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// Copyright (c) the JPEG XL Project Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#ifndef LIB_JXL_CMS_COLOR_ENCODING_CMS_H_
#define LIB_JXL_CMS_COLOR_ENCODING_CMS_H_
#include <jxl/cms_interface.h>
#include <jxl/color_encoding.h>
#include <jxl/types.h>
#include <cmath>
#include <cstdint>
#include <cstring>
#include <utility>
#include <vector>
#include "lib/jxl/base/status.h"
namespace jxl {
namespace cms {
using IccBytes = std::vector<uint8_t>;
// Returns whether the two inputs are approximately equal.
static inline bool ApproxEq(const double a, const double b,
double max_l1 = 1E-3) {
// Threshold should be sufficient for ICC's 15-bit fixed-point numbers.
// We have seen differences of 7.1E-5 with lcms2 and 1E-3 with skcms.
return std::abs(a - b) <= max_l1;
}
// (All CIE units are for the standard 1931 2 degree observer)
// Color space the color pixel data is encoded in. The color pixel data is
// 3-channel in all cases except in case of kGray, where it uses only 1 channel.
// This also determines the amount of channels used in modular encoding.
enum class ColorSpace : uint32_t {
// Trichromatic color data. This also includes CMYK if a kBlack
// ExtraChannelInfo is present. This implies, if there is an ICC profile, that
// the ICC profile uses a 3-channel color space if no kBlack extra channel is
// present, or uses color space 'CMYK' if a kBlack extra channel is present.
kRGB,
// Single-channel data. This implies, if there is an ICC profile, that the ICC
// profile also represents single-channel data and has the appropriate color
// space ('GRAY').
kGray,
// Like kRGB, but implies fixed values for primaries etc.
kXYB,
// For non-RGB/gray data, e.g. from non-electro-optical sensors. Otherwise
// the same conditions as kRGB apply.
kUnknown
// NB: don't forget to update EnumBits!
};
// Values from CICP ColourPrimaries.
enum class WhitePoint : uint32_t {
kD65 = 1, // sRGB/BT.709/Display P3/BT.2020
kCustom = 2, // Actual values encoded in separate fields
kE = 10, // XYZ
kDCI = 11, // DCI-P3
// NB: don't forget to update EnumBits!
};
// Values from CICP ColourPrimaries
enum class Primaries : uint32_t {
kSRGB = 1, // Same as BT.709
kCustom = 2, // Actual values encoded in separate fields
k2100 = 9, // Same as BT.2020
kP3 = 11,
// NB: don't forget to update EnumBits!
};
// Values from CICP TransferCharacteristics
enum class TransferFunction : uint32_t {
k709 = 1,
kUnknown = 2,
kLinear = 8,
kSRGB = 13,
kPQ = 16, // from BT.2100
kDCI = 17, // from SMPTE RP 431-2 reference projector
kHLG = 18, // from BT.2100
// NB: don't forget to update EnumBits!
};
enum class RenderingIntent : uint32_t {
// Values match ICC sRGB encodings.
kPerceptual = 0, // good for photos, requires a profile with LUT.
kRelative, // good for logos.
kSaturation, // perhaps useful for CG with fully saturated colors.
kAbsolute, // leaves white point unchanged; good for proofing.
// NB: don't forget to update EnumBits!
};
// Chromaticity (Y is omitted because it is 1 for white points and implicit for
// primaries)
struct CIExy {
CIExy() = default;
CIExy(double x, double y) : x(x), y(y) {}
double x = 0.0;
double y = 0.0;
};
struct PrimariesCIExy {
CIExy r;
CIExy g;
CIExy b;
};
// Serializable form of CIExy.
struct Customxy {
static constexpr uint32_t kMul = 1000000;
static constexpr double kRoughLimit = 4.0;
static constexpr int32_t kMin = -0x200000;
static constexpr int32_t kMax = 0x1FFFFF;
int32_t x = 0;
int32_t y = 0;
CIExy GetValue() const {
CIExy xy;
xy.x = x * (1.0 / kMul);
xy.y = y * (1.0 / kMul);
return xy;
}
Status SetValue(const CIExy& xy) {
bool ok = (std::abs(xy.x) < kRoughLimit) && (std::abs(xy.y) < kRoughLimit);
if (!ok) return JXL_FAILURE("X or Y is out of bounds");
x = static_cast<int32_t>(roundf(xy.x * kMul));
if (x < kMin || x > kMax) return JXL_FAILURE("X is out of bounds");
y = static_cast<int32_t>(roundf(xy.y * kMul));
if (y < kMin || y > kMax) return JXL_FAILURE("Y is out of bounds");
return true;
}
bool IsSame(const Customxy& other) const {
return (x == other.x) && (y == other.y);
}
};
static inline Status WhitePointFromExternal(const JxlWhitePoint external,
WhitePoint* out) {
switch (external) {
case JXL_WHITE_POINT_D65:
*out = WhitePoint::kD65;
return true;
case JXL_WHITE_POINT_CUSTOM:
*out = WhitePoint::kCustom;
return true;
case JXL_WHITE_POINT_E:
*out = WhitePoint::kE;
return true;
case JXL_WHITE_POINT_DCI:
*out = WhitePoint::kDCI;
return true;
}
return JXL_FAILURE("Invalid WhitePoint enum value %d",
static_cast<int>(external));
}
static inline Status PrimariesFromExternal(const JxlPrimaries external,
Primaries* out) {
switch (external) {
case JXL_PRIMARIES_SRGB:
*out = Primaries::kSRGB;
return true;
case JXL_PRIMARIES_CUSTOM:
*out = Primaries::kCustom;
return true;
case JXL_PRIMARIES_2100:
*out = Primaries::k2100;
return true;
case JXL_PRIMARIES_P3:
*out = Primaries::kP3;
return true;
}
return JXL_FAILURE("Invalid Primaries enum value");
}
static inline Status RenderingIntentFromExternal(
const JxlRenderingIntent external, RenderingIntent* out) {
switch (external) {
case JXL_RENDERING_INTENT_PERCEPTUAL:
*out = RenderingIntent::kPerceptual;
return true;
case JXL_RENDERING_INTENT_RELATIVE:
*out = RenderingIntent::kRelative;
return true;
case JXL_RENDERING_INTENT_SATURATION:
*out = RenderingIntent::kSaturation;
return true;
case JXL_RENDERING_INTENT_ABSOLUTE:
*out = RenderingIntent::kAbsolute;
return true;
}
return JXL_FAILURE("Invalid RenderingIntent enum value");
}
struct CustomTransferFunction {
// Highest reasonable value for the gamma of a transfer curve.
static constexpr uint32_t kMaxGamma = 8192;
static constexpr uint32_t kGammaMul = 10000000;
bool have_gamma = false;
// OETF exponent to go from linear to gamma-compressed.
uint32_t gamma = 0; // Only used if have_gamma_.
// Can be kUnknown.
TransferFunction transfer_function =
TransferFunction::kSRGB; // Only used if !have_gamma_.
TransferFunction GetTransferFunction() const {
JXL_DASSERT(!have_gamma);
return have_gamma ? TransferFunction::kUnknown : transfer_function;
}
void SetTransferFunction(const TransferFunction tf) {
have_gamma = false;
transfer_function = tf;
}
bool IsUnknown() const {
return !have_gamma && (transfer_function == TransferFunction::kUnknown);
}
bool IsSRGB() const {
return !have_gamma && (transfer_function == TransferFunction::kSRGB);
}
bool IsLinear() const {
return !have_gamma && (transfer_function == TransferFunction::kLinear);
}
bool IsPQ() const {
return !have_gamma && (transfer_function == TransferFunction::kPQ);
}
bool IsHLG() const {
return !have_gamma && (transfer_function == TransferFunction::kHLG);
}
bool Is709() const {
return !have_gamma && (transfer_function == TransferFunction::k709);
}
bool IsDCI() const {
return !have_gamma && (transfer_function == TransferFunction::kDCI);
}
double GetGamma() const {
JXL_DASSERT(have_gamma);
if (!have_gamma) return 0.0;
return gamma * (1.0 / kGammaMul); // (0, 1)
}
Status SetGamma(double new_gamma) {
if (new_gamma < (1.0 / kMaxGamma) || new_gamma > 1.0) {
return JXL_FAILURE("Invalid gamma %f", new_gamma);
}
have_gamma = false;
if (ApproxEq(new_gamma, 1.0)) {
transfer_function = TransferFunction::kLinear;
return true;
}
if (ApproxEq(new_gamma, 1.0 / 2.6)) {
transfer_function = TransferFunction::kDCI;
return true;
}
// Don't translate 0.45.. to kSRGB nor k709 - that might change pixel
// values because those curves also have a linear part.
have_gamma = true;
gamma = roundf(new_gamma * kGammaMul);
transfer_function = TransferFunction::kUnknown;
return true;
}
bool IsSame(const CustomTransferFunction& other) const {
if (have_gamma != other.have_gamma) {
return false;
}
if (have_gamma) {
if (gamma != other.gamma) {
return false;
}
} else {
if (transfer_function != other.transfer_function) {
return false;
}
}
return true;
}
};
static inline Status ConvertExternalToInternalTransferFunction(
const JxlTransferFunction external, TransferFunction* internal) {
switch (external) {
case JXL_TRANSFER_FUNCTION_709:
*internal = TransferFunction::k709;
return true;
case JXL_TRANSFER_FUNCTION_UNKNOWN:
*internal = TransferFunction::kUnknown;
return true;
case JXL_TRANSFER_FUNCTION_LINEAR:
*internal = TransferFunction::kLinear;
return true;
case JXL_TRANSFER_FUNCTION_SRGB:
*internal = TransferFunction::kSRGB;
return true;
case JXL_TRANSFER_FUNCTION_PQ:
*internal = TransferFunction::kPQ;
return true;
case JXL_TRANSFER_FUNCTION_DCI:
*internal = TransferFunction::kDCI;
return true;
case JXL_TRANSFER_FUNCTION_HLG:
*internal = TransferFunction::kHLG;
return true;
case JXL_TRANSFER_FUNCTION_GAMMA:
return JXL_FAILURE("Gamma should be handled separately");
}
return JXL_FAILURE("Invalid TransferFunction enum value");
}
// Compact encoding of data required to interpret and translate pixels to a
// known color space. Stored in Metadata. Thread-compatible.
struct ColorEncoding {
// Only valid if HaveFields()
WhitePoint white_point = WhitePoint::kD65;
Primaries primaries = Primaries::kSRGB; // Only valid if HasPrimaries()
RenderingIntent rendering_intent = RenderingIntent::kRelative;
// When false, fields such as white_point and tf are invalid and must not be
// used. This occurs after setting a raw bytes-only ICC profile, only the
// ICC bytes may be used. The color_space_ field is still valid.
bool have_fields = true;
IccBytes icc; // Valid ICC profile
ColorSpace color_space = ColorSpace::kRGB; // Can be kUnknown
bool cmyk = false;
// "late sync" fields
CustomTransferFunction tf;
Customxy white; // Only used if white_point == kCustom
Customxy red; // Only used if primaries == kCustom
Customxy green; // Only used if primaries == kCustom
Customxy blue; // Only used if primaries == kCustom
// Returns false if the field is invalid and unusable.
bool HasPrimaries() const {
return (color_space != ColorSpace::kGray) &&
(color_space != ColorSpace::kXYB);
}
size_t Channels() const { return (color_space == ColorSpace::kGray) ? 1 : 3; }
Status GetPrimaries(PrimariesCIExy& xy) const {
JXL_ENSURE(have_fields);
JXL_ENSURE(HasPrimaries());
xy = {};
switch (primaries) {
case Primaries::kCustom:
xy.r = red.GetValue();
xy.g = green.GetValue();
xy.b = blue.GetValue();
break;
case Primaries::kSRGB:
xy.r.x = 0.639998686;
xy.r.y = 0.330010138;
xy.g.x = 0.300003784;
xy.g.y = 0.600003357;
xy.b.x = 0.150002046;
xy.b.y = 0.059997204;
break;
case Primaries::k2100:
xy.r.x = 0.708;
xy.r.y = 0.292;
xy.g.x = 0.170;
xy.g.y = 0.797;
xy.b.x = 0.131;
xy.b.y = 0.046;
break;
case Primaries::kP3:
xy.r.x = 0.680;
xy.r.y = 0.320;
xy.g.x = 0.265;
xy.g.y = 0.690;
xy.b.x = 0.150;
xy.b.y = 0.060;
break;
default:
JXL_DEBUG_ABORT("internal: unexpected Primaries: %d",
static_cast<int>(primaries));
}
return true;
}
Status SetPrimaries(const PrimariesCIExy& xy) {
JXL_ENSURE(have_fields);
JXL_ENSURE(HasPrimaries());
if (xy.r.x == 0.0 || xy.r.y == 0.0 || xy.g.x == 0.0 || xy.g.y == 0.0 ||
xy.b.x == 0.0 || xy.b.y == 0.0) {
return JXL_FAILURE("Invalid primaries %f %f %f %f %f %f", xy.r.x, xy.r.y,
xy.g.x, xy.g.y, xy.b.x, xy.b.y);
}
if (ApproxEq(xy.r.x, 0.64) && ApproxEq(xy.r.y, 0.33) &&
ApproxEq(xy.g.x, 0.30) && ApproxEq(xy.g.y, 0.60) &&
ApproxEq(xy.b.x, 0.15) && ApproxEq(xy.b.y, 0.06)) {
primaries = Primaries::kSRGB;
return true;
}
if (ApproxEq(xy.r.x, 0.708) && ApproxEq(xy.r.y, 0.292) &&
ApproxEq(xy.g.x, 0.170) && ApproxEq(xy.g.y, 0.797) &&
ApproxEq(xy.b.x, 0.131) && ApproxEq(xy.b.y, 0.046)) {
primaries = Primaries::k2100;
return true;
}
if (ApproxEq(xy.r.x, 0.680) && ApproxEq(xy.r.y, 0.320) &&
ApproxEq(xy.g.x, 0.265) && ApproxEq(xy.g.y, 0.690) &&
ApproxEq(xy.b.x, 0.150) && ApproxEq(xy.b.y, 0.060)) {
primaries = Primaries::kP3;
return true;
}
primaries = Primaries::kCustom;
JXL_RETURN_IF_ERROR(red.SetValue(xy.r));
JXL_RETURN_IF_ERROR(green.SetValue(xy.g));
JXL_RETURN_IF_ERROR(blue.SetValue(xy.b));
return true;
}
CIExy GetWhitePoint() const {
CIExy xy{};
JXL_DASSERT(have_fields);
if (!have_fields) return xy;
switch (white_point) {
case WhitePoint::kCustom:
xy = white.GetValue();
break;
case WhitePoint::kD65:
xy.x = 0.3127;
xy.y = 0.3290;
break;
case WhitePoint::kDCI:
xy.x = 0.314;
xy.y = 0.351;
break;
case WhitePoint::kE:
xy.x = xy.y = 1.0 / 3;
break;
default:
JXL_DEBUG_ABORT("internal: unexpected WhitePoint: %d",
static_cast<int>(white_point));
}
return xy;
}
Status SetWhitePoint(const CIExy& xy) {
JXL_ENSURE(have_fields);
if (xy.x == 0.0 || xy.y == 0.0) {
return JXL_FAILURE("Invalid white point %f %f", xy.x, xy.y);
}
if (ApproxEq(xy.x, 0.3127) && ApproxEq(xy.y, 0.3290)) {
white_point = WhitePoint::kD65;
return true;
}
if (ApproxEq(xy.x, 1.0 / 3) && ApproxEq(xy.y, 1.0 / 3)) {
white_point = WhitePoint::kE;
return true;
}
if (ApproxEq(xy.x, 0.314) && ApproxEq(xy.y, 0.351)) {
white_point = WhitePoint::kDCI;
return true;
}
white_point = WhitePoint::kCustom;
return white.SetValue(xy);
}
// Checks if the color spaces (including white point / primaries) are the
// same, but ignores the transfer function, rendering intent and ICC bytes.
bool SameColorSpace(const ColorEncoding& other) const {
if (color_space != other.color_space) return false;
if (white_point != other.white_point) return false;
if (white_point == WhitePoint::kCustom) {
if (!white.IsSame(other.white)) {
return false;
}
}
if (HasPrimaries() != other.HasPrimaries()) return false;
if (HasPrimaries()) {
if (primaries != other.primaries) return false;
if (primaries == Primaries::kCustom) {
if (!red.IsSame(other.red)) return false;
if (!green.IsSame(other.green)) return false;
if (!blue.IsSame(other.blue)) return false;
}
}
return true;
}
// Checks if the color space and transfer function are the same, ignoring
// rendering intent and ICC bytes
bool SameColorEncoding(const ColorEncoding& other) const {
return SameColorSpace(other) && tf.IsSame(other.tf);
}
// Returns true if all fields have been initialized (possibly to kUnknown).
// Returns false if the ICC profile is invalid or decoding it fails.
Status SetFieldsFromICC(IccBytes&& new_icc, const JxlCmsInterface& cms) {
// In case parsing fails, mark the ColorEncoding as invalid.
JXL_ENSURE(!new_icc.empty());
color_space = ColorSpace::kUnknown;
tf.transfer_function = TransferFunction::kUnknown;
icc.clear();
JxlColorEncoding external;
JXL_BOOL new_cmyk;
JXL_RETURN_IF_ERROR(cms.set_fields_from_icc(cms.set_fields_data,
new_icc.data(), new_icc.size(),
&external, &new_cmyk));
cmyk = static_cast<bool>(new_cmyk);
JXL_RETURN_IF_ERROR(FromExternal(external));
icc = std::move(new_icc);
return true;
}
JxlColorEncoding ToExternal() const {
JxlColorEncoding external = {};
auto set_error = [&]() {
external.color_space = JXL_COLOR_SPACE_UNKNOWN;
external.primaries = JXL_PRIMARIES_CUSTOM;
external.rendering_intent = JXL_RENDERING_INTENT_PERCEPTUAL; //?
external.transfer_function = JXL_TRANSFER_FUNCTION_UNKNOWN;
external.white_point = JXL_WHITE_POINT_CUSTOM;
};
if (!have_fields) {
set_error();
return external;
}
external.color_space = static_cast<JxlColorSpace>(color_space);
external.white_point = static_cast<JxlWhitePoint>(white_point);
CIExy wp = GetWhitePoint();
external.white_point_xy[0] = wp.x;
external.white_point_xy[1] = wp.y;
if (external.color_space == JXL_COLOR_SPACE_RGB ||
external.color_space == JXL_COLOR_SPACE_UNKNOWN) {
external.primaries = static_cast<JxlPrimaries>(primaries);
PrimariesCIExy p;
if (!GetPrimaries(p)) {
set_error();
return external;
}
external.primaries_red_xy[0] = p.r.x;
external.primaries_red_xy[1] = p.r.y;
external.primaries_green_xy[0] = p.g.x;
external.primaries_green_xy[1] = p.g.y;
external.primaries_blue_xy[0] = p.b.x;
external.primaries_blue_xy[1] = p.b.y;
}
if (tf.have_gamma) {
external.transfer_function = JXL_TRANSFER_FUNCTION_GAMMA;
external.gamma = tf.GetGamma();
} else {
external.transfer_function =
static_cast<JxlTransferFunction>(tf.GetTransferFunction());
external.gamma = 0;
}
external.rendering_intent =
static_cast<JxlRenderingIntent>(rendering_intent);
return external;
}
// NB: does not create ICC.
Status FromExternal(const JxlColorEncoding& external) {
// TODO(eustas): update non-serializable on call-site
color_space = static_cast<ColorSpace>(external.color_space);
JXL_RETURN_IF_ERROR(
WhitePointFromExternal(external.white_point, &white_point));
if (external.white_point == JXL_WHITE_POINT_CUSTOM) {
CIExy wp;
wp.x = external.white_point_xy[0];
wp.y = external.white_point_xy[1];
JXL_RETURN_IF_ERROR(SetWhitePoint(wp));
}
if (external.color_space == JXL_COLOR_SPACE_RGB ||
external.color_space == JXL_COLOR_SPACE_UNKNOWN) {
JXL_RETURN_IF_ERROR(
PrimariesFromExternal(external.primaries, &primaries));
if (external.primaries == JXL_PRIMARIES_CUSTOM) {
PrimariesCIExy primaries;
primaries.r.x = external.primaries_red_xy[0];
primaries.r.y = external.primaries_red_xy[1];
primaries.g.x = external.primaries_green_xy[0];
primaries.g.y = external.primaries_green_xy[1];
primaries.b.x = external.primaries_blue_xy[0];
primaries.b.y = external.primaries_blue_xy[1];
JXL_RETURN_IF_ERROR(SetPrimaries(primaries));
}
}
CustomTransferFunction tf;
if (external.transfer_function == JXL_TRANSFER_FUNCTION_GAMMA) {
JXL_RETURN_IF_ERROR(tf.SetGamma(external.gamma));
} else {
TransferFunction tf_enum;
// JXL_TRANSFER_FUNCTION_GAMMA is not handled by this function since
// there's no internal enum value for it.
JXL_RETURN_IF_ERROR(ConvertExternalToInternalTransferFunction(
external.transfer_function, &tf_enum));
tf.SetTransferFunction(tf_enum);
}
this->tf = tf;
JXL_RETURN_IF_ERROR(RenderingIntentFromExternal(external.rendering_intent,
&rendering_intent));
icc.clear();
return true;
}
};
} // namespace cms
} // namespace jxl
#endif // LIB_JXL_CMS_COLOR_ENCODING_CMS_H_