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skia2/third_party/skcms/skcms.cc
skcms-skia-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com 60f1d83f65 Roll skia/third_party/skcms 4642d9fe69e1..23e7777f421d (1 commits) 
https://skia.googlesource.com/skcms.git/+log/4642d9fe69e1..23e7777f421d

2018-07-27 mtklein@google.com clamp before premul


The AutoRoll server is located here: https://skcms-skia-roll.skia.org

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.



CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel
TBR=benjaminwagner@google.com

Change-Id: Ia9898102aae04ad07057e1a5af1de8ad108d9631
Reviewed-on: https://skia-review.googlesource.com/143735
Reviewed-by: skcms-skia-autoroll <skcms-skia-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Commit-Queue: skcms-skia-autoroll <skcms-skia-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
2018-07-27 15:06:27 +00:00

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/*
* Copyright 2018 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "skcms.h"
#include "skcms_internal.h"
#include <assert.h>
#include <float.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
// sizeof(x) will return size_t, which is 32-bit on some machines and 64-bit on others.
// We have better testing on 64-bit machines, so force 32-bit machines to behave like 64-bit.
//
// Please do not use sizeof() directly, and size_t only when required.
// (We have no way of enforcing these requests...)
#define SAFE_SIZEOF(x) ((uint64_t)sizeof(x))
// Same sort of thing for _Layout structs with a variable sized array at the end (named "variable").
#define SAFE_FIXED_SIZE(type) ((uint64_t)offsetof(type, variable))
static const union {
uint32_t bits;
float f;
} inf_ = { 0x7f800000 };
#define INFINITY_ inf_.f
static float fmaxf_(float x, float y) { return x > y ? x : y; }
static float fminf_(float x, float y) { return x < y ? x : y; }
static bool isfinitef_(float x) { return 0 == x*0; }
static float minus_1_ulp(float x) {
int32_t bits;
memcpy(&bits, &x, sizeof(bits));
bits = bits - 1;
memcpy(&x, &bits, sizeof(bits));
return x;
}
static float eval_curve(const skcms_Curve* curve, float x) {
if (curve->table_entries == 0) {
return skcms_TransferFunction_eval(&curve->parametric, x);
}
float ix = fmaxf_(0, fminf_(x, 1)) * (curve->table_entries - 1);
int lo = (int) ix ,
hi = (int)(float)minus_1_ulp(ix + 1.0f);
float t = ix - (float)lo;
float l, h;
if (curve->table_8) {
l = curve->table_8[lo] * (1/255.0f);
h = curve->table_8[hi] * (1/255.0f);
} else {
uint16_t be_l, be_h;
memcpy(&be_l, curve->table_16 + 2*lo, 2);
memcpy(&be_h, curve->table_16 + 2*hi, 2);
uint16_t le_l = ((be_l << 8) | (be_l >> 8)) & 0xffff;
uint16_t le_h = ((be_h << 8) | (be_h >> 8)) & 0xffff;
l = le_l * (1/65535.0f);
h = le_h * (1/65535.0f);
}
return l + (h-l)*t;
}
static float max_roundtrip_error(const skcms_Curve* curve, const skcms_TransferFunction* inv_tf) {
uint32_t N = curve->table_entries > 256 ? curve->table_entries : 256;
const float dx = 1.0f / (N - 1);
float err = 0;
for (uint32_t i = 0; i < N; i++) {
float x = i * dx,
y = eval_curve(curve, x);
err = fmaxf_(err, fabsf_(x - skcms_TransferFunction_eval(inv_tf, y)));
}
return err;
}
bool skcms_AreApproximateInverses(const skcms_Curve* curve, const skcms_TransferFunction* inv_tf) {
return max_roundtrip_error(curve, inv_tf) < (1/512.0f);
}
// Additional ICC signature values that are only used internally
enum {
// File signature
skcms_Signature_acsp = 0x61637370,
// Tag signatures
skcms_Signature_rTRC = 0x72545243,
skcms_Signature_gTRC = 0x67545243,
skcms_Signature_bTRC = 0x62545243,
skcms_Signature_kTRC = 0x6B545243,
skcms_Signature_rXYZ = 0x7258595A,
skcms_Signature_gXYZ = 0x6758595A,
skcms_Signature_bXYZ = 0x6258595A,
skcms_Signature_A2B0 = 0x41324230,
skcms_Signature_A2B1 = 0x41324231,
skcms_Signature_mAB = 0x6D414220,
skcms_Signature_CHAD = 0x63686164,
// Type signatures
skcms_Signature_curv = 0x63757276,
skcms_Signature_mft1 = 0x6D667431,
skcms_Signature_mft2 = 0x6D667432,
skcms_Signature_para = 0x70617261,
skcms_Signature_sf32 = 0x73663332,
// XYZ is also a PCS signature, so it's defined in skcms.h
// skcms_Signature_XYZ = 0x58595A20,
};
static uint16_t read_big_u16(const uint8_t* ptr) {
uint16_t be;
memcpy(&be, ptr, sizeof(be));
#if defined(_MSC_VER)
return _byteswap_ushort(be);
#else
return __builtin_bswap16(be);
#endif
}
static uint32_t read_big_u32(const uint8_t* ptr) {
uint32_t be;
memcpy(&be, ptr, sizeof(be));
#if defined(_MSC_VER)
return _byteswap_ulong(be);
#else
return __builtin_bswap32(be);
#endif
}
static int32_t read_big_i32(const uint8_t* ptr) {
return (int32_t)read_big_u32(ptr);
}
static float read_big_fixed(const uint8_t* ptr) {
return read_big_i32(ptr) * (1.0f / 65536.0f);
}
// Maps to an in-memory profile so that fields line up to the locations specified
// in ICC.1:2010, section 7.2
typedef struct {
uint8_t size [ 4];
uint8_t cmm_type [ 4];
uint8_t version [ 4];
uint8_t profile_class [ 4];
uint8_t data_color_space [ 4];
uint8_t pcs [ 4];
uint8_t creation_date_time [12];
uint8_t signature [ 4];
uint8_t platform [ 4];
uint8_t flags [ 4];
uint8_t device_manufacturer [ 4];
uint8_t device_model [ 4];
uint8_t device_attributes [ 8];
uint8_t rendering_intent [ 4];
uint8_t illuminant_X [ 4];
uint8_t illuminant_Y [ 4];
uint8_t illuminant_Z [ 4];
uint8_t creator [ 4];
uint8_t profile_id [16];
uint8_t reserved [28];
uint8_t tag_count [ 4]; // Technically not part of header, but required
} header_Layout;
typedef struct {
uint8_t signature [4];
uint8_t offset [4];
uint8_t size [4];
} tag_Layout;
static const tag_Layout* get_tag_table(const skcms_ICCProfile* profile) {
return (const tag_Layout*)(profile->buffer + SAFE_SIZEOF(header_Layout));
}
// s15Fixed16ArrayType is technically variable sized, holding N values. However, the only valid
// use of the type is for the CHAD tag that stores exactly nine values.
typedef struct {
uint8_t type [ 4];
uint8_t reserved [ 4];
uint8_t values [36];
} sf32_Layout;
bool skcms_GetCHAD(const skcms_ICCProfile* profile, skcms_Matrix3x3* m) {
skcms_ICCTag tag;
if (!skcms_GetTagBySignature(profile, skcms_Signature_CHAD, &tag)) {
return false;
}
if (tag.type != skcms_Signature_sf32 || tag.size < SAFE_SIZEOF(sf32_Layout)) {
return false;
}
const sf32_Layout* sf32Tag = (const sf32_Layout*)tag.buf;
const uint8_t* values = sf32Tag->values;
for (int r = 0; r < 3; ++r)
for (int c = 0; c < 3; ++c, values += 4) {
m->vals[r][c] = read_big_fixed(values);
}
return true;
}
// XYZType is technically variable sized, holding N XYZ triples. However, the only valid uses of
// the type are for tags/data that store exactly one triple.
typedef struct {
uint8_t type [4];
uint8_t reserved [4];
uint8_t X [4];
uint8_t Y [4];
uint8_t Z [4];
} XYZ_Layout;
static bool read_tag_xyz(const skcms_ICCTag* tag, float* x, float* y, float* z) {
if (tag->type != skcms_Signature_XYZ || tag->size < SAFE_SIZEOF(XYZ_Layout)) {
return false;
}
const XYZ_Layout* xyzTag = (const XYZ_Layout*)tag->buf;
*x = read_big_fixed(xyzTag->X);
*y = read_big_fixed(xyzTag->Y);
*z = read_big_fixed(xyzTag->Z);
return true;
}
static bool read_to_XYZD50(const skcms_ICCTag* rXYZ, const skcms_ICCTag* gXYZ,
const skcms_ICCTag* bXYZ, skcms_Matrix3x3* toXYZ) {
return read_tag_xyz(rXYZ, &toXYZ->vals[0][0], &toXYZ->vals[1][0], &toXYZ->vals[2][0]) &&
read_tag_xyz(gXYZ, &toXYZ->vals[0][1], &toXYZ->vals[1][1], &toXYZ->vals[2][1]) &&
read_tag_xyz(bXYZ, &toXYZ->vals[0][2], &toXYZ->vals[1][2], &toXYZ->vals[2][2]);
}
static bool tf_is_valid(const skcms_TransferFunction* tf) {
// Reject obviously malformed inputs
if (!isfinitef_(tf->a + tf->b + tf->c + tf->d + tf->e + tf->f + tf->g)) {
return false;
}
// All of these parameters should be non-negative
if (tf->a < 0 || tf->c < 0 || tf->d < 0 || tf->g < 0) {
return false;
}
return true;
}
typedef struct {
uint8_t type [4];
uint8_t reserved_a [4];
uint8_t function_type [2];
uint8_t reserved_b [2];
uint8_t variable [1/*variable*/]; // 1, 3, 4, 5, or 7 s15.16, depending on function_type
} para_Layout;
static bool read_curve_para(const uint8_t* buf, uint32_t size,
skcms_Curve* curve, uint32_t* curve_size) {
if (size < SAFE_FIXED_SIZE(para_Layout)) {
return false;
}
const para_Layout* paraTag = (const para_Layout*)buf;
enum { kG = 0, kGAB = 1, kGABC = 2, kGABCD = 3, kGABCDEF = 4 };
uint16_t function_type = read_big_u16(paraTag->function_type);
if (function_type > kGABCDEF) {
return false;
}
static const uint32_t curve_bytes[] = { 4, 12, 16, 20, 28 };
if (size < SAFE_FIXED_SIZE(para_Layout) + curve_bytes[function_type]) {
return false;
}
if (curve_size) {
*curve_size = SAFE_FIXED_SIZE(para_Layout) + curve_bytes[function_type];
}
curve->table_entries = 0;
curve->parametric.a = 1.0f;
curve->parametric.b = 0.0f;
curve->parametric.c = 0.0f;
curve->parametric.d = 0.0f;
curve->parametric.e = 0.0f;
curve->parametric.f = 0.0f;
curve->parametric.g = read_big_fixed(paraTag->variable);
switch (function_type) {
case kGAB:
curve->parametric.a = read_big_fixed(paraTag->variable + 4);
curve->parametric.b = read_big_fixed(paraTag->variable + 8);
if (curve->parametric.a == 0) {
return false;
}
curve->parametric.d = -curve->parametric.b / curve->parametric.a;
break;
case kGABC:
curve->parametric.a = read_big_fixed(paraTag->variable + 4);
curve->parametric.b = read_big_fixed(paraTag->variable + 8);
curve->parametric.e = read_big_fixed(paraTag->variable + 12);
if (curve->parametric.a == 0) {
return false;
}
curve->parametric.d = -curve->parametric.b / curve->parametric.a;
curve->parametric.f = curve->parametric.e;
break;
case kGABCD:
curve->parametric.a = read_big_fixed(paraTag->variable + 4);
curve->parametric.b = read_big_fixed(paraTag->variable + 8);
curve->parametric.c = read_big_fixed(paraTag->variable + 12);
curve->parametric.d = read_big_fixed(paraTag->variable + 16);
break;
case kGABCDEF:
curve->parametric.a = read_big_fixed(paraTag->variable + 4);
curve->parametric.b = read_big_fixed(paraTag->variable + 8);
curve->parametric.c = read_big_fixed(paraTag->variable + 12);
curve->parametric.d = read_big_fixed(paraTag->variable + 16);
curve->parametric.e = read_big_fixed(paraTag->variable + 20);
curve->parametric.f = read_big_fixed(paraTag->variable + 24);
break;
}
return tf_is_valid(&curve->parametric);
}
typedef struct {
uint8_t type [4];
uint8_t reserved [4];
uint8_t value_count [4];
uint8_t variable [1/*variable*/]; // value_count, 8.8 if 1, uint16 (n*65535) if > 1
} curv_Layout;
static bool read_curve_curv(const uint8_t* buf, uint32_t size,
skcms_Curve* curve, uint32_t* curve_size) {
if (size < SAFE_FIXED_SIZE(curv_Layout)) {
return false;
}
const curv_Layout* curvTag = (const curv_Layout*)buf;
uint32_t value_count = read_big_u32(curvTag->value_count);
if (size < SAFE_FIXED_SIZE(curv_Layout) + value_count * SAFE_SIZEOF(uint16_t)) {
return false;
}
if (curve_size) {
*curve_size = SAFE_FIXED_SIZE(curv_Layout) + value_count * SAFE_SIZEOF(uint16_t);
}
if (value_count < 2) {
curve->table_entries = 0;
curve->parametric.a = 1.0f;
curve->parametric.b = 0.0f;
curve->parametric.c = 0.0f;
curve->parametric.d = 0.0f;
curve->parametric.e = 0.0f;
curve->parametric.f = 0.0f;
if (value_count == 0) {
// Empty tables are a shorthand for an identity curve
curve->parametric.g = 1.0f;
} else {
// Single entry tables are a shorthand for simple gamma
curve->parametric.g = read_big_u16(curvTag->variable) * (1.0f / 256.0f);
}
} else {
curve->table_8 = nullptr;
curve->table_16 = curvTag->variable;
curve->table_entries = value_count;
}
return true;
}
// Parses both curveType and parametricCurveType data. Ensures that at most 'size' bytes are read.
// If curve_size is not nullptr, writes the number of bytes used by the curve in (*curve_size).
static bool read_curve(const uint8_t* buf, uint32_t size,
skcms_Curve* curve, uint32_t* curve_size) {
if (!buf || size < 4 || !curve) {
return false;
}
uint32_t type = read_big_u32(buf);
if (type == skcms_Signature_para) {
return read_curve_para(buf, size, curve, curve_size);
} else if (type == skcms_Signature_curv) {
return read_curve_curv(buf, size, curve, curve_size);
}
return false;
}
// mft1 and mft2 share a large chunk of data
typedef struct {
uint8_t type [ 4];
uint8_t reserved_a [ 4];
uint8_t input_channels [ 1];
uint8_t output_channels [ 1];
uint8_t grid_points [ 1];
uint8_t reserved_b [ 1];
uint8_t matrix [36];
} mft_CommonLayout;
typedef struct {
mft_CommonLayout common [1];
uint8_t variable [1/*variable*/];
} mft1_Layout;
typedef struct {
mft_CommonLayout common [1];
uint8_t input_table_entries [2];
uint8_t output_table_entries [2];
uint8_t variable [1/*variable*/];
} mft2_Layout;
static bool read_mft_common(const mft_CommonLayout* mftTag, skcms_A2B* a2b) {
// MFT matrices are applied before the first set of curves, but must be identity unless the
// input is PCSXYZ. We don't support PCSXYZ profiles, so we ignore this matrix. Note that the
// matrix in skcms_A2B is applied later in the pipe, so supporting this would require another
// field/flag.
a2b->matrix_channels = 0;
a2b->input_channels = mftTag->input_channels[0];
a2b->output_channels = mftTag->output_channels[0];
// We require exactly three (ie XYZ/Lab/RGB) output channels
if (a2b->output_channels != ARRAY_COUNT(a2b->output_curves)) {
return false;
}
// We require at least one, and no more than four (ie CMYK) input channels
if (a2b->input_channels < 1 || a2b->input_channels > ARRAY_COUNT(a2b->input_curves)) {
return false;
}
for (uint32_t i = 0; i < a2b->input_channels; ++i) {
a2b->grid_points[i] = mftTag->grid_points[0];
}
// The grid only makes sense with at least two points along each axis
if (a2b->grid_points[0] < 2) {
return false;
}
return true;
}
static bool init_a2b_tables(const uint8_t* table_base, uint64_t max_tables_len, uint32_t byte_width,
uint32_t input_table_entries, uint32_t output_table_entries,
skcms_A2B* a2b) {
// byte_width is 1 or 2, [input|output]_table_entries are in [2, 4096], so no overflow
uint32_t byte_len_per_input_table = input_table_entries * byte_width;
uint32_t byte_len_per_output_table = output_table_entries * byte_width;
// [input|output]_channels are <= 4, so still no overflow
uint32_t byte_len_all_input_tables = a2b->input_channels * byte_len_per_input_table;
uint32_t byte_len_all_output_tables = a2b->output_channels * byte_len_per_output_table;
uint64_t grid_size = a2b->output_channels * byte_width;
for (uint32_t axis = 0; axis < a2b->input_channels; ++axis) {
grid_size *= a2b->grid_points[axis];
}
if (max_tables_len < byte_len_all_input_tables + grid_size + byte_len_all_output_tables) {
return false;
}
for (uint32_t i = 0; i < a2b->input_channels; ++i) {
a2b->input_curves[i].table_entries = input_table_entries;
if (byte_width == 1) {
a2b->input_curves[i].table_8 = table_base + i * byte_len_per_input_table;
a2b->input_curves[i].table_16 = nullptr;
} else {
a2b->input_curves[i].table_8 = nullptr;
a2b->input_curves[i].table_16 = table_base + i * byte_len_per_input_table;
}
}
if (byte_width == 1) {
a2b->grid_8 = table_base + byte_len_all_input_tables;
a2b->grid_16 = nullptr;
} else {
a2b->grid_8 = nullptr;
a2b->grid_16 = table_base + byte_len_all_input_tables;
}
const uint8_t* output_table_base = table_base + byte_len_all_input_tables + grid_size;
for (uint32_t i = 0; i < a2b->output_channels; ++i) {
a2b->output_curves[i].table_entries = output_table_entries;
if (byte_width == 1) {
a2b->output_curves[i].table_8 = output_table_base + i * byte_len_per_output_table;
a2b->output_curves[i].table_16 = nullptr;
} else {
a2b->output_curves[i].table_8 = nullptr;
a2b->output_curves[i].table_16 = output_table_base + i * byte_len_per_output_table;
}
}
return true;
}
static bool read_tag_mft1(const skcms_ICCTag* tag, skcms_A2B* a2b) {
if (tag->size < SAFE_FIXED_SIZE(mft1_Layout)) {
return false;
}
const mft1_Layout* mftTag = (const mft1_Layout*)tag->buf;
if (!read_mft_common(mftTag->common, a2b)) {
return false;
}
uint32_t input_table_entries = 256;
uint32_t output_table_entries = 256;
return init_a2b_tables(mftTag->variable, tag->size - SAFE_FIXED_SIZE(mft1_Layout), 1,
input_table_entries, output_table_entries, a2b);
}
static bool read_tag_mft2(const skcms_ICCTag* tag, skcms_A2B* a2b) {
if (tag->size < SAFE_FIXED_SIZE(mft2_Layout)) {
return false;
}
const mft2_Layout* mftTag = (const mft2_Layout*)tag->buf;
if (!read_mft_common(mftTag->common, a2b)) {
return false;
}
uint32_t input_table_entries = read_big_u16(mftTag->input_table_entries);
uint32_t output_table_entries = read_big_u16(mftTag->output_table_entries);
// ICC spec mandates that 2 <= table_entries <= 4096
if (input_table_entries < 2 || input_table_entries > 4096 ||
output_table_entries < 2 || output_table_entries > 4096) {
return false;
}
return init_a2b_tables(mftTag->variable, tag->size - SAFE_FIXED_SIZE(mft2_Layout), 2,
input_table_entries, output_table_entries, a2b);
}
static bool read_curves(const uint8_t* buf, uint32_t size, uint32_t curve_offset,
uint32_t num_curves, skcms_Curve* curves) {
for (uint32_t i = 0; i < num_curves; ++i) {
if (curve_offset > size) {
return false;
}
uint32_t curve_bytes;
if (!read_curve(buf + curve_offset, size - curve_offset, &curves[i], &curve_bytes)) {
return false;
}
if (curve_bytes > UINT32_MAX - 3) {
return false;
}
curve_bytes = (curve_bytes + 3) & ~3U;
uint64_t new_offset_64 = (uint64_t)curve_offset + curve_bytes;
curve_offset = (uint32_t)new_offset_64;
if (new_offset_64 != curve_offset) {
return false;
}
}
return true;
}
typedef struct {
uint8_t type [ 4];
uint8_t reserved_a [ 4];
uint8_t input_channels [ 1];
uint8_t output_channels [ 1];
uint8_t reserved_b [ 2];
uint8_t b_curve_offset [ 4];
uint8_t matrix_offset [ 4];
uint8_t m_curve_offset [ 4];
uint8_t clut_offset [ 4];
uint8_t a_curve_offset [ 4];
} mAB_Layout;
typedef struct {
uint8_t grid_points [16];
uint8_t grid_byte_width [ 1];
uint8_t reserved [ 3];
uint8_t variable [1/*variable*/];
} mABCLUT_Layout;
static bool read_tag_mab(const skcms_ICCTag* tag, skcms_A2B* a2b, bool pcs_is_xyz) {
if (tag->size < SAFE_SIZEOF(mAB_Layout)) {
return false;
}
const mAB_Layout* mABTag = (const mAB_Layout*)tag->buf;
a2b->input_channels = mABTag->input_channels[0];
a2b->output_channels = mABTag->output_channels[0];
// We require exactly three (ie XYZ/Lab/RGB) output channels
if (a2b->output_channels != ARRAY_COUNT(a2b->output_curves)) {
return false;
}
// We require no more than four (ie CMYK) input channels
if (a2b->input_channels > ARRAY_COUNT(a2b->input_curves)) {
return false;
}
uint32_t b_curve_offset = read_big_u32(mABTag->b_curve_offset);
uint32_t matrix_offset = read_big_u32(mABTag->matrix_offset);
uint32_t m_curve_offset = read_big_u32(mABTag->m_curve_offset);
uint32_t clut_offset = read_big_u32(mABTag->clut_offset);
uint32_t a_curve_offset = read_big_u32(mABTag->a_curve_offset);
// "B" curves must be present
if (0 == b_curve_offset) {
return false;
}
if (!read_curves(tag->buf, tag->size, b_curve_offset, a2b->output_channels,
a2b->output_curves)) {
return false;
}
// "M" curves and Matrix must be used together
if (0 != m_curve_offset) {
if (0 == matrix_offset) {
return false;
}
a2b->matrix_channels = a2b->output_channels;
if (!read_curves(tag->buf, tag->size, m_curve_offset, a2b->matrix_channels,
a2b->matrix_curves)) {
return false;
}
// Read matrix, which is stored as a row-major 3x3, followed by the fourth column
if (tag->size < matrix_offset + 12 * SAFE_SIZEOF(uint32_t)) {
return false;
}
float encoding_factor = pcs_is_xyz ? 65535 / 32768.0f : 1.0f;
const uint8_t* mtx_buf = tag->buf + matrix_offset;
a2b->matrix.vals[0][0] = encoding_factor * read_big_fixed(mtx_buf + 0);
a2b->matrix.vals[0][1] = encoding_factor * read_big_fixed(mtx_buf + 4);
a2b->matrix.vals[0][2] = encoding_factor * read_big_fixed(mtx_buf + 8);
a2b->matrix.vals[1][0] = encoding_factor * read_big_fixed(mtx_buf + 12);
a2b->matrix.vals[1][1] = encoding_factor * read_big_fixed(mtx_buf + 16);
a2b->matrix.vals[1][2] = encoding_factor * read_big_fixed(mtx_buf + 20);
a2b->matrix.vals[2][0] = encoding_factor * read_big_fixed(mtx_buf + 24);
a2b->matrix.vals[2][1] = encoding_factor * read_big_fixed(mtx_buf + 28);
a2b->matrix.vals[2][2] = encoding_factor * read_big_fixed(mtx_buf + 32);
a2b->matrix.vals[0][3] = encoding_factor * read_big_fixed(mtx_buf + 36);
a2b->matrix.vals[1][3] = encoding_factor * read_big_fixed(mtx_buf + 40);
a2b->matrix.vals[2][3] = encoding_factor * read_big_fixed(mtx_buf + 44);
} else {
if (0 != matrix_offset) {
return false;
}
a2b->matrix_channels = 0;
}
// "A" curves and CLUT must be used together
if (0 != a_curve_offset) {
if (0 == clut_offset) {
return false;
}
if (!read_curves(tag->buf, tag->size, a_curve_offset, a2b->input_channels,
a2b->input_curves)) {
return false;
}
if (tag->size < clut_offset + SAFE_FIXED_SIZE(mABCLUT_Layout)) {
return false;
}
const mABCLUT_Layout* clut = (const mABCLUT_Layout*)(tag->buf + clut_offset);
if (clut->grid_byte_width[0] == 1) {
a2b->grid_8 = clut->variable;
a2b->grid_16 = nullptr;
} else if (clut->grid_byte_width[0] == 2) {
a2b->grid_8 = nullptr;
a2b->grid_16 = clut->variable;
} else {
return false;
}
uint64_t grid_size = a2b->output_channels * clut->grid_byte_width[0];
for (uint32_t i = 0; i < a2b->input_channels; ++i) {
a2b->grid_points[i] = clut->grid_points[i];
// The grid only makes sense with at least two points along each axis
if (a2b->grid_points[i] < 2) {
return false;
}
grid_size *= a2b->grid_points[i];
}
if (tag->size < clut_offset + SAFE_FIXED_SIZE(mABCLUT_Layout) + grid_size) {
return false;
}
} else {
if (0 != clut_offset) {
return false;
}
// If there is no CLUT, the number of input and output channels must match
if (a2b->input_channels != a2b->output_channels) {
return false;
}
// Zero out the number of input channels to signal that we're skipping this stage
a2b->input_channels = 0;
}
return true;
}
static int fit_linear(const skcms_Curve* curve, int N, float tol, float* c, float* d, float* f) {
assert(N > 1);
// We iteratively fit the first points to the TF's linear piece.
// We want the cx + f line to pass through the first and last points we fit exactly.
//
// As we walk along the points we find the minimum and maximum slope of the line before the
// error would exceed our tolerance. We stop when the range [slope_min, slope_max] becomes
// emtpy, when we definitely can't add any more points.
//
// Some points' error intervals may intersect the running interval but not lie fully
// within it. So we keep track of the last point we saw that is a valid end point candidate,
// and once the search is done, back up to build the line through *that* point.
const float dx = 1.0f / (N - 1);
int lin_points = 1;
*f = eval_curve(curve, 0);
float slope_min = -INFINITY_;
float slope_max = +INFINITY_;
for (int i = 1; i < N; ++i) {
float x = i * dx;
float y = eval_curve(curve, x);
float slope_max_i = (y + tol - *f) / x,
slope_min_i = (y - tol - *f) / x;
if (slope_max_i < slope_min || slope_max < slope_min_i) {
// Slope intervals would no longer overlap.
break;
}
slope_max = fminf_(slope_max, slope_max_i);
slope_min = fmaxf_(slope_min, slope_min_i);
float cur_slope = (y - *f) / x;
if (slope_min <= cur_slope && cur_slope <= slope_max) {
lin_points = i + 1;
*c = cur_slope;
}
}
// Set D to the last point that met our tolerance.
*d = (lin_points - 1) * dx;
return lin_points;
}
static bool read_a2b(const skcms_ICCTag* tag, skcms_A2B* a2b, bool pcs_is_xyz) {
bool ok = false;
if (tag->type == skcms_Signature_mft1) {
ok = read_tag_mft1(tag, a2b);
} else if (tag->type == skcms_Signature_mft2) {
ok = read_tag_mft2(tag, a2b);
} else if (tag->type == skcms_Signature_mAB) {
ok = read_tag_mab(tag, a2b, pcs_is_xyz);
}
if (!ok) {
return false;
}
// Detect and canonicalize identity tables.
skcms_Curve* curves[] = {
a2b->input_channels > 0 ? a2b->input_curves + 0 : nullptr,
a2b->input_channels > 1 ? a2b->input_curves + 1 : nullptr,
a2b->input_channels > 2 ? a2b->input_curves + 2 : nullptr,
a2b->input_channels > 3 ? a2b->input_curves + 3 : nullptr,
a2b->matrix_channels > 0 ? a2b->matrix_curves + 0 : nullptr,
a2b->matrix_channels > 1 ? a2b->matrix_curves + 1 : nullptr,
a2b->matrix_channels > 2 ? a2b->matrix_curves + 2 : nullptr,
a2b->output_channels > 0 ? a2b->output_curves + 0 : nullptr,
a2b->output_channels > 1 ? a2b->output_curves + 1 : nullptr,
a2b->output_channels > 2 ? a2b->output_curves + 2 : nullptr,
};
for (int i = 0; i < ARRAY_COUNT(curves); i++) {
skcms_Curve* curve = curves[i];
if (curve && curve->table_entries && curve->table_entries <= (uint32_t)INT_MAX) {
int N = (int)curve->table_entries;
float c,d,f;
if (N == fit_linear(curve, N, 1.0f/(2*N), &c,&d,&f)
&& c == 1.0f
&& f == 0.0f) {
curve->table_entries = 0;
curve->table_8 = nullptr;
curve->table_16 = nullptr;
curve->parametric = skcms_TransferFunction{1,1,0,0,0,0,0};
}
}
}
return true;
}
void skcms_GetTagByIndex(const skcms_ICCProfile* profile, uint32_t idx, skcms_ICCTag* tag) {
if (!profile || !profile->buffer || !tag) { return; }
if (idx > profile->tag_count) { return; }
const tag_Layout* tags = get_tag_table(profile);
tag->signature = read_big_u32(tags[idx].signature);
tag->size = read_big_u32(tags[idx].size);
tag->buf = read_big_u32(tags[idx].offset) + profile->buffer;
tag->type = read_big_u32(tag->buf);
}
bool skcms_GetTagBySignature(const skcms_ICCProfile* profile, uint32_t sig, skcms_ICCTag* tag) {
if (!profile || !profile->buffer || !tag) { return false; }
const tag_Layout* tags = get_tag_table(profile);
for (uint32_t i = 0; i < profile->tag_count; ++i) {
if (read_big_u32(tags[i].signature) == sig) {
tag->signature = sig;
tag->size = read_big_u32(tags[i].size);
tag->buf = read_big_u32(tags[i].offset) + profile->buffer;
tag->type = read_big_u32(tag->buf);
return true;
}
}
return false;
}
static bool usable_as_src(const skcms_ICCProfile* profile) {
return profile->has_A2B
|| (profile->has_trc && profile->has_toXYZD50);
}
bool skcms_Parse(const void* buf, size_t len, skcms_ICCProfile* profile) {
assert(SAFE_SIZEOF(header_Layout) == 132);
if (!profile) {
return false;
}
memset(profile, 0, SAFE_SIZEOF(*profile));
if (len < SAFE_SIZEOF(header_Layout)) {
return false;
}
// Byte-swap all header fields
const header_Layout* header = (const header_Layout*)buf;
profile->buffer = (const uint8_t*)buf;
profile->size = read_big_u32(header->size);
uint32_t version = read_big_u32(header->version);
profile->data_color_space = read_big_u32(header->data_color_space);
profile->pcs = read_big_u32(header->pcs);
uint32_t signature = read_big_u32(header->signature);
float illuminant_X = read_big_fixed(header->illuminant_X);
float illuminant_Y = read_big_fixed(header->illuminant_Y);
float illuminant_Z = read_big_fixed(header->illuminant_Z);
profile->tag_count = read_big_u32(header->tag_count);
// Validate signature, size (smaller than buffer, large enough to hold tag table),
// and major version
uint64_t tag_table_size = profile->tag_count * SAFE_SIZEOF(tag_Layout);
if (signature != skcms_Signature_acsp ||
profile->size > len ||
profile->size < SAFE_SIZEOF(header_Layout) + tag_table_size ||
(version >> 24) > 4) {
return false;
}
// Validate that illuminant is D50 white
if (fabsf_(illuminant_X - 0.9642f) > 0.0100f ||
fabsf_(illuminant_Y - 1.0000f) > 0.0100f ||
fabsf_(illuminant_Z - 0.8249f) > 0.0100f) {
return false;
}
// Validate that all tag entries have sane offset + size
const tag_Layout* tags = get_tag_table(profile);
for (uint32_t i = 0; i < profile->tag_count; ++i) {
uint32_t tag_offset = read_big_u32(tags[i].offset);
uint32_t tag_size = read_big_u32(tags[i].size);
uint64_t tag_end = (uint64_t)tag_offset + (uint64_t)tag_size;
if (tag_size < 4 || tag_end > profile->size) {
return false;
}
}
if (profile->pcs != skcms_Signature_XYZ && profile->pcs != skcms_Signature_Lab) {
return false;
}
bool pcs_is_xyz = profile->pcs == skcms_Signature_XYZ;
// Pre-parse commonly used tags.
skcms_ICCTag kTRC;
if (profile->data_color_space == skcms_Signature_Gray &&
skcms_GetTagBySignature(profile, skcms_Signature_kTRC, &kTRC)) {
if (!read_curve(kTRC.buf, kTRC.size, &profile->trc[0], nullptr)) {
// Malformed tag
return false;
}
profile->trc[1] = profile->trc[0];
profile->trc[2] = profile->trc[0];
profile->has_trc = true;
if (pcs_is_xyz) {
profile->toXYZD50.vals[0][0] = illuminant_X;
profile->toXYZD50.vals[1][1] = illuminant_Y;
profile->toXYZD50.vals[2][2] = illuminant_Z;
profile->has_toXYZD50 = true;
}
} else {
skcms_ICCTag rTRC, gTRC, bTRC;
if (skcms_GetTagBySignature(profile, skcms_Signature_rTRC, &rTRC) &&
skcms_GetTagBySignature(profile, skcms_Signature_gTRC, &gTRC) &&
skcms_GetTagBySignature(profile, skcms_Signature_bTRC, &bTRC)) {
if (!read_curve(rTRC.buf, rTRC.size, &profile->trc[0], nullptr) ||
!read_curve(gTRC.buf, gTRC.size, &profile->trc[1], nullptr) ||
!read_curve(bTRC.buf, bTRC.size, &profile->trc[2], nullptr)) {
// Malformed TRC tags
return false;
}
profile->has_trc = true;
}
skcms_ICCTag rXYZ, gXYZ, bXYZ;
if (skcms_GetTagBySignature(profile, skcms_Signature_rXYZ, &rXYZ) &&
skcms_GetTagBySignature(profile, skcms_Signature_gXYZ, &gXYZ) &&
skcms_GetTagBySignature(profile, skcms_Signature_bXYZ, &bXYZ)) {
if (!read_to_XYZD50(&rXYZ, &gXYZ, &bXYZ, &profile->toXYZD50)) {
// Malformed XYZ tags
return false;
}
profile->has_toXYZD50 = true;
}
}
skcms_ICCTag a2b_tag;
// For now, we're preferring A2B0, like Skia does and the ICC spec tells us to.
// TODO: prefer A2B1 (relative colormetric) over A2B0 (perceptual)?
// This breaks with the ICC spec, but we think it's a good idea, given that TRC curves
// and all our known users are thinking exclusively in terms of relative colormetric.
const uint32_t sigs[] = { skcms_Signature_A2B0, skcms_Signature_A2B1 };
for (int i = 0; i < ARRAY_COUNT(sigs); i++) {
if (skcms_GetTagBySignature(profile, sigs[i], &a2b_tag)) {
if (!read_a2b(&a2b_tag, &profile->A2B, pcs_is_xyz)) {
// Malformed A2B tag
return false;
}
profile->has_A2B = true;
break;
}
}
return usable_as_src(profile);
}
const skcms_ICCProfile* skcms_sRGB_profile() {
static const skcms_ICCProfile sRGB_profile = {
nullptr, // buffer, moot here
0, // size, moot here
skcms_Signature_RGB, // data_color_space
skcms_Signature_XYZ, // pcs
0, // tag count, moot here
// We choose to represent sRGB with its canonical transfer function,
// and with its canonical XYZD50 gamut matrix.
true, // has_trc, followed by the 3 trc curves
{
{{0, {2.4f, (float)(1/1.055), (float)(0.055/1.055), (float)(1/12.92), 0.04045f, 0, 0}}},
{{0, {2.4f, (float)(1/1.055), (float)(0.055/1.055), (float)(1/12.92), 0.04045f, 0, 0}}},
{{0, {2.4f, (float)(1/1.055), (float)(0.055/1.055), (float)(1/12.92), 0.04045f, 0, 0}}},
},
true, // has_toXYZD50, followed by 3x3 toXYZD50 matrix
{{
{ 0.436065674f, 0.385147095f, 0.143066406f },
{ 0.222488403f, 0.716873169f, 0.060607910f },
{ 0.013916016f, 0.097076416f, 0.714096069f },
}},
false, // has_A2B, followed by a2b itself which we don't care about.
{
0,
{
{{0, {1,1, 0,0,0,0,0}}},
{{0, {1,1, 0,0,0,0,0}}},
{{0, {1,1, 0,0,0,0,0}}},
{{0, {1,1, 0,0,0,0,0}}},
},
{0,0,0,0},
nullptr,
nullptr,
0,
{
{{0, {1,1, 0,0,0,0,0}}},
{{0, {1,1, 0,0,0,0,0}}},
{{0, {1,1, 0,0,0,0,0}}},
},
{{
{ 1,0,0,0 },
{ 0,1,0,0 },
{ 0,0,1,0 },
}},
0,
{
{{0, {1,1, 0,0,0,0,0}}},
{{0, {1,1, 0,0,0,0,0}}},
{{0, {1,1, 0,0,0,0,0}}},
},
},
};
return &sRGB_profile;
}
const skcms_ICCProfile* skcms_XYZD50_profile() {
// Just like sRGB above, but with identity transfer functions and toXYZD50 matrix.
static const skcms_ICCProfile XYZD50_profile = {
nullptr, // buffer, moot here
0, // size, moot here
skcms_Signature_RGB, // data_color_space
skcms_Signature_XYZ, // pcs
0, // tag count, moot here
true, // has_trc, followed by the 3 trc curves
{
{{0, {1,1, 0,0,0,0,0}}},
{{0, {1,1, 0,0,0,0,0}}},
{{0, {1,1, 0,0,0,0,0}}},
},
true, // has_toXYZD50, followed by 3x3 toXYZD50 matrix
{{
{ 1,0,0 },
{ 0,1,0 },
{ 0,0,1 },
}},
false, // has_A2B, followed by a2b itself which we don't care about.
{
0,
{
{{0, {1,1, 0,0,0,0,0}}},
{{0, {1,1, 0,0,0,0,0}}},
{{0, {1,1, 0,0,0,0,0}}},
{{0, {1,1, 0,0,0,0,0}}},
},
{0,0,0,0},
nullptr,
nullptr,
0,
{
{{0, {1,1, 0,0,0,0,0}}},
{{0, {1,1, 0,0,0,0,0}}},
{{0, {1,1, 0,0,0,0,0}}},
},
{{
{ 1,0,0,0 },
{ 0,1,0,0 },
{ 0,0,1,0 },
}},
0,
{
{{0, {1,1, 0,0,0,0,0}}},
{{0, {1,1, 0,0,0,0,0}}},
{{0, {1,1, 0,0,0,0,0}}},
},
},
};
return &XYZD50_profile;
}
const skcms_TransferFunction* skcms_sRGB_TransferFunction() {
return &skcms_sRGB_profile()->trc[0].parametric;
}
const skcms_TransferFunction* skcms_sRGB_Inverse_TransferFunction() {
static const skcms_TransferFunction sRGB_inv =
{ (float)(1/2.4), 1.137119f, 0, 12.92f, 0.0031308f, -0.055f, 0 };
return &sRGB_inv;
}
const skcms_TransferFunction* skcms_Identity_TransferFunction() {
static const skcms_TransferFunction identity = {1,1,0,0,0,0,0};
return &identity;
}
const uint8_t skcms_252_random_bytes[] = {
8, 179, 128, 204, 253, 38, 134, 184, 68, 102, 32, 138, 99, 39, 169, 215,
119, 26, 3, 223, 95, 239, 52, 132, 114, 74, 81, 234, 97, 116, 244, 205, 30,
154, 173, 12, 51, 159, 122, 153, 61, 226, 236, 178, 229, 55, 181, 220, 191,
194, 160, 126, 168, 82, 131, 18, 180, 245, 163, 22, 246, 69, 235, 252, 57,
108, 14, 6, 152, 240, 255, 171, 242, 20, 227, 177, 238, 96, 85, 16, 211,
70, 200, 149, 155, 146, 127, 145, 100, 151, 109, 19, 165, 208, 195, 164,
137, 254, 182, 248, 64, 201, 45, 209, 5, 147, 207, 210, 113, 162, 83, 225,
9, 31, 15, 231, 115, 37, 58, 53, 24, 49, 197, 56, 120, 172, 48, 21, 214,
129, 111, 11, 50, 187, 196, 34, 60, 103, 71, 144, 47, 203, 77, 80, 232,
140, 222, 250, 206, 166, 247, 139, 249, 221, 72, 106, 27, 199, 117, 54,
219, 135, 118, 40, 79, 41, 251, 46, 93, 212, 92, 233, 148, 28, 121, 63,
123, 158, 105, 59, 29, 42, 143, 23, 0, 107, 176, 87, 104, 183, 156, 193,
189, 90, 188, 65, 190, 17, 198, 7, 186, 161, 1, 124, 78, 125, 170, 133,
174, 218, 67, 157, 75, 101, 89, 217, 62, 33, 141, 228, 25, 35, 91, 230, 4,
2, 13, 73, 86, 167, 237, 84, 243, 44, 185, 66, 130, 110, 150, 142, 216, 88,
112, 36, 224, 136, 202, 76, 94, 98, 175, 213
};
bool skcms_ApproximatelyEqualProfiles(const skcms_ICCProfile* A, const skcms_ICCProfile* B) {
// For now this is the essentially the same strategy we use in test_only.c
// for our skcms_Transform() smoke tests:
// 1) transform A to XYZD50
// 2) transform B to XYZD50
// 3) return true if they're similar enough
// Our current criterion in 3) is maximum 1 bit error per XYZD50 byte.
// Here are 252 of a random shuffle of all possible bytes.
// 252 is evenly divisible by 3 and 4. Only 192, 10, 241, and 43 are missing.
if (A->data_color_space != B->data_color_space) {
return false;
}
// Interpret as RGB_888 if data color space is RGB or GRAY, RGBA_8888 if CMYK.
skcms_PixelFormat fmt = skcms_PixelFormat_RGB_888;
size_t npixels = 84;
if (A->data_color_space == skcms_Signature_CMYK) {
fmt = skcms_PixelFormat_RGBA_8888;
npixels = 63;
}
uint8_t dstA[252],
dstB[252];
if (!skcms_Transform(
skcms_252_random_bytes, fmt, skcms_AlphaFormat_Unpremul, A,
dstA, skcms_PixelFormat_RGB_888, skcms_AlphaFormat_Unpremul, skcms_XYZD50_profile(),
npixels)) {
return false;
}
if (!skcms_Transform(
skcms_252_random_bytes, fmt, skcms_AlphaFormat_Unpremul, B,
dstB, skcms_PixelFormat_RGB_888, skcms_AlphaFormat_Unpremul, skcms_XYZD50_profile(),
npixels)) {
return false;
}
for (size_t i = 0; i < 252; i++) {
if (abs((int)dstA[i] - (int)dstB[i]) > 1) {
return false;
}
}
return true;
}
bool skcms_TRCs_AreApproximateInverse(const skcms_ICCProfile* profile,
const skcms_TransferFunction* inv_tf) {
if (!profile || !profile->has_trc) {
return false;
}
return skcms_AreApproximateInverses(&profile->trc[0], inv_tf) &&
skcms_AreApproximateInverses(&profile->trc[1], inv_tf) &&
skcms_AreApproximateInverses(&profile->trc[2], inv_tf);
}
static bool is_zero_to_one(float x) {
return 0 <= x && x <= 1;
}
typedef struct { float vals[3]; } skcms_Vector3;
static skcms_Vector3 mv_mul(const skcms_Matrix3x3* m, const skcms_Vector3* v) {
skcms_Vector3 dst = {{0,0,0}};
for (int row = 0; row < 3; ++row) {
dst.vals[row] = m->vals[row][0] * v->vals[0]
+ m->vals[row][1] * v->vals[1]
+ m->vals[row][2] * v->vals[2];
}
return dst;
}
bool skcms_PrimariesToXYZD50(float rx, float ry,
float gx, float gy,
float bx, float by,
float wx, float wy,
skcms_Matrix3x3* toXYZD50) {
if (!is_zero_to_one(rx) || !is_zero_to_one(ry) ||
!is_zero_to_one(gx) || !is_zero_to_one(gy) ||
!is_zero_to_one(bx) || !is_zero_to_one(by) ||
!is_zero_to_one(wx) || !is_zero_to_one(wy) ||
!toXYZD50) {
return false;
}
// First, we need to convert xy values (primaries) to XYZ.
skcms_Matrix3x3 primaries = {{
{ rx, gx, bx },
{ ry, gy, by },
{ 1 - rx - ry, 1 - gx - gy, 1 - bx - by },
}};
skcms_Matrix3x3 primaries_inv;
if (!skcms_Matrix3x3_invert(&primaries, &primaries_inv)) {
return false;
}
// Assumes that Y is 1.0f.
skcms_Vector3 wXYZ = { { wx / wy, 1, (1 - wx - wy) / wy } };
skcms_Vector3 XYZ = mv_mul(&primaries_inv, &wXYZ);
skcms_Matrix3x3 toXYZ = {{
{ XYZ.vals[0], 0, 0 },
{ 0, XYZ.vals[1], 0 },
{ 0, 0, XYZ.vals[2] },
}};
toXYZ = skcms_Matrix3x3_concat(&primaries, &toXYZ);
// Now convert toXYZ matrix to toXYZD50.
skcms_Vector3 wXYZD50 = { { 0.96422f, 1.0f, 0.82521f } };
// Calculate the chromatic adaptation matrix. We will use the Bradford method, thus
// the matrices below. The Bradford method is used by Adobe and is widely considered
// to be the best.
skcms_Matrix3x3 xyz_to_lms = {{
{ 0.8951f, 0.2664f, -0.1614f },
{ -0.7502f, 1.7135f, 0.0367f },
{ 0.0389f, -0.0685f, 1.0296f },
}};
skcms_Matrix3x3 lms_to_xyz = {{
{ 0.9869929f, -0.1470543f, 0.1599627f },
{ 0.4323053f, 0.5183603f, 0.0492912f },
{ -0.0085287f, 0.0400428f, 0.9684867f },
}};
skcms_Vector3 srcCone = mv_mul(&xyz_to_lms, &wXYZ);
skcms_Vector3 dstCone = mv_mul(&xyz_to_lms, &wXYZD50);
skcms_Matrix3x3 DXtoD50 = {{
{ dstCone.vals[0] / srcCone.vals[0], 0, 0 },
{ 0, dstCone.vals[1] / srcCone.vals[1], 0 },
{ 0, 0, dstCone.vals[2] / srcCone.vals[2] },
}};
DXtoD50 = skcms_Matrix3x3_concat(&DXtoD50, &xyz_to_lms);
DXtoD50 = skcms_Matrix3x3_concat(&lms_to_xyz, &DXtoD50);
*toXYZD50 = skcms_Matrix3x3_concat(&DXtoD50, &toXYZ);
return true;
}
bool skcms_Matrix3x3_invert(const skcms_Matrix3x3* src, skcms_Matrix3x3* dst) {
double a00 = src->vals[0][0],
a01 = src->vals[1][0],
a02 = src->vals[2][0],
a10 = src->vals[0][1],
a11 = src->vals[1][1],
a12 = src->vals[2][1],
a20 = src->vals[0][2],
a21 = src->vals[1][2],
a22 = src->vals[2][2];
double b0 = a00*a11 - a01*a10,
b1 = a00*a12 - a02*a10,
b2 = a01*a12 - a02*a11,
b3 = a20,
b4 = a21,
b5 = a22;
double determinant = b0*b5
- b1*b4
+ b2*b3;
if (determinant == 0) {
return false;
}
double invdet = 1.0 / determinant;
if (invdet > +FLT_MAX || invdet < -FLT_MAX || !isfinitef_((float)invdet)) {
return false;
}
b0 *= invdet;
b1 *= invdet;
b2 *= invdet;
b3 *= invdet;
b4 *= invdet;
b5 *= invdet;
dst->vals[0][0] = (float)( a11*b5 - a12*b4 );
dst->vals[1][0] = (float)( a02*b4 - a01*b5 );
dst->vals[2][0] = (float)( + b2 );
dst->vals[0][1] = (float)( a12*b3 - a10*b5 );
dst->vals[1][1] = (float)( a00*b5 - a02*b3 );
dst->vals[2][1] = (float)( - b1 );
dst->vals[0][2] = (float)( a10*b4 - a11*b3 );
dst->vals[1][2] = (float)( a01*b3 - a00*b4 );
dst->vals[2][2] = (float)( + b0 );
for (int r = 0; r < 3; ++r)
for (int c = 0; c < 3; ++c) {
if (!isfinitef_(dst->vals[r][c])) {
return false;
}
}
return true;
}
skcms_Matrix3x3 skcms_Matrix3x3_concat(const skcms_Matrix3x3* A, const skcms_Matrix3x3* B) {
skcms_Matrix3x3 m = { { { 0,0,0 },{ 0,0,0 },{ 0,0,0 } } };
for (int r = 0; r < 3; r++)
for (int c = 0; c < 3; c++) {
m.vals[r][c] = A->vals[r][0] * B->vals[0][c]
+ A->vals[r][1] * B->vals[1][c]
+ A->vals[r][2] * B->vals[2][c];
}
return m;
}
#if defined(__clang__) || defined(__GNUC__)
#define small_memcpy __builtin_memcpy
#else
#define small_memcpy memcpy
#endif
static float log2f_(float x) {
// The first approximation of log2(x) is its exponent 'e', minus 127.
int32_t bits;
small_memcpy(&bits, &x, sizeof(bits));
float e = (float)bits * (1.0f / (1<<23));
// If we use the mantissa too we can refine the error signficantly.
int32_t m_bits = (bits & 0x007fffff) | 0x3f000000;
float m;
small_memcpy(&m, &m_bits, sizeof(m));
return (e - 124.225514990f
- 1.498030302f*m
- 1.725879990f/(0.3520887068f + m));
}
static float exp2f_(float x) {
float fract = x - floorf_(x);
float fbits = (1.0f * (1<<23)) * (x + 121.274057500f
- 1.490129070f*fract
+ 27.728023300f/(4.84252568f - fract));
if (fbits > INT_MAX) {
return INFINITY_;
} else if (fbits < INT_MIN) {
return -INFINITY_;
}
int32_t bits = (int32_t)fbits;
small_memcpy(&x, &bits, sizeof(x));
return x;
}
float powf_(float x, float y) {
return (x == 0) || (x == 1) ? x
: exp2f_(log2f_(x) * y);
}
float skcms_TransferFunction_eval(const skcms_TransferFunction* tf, float x) {
float sign = x < 0 ? -1.0f : 1.0f;
x *= sign;
return sign * (x < tf->d ? tf->c * x + tf->f
: powf_(tf->a * x + tf->b, tf->g) + tf->e);
}
// TODO: Adjust logic here? This still assumes that purely linear inputs will have D > 1, which
// we never generate. It also emits inverted linear using the same formulation. Standardize on
// G == 1 here, too?
bool skcms_TransferFunction_invert(const skcms_TransferFunction* src, skcms_TransferFunction* dst) {
// Original equation is: y = (ax + b)^g + e for x >= d
// y = cx + f otherwise
//
// so 1st inverse is: (y - e)^(1/g) = ax + b
// x = ((y - e)^(1/g) - b) / a
//
// which can be re-written as: x = (1/a)(y - e)^(1/g) - b/a
// x = ((1/a)^g)^(1/g) * (y - e)^(1/g) - b/a
// x = ([(1/a)^g]y + [-((1/a)^g)e]) ^ [1/g] + [-b/a]
//
// and 2nd inverse is: x = (y - f) / c
// which can be re-written as: x = [1/c]y + [-f/c]
//
// and now both can be expressed in terms of the same parametric form as the
// original - parameters are enclosed in square brackets.
skcms_TransferFunction tf_inv = { 0, 0, 0, 0, 0, 0, 0 };
// This rejects obviously malformed inputs, as well as decreasing functions
if (!tf_is_valid(src)) {
return false;
}
// There are additional constraints to be invertible
bool has_nonlinear = (src->d <= 1);
bool has_linear = (src->d > 0);
// Is the linear section not invertible?
if (has_linear && src->c == 0) {
return false;
}
// Is the nonlinear section not invertible?
if (has_nonlinear && (src->a == 0 || src->g == 0)) {
return false;
}
// If both segments are present, they need to line up
if (has_linear && has_nonlinear) {
float l_at_d = src->c * src->d + src->f;
float n_at_d = powf_(src->a * src->d + src->b, src->g) + src->e;
if (fabsf_(l_at_d - n_at_d) > (1 / 512.0f)) {
return false;
}
}
// Invert linear segment
if (has_linear) {
tf_inv.c = 1.0f / src->c;
tf_inv.f = -src->f / src->c;
}
// Invert nonlinear segment
if (has_nonlinear) {
tf_inv.g = 1.0f / src->g;
tf_inv.a = powf_(1.0f / src->a, src->g);
tf_inv.b = -tf_inv.a * src->e;
tf_inv.e = -src->b / src->a;
}
if (!has_linear) {
tf_inv.d = 0;
} else if (!has_nonlinear) {
// Any value larger than 1 works
tf_inv.d = 2.0f;
} else {
tf_inv.d = src->c * src->d + src->f;
}
*dst = tf_inv;
return true;
}
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ //
// From here below we're approximating an skcms_Curve with an skcms_TransferFunction{g,a,b,c,d,e,f}:
//
// tf(x) = cx + f x < d
// tf(x) = (ax + b)^g + e x ≥ d
//
// When fitting, we add the additional constraint that both pieces meet at d:
//
// cd + f = (ad + b)^g + e
//
// Solving for e and folding it through gives an alternate formulation of the non-linear piece:
//
// tf(x) = cx + f x < d
// tf(x) = (ax + b)^g - (ad + b)^g + cd + f x ≥ d
//
// Our overall strategy is then:
// For a couple tolerances,
// - fit_linear(): fit c,d,f iteratively to as many points as our tolerance allows
// - invert c,d,f
// - fit_nonlinear(): fit g,a,b using Gauss-Newton given those inverted c,d,f
// (and by constraint, inverted e) to the inverse of the table.
// Return the parameters with least maximum error.
//
// To run Gauss-Newton to find g,a,b, we'll also need the gradient of the residuals
// of round-trip f_inv(x), the inverse of the non-linear piece of f(x).
//
// let y = Table(x)
// r(x) = x - f_inv(y)
//
// ∂r/∂g = ln(ay + b)*(ay + b)^g
// - ln(ad + b)*(ad + b)^g
// ∂r/∂a = yg(ay + b)^(g-1)
// - dg(ad + b)^(g-1)
// ∂r/∂b = g(ay + b)^(g-1)
// - g(ad + b)^(g-1)
// Return the residual of roundtripping skcms_Curve(x) through f_inv(y) with parameters P,
// and fill out the gradient of the residual into dfdP.
static float rg_nonlinear(float x,
const skcms_Curve* curve,
const skcms_TransferFunction* tf,
const float P[3],
float dfdP[3]) {
const float y = eval_curve(curve, x);
const float g = P[0], a = P[1], b = P[2],
c = tf->c, d = tf->d, f = tf->f;
const float Y = fmaxf_(a*y + b, 0.0f),
D = a*d + b;
assert (D >= 0);
// The gradient.
dfdP[0] = 0.69314718f*log2f_(Y)*powf_(Y, g)
- 0.69314718f*log2f_(D)*powf_(D, g);
dfdP[1] = y*g*powf_(Y, g-1)
- d*g*powf_(D, g-1);
dfdP[2] = g*powf_(Y, g-1)
- g*powf_(D, g-1);
// The residual.
const float f_inv = powf_(Y, g)
- powf_(D, g)
+ c*d + f;
return x - f_inv;
}
static bool gauss_newton_step(const skcms_Curve* curve,
const skcms_TransferFunction* tf,
float P[3],
float x0, float dx, int N) {
// We'll sample x from the range [x0,x1] (both inclusive) N times with even spacing.
//
// We want to do P' = P + (Jf^T Jf)^-1 Jf^T r(P),
// where r(P) is the residual vector
// and Jf is the Jacobian matrix of f(), ∂r/∂P.
//
// Let's review the shape of each of these expressions:
// r(P) is [N x 1], a column vector with one entry per value of x tested
// Jf is [N x 3], a matrix with an entry for each (x,P) pair
// Jf^T is [3 x N], the transpose of Jf
//
// Jf^T Jf is [3 x N] * [N x 3] == [3 x 3], a 3x3 matrix,
// and so is its inverse (Jf^T Jf)^-1
// Jf^T r(P) is [3 x N] * [N x 1] == [3 x 1], a column vector with the same shape as P
//
// Our implementation strategy to get to the final ∆P is
// 1) evaluate Jf^T Jf, call that lhs
// 2) evaluate Jf^T r(P), call that rhs
// 3) invert lhs
// 4) multiply inverse lhs by rhs
//
// This is a friendly implementation strategy because we don't have to have any
// buffers that scale with N, and equally nice don't have to perform any matrix
// operations that are variable size.
//
// Other implementation strategies could trade this off, e.g. evaluating the
// pseudoinverse of Jf ( (Jf^T Jf)^-1 Jf^T ) directly, then multiplying that by
// the residuals. That would probably require implementing singular value
// decomposition, and would create a [3 x N] matrix to be multiplied by the
// [N x 1] residual vector, but on the upside I think that'd eliminate the
// possibility of this gauss_newton_step() function ever failing.
// 0) start off with lhs and rhs safely zeroed.
skcms_Matrix3x3 lhs = {{ {0,0,0}, {0,0,0}, {0,0,0} }};
skcms_Vector3 rhs = { {0,0,0} };
// 1,2) evaluate lhs and evaluate rhs
// We want to evaluate Jf only once, but both lhs and rhs involve Jf^T,
// so we'll have to update lhs and rhs at the same time.
for (int i = 0; i < N; i++) {
float x = x0 + i*dx;
float dfdP[3] = {0,0,0};
float resid = rg_nonlinear(x,curve,tf,P, dfdP);
for (int r = 0; r < 3; r++) {
for (int c = 0; c < 3; c++) {
lhs.vals[r][c] += dfdP[r] * dfdP[c];
}
rhs.vals[r] += dfdP[r] * resid;
}
}
// If any of the 3 P parameters are unused, this matrix will be singular.
// Detect those cases and fix them up to indentity instead, so we can invert.
for (int k = 0; k < 3; k++) {
if (lhs.vals[0][k]==0 && lhs.vals[1][k]==0 && lhs.vals[2][k]==0 &&
lhs.vals[k][0]==0 && lhs.vals[k][1]==0 && lhs.vals[k][2]==0) {
lhs.vals[k][k] = 1;
}
}
// 3) invert lhs
skcms_Matrix3x3 lhs_inv;
if (!skcms_Matrix3x3_invert(&lhs, &lhs_inv)) {
return false;
}
// 4) multiply inverse lhs by rhs
skcms_Vector3 dP = mv_mul(&lhs_inv, &rhs);
P[0] += dP.vals[0];
P[1] += dP.vals[1];
P[2] += dP.vals[2];
return isfinitef_(P[0]) && isfinitef_(P[1]) && isfinitef_(P[2]);
}
// Fit the points in [L,N) to the non-linear piece of tf, or return false if we can't.
static bool fit_nonlinear(const skcms_Curve* curve, int L, int N, skcms_TransferFunction* tf) {
float P[3] = { tf->g, tf->a, tf->b };
// No matter where we start, dx should always represent N even steps from 0 to 1.
const float dx = 1.0f / (N-1);
for (int j = 0; j < 3/*TODO: tune*/; j++) {
// These extra constraints a >= 0 and ad+b >= 0 are not modeled in the optimization.
// We don't really know how to fix up a if it goes negative.
if (P[1] < 0) {
return false;
}
// If ad+b goes negative, we feel just barely not uneasy enough to tweak b so ad+b is zero.
if (P[1] * tf->d + P[2] < 0) {
P[2] = -P[1] * tf->d;
}
assert (P[1] >= 0 &&
P[1] * tf->d + P[2] >= 0);
if (!gauss_newton_step(curve, tf,
P,
L*dx, dx, N-L)) {
return false;
}
}
// We need to apply our fixups one last time
if (P[1] < 0) {
return false;
}
if (P[1] * tf->d + P[2] < 0) {
P[2] = -P[1] * tf->d;
}
tf->g = P[0];
tf->a = P[1];
tf->b = P[2];
tf->e = tf->c*tf->d + tf->f
- powf_(tf->a*tf->d + tf->b, tf->g);
return true;
}
bool skcms_ApproximateCurve(const skcms_Curve* curve,
skcms_TransferFunction* approx,
float* max_error) {
if (!curve || !approx || !max_error) {
return false;
}
if (curve->table_entries == 0) {
// No point approximating an skcms_TransferFunction with an skcms_TransferFunction!
return false;
}
if (curve->table_entries == 1 || curve->table_entries > (uint32_t)INT_MAX) {
// We need at least two points, and must put some reasonable cap on the maximum number.
return false;
}
int N = (int)curve->table_entries;
const float dx = 1.0f / (N - 1);
*max_error = INFINITY_;
const float kTolerances[] = { 1.5f / 65535.0f, 1.0f / 512.0f };
for (int t = 0; t < ARRAY_COUNT(kTolerances); t++) {
skcms_TransferFunction tf,
tf_inv;
int L = fit_linear(curve, N, kTolerances[t], &tf.c, &tf.d, &tf.f);
if (L == N) {
// If the entire data set was linear, move the coefficients to the nonlinear portion
// with G == 1. This lets use a canonical representation with d == 0.
tf.g = 1;
tf.a = tf.c;
tf.b = tf.f;
tf.c = tf.d = tf.e = tf.f = 0;
} else if (L == N - 1) {
// Degenerate case with only two points in the nonlinear segment. Solve directly.
tf.g = 1;
tf.a = (eval_curve(curve, (N-1)*dx) -
eval_curve(curve, (N-2)*dx))
/ dx;
tf.b = eval_curve(curve, (N-2)*dx)
- tf.a * (N-2)*dx;
tf.e = 0;
} else {
// Start by guessing a gamma-only curve through the midpoint.
int mid = (L + N) / 2;
float mid_x = mid / (N - 1.0f);
float mid_y = eval_curve(curve, mid_x);
tf.g = log2f_(mid_y) / log2f_(mid_x);;
tf.a = 1;
tf.b = 0;
tf.e = tf.c*tf.d + tf.f
- powf_(tf.a*tf.d + tf.b, tf.g);
if (!skcms_TransferFunction_invert(&tf, &tf_inv) ||
!fit_nonlinear(curve, L,N, &tf_inv)) {
continue;
}
// We fit tf_inv, so calculate tf to keep in sync.
if (!skcms_TransferFunction_invert(&tf_inv, &tf)) {
continue;
}
}
// We find our error by roundtripping the table through tf_inv.
//
// (The most likely use case for this approximation is to be inverted and
// used as the transfer function for a destination color space.)
//
// We've kept tf and tf_inv in sync above, but we can't guarantee that tf is
// invertible, so re-verify that here (and use the new inverse for testing).
if (!skcms_TransferFunction_invert(&tf, &tf_inv)) {
continue;
}
float err = max_roundtrip_error(curve, &tf_inv);
if (*max_error > err) {
*max_error = err;
*approx = tf;
}
}
return isfinitef_(*max_error);
}
// ~~~~ Impl. of skcms_Transform() ~~~~
typedef enum {
Op_noop,
Op_load_a8,
Op_load_g8,
Op_load_4444,
Op_load_565,
Op_load_888,
Op_load_8888,
Op_load_1010102,
Op_load_161616,
Op_load_16161616,
Op_load_hhh,
Op_load_hhhh,
Op_load_fff,
Op_load_ffff,
Op_swap_rb,
Op_clamp,
Op_invert,
Op_force_opaque,
Op_premul,
Op_unpremul,
Op_matrix_3x3,
Op_matrix_3x4,
Op_lab_to_xyz,
Op_tf_r,
Op_tf_g,
Op_tf_b,
Op_tf_a,
Op_table_8_r,
Op_table_8_g,
Op_table_8_b,
Op_table_8_a,
Op_table_16_r,
Op_table_16_g,
Op_table_16_b,
Op_table_16_a,
Op_clut_3D_8,
Op_clut_3D_16,
Op_clut_4D_8,
Op_clut_4D_16,
Op_store_a8,
Op_store_g8,
Op_store_4444,
Op_store_565,
Op_store_888,
Op_store_8888,
Op_store_1010102,
Op_store_161616,
Op_store_16161616,
Op_store_hhh,
Op_store_hhhh,
Op_store_fff,
Op_store_ffff,
} Op;
// Without this wasm would try to use the N=4 128-bit vector code path,
// which while ideal, causes tons of compiler problems. This would be
// a good thing to revisit as emcc matures (currently 1.38.5).
#if 1 && defined(__EMSCRIPTEN_major__)
#if !defined(SKCMS_PORTABLE)
#define SKCMS_PORTABLE
#endif
#endif
#if defined(__clang__)
typedef float __attribute__((ext_vector_type(4))) Fx4;
typedef int32_t __attribute__((ext_vector_type(4))) I32x4;
typedef uint64_t __attribute__((ext_vector_type(4))) U64x4;
typedef uint32_t __attribute__((ext_vector_type(4))) U32x4;
typedef uint16_t __attribute__((ext_vector_type(4))) U16x4;
typedef uint8_t __attribute__((ext_vector_type(4))) U8x4;
typedef float __attribute__((ext_vector_type(8))) Fx8;
typedef int32_t __attribute__((ext_vector_type(8))) I32x8;
typedef uint64_t __attribute__((ext_vector_type(8))) U64x8;
typedef uint32_t __attribute__((ext_vector_type(8))) U32x8;
typedef uint16_t __attribute__((ext_vector_type(8))) U16x8;
typedef uint8_t __attribute__((ext_vector_type(8))) U8x8;
typedef float __attribute__((ext_vector_type(16))) Fx16;
typedef int32_t __attribute__((ext_vector_type(16))) I32x16;
typedef uint64_t __attribute__((ext_vector_type(16))) U64x16;
typedef uint32_t __attribute__((ext_vector_type(16))) U32x16;
typedef uint16_t __attribute__((ext_vector_type(16))) U16x16;
typedef uint8_t __attribute__((ext_vector_type(16))) U8x16;
#elif defined(__GNUC__)
typedef float __attribute__((vector_size(16))) Fx4;
typedef int32_t __attribute__((vector_size(16))) I32x4;
typedef uint64_t __attribute__((vector_size(32))) U64x4;
typedef uint32_t __attribute__((vector_size(16))) U32x4;
typedef uint16_t __attribute__((vector_size( 8))) U16x4;
typedef uint8_t __attribute__((vector_size( 4))) U8x4;
typedef float __attribute__((vector_size(32))) Fx8;
typedef int32_t __attribute__((vector_size(32))) I32x8;
typedef uint64_t __attribute__((vector_size(64))) U64x8;
typedef uint32_t __attribute__((vector_size(32))) U32x8;
typedef uint16_t __attribute__((vector_size(16))) U16x8;
typedef uint8_t __attribute__((vector_size( 8))) U8x8;
typedef float __attribute__((vector_size( 64))) Fx16;
typedef int32_t __attribute__((vector_size( 64))) I32x16;
typedef uint64_t __attribute__((vector_size(128))) U64x16;
typedef uint32_t __attribute__((vector_size( 64))) U32x16;
typedef uint16_t __attribute__((vector_size( 32))) U16x16;
typedef uint8_t __attribute__((vector_size( 16))) U8x16;
#endif
// First, instantiate our default exec_ops() implementation using the default compiliation target.
#if defined(SKCMS_PORTABLE) || !(defined(__clang__) || defined(__GNUC__))
#define N 1
#define F float
#define U64 uint64_t
#define U32 uint32_t
#define I32 int32_t
#define U16 uint16_t
#define U8 uint8_t
#define F0 0.0f
#define F1 1.0f
#elif defined(__AVX512F__)
#define N 16
#define F Fx16
#define U64 U64x16
#define U32 U32x16
#define I32 I32x16
#define U16 U16x16
#define U8 U8x16
#define F0 F{0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0}
#define F1 F{1,1,1,1, 1,1,1,1, 1,1,1,1, 1,1,1,1}
#elif defined(__AVX__)
#define N 8
#define F Fx8
#define U64 U64x8
#define U32 U32x8
#define I32 I32x8
#define U16 U16x8
#define U8 U8x8
#define F0 F{0,0,0,0, 0,0,0,0}
#define F1 F{1,1,1,1, 1,1,1,1}
#else
#define N 4
#define F Fx4
#define U64 U64x4
#define U32 U32x4
#define I32 I32x4
#define U16 U16x4
#define U8 U8x4
#define F0 F{0,0,0,0}
#define F1 F{1,1,1,1}
#endif
#define NS(id) id
#define ATTR
#include "src/Transform_inl.h"
#undef N
#undef F
#undef U64
#undef U32
#undef I32
#undef U16
#undef U8
#undef F0
#undef F1
#undef NS
#undef ATTR
// Now, instantiate any other versions of run_program() we may want for runtime detection.
#if !defined(SKCMS_PORTABLE) && (defined(__clang__) || defined(__GNUC__)) \
&& defined(__x86_64__) && !defined(__AVX2__)
#define N 8
#define F Fx8
#define U64 U64x8
#define U32 U32x8
#define I32 I32x8
#define U16 U16x8
#define U8 U8x8
#define F0 F{0,0,0,0, 0,0,0,0}
#define F1 F{1,1,1,1, 1,1,1,1}
#define NS(id) id ## _hsw
#define ATTR __attribute__((target("avx2,f16c")))
// We check these guards to see if we have support for these features.
// They're likely _not_ defined here in our baseline build config.
#ifndef __AVX__
#define __AVX__ 1
#define UNDEF_AVX
#endif
#ifndef __F16C__
#define __F16C__ 1
#define UNDEF_F16C
#endif
#ifndef __AVX2__
#define __AVX2__ 1
#define UNDEF_AVX2
#endif
#include "src/Transform_inl.h"
#undef N
#undef F
#undef U64
#undef U32
#undef I32
#undef U16
#undef U8
#undef F0
#undef F1
#undef NS
#undef ATTR
#ifdef UNDEF_AVX
#undef __AVX__
#undef UNDEF_AVX
#endif
#ifdef UNDEF_F16C
#undef __F16C__
#undef UNDEF_F16C
#endif
#ifdef UNDEF_AVX2
#undef __AVX2__
#undef UNDEF_AVX2
#endif
#define TEST_FOR_HSW
static bool hsw_ok() {
static const bool ok = []{
// See http://www.sandpile.org/x86/cpuid.htm
// First, a basic cpuid(1).
uint32_t eax, ebx, ecx, edx;
__asm__ __volatile__("cpuid" : "=a"(eax), "=b"(ebx), "=c"(ecx), "=d"(edx)
: "0"(1), "2"(0));
// Sanity check for prerequisites.
if ((edx & (1<<25)) != (1<<25)) { return false; } // SSE
if ((edx & (1<<26)) != (1<<26)) { return false; } // SSE2
if ((ecx & (1<< 0)) != (1<< 0)) { return false; } // SSE3
if ((ecx & (1<< 9)) != (1<< 9)) { return false; } // SSSE3
if ((ecx & (1<<19)) != (1<<19)) { return false; } // SSE4.1
if ((ecx & (1<<20)) != (1<<20)) { return false; } // SSE4.2
if ((ecx & (3<<26)) != (3<<26)) { return false; } // XSAVE + OSXSAVE
{
uint32_t eax_xgetbv, edx_xgetbv;
__asm__ __volatile__("xgetbv" : "=a"(eax_xgetbv), "=d"(edx_xgetbv) : "c"(0));
if ((eax_xgetbv & (3<<1)) != (3<<1)) { return false; } // XMM+YMM state saved?
}
if ((ecx & (1<<28)) != (1<<28)) { return false; } // AVX
if ((ecx & (1<<29)) != (1<<29)) { return false; } // F16C
if ((ecx & (1<<12)) != (1<<12)) { return false; } // FMA (TODO: not currently used)
// Call cpuid(7) to check for our final AVX2 feature bit!
__asm__ __volatile__("cpuid" : "=a"(eax), "=b"(ebx), "=c"(ecx), "=d"(edx)
: "0"(7), "2"(0));
if ((ebx & (1<< 5)) != (1<< 5)) { return false; } // AVX2
return true;
}();
return ok;
}
#endif
static bool is_identity_tf(const skcms_TransferFunction* tf) {
return tf->g == 1 && tf->a == 1
&& tf->b == 0 && tf->c == 0 && tf->d == 0 && tf->e == 0 && tf->f == 0;
}
typedef struct {
Op op;
const void* arg;
} OpAndArg;
static OpAndArg select_curve_op(const skcms_Curve* curve, int channel) {
static const struct { Op parametric, table_8, table_16; } ops[] = {
{ Op_tf_r, Op_table_8_r, Op_table_16_r },
{ Op_tf_g, Op_table_8_g, Op_table_16_g },
{ Op_tf_b, Op_table_8_b, Op_table_16_b },
{ Op_tf_a, Op_table_8_a, Op_table_16_a },
};
if (curve->table_entries == 0) {
return is_identity_tf(&curve->parametric)
? OpAndArg{ Op_noop, nullptr }
: OpAndArg{ ops[channel].parametric, &curve->parametric };
} else if (curve->table_8) {
return OpAndArg{ ops[channel].table_8, curve };
} else if (curve->table_16) {
return OpAndArg{ ops[channel].table_16, curve };
}
assert(false);
return OpAndArg{Op_noop,nullptr};
}
static size_t bytes_per_pixel(skcms_PixelFormat fmt) {
switch (fmt >> 1) { // ignore rgb/bgr
case skcms_PixelFormat_A_8 >> 1: return 1;
case skcms_PixelFormat_G_8 >> 1: return 1;
case skcms_PixelFormat_ABGR_4444 >> 1: return 2;
case skcms_PixelFormat_RGB_565 >> 1: return 2;
case skcms_PixelFormat_RGB_888 >> 1: return 3;
case skcms_PixelFormat_RGBA_8888 >> 1: return 4;
case skcms_PixelFormat_RGBA_1010102 >> 1: return 4;
case skcms_PixelFormat_RGB_161616 >> 1: return 6;
case skcms_PixelFormat_RGBA_16161616 >> 1: return 8;
case skcms_PixelFormat_RGB_hhh >> 1: return 6;
case skcms_PixelFormat_RGBA_hhhh >> 1: return 8;
case skcms_PixelFormat_RGB_fff >> 1: return 12;
case skcms_PixelFormat_RGBA_ffff >> 1: return 16;
}
assert(false);
return 0;
}
static bool prep_for_destination(const skcms_ICCProfile* profile,
skcms_Matrix3x3* fromXYZD50,
skcms_TransferFunction* invR,
skcms_TransferFunction* invG,
skcms_TransferFunction* invB) {
// We only support destinations with parametric transfer functions
// and with gamuts that can be transformed from XYZD50.
return profile->has_trc
&& profile->has_toXYZD50
&& profile->trc[0].table_entries == 0
&& profile->trc[1].table_entries == 0
&& profile->trc[2].table_entries == 0
&& skcms_TransferFunction_invert(&profile->trc[0].parametric, invR)
&& skcms_TransferFunction_invert(&profile->trc[1].parametric, invG)
&& skcms_TransferFunction_invert(&profile->trc[2].parametric, invB)
&& skcms_Matrix3x3_invert(&profile->toXYZD50, fromXYZD50);
}
bool skcms_Transform(const void* src,
skcms_PixelFormat srcFmt,
skcms_AlphaFormat srcAlpha,
const skcms_ICCProfile* srcProfile,
void* dst,
skcms_PixelFormat dstFmt,
skcms_AlphaFormat dstAlpha,
const skcms_ICCProfile* dstProfile,
size_t nz) {
const size_t dst_bpp = bytes_per_pixel(dstFmt),
src_bpp = bytes_per_pixel(srcFmt);
// Let's just refuse if the request is absurdly big.
if (nz * dst_bpp > INT_MAX || nz * src_bpp > INT_MAX) {
return false;
}
int n = (int)nz;
// Null profiles default to sRGB. Passing null for both is handy when doing format conversion.
if (!srcProfile) {
srcProfile = skcms_sRGB_profile();
}
if (!dstProfile) {
dstProfile = skcms_sRGB_profile();
}
// We can't transform in place unless the PixelFormats are the same size.
if (dst == src && (dstFmt >> 1) != (srcFmt >> 1)) {
return false;
}
// TODO: this check lazilly disallows U16 <-> F16, but that would actually be fine.
// TODO: more careful alias rejection (like, dst == src + 1)?
Op program [32];
const void* arguments[32];
Op* ops = program;
const void** args = arguments;
skcms_TransferFunction inv_dst_tf_r, inv_dst_tf_g, inv_dst_tf_b;
skcms_Matrix3x3 from_xyz;
switch (srcFmt >> 1) {
default: return false;
case skcms_PixelFormat_A_8 >> 1: *ops++ = Op_load_a8; break;
case skcms_PixelFormat_G_8 >> 1: *ops++ = Op_load_g8; break;
case skcms_PixelFormat_ABGR_4444 >> 1: *ops++ = Op_load_4444; break;
case skcms_PixelFormat_RGB_565 >> 1: *ops++ = Op_load_565; break;
case skcms_PixelFormat_RGB_888 >> 1: *ops++ = Op_load_888; break;
case skcms_PixelFormat_RGBA_8888 >> 1: *ops++ = Op_load_8888; break;
case skcms_PixelFormat_RGBA_1010102 >> 1: *ops++ = Op_load_1010102; break;
case skcms_PixelFormat_RGB_161616 >> 1: *ops++ = Op_load_161616; break;
case skcms_PixelFormat_RGBA_16161616 >> 1: *ops++ = Op_load_16161616; break;
case skcms_PixelFormat_RGB_hhh >> 1: *ops++ = Op_load_hhh; break;
case skcms_PixelFormat_RGBA_hhhh >> 1: *ops++ = Op_load_hhhh; break;
case skcms_PixelFormat_RGB_fff >> 1: *ops++ = Op_load_fff; break;
case skcms_PixelFormat_RGBA_ffff >> 1: *ops++ = Op_load_ffff; break;
}
if (srcFmt & 1) {
*ops++ = Op_swap_rb;
}
skcms_ICCProfile gray_dst_profile;
if ((dstFmt >> 1) == (skcms_PixelFormat_G_8 >> 1)) {
// When transforming to gray, stop at XYZ (by setting toXYZ to identity), then transform
// luminance (Y) by the destination transfer function.
gray_dst_profile = *dstProfile;
skcms_SetXYZD50(&gray_dst_profile, &skcms_XYZD50_profile()->toXYZD50);
dstProfile = &gray_dst_profile;
}
if (srcProfile->data_color_space == skcms_Signature_CMYK) {
// Photoshop creates CMYK images as inverse CMYK.
// These happen to be the only ones we've _ever_ seen.
*ops++ = Op_invert;
// With CMYK, ignore the alpha type, to avoid changing K or conflating CMY with K.
srcAlpha = skcms_AlphaFormat_Unpremul;
}
if (srcAlpha == skcms_AlphaFormat_Opaque) {
*ops++ = Op_force_opaque;
} else if (srcAlpha == skcms_AlphaFormat_PremulAsEncoded) {
*ops++ = Op_unpremul;
}
// TODO: We can skip this work if both srcAlpha and dstAlpha are PremulLinear, and the profiles
// are the same. Also, if dstAlpha is PremulLinear, and SrcAlpha is Opaque.
if (dstProfile != srcProfile ||
srcAlpha == skcms_AlphaFormat_PremulLinear ||
dstAlpha == skcms_AlphaFormat_PremulLinear) {
if (!prep_for_destination(dstProfile,
&from_xyz, &inv_dst_tf_r, &inv_dst_tf_b, &inv_dst_tf_g)) {
return false;
}
if (srcProfile->has_A2B) {
if (srcProfile->A2B.input_channels) {
for (int i = 0; i < (int)srcProfile->A2B.input_channels; i++) {
OpAndArg oa = select_curve_op(&srcProfile->A2B.input_curves[i], i);
if (oa.op != Op_noop) {
*ops++ = oa.op;
*args++ = oa.arg;
}
}
switch (srcProfile->A2B.input_channels) {
case 3: *ops++ = srcProfile->A2B.grid_8 ? Op_clut_3D_8 : Op_clut_3D_16; break;
case 4: *ops++ = srcProfile->A2B.grid_8 ? Op_clut_4D_8 : Op_clut_4D_16; break;
default: return false;
}
*args++ = &srcProfile->A2B;
}
if (srcProfile->A2B.matrix_channels == 3) {
for (int i = 0; i < 3; i++) {
OpAndArg oa = select_curve_op(&srcProfile->A2B.matrix_curves[i], i);
if (oa.op != Op_noop) {
*ops++ = oa.op;
*args++ = oa.arg;
}
}
static const skcms_Matrix3x4 I = {{
{1,0,0,0},
{0,1,0,0},
{0,0,1,0},
}};
if (0 != memcmp(&I, &srcProfile->A2B.matrix, sizeof(I))) {
*ops++ = Op_matrix_3x4;
*args++ = &srcProfile->A2B.matrix;
}
}
if (srcProfile->A2B.output_channels == 3) {
for (int i = 0; i < 3; i++) {
OpAndArg oa = select_curve_op(&srcProfile->A2B.output_curves[i], i);
if (oa.op != Op_noop) {
*ops++ = oa.op;
*args++ = oa.arg;
}
}
}
if (srcProfile->pcs == skcms_Signature_Lab) {
*ops++ = Op_lab_to_xyz;
}
} else if (srcProfile->has_trc && srcProfile->has_toXYZD50) {
for (int i = 0; i < 3; i++) {
OpAndArg oa = select_curve_op(&srcProfile->trc[i], i);
if (oa.op != Op_noop) {
*ops++ = oa.op;
*args++ = oa.arg;
}
}
} else {
return false;
}
// At this point our source colors are linear, either RGB (XYZ-type profiles)
// or XYZ (A2B-type profiles). Unpremul is a linear operation (multiply by a
// constant 1/a), so either way we can do it now if needed.
if (srcAlpha == skcms_AlphaFormat_PremulLinear) {
*ops++ = Op_unpremul;
}
// A2B sources should already be in XYZD50 at this point.
// Others still need to be transformed using their toXYZD50 matrix.
// N.B. There are profiles that contain both A2B tags and toXYZD50 matrices.
// If we use the A2B tags, we need to ignore the XYZD50 matrix entirely.
assert (srcProfile->has_A2B || srcProfile->has_toXYZD50);
static const skcms_Matrix3x3 I = {{
{ 1.0f, 0.0f, 0.0f },
{ 0.0f, 1.0f, 0.0f },
{ 0.0f, 0.0f, 1.0f },
}};
const skcms_Matrix3x3* to_xyz = srcProfile->has_A2B ? &I : &srcProfile->toXYZD50;
// There's a chance the source and destination gamuts are identical,
// in which case we can skip the gamut transform.
if (0 != memcmp(&dstProfile->toXYZD50, to_xyz, sizeof(skcms_Matrix3x3))) {
// Concat the entire gamut transform into from_xyz,
// now slightly misnamed but it's a handy spot to stash the result.
from_xyz = skcms_Matrix3x3_concat(&from_xyz, to_xyz);
*ops++ = Op_matrix_3x3;
*args++ = &from_xyz;
}
if (dstAlpha == skcms_AlphaFormat_PremulLinear) {
*ops++ = Op_premul;
}
// Encode back to dst RGB using its parametric transfer functions.
if (!is_identity_tf(&inv_dst_tf_r)) { *ops++ = Op_tf_r; *args++ = &inv_dst_tf_r; }
if (!is_identity_tf(&inv_dst_tf_g)) { *ops++ = Op_tf_g; *args++ = &inv_dst_tf_g; }
if (!is_identity_tf(&inv_dst_tf_b)) { *ops++ = Op_tf_b; *args++ = &inv_dst_tf_b; }
}
// Clamp here before premul to make sure we're clamping to fixed-point values _and_ gamut,
// not just to values that fit in the fixed point representation.
//
// E.g. r = 1.1, a = 0.5 would fit fine in fixed point after premul (ra=0.55,a=0.5),
// but would be carrying r > 1, which is really unexpected for downstream consumers.
// TODO(mtklein): add a unit test
if (dstFmt < skcms_PixelFormat_RGB_hhh) {
*ops++ = Op_clamp;
}
if (dstAlpha == skcms_AlphaFormat_Opaque) {
*ops++ = Op_force_opaque;
} else if (dstAlpha == skcms_AlphaFormat_PremulAsEncoded) {
*ops++ = Op_premul;
}
if (dstFmt & 1) {
*ops++ = Op_swap_rb;
}
switch (dstFmt >> 1) {
default: return false;
case skcms_PixelFormat_A_8 >> 1: *ops++ = Op_store_a8; break;
case skcms_PixelFormat_G_8 >> 1: *ops++ = Op_store_g8; break;
case skcms_PixelFormat_ABGR_4444 >> 1: *ops++ = Op_store_4444; break;
case skcms_PixelFormat_RGB_565 >> 1: *ops++ = Op_store_565; break;
case skcms_PixelFormat_RGB_888 >> 1: *ops++ = Op_store_888; break;
case skcms_PixelFormat_RGBA_8888 >> 1: *ops++ = Op_store_8888; break;
case skcms_PixelFormat_RGBA_1010102 >> 1: *ops++ = Op_store_1010102; break;
case skcms_PixelFormat_RGB_161616 >> 1: *ops++ = Op_store_161616; break;
case skcms_PixelFormat_RGBA_16161616 >> 1: *ops++ = Op_store_16161616; break;
case skcms_PixelFormat_RGB_hhh >> 1: *ops++ = Op_store_hhh; break;
case skcms_PixelFormat_RGBA_hhhh >> 1: *ops++ = Op_store_hhhh; break;
case skcms_PixelFormat_RGB_fff >> 1: *ops++ = Op_store_fff; break;
case skcms_PixelFormat_RGBA_ffff >> 1: *ops++ = Op_store_ffff; break;
}
void (*run)(const Op*, const void**, const char*, char*, int, size_t,size_t) = run_program;
#if defined(TEST_FOR_HSW)
if (hsw_ok()) {
run = run_program_hsw;
}
#endif
run(program, arguments, (const char*)src, (char*)dst, n, src_bpp,dst_bpp);
return true;
}
static void assert_usable_as_destination(const skcms_ICCProfile* profile) {
#if defined(NDEBUG)
(void)profile;
#else
skcms_Matrix3x3 fromXYZD50;
skcms_TransferFunction invR, invG, invB;
assert(prep_for_destination(profile, &fromXYZD50, &invR, &invG, &invB));
#endif
}
bool skcms_MakeUsableAsDestination(skcms_ICCProfile* profile) {
skcms_Matrix3x3 fromXYZD50;
if (!profile->has_trc || !profile->has_toXYZD50
|| !skcms_Matrix3x3_invert(&profile->toXYZD50, &fromXYZD50)) {
return false;
}
skcms_TransferFunction tf[3];
for (int i = 0; i < 3; i++) {
skcms_TransferFunction inv;
if (profile->trc[i].table_entries == 0
&& skcms_TransferFunction_invert(&profile->trc[i].parametric, &inv)) {
tf[i] = profile->trc[i].parametric;
continue;
}
float max_error;
// Parametric curves from skcms_ApproximateCurve() are guaranteed to be invertible.
if (!skcms_ApproximateCurve(&profile->trc[i], &tf[i], &max_error)) {
return false;
}
}
for (int i = 0; i < 3; ++i) {
profile->trc[i].table_entries = 0;
profile->trc[i].parametric = tf[i];
}
assert_usable_as_destination(profile);
return true;
}
bool skcms_MakeUsableAsDestinationWithSingleCurve(skcms_ICCProfile* profile) {
// Operate on a copy of profile, so we can choose the best TF for the original curves
skcms_ICCProfile result = *profile;
if (!skcms_MakeUsableAsDestination(&result)) {
return false;
}
int best_tf = 0;
float min_max_error = INFINITY_;
for (int i = 0; i < 3; i++) {
skcms_TransferFunction inv;
skcms_TransferFunction_invert(&result.trc[i].parametric, &inv);
float err = 0;
for (int j = 0; j < 3; ++j) {
err = fmaxf_(err, max_roundtrip_error(&profile->trc[j], &inv));
}
if (min_max_error > err) {
min_max_error = err;
best_tf = i;
}
}
for (int i = 0; i < 3; i++) {
result.trc[i].parametric = result.trc[best_tf].parametric;
}
*profile = result;
assert_usable_as_destination(profile);
return true;
}
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