From dc27a648d2ff23b2e96232c00c15976c46e1d48d Mon Sep 17 00:00:00 2001 From: msarett Date: Mon, 6 Jun 2016 12:02:31 -0700 Subject: [PATCH] Add SkDefaultXform as a catch-all to handle color conversions I'd like to start optimizing the common case for color xforms, but before doing that, I think it makes sense to have correct code to support all xforms. BUG=skia: GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2038823002 Review-Url: https://codereview.chromium.org/2038823002 --- src/core/SkColorSpace.cpp | 26 +++-- src/core/SkColorSpaceXform.cpp | 208 +++++++++++++++++++++++++++++---- src/core/SkColorSpaceXform.h | 23 +++- src/core/SkColorSpace_Base.h | 7 ++ tests/ColorSpaceXformTest.cpp | 103 ++++++++++++++++ 5 files changed, 331 insertions(+), 36 deletions(-) create mode 100644 tests/ColorSpaceXformTest.cpp diff --git a/src/core/SkColorSpace.cpp b/src/core/SkColorSpace.cpp index 1652de37a8..6bc897c8a9 100644 --- a/src/core/SkColorSpace.cpp +++ b/src/core/SkColorSpace.cpp @@ -719,19 +719,21 @@ bool load_matrix(SkMatrix44* toXYZ, const uint8_t* src, size_t len) { return false; } + // For this matrix to behave like our "to XYZ D50" matrices, it needs to be scaled. + constexpr float scale = 65535.0 / 32768.0; float array[16]; - array[ 0] = SkFixedToFloat(read_big_endian_int(src)); - array[ 1] = SkFixedToFloat(read_big_endian_int(src + 4)); - array[ 2] = SkFixedToFloat(read_big_endian_int(src + 8)); - array[ 3] = SkFixedToFloat(read_big_endian_int(src + 36)); // translate R - array[ 4] = SkFixedToFloat(read_big_endian_int(src + 12)); - array[ 5] = SkFixedToFloat(read_big_endian_int(src + 16)); - array[ 6] = SkFixedToFloat(read_big_endian_int(src + 20)); - array[ 7] = SkFixedToFloat(read_big_endian_int(src + 40)); // translate G - array[ 8] = SkFixedToFloat(read_big_endian_int(src + 24)); - array[ 9] = SkFixedToFloat(read_big_endian_int(src + 28)); - array[10] = SkFixedToFloat(read_big_endian_int(src + 32)); - array[11] = SkFixedToFloat(read_big_endian_int(src + 44)); // translate B + array[ 0] = scale * SkFixedToFloat(read_big_endian_int(src)); + array[ 1] = scale * SkFixedToFloat(read_big_endian_int(src + 4)); + array[ 2] = scale * SkFixedToFloat(read_big_endian_int(src + 8)); + array[ 3] = scale * SkFixedToFloat(read_big_endian_int(src + 36)); // translate R + array[ 4] = scale * SkFixedToFloat(read_big_endian_int(src + 12)); + array[ 5] = scale * SkFixedToFloat(read_big_endian_int(src + 16)); + array[ 6] = scale * SkFixedToFloat(read_big_endian_int(src + 20)); + array[ 7] = scale * SkFixedToFloat(read_big_endian_int(src + 40)); // translate G + array[ 8] = scale * SkFixedToFloat(read_big_endian_int(src + 24)); + array[ 9] = scale * SkFixedToFloat(read_big_endian_int(src + 28)); + array[10] = scale * SkFixedToFloat(read_big_endian_int(src + 32)); + array[11] = scale * SkFixedToFloat(read_big_endian_int(src + 44)); // translate B array[12] = 0.0f; array[13] = 0.0f; array[14] = 0.0f; diff --git a/src/core/SkColorSpaceXform.cpp b/src/core/SkColorSpaceXform.cpp index 473e715353..216e9931ba 100644 --- a/src/core/SkColorSpaceXform.cpp +++ b/src/core/SkColorSpaceXform.cpp @@ -9,8 +9,8 @@ #include "SkColorSpace_Base.h" #include "SkColorSpaceXform.h" -bool compute_gamut_xform(SkMatrix44* srcToDst, const SkMatrix44& srcToXYZ, - const SkMatrix44& dstToXYZ) { +static inline bool compute_gamut_xform(SkMatrix44* srcToDst, const SkMatrix44& srcToXYZ, + const SkMatrix44& dstToXYZ) { if (!dstToXYZ.invert(srcToDst)) { return false; } @@ -22,15 +22,21 @@ bool compute_gamut_xform(SkMatrix44* srcToDst, const SkMatrix44& srcToXYZ, std::unique_ptr SkColorSpaceXform::New(const sk_sp& srcSpace, const sk_sp& dstSpace) { if (!srcSpace || !dstSpace) { + // Invalid input + return nullptr; + } + + if (as_CSB(srcSpace)->colorLUT() || as_CSB(dstSpace)->colorLUT()) { + // Unimplemented + return nullptr; + } + + SkMatrix44 srcToDst(SkMatrix44::kUninitialized_Constructor); + if (!compute_gamut_xform(&srcToDst, srcSpace->xyz(), dstSpace->xyz())) { return nullptr; } if (as_CSB(srcSpace)->gammas()->isValues() && as_CSB(dstSpace)->gammas()->isValues()) { - SkMatrix44 srcToDst(SkMatrix44::kUninitialized_Constructor); - if (!compute_gamut_xform(&srcToDst, srcSpace->xyz(), dstSpace->xyz())) { - return nullptr; - } - float srcGammas[3]; float dstGammas[3]; srcGammas[0] = as_CSB(srcSpace)->gammas()->fRed.fValue; @@ -44,8 +50,25 @@ std::unique_ptr SkColorSpaceXform::New(const sk_sp( + new SkDefaultXform(as_CSB(srcSpace)->gammas(), srcToDst, as_CSB(dstSpace)->gammas())); +} + +/////////////////////////////////////////////////////////////////////////////////////////////////// + +static inline float byte_to_float(uint8_t v) { + return ((float) v) * (1.0f / 255.0f); +} + +static inline uint8_t clamp_float_to_byte(float v) { + v = v * 255.0f; + if (v > 255.0f) { + return 255; + } else if (v <= 0.0f) { + return 0; + } else { + return (uint8_t) (v + 0.5f); + } } /////////////////////////////////////////////////////////////////////////////////////////////////// @@ -58,23 +81,12 @@ SkGammaByValueXform::SkGammaByValueXform(float srcGammas[3], const SkMatrix44& s memcpy(fDstGammas, dstGammas, 3 * sizeof(float)); } -static uint8_t clamp_float_to_byte(float v) { - v = v * 255.0f; - if (v > 255.0f) { - return 255; - } else if (v <= 0.0f) { - return 0; - } else { - return (uint8_t) (v + 0.5f); - } -} - void SkGammaByValueXform::xform_RGBA_8888(uint32_t* dst, const uint32_t* src, uint32_t len) const { while (len-- > 0) { float srcFloats[3]; - srcFloats[0] = ((*src >> 0) & 0xFF) * (1.0f / 255.0f); - srcFloats[1] = ((*src >> 8) & 0xFF) * (1.0f / 255.0f); - srcFloats[2] = ((*src >> 16) & 0xFF) * (1.0f / 255.0f); + srcFloats[0] = byte_to_float((*src >> 0) & 0xFF); + srcFloats[1] = byte_to_float((*src >> 8) & 0xFF); + srcFloats[2] = byte_to_float((*src >> 16) & 0xFF); // Convert to linear. srcFloats[0] = pow(srcFloats[0], fSrcGammas[0]); @@ -107,3 +119,153 @@ void SkGammaByValueXform::xform_RGBA_8888(uint32_t* dst, const uint32_t* src, ui src++; } } + +/////////////////////////////////////////////////////////////////////////////////////////////////// + +// Interpolating lookup in a variably sized table. +static inline float interp_lut(uint8_t byte, float* table, size_t tableSize) { + float index = byte_to_float(byte) * (tableSize - 1); + float diff = index - sk_float_floor2int(index); + return table[(int) sk_float_floor2int(index)] * (1.0f - diff) + + table[(int) sk_float_ceil2int(index)] * diff; +} + +// Inverse table lookup. Ex: what index corresponds to the input value? This will +// have strange results when the table is non-increasing. But any sane gamma +// function will be increasing. +// FIXME (msarett): +// This is a placeholder implementation for inverting table gammas. First, I need to +// verify if there are actually destination profiles that require this functionality. +// Next, there are certainly faster and more robust approaches to solving this problem. +// The LUT based approach in QCMS would be a good place to start. +static inline float interp_lut_inv(float input, float* table, size_t tableSize) { + if (input <= table[0]) { + return table[0]; + } else if (input >= table[tableSize - 1]) { + return 1.0f; + } + + for (uint32_t i = 1; i < tableSize; i++) { + if (table[i] >= input) { + // We are guaranteed that input is greater than table[i - 1]. + float diff = input - table[i - 1]; + float distance = table[i] - table[i - 1]; + float index = (i - 1) + diff / distance; + return index / (tableSize - 1); + } + } + + // Should be unreachable, since we'll return before the loop if input is + // larger than the last entry. + SkASSERT(false); + return 0.0f; +} + +SkDefaultXform::SkDefaultXform(const sk_sp& srcGammas, const SkMatrix44& srcToDst, + const sk_sp& dstGammas) + : fSrcGammas(srcGammas) + , fSrcToDst(srcToDst) + , fDstGammas(dstGammas) +{} + +void SkDefaultXform::xform_RGBA_8888(uint32_t* dst, const uint32_t* src, uint32_t len) const { + while (len-- > 0) { + // Convert to linear. + // FIXME (msarett): + // Rather than support three different strategies of transforming gamma, QCMS + // builds a 256 entry float lookup table from the gamma info. This handles + // the gamma transform and the conversion from bytes to floats. This may + // be simpler and faster than our current approach. + float srcFloats[3]; + for (int i = 0; i < 3; i++) { + const SkGammaCurve& gamma = (*fSrcGammas)[i]; + uint8_t byte = (*src >> (8 * i)) & 0xFF; + if (gamma.isValue()) { + srcFloats[i] = pow(byte_to_float(byte), gamma.fValue); + } else if (gamma.isTable()) { + srcFloats[i] = interp_lut(byte, gamma.fTable.get(), gamma.fTableSize); + } else { + SkASSERT(gamma.isParametric()); + float component = byte_to_float(byte); + if (component < gamma.fD) { + // Y = E * X + F + srcFloats[i] = gamma.fE * component + gamma.fF; + } else { + // Y = (A * X + B)^G + C + srcFloats[i] = pow(gamma.fA * component + gamma.fB, gamma.fG) + gamma.fC; + } + } + } + + // Convert to dst gamut. + float dstFloats[3]; + dstFloats[0] = srcFloats[0] * fSrcToDst.getFloat(0, 0) + + srcFloats[1] * fSrcToDst.getFloat(1, 0) + + srcFloats[2] * fSrcToDst.getFloat(2, 0) + fSrcToDst.getFloat(3, 0); + dstFloats[1] = srcFloats[0] * fSrcToDst.getFloat(0, 1) + + srcFloats[1] * fSrcToDst.getFloat(1, 1) + + srcFloats[2] * fSrcToDst.getFloat(2, 1) + fSrcToDst.getFloat(3, 1); + dstFloats[2] = srcFloats[0] * fSrcToDst.getFloat(0, 2) + + srcFloats[1] * fSrcToDst.getFloat(1, 2) + + srcFloats[2] * fSrcToDst.getFloat(2, 2) + fSrcToDst.getFloat(3, 2); + + // Convert to dst gamma. + // FIXME (msarett): + // Rather than support three different strategies of transforming inverse gamma, + // QCMS builds a large float lookup table from the gamma info. Is this faster or + // better than our approach? + for (int i = 0; i < 3; i++) { + const SkGammaCurve& gamma = (*fDstGammas)[i]; + if (gamma.isValue()) { + dstFloats[i] = pow(dstFloats[i], 1.0f / gamma.fValue); + } else if (gamma.isTable()) { + // FIXME (msarett): + // An inverse table lookup is particularly strange and non-optimal. + dstFloats[i] = interp_lut_inv(dstFloats[i], gamma.fTable.get(), gamma.fTableSize); + } else { + SkASSERT(gamma.isParametric()); + // FIXME (msarett): + // This is a placeholder implementation for inverting parametric gammas. + // First, I need to verify if there are actually destination profiles that + // require this functionality. Next, I need to explore other possibilities + // for this implementation. The LUT based approach in QCMS would be a good + // place to start. + + // We need to take the inverse of a piecewise function. Assume that + // the gamma function is continuous, or this won't make much sense + // anyway. + // Plug in |fD| to the first equation to calculate the new piecewise + // interval. Then simply use the inverse of the original functions. + float interval = gamma.fE * gamma.fD + gamma.fF; + if (dstFloats[i] < interval) { + // X = (Y - F) / E + if (0.0f == gamma.fE) { + // The gamma curve for this segment is constant, so the inverse + // is undefined. + dstFloats[i] = 0.0f; + } else { + dstFloats[i] = (dstFloats[i] - gamma.fF) / gamma.fE; + } + } else { + // X = ((Y - C)^(1 / G) - B) / A + if (0.0f == gamma.fA || 0.0f == gamma.fG) { + // The gamma curve for this segment is constant, so the inverse + // is undefined. + dstFloats[i] = 0.0f; + } else { + dstFloats[i] = (pow(dstFloats[i] - gamma.fC, 1.0f / gamma.fG) - gamma.fB) + / gamma.fA; + } + } + } + } + + *dst = SkPackARGB32NoCheck(((*src >> 24) & 0xFF), + clamp_float_to_byte(dstFloats[0]), + clamp_float_to_byte(dstFloats[1]), + clamp_float_to_byte(dstFloats[2])); + + dst++; + src++; + } +} diff --git a/src/core/SkColorSpaceXform.h b/src/core/SkColorSpaceXform.h index c3010f0cca..d54d1b812d 100644 --- a/src/core/SkColorSpaceXform.h +++ b/src/core/SkColorSpaceXform.h @@ -9,8 +9,9 @@ #define SkColorSpaceXform_DEFINED #include "SkColorSpace.h" +#include "SkColorSpace_Base.h" -class SkColorSpaceXform { +class SkColorSpaceXform : SkNoncopyable { public: /** @@ -48,4 +49,24 @@ private: friend class SkColorSpaceXform; }; +/** + * Works for any valid src and dst profiles. + */ +class SkDefaultXform : public SkColorSpaceXform { +public: + + void xform_RGBA_8888(uint32_t* dst, const uint32_t* src, uint32_t len) const override; + +private: + SkDefaultXform(const sk_sp& srcGammas, const SkMatrix44& srcToDst, + const sk_sp& dstGammas); + + sk_sp fSrcGammas; + const SkMatrix44 fSrcToDst; + sk_sp fDstGammas; + + friend class SkColorSpaceXform; + friend class ColorSpaceXformTest; +}; + #endif diff --git a/src/core/SkColorSpace_Base.h b/src/core/SkColorSpace_Base.h index 68514d0ad6..ffab17a1fd 100644 --- a/src/core/SkColorSpace_Base.h +++ b/src/core/SkColorSpace_Base.h @@ -78,6 +78,11 @@ public: return fRed.isValue() && fGreen.isValue() && fBlue.isValue(); } + const SkGammaCurve& operator[](int i) { + SkASSERT(0 <= i && i < 3); + return (&fRed)[i]; + } + const SkGammaCurve fRed; const SkGammaCurve fGreen; const SkGammaCurve fBlue; @@ -117,6 +122,8 @@ public: const sk_sp& gammas() const { return fGammas; } + SkColorLookUpTable* colorLUT() const { return fColorLUT.get(); } + /** * Writes this object as an ICC profile. */ diff --git a/tests/ColorSpaceXformTest.cpp b/tests/ColorSpaceXformTest.cpp new file mode 100644 index 0000000000..220509b9f6 --- /dev/null +++ b/tests/ColorSpaceXformTest.cpp @@ -0,0 +1,103 @@ +/* + * Copyright 2016 Google Inc. + * + * Use of this source code is governed by a BSD-style license that can be + * found in the LICENSE file. + */ + +#include "Resources.h" +#include "SkCodec.h" +#include "SkColorPriv.h" +#include "SkColorSpace.h" +#include "SkColorSpace_Base.h" +#include "SkColorSpaceXform.h" +#include "Test.h" + +class ColorSpaceXformTest { +public: + static SkDefaultXform* CreateDefaultXform(const sk_sp& srcGamma, + const SkMatrix44& srcToDst, const sk_sp& dstGamma) { + return new SkDefaultXform(srcGamma, srcToDst, dstGamma); + } +}; + +static void test_xform(skiatest::Reporter* r, const sk_sp& gammas) { + // Arbitrary set of 10 pixels + constexpr int width = 10; + constexpr uint32_t srcPixels[width] = { + 0xFFABCDEF, 0xFF146829, 0xFF382759, 0xFF184968, 0xFFDE8271, + 0xFF32AB52, 0xFF0383BC, 0xFF000000, 0xFFFFFFFF, 0xFFDDEEFF, }; + uint32_t dstPixels[width]; + + // Identity matrix + SkMatrix44 srcToDst = SkMatrix44::I(); + + // Create and perform xform + std::unique_ptr xform( + ColorSpaceXformTest::CreateDefaultXform(gammas, srcToDst, gammas)); + xform->xform_RGBA_8888(dstPixels, srcPixels, width); + + // Since the matrix is the identity, and the gamma curves match, the pixels + // should be unchanged. + for (int i = 0; i < width; i++) { + // TODO (msarett): + // As the implementation changes, we may want to use a tolerance here. + REPORTER_ASSERT(r, ((srcPixels[i] >> 0) & 0xFF) == SkGetPackedR32(dstPixels[i])); + REPORTER_ASSERT(r, ((srcPixels[i] >> 8) & 0xFF) == SkGetPackedG32(dstPixels[i])); + REPORTER_ASSERT(r, ((srcPixels[i] >> 16) & 0xFF) == SkGetPackedB32(dstPixels[i])); + REPORTER_ASSERT(r, ((srcPixels[i] >> 24) & 0xFF) == SkGetPackedA32(dstPixels[i])); + } +} + +DEF_TEST(ColorSpaceXform_TableGamma, r) { + // Lookup-table based gamma curves + SkGammaCurve red, green, blue; + constexpr size_t tableSize = 10; + red.fTable = std::unique_ptr(new float[tableSize]); + green.fTable = std::unique_ptr(new float[tableSize]); + blue.fTable = std::unique_ptr(new float[tableSize]); + red.fTableSize = green.fTableSize = blue.fTableSize = 10; + red.fTable[0] = green.fTable[0] = blue.fTable[0] = 0.00f; + red.fTable[1] = green.fTable[1] = blue.fTable[1] = 0.05f; + red.fTable[2] = green.fTable[2] = blue.fTable[2] = 0.10f; + red.fTable[3] = green.fTable[3] = blue.fTable[3] = 0.15f; + red.fTable[4] = green.fTable[4] = blue.fTable[4] = 0.25f; + red.fTable[5] = green.fTable[5] = blue.fTable[5] = 0.35f; + red.fTable[6] = green.fTable[6] = blue.fTable[6] = 0.45f; + red.fTable[7] = green.fTable[7] = blue.fTable[7] = 0.60f; + red.fTable[8] = green.fTable[8] = blue.fTable[8] = 0.75f; + red.fTable[9] = green.fTable[9] = blue.fTable[9] = 1.00f; + sk_sp gammas = + sk_make_sp(std::move(red), std::move(green), std::move(blue)); + test_xform(r, gammas); +} + +DEF_TEST(ColorSpaceXform_ParametricGamma, r) { + // Parametric gamma curves + SkGammaCurve red, green, blue; + + // Interval, switch xforms at 0.5f + red.fD = green.fD = blue.fD = 0.5f; + + // First equation, Y = 0.5f * X + red.fE = green.fE = blue.fE = 0.5f; + + // Second equation, Y = ((1.0f * X) + 0.0f) ^ 3.0f + 0.125f + // Note that the function is continuous: + // 0.5f * 0.5f = ((1.0f * 0.5f) + 0.0f) ^ 3.0f + 0.125f = 0.25f + red.fA = green.fA = blue.fA = 1.0f; + red.fB = green.fB = blue.fB = 0.0f; + red.fC = green.fC = blue.fC = 0.125f; + red.fG = green.fG = blue.fG = 3.0f; + sk_sp gammas = sk_make_sp(std::move(red), std::move(green), std::move(blue)); + test_xform(r, gammas); +} + +DEF_TEST(ColorSpaceXform_ExponentialGamma, r) { + // Exponential gamma curves + SkGammaCurve red, green, blue; + red.fValue = green.fValue = blue.fValue = 4.0f; + sk_sp gammas = + sk_make_sp(std::move(red), std::move(green), std::move(blue)); + test_xform(r, gammas); +}