[libpng16] Avoid the double gamma correction warning in the simplified API.
This allows the --strict option to pass in the pngstest checks
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2
ANNOUNCE
2
ANNOUNCE
@ -336,6 +336,8 @@ Version 1.6.0beta19 [March 19, 2012]
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Added application error reporting and added chunk names to read
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benign errors; also added --strict to pngstest - not enabled
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yet because a warning is produced.
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Avoid the double gamma correction warning in the simplified API.
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This allows the --strict option to pass in the pngstest checks
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Send comments/corrections/commendations to png-mng-implement at lists.sf.net
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(subscription required; visit
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2
CHANGES
2
CHANGES
@ -4087,6 +4087,8 @@ Version 1.6.0beta19 [March 19, 2012]
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Added application error reporting and added chunk names to read
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benign errors; also added --strict to pngstest - not enabled
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yet because a warning is produced.
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Avoid the double gamma correction warning in the simplified API.
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This allows the --strict option to pass in the pngstest checks
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Send comments/corrections/commendations to png-mng-implement at lists.sf.net
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(subscription required; visit
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@ -299,7 +299,7 @@ compare_16bit(int v1, int v2, int error_limit, int multiple_algorithms)
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#define READ_FILE 1 /* else memory */
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#define USE_STDIO 2 /* else use file name */
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/* 4: unused */
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#define STRICT 4 /* fail on warnings too */
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#define VERBOSE 8
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#define KEEP_TMPFILES 16 /* else delete temporary files */
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#define KEEP_GOING 32
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@ -313,6 +313,8 @@ print_opts(png_uint_32 opts)
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printf(" --file");
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if (opts & USE_STDIO)
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printf(" --stdio");
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if (opts & STRICT)
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printf(" --strict");
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if (opts & VERBOSE)
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printf(" --verbose");
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if (opts & KEEP_TMPFILES)
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@ -321,6 +323,8 @@ print_opts(png_uint_32 opts)
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printf(" --keep-going");
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if (opts & ACCUMULATE)
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printf(" --accumulate");
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if (!(opts & FAST_WRITE)) /* --fast is currently the default */
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printf(" --slow");
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}
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#define FORMAT_NO_CHANGE 0x80000000 /* additional flag */
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@ -715,6 +719,9 @@ checkopaque(Image *image)
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return logerror(image, image->file_name, ": opaque not NULL", "");
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}
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else if (image->image.warning_or_error != 0 && (image->opts & STRICT) != 0)
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return logerror(image, image->file_name, " --strict", "");
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else
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return 1;
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}
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@ -3454,6 +3461,8 @@ main(int argc, char **argv)
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redundant = 1;
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else if (strcmp(arg, "--stop") == 0)
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opts &= ~KEEP_GOING;
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else if (strcmp(arg, "--strict") == 0)
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opts |= STRICT;
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else if (strcmp(arg, "--touch") == 0)
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{
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if (c+1 < argc)
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64
pngread.c
64
pngread.c
@ -1838,6 +1838,17 @@ png_create_colormap_entry(png_image_read_control *display,
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}
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}
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static int
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make_gray_file_colormap(png_image_read_control *display)
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{
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unsigned int i;
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for (i=0; i<256; ++i)
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png_create_colormap_entry(display, i, i, i, i, 255, E_FILE);
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return i;
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}
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static int
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make_gray_colormap(png_image_read_control *display)
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{
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@ -2368,7 +2379,23 @@ png_image_read_colormap(png_voidp argument)
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if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
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png_error(png_ptr, "rgb[gray] color-map: too few entries");
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cmap_entries = make_gray_colormap(display);
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/* Ideally this code would use libpng to do the gamma correction,
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* but if an input alpha channel is to be removed we will hit the
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* libpng bug in gamma+compose+rgb-to-gray (the double gamma
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* correction bug). Fix this by dropping the gamma correction in
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* this case and doing it in the palette; this will result in
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* duplicate palette entries, but that's better than the
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* alternative of double gamma correction.
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*/
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if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
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png_ptr->num_trans > 0) && png_gamma_not_sRGB(png_ptr->gamma))
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{
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cmap_entries = make_gray_file_colormap(display);
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data_encoding = E_FILE;
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}
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else
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cmap_entries = make_gray_colormap(display);
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/* But if the input has alpha or transparency it must be removed
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*/
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@ -2383,18 +2410,38 @@ png_image_read_colormap(png_voidp argument)
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* it. Achieve this simply by ensuring that the entry
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* selected for the background really is the background color.
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*/
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if (output_encoding == E_LINEAR)
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if (data_encoding == E_FILE) /* from the fixup above */
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{
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/* The app supplied a gray which is in output_encoding, we
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* need to convert it to a value of the input (E_FILE)
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* encoding then set this palette entry to the required
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* output encoding.
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*/
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if (output_encoding == E_sRGB)
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gray = png_sRGB_table[gray]; /* now E_LINEAR */
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gray = PNG_DIV257(png_gamma_16bit_correct(gray,
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png_ptr->gamma)); /* now E_FILE */
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/* And make sure the corresponding palette entry contains
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* exactly the required sRGB value.
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*/
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png_create_colormap_entry(display, gray, back_g, back_g,
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back_g, 0/*unused*/, output_encoding);
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}
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else if (output_encoding == E_LINEAR)
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{
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gray = PNG_sRGB_FROM_LINEAR(gray * 255);
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/* And make sure the corresponding palette entry matches.
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*/
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png_create_colormap_entry(display, gray, back_g, back_g,
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back_g, 65535, E_LINEAR);
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back_g, 0/*unused*/, E_LINEAR);
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}
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/* The background passed to libpng, however, must be the sRGB
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* value.
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/* The background passed to libpng, however, must be the
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* output (normally sRGB) value.
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*/
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c.index = 0; /*unused*/
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c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
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@ -2657,13 +2704,12 @@ png_image_read_colormap(png_voidp argument)
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png_error(png_ptr, "bad data option (internal error)");
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break;
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case E_FILE:
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/* Make no changes */
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break;
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case E_sRGB:
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/* Change to 8-bit sRGB */
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png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, PNG_GAMMA_sRGB);
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/* FALL THROUGH */
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case E_FILE:
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if (png_ptr->bit_depth > 8)
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png_set_scale_16(png_ptr);
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break;
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@ -11,7 +11,7 @@ for image in ${srcdir}/contrib/pngsuite/*.png
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do
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for opts in ""
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do
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if ./pngstest --log "$@" $opts $image >>pngtest-log.txt 2>&1
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if ./pngstest --strict --log "$@" $opts $image >>pngtest-log.txt 2>&1
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then
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echo " PASS: pngstest $opts $image"
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else
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