From a5a31dd99467604f345850881dc8540c62aa506c Mon Sep 17 00:00:00 2001 From: msarett Date: Tue, 11 Oct 2016 09:41:16 -0700 Subject: Add SkColorSpacePrimaries to help with making D50 matrices BUG=skia: GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2304753002 Review-Url: https://codereview.chromium.org/2304753002 --- src/codec/SkPngCodec.cpp | 85 ++++++++---------------------------------------- 1 file changed, 13 insertions(+), 72 deletions(-) (limited to 'src/codec') diff --git a/src/codec/SkPngCodec.cpp b/src/codec/SkPngCodec.cpp index dde49d037d..55a29604a9 100644 --- a/src/codec/SkPngCodec.cpp +++ b/src/codec/SkPngCodec.cpp @@ -322,63 +322,6 @@ static constexpr float gSRGB_toXYZD50[] { 0.0139f, 0.0971f, 0.7139f, // Rz, Gz, Bz }; -static bool convert_to_D50(SkMatrix44* toXYZD50, float toXYZ[9], float whitePoint[2]) { - float wX = whitePoint[0]; - float wY = whitePoint[1]; - if (wX < 0.0f || wY < 0.0f || (wX + wY > 1.0f)) { - return false; - } - - // Calculate the XYZ illuminant. Call this the src illuminant. - float wZ = 1.0f - wX - wY; - float scale = 1.0f / wY; - // TODO (msarett): - // What are common src illuminants? I'm guessing we will almost always see D65. Should - // we go ahead and save a precomputed D65->D50 Bradford matrix? Should we exit early if - // if the src illuminant is D50? - SkVector3 srcXYZ = SkVector3::Make(wX * scale, 1.0f, wZ * scale); - - // The D50 illuminant. - SkVector3 dstXYZ = SkVector3::Make(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. - // http://www.brucelindbloom.com/index.html?Eqn_ChromAdapt.html - SkMatrix mA, mAInv; - mA.setAll(0.8951f, 0.2664f, -0.1614f, -0.7502f, 1.7135f, 0.0367f, 0.0389f, -0.0685f, 1.0296f); - mAInv.setAll(0.9869929f, -0.1470543f, 0.1599627f, 0.4323053f, 0.5183603f, 0.0492912f, - -0.0085287f, 0.0400428f, 0.9684867f); - - // Map illuminant into cone response domain. - SkVector3 srcCone; - srcCone.fX = mA[0] * srcXYZ.fX + mA[1] * srcXYZ.fY + mA[2] * srcXYZ.fZ; - srcCone.fY = mA[3] * srcXYZ.fX + mA[4] * srcXYZ.fY + mA[5] * srcXYZ.fZ; - srcCone.fZ = mA[6] * srcXYZ.fX + mA[7] * srcXYZ.fY + mA[8] * srcXYZ.fZ; - SkVector3 dstCone; - dstCone.fX = mA[0] * dstXYZ.fX + mA[1] * dstXYZ.fY + mA[2] * dstXYZ.fZ; - dstCone.fY = mA[3] * dstXYZ.fX + mA[4] * dstXYZ.fY + mA[5] * dstXYZ.fZ; - dstCone.fZ = mA[6] * dstXYZ.fX + mA[7] * dstXYZ.fY + mA[8] * dstXYZ.fZ; - - SkMatrix DXToD50; - DXToD50.setIdentity(); - DXToD50[0] = dstCone.fX / srcCone.fX; - DXToD50[4] = dstCone.fY / srcCone.fY; - DXToD50[8] = dstCone.fZ / srcCone.fZ; - DXToD50.postConcat(mAInv); - DXToD50.preConcat(mA); - - SkMatrix toXYZ3x3; - toXYZ3x3.setAll(toXYZ[0], toXYZ[3], toXYZ[6], toXYZ[1], toXYZ[4], toXYZ[7], toXYZ[2], toXYZ[5], - toXYZ[8]); - toXYZ3x3.postConcat(DXToD50); - - toXYZD50->set3x3(toXYZ3x3[0], toXYZ3x3[3], toXYZ3x3[6], - toXYZ3x3[1], toXYZ3x3[4], toXYZ3x3[7], - toXYZ3x3[2], toXYZ3x3[5], toXYZ3x3[8]); - return true; -} - #endif // LIBPNG >= 1.6 // Returns a colorSpace object that represents any color space information in @@ -416,26 +359,24 @@ sk_sp read_color_space(png_structp png_ptr, png_infop info_ptr) { } // Next, check for chromaticities. - png_fixed_point toXYZFixed[9]; - float toXYZ[9]; - png_fixed_point whitePointFixed[2]; - float whitePoint[2]; + png_fixed_point chrm[8]; png_fixed_point gamma; float gammas[3]; - if (png_get_cHRM_XYZ_fixed(png_ptr, info_ptr, &toXYZFixed[0], &toXYZFixed[1], &toXYZFixed[2], - &toXYZFixed[3], &toXYZFixed[4], &toXYZFixed[5], &toXYZFixed[6], - &toXYZFixed[7], &toXYZFixed[8]) && - png_get_cHRM_fixed(png_ptr, info_ptr, &whitePointFixed[0], &whitePointFixed[1], nullptr, - nullptr, nullptr, nullptr, nullptr, nullptr)) + if (png_get_cHRM_fixed(png_ptr, info_ptr, &chrm[0], &chrm[1], &chrm[2], &chrm[3], &chrm[4], + &chrm[5], &chrm[6], &chrm[7])) { - for (int i = 0; i < 9; i++) { - toXYZ[i] = png_fixed_point_to_float(toXYZFixed[i]); - } - whitePoint[0] = png_fixed_point_to_float(whitePointFixed[0]); - whitePoint[1] = png_fixed_point_to_float(whitePointFixed[1]); + SkColorSpacePrimaries primaries; + primaries.fRX = png_fixed_point_to_float(chrm[2]); + primaries.fRY = png_fixed_point_to_float(chrm[3]); + primaries.fGX = png_fixed_point_to_float(chrm[4]); + primaries.fGY = png_fixed_point_to_float(chrm[5]); + primaries.fBX = png_fixed_point_to_float(chrm[6]); + primaries.fBY = png_fixed_point_to_float(chrm[7]); + primaries.fWX = png_fixed_point_to_float(chrm[0]); + primaries.fWY = png_fixed_point_to_float(chrm[1]); SkMatrix44 toXYZD50(SkMatrix44::kUninitialized_Constructor); - if (!convert_to_D50(&toXYZD50, toXYZ, whitePoint)) { + if (!primaries.toXYZD50(&toXYZD50)) { toXYZD50.set3x3RowMajorf(gSRGB_toXYZD50); } -- cgit v1.2.3