| /* |
| * 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 "SkColorPriv.h" |
| #include "SkColorSpace_Base.h" |
| #include "SkColorSpaceXform.h" |
| #include "SkOpts.h" |
| |
| static inline bool compute_gamut_xform(SkMatrix44* srcToDst, const SkMatrix44& srcToXYZ, |
| const SkMatrix44& dstToXYZ) { |
| if (!dstToXYZ.invert(srcToDst)) { |
| return false; |
| } |
| |
| srcToDst->postConcat(srcToXYZ); |
| return true; |
| } |
| |
| std::unique_ptr<SkColorSpaceXform> SkColorSpaceXform::New(const sk_sp<SkColorSpace>& srcSpace, |
| const sk_sp<SkColorSpace>& 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 (SkColorSpace::k2Dot2Curve_GammaNamed == srcSpace->gammaNamed() && |
| SkColorSpace::k2Dot2Curve_GammaNamed == dstSpace->gammaNamed()) |
| { |
| return std::unique_ptr<SkColorSpaceXform>(new Sk2Dot2Xform(srcToDst)); |
| } |
| |
| return std::unique_ptr<SkColorSpaceXform>( |
| new SkDefaultXform(as_CSB(srcSpace)->gammas(), srcToDst, as_CSB(dstSpace)->gammas())); |
| } |
| |
| /////////////////////////////////////////////////////////////////////////////////////////////////// |
| |
| Sk2Dot2Xform::Sk2Dot2Xform(const SkMatrix44& srcToDst) |
| { |
| // Build row major 4x4 matrix: |
| // rX gX bX 0 |
| // rY gY bY 0 |
| // rZ gZ bZ 0 |
| // rQ gQ bQ 0 |
| fSrcToDst[0] = srcToDst.getFloat(0, 0); |
| fSrcToDst[1] = srcToDst.getFloat(0, 1); |
| fSrcToDst[2] = srcToDst.getFloat(0, 2); |
| fSrcToDst[3] = 0.0f; |
| fSrcToDst[4] = srcToDst.getFloat(1, 0); |
| fSrcToDst[5] = srcToDst.getFloat(1, 1); |
| fSrcToDst[6] = srcToDst.getFloat(1, 2); |
| fSrcToDst[7] = 0.0f; |
| fSrcToDst[8] = srcToDst.getFloat(2, 0); |
| fSrcToDst[9] = srcToDst.getFloat(2, 1); |
| fSrcToDst[10] = srcToDst.getFloat(2, 2); |
| fSrcToDst[11] = 0.0f; |
| fSrcToDst[12] = srcToDst.getFloat(3, 0); |
| fSrcToDst[13] = srcToDst.getFloat(3, 1); |
| fSrcToDst[14] = srcToDst.getFloat(3, 2); |
| fSrcToDst[15] = 0.0f; |
| } |
| |
| void Sk2Dot2Xform::xform_RGBA_8888(uint32_t* dst, const uint32_t* src, uint32_t len) const { |
| SkOpts::color_xform_2Dot2_RGBA_to_8888(dst, src, len, fSrcToDst); |
| } |
| |
| /////////////////////////////////////////////////////////////////////////////////////////////////// |
| |
| static inline float byte_to_float(uint8_t v) { |
| return ((float) v) * (1.0f / 255.0f); |
| } |
| |
| // Expand range from 0-1 to 0-255, then convert. |
| static inline uint8_t clamp_normalized_float_to_byte(float v) { |
| v = v * 255.0f; |
| if (v >= 254.5f) { |
| return 255; |
| } else if (v < 0.5f) { |
| return 0; |
| } else { |
| return (uint8_t) (v + 0.5f); |
| } |
| } |
| |
| // 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<SkGammas>& srcGammas, const SkMatrix44& srcToDst, |
| const sk_sp<SkGammas>& 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_normalized_float_to_byte(dstFloats[0]), |
| clamp_normalized_float_to_byte(dstFloats[1]), |
| clamp_normalized_float_to_byte(dstFloats[2])); |
| |
| dst++; |
| src++; |
| } |
| } |