_16_to_1 != NULL)
{
sp = row;
dp = row;
for (i = 0; i < row_width; i++, sp += 8, dp += 6)
{
png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
<< 8) + (png_uint_16)(*(sp + 7)));
if (a == (png_uint_16)0xffff)
{
png_uint_16 v;
v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
*dp = (png_byte)((v >> 8) & 0xff);
*(dp + 1) = (png_byte)(v & 0xff);
v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
*(dp + 2) = (png_byte)((v >> 8) & 0xff);
*(dp + 3) = (png_byte)(v & 0xff);
v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
*(dp + 4) = (png_byte)((v >> 8) & 0xff);
*(dp + 5) = (png_byte)(v & 0xff);
}
else if (a == 0)
{
/* Background is already in screen gamma */
*dp = (png_byte)((background->red >> 8) & 0xff);
*(dp + 1) = (png_byte)(background->red & 0xff);
*(dp + 2) = (png_byte)((background->green >> 8) & 0xff);
*(dp + 3) = (png_byte)(background->green & 0xff);
*(dp + 4) = (png_byte)((background->blue >> 8) & 0xff);
*(dp + 5) = (png_byte)(background->blue & 0xff);
}
else
{
png_uint_16 v, w, x;
v = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
png_composite_16(w, v, a, background_1->red);
x = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >> 8];
*dp = (png_byte)((x >> 8) & 0xff);
*(dp + 1) = (png_byte)(x & 0xff);
v = gamma_16_to_1[*(sp + 3) >> gamma_shift][*(sp + 2)];
png_composite_16(w, v, a, background_1->green);
x = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >> 8];
*(dp + 2) = (png_byte)((x >> 8) & 0xff);
*(dp + 3) = (png_byte)(x & 0xff);
v = gamma_16_to_1[*(sp + 5) >> gamma_shift][*(sp + 4)];
png_composite_16(w, v, a, background_1->blue);
x = gamma_16_from_1[(w & 0xff) >> gamma_shift][w >> 8];
*(dp + 4) = (png_byte)((x >> 8) & 0xff);
*(dp + 5) = (png_byte)(x & 0xff);
}
}
}
else
#endif
{
sp = row;
dp = row;
for (i = 0; i < row_width; i++, sp += 8, dp += 6)
{
png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
<< 8) + (png_uint_16)(*(sp + 7)));
if (a == (png_uint_16)0xffff)
{
png_memcpy(dp, sp, 6);
}
else if (a == 0)
{
*dp = (png_byte)((background->red >> 8) & 0xff);
*(dp + 1) = (png_byte)(background->red & 0xff);
*(dp + 2) = (png_byte)((background->green >> 8) & 0xff);
*(dp + 3) = (png_byte)(background->green & 0xff);
*(dp + 4) = (png_byte)((background->blue >> 8) & 0xff);
*(dp + 5) = (png_byte)(background->blue & 0xff);
}
else
{
png_uint_16 v;
png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
+ *(sp + 3));
png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
+ *(sp + 5));
png_composite_16(v, r, a, background->red);
*dp = (png_byte)((v >> 8) & 0xff);
*(dp + 1) = (png_byte)(v & 0xff);
png_composite_16(v, g, a, background->green);
*(dp + 2) = (png_byte)((v >> 8) & 0xff);
*(dp + 3) = (png_byte)(v & 0xff);
png_composite_16(v, b, a, background->blue);
*(dp + 4) = (png_byte)((v >> 8) & 0xff);
*(dp + 5) = (png_byte)(v & 0xff);
}
}
}
}
break;
}
}
if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
{
row_info->color_type &= ~PNG_COLOR_MASK_ALPHA;
row_info->channels--;
row_info->pixel_depth = (png_byte)(row_info->channels *
row_info->bit_depth);
row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
}
}
}
#endif
#ifdef PNG_READ_GAMMA_SUPPORTED
/* Gamma correct the image, avoiding the alpha channel. Make sure
* you do this after you deal with the transparency issue on grayscale
* or RGB images. If your bit depth is 8, use gamma_table, if it
* is 16, use gamma_16_table and gamma_shift. Build these with
* build_gamma_table().
*/
void /* PRIVATE */
png_do_gamma(png_row_infop row_info, png_bytep row,
png_bytep gamma_table, png_uint_16pp gamma_16_table,
int gamma_shift)
{
png_bytep sp;
png_uint_32 i;
png_uint_32 row_width=row_info->width;
png_debug(1, "in png_do_gamma");
if (((row_info->bit_depth <= 8 && gamma_table != NULL) ||
(row_info->bit_depth == 16 && gamma_16_table != NULL)))
{
switch (row_info->color_type)
{
case PNG_COLOR_TYPE_RGB:
{
if (row_info->bit_depth == 8)
{
sp = row;
for (i = 0; i < row_width; i++)
{
*sp = gamma_table[*sp];
sp++;
*sp = gamma_table[*sp];
sp++;
*sp = gamma_table[*sp];
sp++;
}
}
else /* if (row_info->bit_depth == 16) */
{
sp = row;
for (i = 0; i < row_width; i++)
{
png_uint_16 v;
v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
*sp = (png_byte)((v >> 8) & 0xff);
*(sp + 1) = (png_byte)(v & 0xff);
sp += 2;
v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
*sp = (png_byte)((v >> 8) & 0xff);
*(sp + 1) = (png_byte)(v & 0xff);
sp += 2;
v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
*sp = (png_byte)((v >> 8) & 0xff);
*(sp + 1) = (png_byte)(v & 0xff);
sp += 2;
}
}
break;
}
case PNG_COLOR_TYPE_RGB_ALPHA:
{
if (row_info->bit_depth == 8)
{
sp = row;
for (i = 0; i < row_width; i++)
{
*sp = gamma_table[*sp];
sp++;
*sp = gamma_table[*sp];
sp++;
*sp = gamma_table[*sp];
sp++;
sp++;
}
}
else /* if (row_info->bit_depth == 16) */
{
sp = row;
for (i = 0; i < row_width; i++)
{
png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
*sp = (png_byte)((v >> 8) & 0xff);
*(sp + 1) = (png_byte)(v & 0xff);
sp += 2;
v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
*sp = (png_byte)((v >> 8) & 0xff);
*(sp + 1) = (png_byte)(v & 0xff);
sp += 2;
v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
*sp = (png_byte)((v >> 8) & 0xff);
*(sp + 1) = (png_byte)(v & 0xff);
sp += 4;
}
}
break;
}
case PNG_COLOR_TYPE_GRAY_ALPHA:
{
if (row_info->bit_depth == 8)
{
sp = row;
for (i = 0; i < row_width; i++)
{
*sp = gamma_table[*sp];
sp += 2;
}
}
else /* if (row_info->bit_depth == 16) */
{
sp = row;
for (i = 0; i < row_width; i++)
{
png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
*sp = (png_byte)((v >> 8) & 0xff);
*(sp + 1) = (png_byte)(v & 0xff);
sp += 4;
}
}
break;
}
case PNG_COLOR_TYPE_GRAY:
{
if (row_info->bit_depth == 2)
{
sp = row;
for (i = 0; i < row_width; i += 4)
{
int a = *sp & 0xc0;
int b = *sp & 0x30;
int c = *sp & 0x0c;
int d = *sp & 0x03;
*sp = (png_byte)(
((((int)gamma_table[a|(a>>2)|(a>>4)|(a>>6)]) ) & 0xc0)|
((((int)gamma_table[(b<<2)|b|(b>>2)|(b>>4)])>>2) & 0x30)|
((((int)gamma_table[(c<<4)|(c<<2)|c|(c>>2)])>>4) & 0x0c)|
((((int)gamma_table[(d<<6)|(d<<4)|(d<<2)|d])>>6) ));
sp++;
}
}
if (row_info->bit_depth == 4)
{
sp = row;
for (i = 0; i < row_width; i += 2)
{
int msb = *sp & 0xf0;
int lsb = *sp & 0x0f;
*sp = (png_byte)((((int)gamma_table[msb | (msb >> 4)]) & 0xf0)
| (((int)gamma_table[(lsb << 4) | lsb]) >> 4));
sp++;
}
}
else if (row_info->bit_depth == 8)
{
sp = row;
for (i = 0; i < row_width; i++)
{
*sp = gamma_table[*sp];
sp++;
}
}
else if (row_info->bit_depth == 16)
{
sp = row;
for (i = 0; i < row_width; i++)
{
png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
*sp = (png_byte)((v >> 8) & 0xff);
*(sp + 1) = (png_byte)(v & 0xff);
sp += 2;
}
}
break;
}
}
}
}
#endif
#ifdef PNG_READ_EXPAND_SUPPORTED
/* Expands a palette row to an RGB or RGBA row depending
* upon whether you supply trans and num_trans.
*/
void /* PRIVATE */
png_do_expand_palette(png_row_infop row_info, png_bytep row,
png_colorp palette, png_bytep trans_alpha, int num_trans)
{
int shift, value;
png_bytep sp, dp;
png_uint_32 i;
png_uint_32 row_width=row_info->width;
png_debug(1, "in png_do_expand_palette");
if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
{
if (row_info->bit_depth < 8)
{
switch (row_info->bit_depth)
{
case 1:
{
sp = row + (png_size_t)((row_width - 1) >> 3);
dp = row + (png_size_t)row_width - 1;
shift = 7 - (int)((row_width + 7) & 0x07);
for (i = 0; i < row_width; i++)
{
if ((*sp >> shift) & 0x01)
*dp = 1;
else
*dp = 0;
if (shift == 7)
{
shift = 0;
sp--;
}
else
shift++;
dp--;
}
break;
}
case 2:
{
sp = row + (png_size_t)((row_width - 1) >> 2);
dp = row + (png_size_t)row_width - 1;
shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
for (i = 0; i < row_width; i++)
{
value = (*sp >> shift) & 0x03;
*dp = (png_byte)value;
if (shift == 6)
{
shift = 0;
sp--;
}
else
shift += 2;
dp--;
}
break;
}
case 4:
{
sp = row + (png_size_t)((row_width - 1) >> 1);
dp = row + (png_size_t)row_width - 1;
shift = (int)((row_width & 0x01) << 2);
for (i = 0; i < row_width; i++)
{
value = (*sp >> shift) & 0x0f;
*dp = (png_byte)value;
if (shift == 4)
{
shift = 0;
sp--;
}
else
shift += 4;
dp--;
}
break;
}
}
row_info->bit_depth = 8;
row_info->pixel_depth = 8;
row_info->rowbytes = row_width;
}
switch (row_info->bit_depth)
{
case 8:
{
if (trans_alpha != NULL)
{
sp = row + (png_size_t)row_width - 1;
dp = row + (png_size_t)(row_width << 2) - 1;
for (i = 0; i < row_width; i++)
{
if ((int)(*sp) >= num_trans)
*dp-- = 0xff;
else
*dp-- = trans_alpha[*sp];
*dp-- = palette[*sp].blue;
*dp-- = palette[*sp].green;
*dp-- = palette[*sp].red;
sp--;
}
row_info->bit_depth = 8;
row_info->pixel_depth = 32;
row_info->rowbytes = row_width * 4;
row_info->color_type = 6;
row_info->channels = 4;
}
else
{
sp = row + (png_size_t)row_width - 1;
dp = row + (png_size_t)(row_width * 3) - 1;
for (i = 0; i < row_width; i++)
{
*dp-- = palette[*sp].blue;
*dp-- = palette[*sp].green;
*dp-- = palette[*sp].red;
sp--;
}
row_info->bit_depth = 8;
row_info->pixel_depth = 24;
row_info->rowbytes = row_width * 3;
row_info->color_type = 2;
row_info->channels = 3;
}
break;
}
}
}
}
/* If the bit depth < 8, it is expanded to 8. Also, if the already
* expanded transparency value is supplied, an alpha channel is built.
*/
void /* PRIVATE */
png_do_expand(png_row_infop row_info, png_bytep row,
png_color_16p trans_value)
{
int shift, value;
png_bytep sp, dp;
png_uint_32 i;
png_uint_32 row_width=row_info->width;
png_debug(1, "in png_do_expand");
{
if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
{
png_uint_16 gray = (png_uint_16)(trans_value ? trans_value->gray : 0);
if (row_info->bit_depth < 8)
{
switch (row_info->bit_depth)
{
case 1:
{
gray = (png_uint_16)((gray & 0x01) * 0xff);
sp = row + (png_size_t)((row_width - 1) >> 3);
dp = row + (png_size_t)row_width - 1;
shift = 7 - (int)((row_width + 7) & 0x07);
for (i = 0; i < row_width; i++)
{
if ((*sp >> shift) & 0x01)
*dp = 0xff;
else
*dp = 0;
if (shift == 7)
{
shift = 0;
sp--;
}
else
shift++;
dp--;
}
break;
}
case 2:
{
gray = (png_uint_16)((gray & 0x03) * 0x55);
sp = row + (png_size_t)((row_width - 1) >> 2);
dp = row + (png_size_t)row_width - 1;
shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
for (i = 0; i < row_width; i++)
{
value = (*sp >> shift) & 0x03;
*dp = (png_byte)(value | (value << 2) | (value << 4) |
(value << 6));
if (shift == 6)
{
shift = 0;
sp--;
}
else
shift += 2;
dp--;
}
break;
}
case 4:
{
gray = (png_uint_16)((gray & 0x0f) * 0x11);
sp = row + (png_size_t)((row_width - 1) >> 1);
dp = row + (png_size_t)row_width - 1;
shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
for (i = 0; i < row_width; i++)
{
value = (*sp >> shift) & 0x0f;
*dp = (png_byte)(value | (value << 4));
if (shift == 4)
{
shift = 0;
sp--;
}
else
shift = 4;
dp--;
}
break;
}
}
row_info->bit_depth = 8;
row_info->pixel_depth = 8;
row_info->rowbytes = row_width;
}
if (trans_value != NULL)
{
if (row_info->bit_depth == 8)
{
gray = gray & 0xff;
sp = row + (png_size_t)row_width - 1;
dp = row + (png_size_t)(row_width << 1) - 1;
for (i = 0; i < row_width; i++)
{
if (*sp == gray)
*dp-- = 0;
else
*dp-- = 0xff;
*dp-- = *sp--;
}
}
else if (row_info->bit_depth == 16)
{
png_byte gray_high = (gray >> 8) & 0xff;
png_byte gray_low = gray & 0xff;
sp = row + row_info->rowbytes - 1;
dp = row + (row_info->rowbytes << 1) - 1;
for (i = 0; i < row_width; i++)
{
if (*(sp - 1) == gray_high && *(sp) == gray_low)
{
*dp-- = 0;
*dp-- = 0;
}
else
{
*dp-- = 0xff;
*dp-- = 0xff;
}
*dp-- = *sp--;
*dp-- = *sp--;
}
}
row_info->color_type = PNG_COLOR_TYPE_GRAY_ALPHA;
row_info->channels = 2;
row_info->pixel_depth = (png_byte)(row_info->bit_depth << 1);
row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
row_width);
}
}
else if (row_info->color_type == PNG_COLOR_TYPE_RGB && trans_value)
{
if (row_info->bit_depth == 8)
{
png_byte red = trans_value->red & 0xff;
png_byte green = trans_value->green & 0xff;
png_byte blue = trans_value->blue & 0xff;
sp = row + (png_size_t)row_info->rowbytes - 1;
dp = row + (png_size_t)(row_width << 2) - 1;
for (i = 0; i < row_width; i++)
{
if (*(sp - 2) == red && *(sp - 1) == green && *(sp) == blue)
*dp-- = 0;
else
*dp-- = 0xff;
*dp-- = *sp--;
*dp-- = *sp--;
*dp-- = *sp--;
}
}
else if (row_info->bit_depth == 16)
{
png_byte red_high = (trans_value->red >> 8) & 0xff;
png_byte green_high = (trans_value->green >> 8) & 0xff;
png_byte blue_high = (trans_value->blue >> 8) & 0xff;
png_byte red_low = trans_value->red & 0xff;
png_byte green_low = trans_value->green & 0xff;
png_byte blue_low = trans_value->blue & 0xff;
sp = row + row_info->rowbytes - 1;
dp = row + (png_size_t)(row_width << 3) - 1;
for (i = 0; i < row_width; i++)
{
if (*(sp - 5) == red_high &&
*(sp - 4) == red_low &&
*(sp - 3) == green_high &&
*(sp - 2) == green_low &&
*(sp - 1) == blue_high &&
*(sp ) == blue_low)
{
*dp-- = 0;
*dp-- = 0;
}
else
{
*dp-- = 0xff;
*dp-- = 0xff;
}
*dp-- = *sp--;
*dp-- = *sp--;
*dp-- = *sp--;
*dp-- = *sp--;
*dp-- = *sp--;
*dp-- = *sp--;
}
}
row_info->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
row_info->channels = 4;
row_info->pixel_depth = (png_byte)(row_info->bit_depth << 2);
row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
}
}
}
#endif
#ifdef PNG_READ_QUANTIZE_SUPPORTED
void /* PRIVATE */
png_do_quantize(png_row_infop row_info, png_bytep row,
png_bytep palette_lookup, png_bytep quantize_lookup)
{
png_bytep sp, dp;
png_uint_32 i;
png_uint_32 row_width=row_info->width;
png_debug(1, "in png_do_quantize");
{
if (row_info->color_type == PNG_COLOR_TYPE_RGB &&
palette_lookup && row_info->bit_depth == 8)
{
int r, g, b, p;
sp = row;
dp = row;
for (i = 0; i < row_width; i++)
{
r = *sp++;
g = *sp++;
b = *sp++;
/* This looks real messy, but the compiler will reduce
* it down to a reasonable formula. For example, with
* 5 bits per color, we get:
* p = (((r >> 3) & 0x1f) << 10) |
* (((g >> 3) & 0x1f) << 5) |
* ((b >> 3) & 0x1f);
*/
p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) &
((1 << PNG_QUANTIZE_RED_BITS) - 1)) <<
(PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) |
(((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) &
((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) <<
(PNG_QUANTIZE_BLUE_BITS)) |
((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) &
((1 << PNG_QUANTIZE_BLUE_BITS) - 1));
*dp++ = palette_lookup[p];
}
row_info->color_type = PNG_COLOR_TYPE_PALETTE;
row_info->channels = 1;
row_info->pixel_depth = row_info->bit_depth;
row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
}
else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA &&
palette_lookup != NULL && row_info->bit_depth == 8)
{
int r, g, b, p;
sp = row;
dp = row;
for (i = 0; i < row_width; i++)
{
r = *sp++;
g = *sp++;
b = *sp++;
sp++;
p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) &
((1 << PNG_QUANTIZE_RED_BITS) - 1)) <<
(PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) |
(((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) &
((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) <<
(PNG_QUANTIZE_BLUE_BITS)) |
((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) &
((1 << PNG_QUANTIZE_BLUE_BITS) - 1));
*dp++ = palette_lookup[p];
}
row_info->color_type = PNG_COLOR_TYPE_PALETTE;
row_info->channels = 1;
row_info->pixel_depth = row_info->bit_depth;
row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
}
else if (row_info->color_type == PNG_COLOR_TYPE_PALETTE &&
quantize_lookup && row_info->bit_depth == 8)
{
sp = row;
for (i = 0; i < row_width; i++, sp++)
{
*sp = quantize_lookup[*sp];
}
}
}
}
#endif /* PNG_READ_QUANTIZE_SUPPORTED */
#ifdef PNG_MNG_FEATURES_SUPPORTED
/* Undoes intrapixel differencing */
void /* PRIVATE */
png_do_read_intrapixel(png_row_infop row_info, png_bytep row)
{
png_debug(1, "in png_do_read_intrapixel");
if (
(row_info->color_type & PNG_COLOR_MASK_COLOR))
{
int bytes_per_pixel;
png_uint_32 row_width = row_info->width;
if (row_info->bit_depth == 8)
{
png_bytep rp;
png_uint_32 i;
if (row_info->color_type == PNG_COLOR_TYPE_RGB)
bytes_per_pixel = 3;
else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
bytes_per_pixel = 4;
else
return;
for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
{
*(rp) = (png_byte)((256 + *rp + *(rp + 1)) & 0xff);
*(rp+2) = (png_byte)((256 + *(rp + 2) + *(rp + 1)) & 0xff);
}
}
else if (row_info->bit_depth == 16)
{
png_bytep rp;
png_uint_32 i;
if (row_info->color_type == PNG_COLOR_TYPE_RGB)
bytes_per_pixel = 6;
else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
bytes_per_pixel = 8;
else
return;
for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
{
png_uint_32 s0 = (*(rp ) << 8) | *(rp + 1);
png_uint_32 s1 = (*(rp + 2) << 8) | *(rp + 3);
png_uint_32 s2 = (*(rp + 4) << 8) | *(rp + 5);
png_uint_32 red = (png_uint_32)((s0 + s1 + 65536L) & 0xffffL);
png_uint_32 blue = (png_uint_32)((s2 + s1 + 65536L) & 0xffffL);
*(rp ) = (png_byte)((red >> 8) & 0xff);
*(rp + 1) = (png_byte)(red & 0xff);
*(rp + 4) = (png_byte)((blue >> 8) & 0xff);
*(rp + 5) = (png_byte)(blue & 0xff);
}
}
}
}
#endif /* PNG_MNG_FEATURES_SUPPORTED */
#endif /* PNG_READ_SUPPORTED */
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