diff options
| -rw-r--r-- | gyp/core.gypi | 1 | ||||
| -rw-r--r-- | src/core/SkColorSpaceXform.cpp | 68 | ||||
| -rw-r--r-- | src/core/SkSRGB.cpp | 75 | ||||
| -rw-r--r-- | src/core/SkSRGB.h | 50 | ||||
| -rw-r--r-- | src/opts/SkColorXform_opts.h | 26 | ||||
| -rw-r--r-- | tests/SRGBTest.cpp | 34 |
6 files changed, 164 insertions, 90 deletions
diff --git a/gyp/core.gypi b/gyp/core.gypi index 91387a39d0..97e38c2cc6 100644 --- a/gyp/core.gypi +++ b/gyp/core.gypi @@ -291,6 +291,7 @@ '<(skia_src_path)/core/SkStrokerPriv.h', '<(skia_src_path)/core/SkSurfacePriv.h', '<(skia_src_path)/core/SkSwizzle.cpp', + '<(skia_src_path)/core/SkSRGB.cpp', '<(skia_src_path)/core/SkTaskGroup.cpp', '<(skia_src_path)/core/SkTaskGroup.h', '<(skia_src_path)/core/SkTDPQueue.h', diff --git a/src/core/SkColorSpaceXform.cpp b/src/core/SkColorSpaceXform.cpp index cb95c2999d..e913c5555a 100644 --- a/src/core/SkColorSpaceXform.cpp +++ b/src/core/SkColorSpaceXform.cpp @@ -9,6 +9,7 @@ #include "SkColorSpace_Base.h" #include "SkColorSpaceXform.h" #include "SkOpts.h" +#include "SkSRGB.h" static inline bool compute_gamut_xform(SkMatrix44* srcToDst, const SkMatrix44& srcToXYZ, const SkMatrix44& dstToXYZ) { @@ -147,73 +148,6 @@ void SkFastXform<SkColorSpace::k2Dot2Curve_GammaNamed, SkColorSpace::k2Dot2Curve /////////////////////////////////////////////////////////////////////////////////////////////////// -extern const float sk_linear_from_srgb[256] = { - 0.000000000000000000f, 0.000303526983548838f, 0.000607053967097675f, 0.000910580950646513f, - 0.001214107934195350f, 0.001517634917744190f, 0.001821161901293030f, 0.002124688884841860f, - 0.002428215868390700f, 0.002731742851939540f, 0.003034518678424960f, 0.003346535763899160f, - 0.003676507324047440f, 0.004024717018496310f, 0.004391442037410290f, 0.004776953480693730f, - 0.005181516702338390f, 0.005605391624202720f, 0.006048833022857060f, 0.006512090792594470f, - 0.006995410187265390f, 0.007499032043226180f, 0.008023192985384990f, 0.008568125618069310f, - 0.009134058702220790f, 0.009721217320237850f, 0.010329823029626900f, 0.010960094006488200f, - 0.011612245179743900f, 0.012286488356915900f, 0.012983032342173000f, 0.013702083047289700f, - 0.014443843596092500f, 0.015208514422912700f, 0.015996293365509600f, 0.016807375752887400f, - 0.017641954488384100f, 0.018500220128379700f, 0.019382360956935700f, 0.020288563056652400f, - 0.021219010376003600f, 0.022173884793387400f, 0.023153366178110400f, 0.024157632448504800f, - 0.025186859627361600f, 0.026241221894849900f, 0.027320891639074900f, 0.028426039504420800f, - 0.029556834437808800f, 0.030713443732993600f, 0.031896033073011500f, 0.033104766570885100f, - 0.034339806808682200f, 0.035601314875020300f, 0.036889450401100000f, 0.038204371595346500f, - 0.039546235276732800f, 0.040915196906853200f, 0.042311410620809700f, 0.043735029256973500f, - 0.045186204385675500f, 0.046665086336880100f, 0.048171824226889400f, 0.049706565984127200f, - 0.051269458374043200f, 0.052860647023180200f, 0.054480276442442400f, 0.056128490049600100f, - 0.057805430191067200f, 0.059511238162981200f, 0.061246054231617600f, 0.063010017653167700f, - 0.064803266692905800f, 0.066625938643772900f, 0.068478169844400200f, 0.070360095696595900f, - 0.072271850682317500f, 0.074213568380149600f, 0.076185381481307900f, 0.078187421805186300f, - 0.080219820314468300f, 0.082282707129814800f, 0.084376211544148800f, 0.086500462036549800f, - 0.088655586285772900f, 0.090841711183407700f, 0.093058962846687500f, 0.095307466630964700f, - 0.097587347141862500f, 0.099898728247113900f, 0.102241733088101000f, 0.104616484091104000f, - 0.107023102978268000f, 0.109461710778299000f, 0.111932427836906000f, 0.114435373826974000f, - 0.116970667758511000f, 0.119538427988346000f, 0.122138772229602000f, 0.124771817560950000f, - 0.127437680435647000f, 0.130136476690364000f, 0.132868321553818000f, 0.135633329655206000f, - 0.138431615032452000f, 0.141263291140272000f, 0.144128470858058000f, 0.147027266497595000f, - 0.149959789810609000f, 0.152926151996150000f, 0.155926463707827000f, 0.158960835060880000f, - 0.162029375639111000f, 0.165132194501668000f, 0.168269400189691000f, 0.171441100732823000f, - 0.174647403655585000f, 0.177888415983629000f, 0.181164244249860000f, 0.184474994500441000f, - 0.187820772300678000f, 0.191201682740791000f, 0.194617830441576000f, 0.198069319559949000f, - 0.201556253794397000f, 0.205078736390317000f, 0.208636870145256000f, 0.212230757414055000f, - 0.215860500113899000f, 0.219526199729269000f, 0.223227957316809000f, 0.226965873510098000f, - 0.230740048524349000f, 0.234550582161005000f, 0.238397573812271000f, 0.242281122465555000f, - 0.246201326707835000f, 0.250158284729953000f, 0.254152094330827000f, 0.258182852921596000f, - 0.262250657529696000f, 0.266355604802862000f, 0.270497791013066000f, 0.274677312060385000f, - 0.278894263476810000f, 0.283148740429992000f, 0.287440837726918000f, 0.291770649817536000f, - 0.296138270798321000f, 0.300543794415777000f, 0.304987314069886000f, 0.309468922817509000f, - 0.313988713375718000f, 0.318546778125092000f, 0.323143209112951000f, 0.327778098056542000f, - 0.332451536346179000f, 0.337163615048330000f, 0.341914424908661000f, 0.346704056355030000f, - 0.351532599500439000f, 0.356400144145944000f, 0.361306779783510000f, 0.366252595598840000f, - 0.371237680474149000f, 0.376262122990906000f, 0.381326011432530000f, 0.386429433787049000f, - 0.391572477749723000f, 0.396755230725627000f, 0.401977779832196000f, 0.407240211901737000f, - 0.412542613483904000f, 0.417885070848138000f, 0.423267669986072000f, 0.428690496613907000f, - 0.434153636174749000f, 0.439657173840919000f, 0.445201194516228000f, 0.450785782838223000f, - 0.456411023180405000f, 0.462076999654407000f, 0.467783796112159000f, 0.473531496148010000f, - 0.479320183100827000f, 0.485149940056070000f, 0.491020849847836000f, 0.496932995060870000f, - 0.502886458032569000f, 0.508881320854934000f, 0.514917665376521000f, 0.520995573204354000f, - 0.527115125705813000f, 0.533276404010505000f, 0.539479489012107000f, 0.545724461370187000f, - 0.552011401512000000f, 0.558340389634268000f, 0.564711505704929000f, 0.571124829464873000f, - 0.577580440429651000f, 0.584078417891164000f, 0.590618840919337000f, 0.597201788363763000f, - 0.603827338855338000f, 0.610495570807865000f, 0.617206562419651000f, 0.623960391675076000f, - 0.630757136346147000f, 0.637596873994033000f, 0.644479681970582000f, 0.651405637419824000f, - 0.658374817279448000f, 0.665387298282272000f, 0.672443156957688000f, 0.679542469633094000f, - 0.686685312435314000f, 0.693871761291990000f, 0.701101891932973000f, 0.708375779891687000f, - 0.715693500506481000f, 0.723055128921969000f, 0.730460740090354000f, 0.737910408772731000f, - 0.745404209540387000f, 0.752942216776078000f, 0.760524504675292000f, 0.768151147247507000f, - 0.775822218317423000f, 0.783537791526194000f, 0.791297940332630000f, 0.799102738014409000f, - 0.806952257669252000f, 0.814846572216101000f, 0.822785754396284000f, 0.830769876774655000f, - 0.838799011740740000f, 0.846873231509858000f, 0.854992608124234000f, 0.863157213454102000f, - 0.871367119198797000f, 0.879622396887832000f, 0.887923117881966000f, 0.896269353374266000f, - 0.904661174391149000f, 0.913098651793419000f, 0.921581856277295000f, 0.930110858375424000f, - 0.938685728457888000f, 0.947306536733200000f, 0.955973353249286000f, 0.964686247894465000f, - 0.973445290398413000f, 0.982250550333117000f, 0.991102097113830000f, 1.000000000000000000f, -}; - extern const float sk_linear_from_2dot2[256] = { 0.000000000000000000f, 0.000005077051900662f, 0.000023328004666099f, 0.000056921765712193f, 0.000107187362341244f, 0.000175123977503027f, 0.000261543754548491f, 0.000367136269815943f, diff --git a/src/core/SkSRGB.cpp b/src/core/SkSRGB.cpp new file mode 100644 index 0000000000..57d2ae0373 --- /dev/null +++ b/src/core/SkSRGB.cpp @@ -0,0 +1,75 @@ +/* + * 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 "SkSRGB.h" + +const float sk_linear_from_srgb[256] = { + 0.000000000000000000f, 0.000303526983548838f, 0.000607053967097675f, 0.000910580950646513f, + 0.001214107934195350f, 0.001517634917744190f, 0.001821161901293030f, 0.002124688884841860f, + 0.002428215868390700f, 0.002731742851939540f, 0.003034518678424960f, 0.003346535763899160f, + 0.003676507324047440f, 0.004024717018496310f, 0.004391442037410290f, 0.004776953480693730f, + 0.005181516702338390f, 0.005605391624202720f, 0.006048833022857060f, 0.006512090792594470f, + 0.006995410187265390f, 0.007499032043226180f, 0.008023192985384990f, 0.008568125618069310f, + 0.009134058702220790f, 0.009721217320237850f, 0.010329823029626900f, 0.010960094006488200f, + 0.011612245179743900f, 0.012286488356915900f, 0.012983032342173000f, 0.013702083047289700f, + 0.014443843596092500f, 0.015208514422912700f, 0.015996293365509600f, 0.016807375752887400f, + 0.017641954488384100f, 0.018500220128379700f, 0.019382360956935700f, 0.020288563056652400f, + 0.021219010376003600f, 0.022173884793387400f, 0.023153366178110400f, 0.024157632448504800f, + 0.025186859627361600f, 0.026241221894849900f, 0.027320891639074900f, 0.028426039504420800f, + 0.029556834437808800f, 0.030713443732993600f, 0.031896033073011500f, 0.033104766570885100f, + 0.034339806808682200f, 0.035601314875020300f, 0.036889450401100000f, 0.038204371595346500f, + 0.039546235276732800f, 0.040915196906853200f, 0.042311410620809700f, 0.043735029256973500f, + 0.045186204385675500f, 0.046665086336880100f, 0.048171824226889400f, 0.049706565984127200f, + 0.051269458374043200f, 0.052860647023180200f, 0.054480276442442400f, 0.056128490049600100f, + 0.057805430191067200f, 0.059511238162981200f, 0.061246054231617600f, 0.063010017653167700f, + 0.064803266692905800f, 0.066625938643772900f, 0.068478169844400200f, 0.070360095696595900f, + 0.072271850682317500f, 0.074213568380149600f, 0.076185381481307900f, 0.078187421805186300f, + 0.080219820314468300f, 0.082282707129814800f, 0.084376211544148800f, 0.086500462036549800f, + 0.088655586285772900f, 0.090841711183407700f, 0.093058962846687500f, 0.095307466630964700f, + 0.097587347141862500f, 0.099898728247113900f, 0.102241733088101000f, 0.104616484091104000f, + 0.107023102978268000f, 0.109461710778299000f, 0.111932427836906000f, 0.114435373826974000f, + 0.116970667758511000f, 0.119538427988346000f, 0.122138772229602000f, 0.124771817560950000f, + 0.127437680435647000f, 0.130136476690364000f, 0.132868321553818000f, 0.135633329655206000f, + 0.138431615032452000f, 0.141263291140272000f, 0.144128470858058000f, 0.147027266497595000f, + 0.149959789810609000f, 0.152926151996150000f, 0.155926463707827000f, 0.158960835060880000f, + 0.162029375639111000f, 0.165132194501668000f, 0.168269400189691000f, 0.171441100732823000f, + 0.174647403655585000f, 0.177888415983629000f, 0.181164244249860000f, 0.184474994500441000f, + 0.187820772300678000f, 0.191201682740791000f, 0.194617830441576000f, 0.198069319559949000f, + 0.201556253794397000f, 0.205078736390317000f, 0.208636870145256000f, 0.212230757414055000f, + 0.215860500113899000f, 0.219526199729269000f, 0.223227957316809000f, 0.226965873510098000f, + 0.230740048524349000f, 0.234550582161005000f, 0.238397573812271000f, 0.242281122465555000f, + 0.246201326707835000f, 0.250158284729953000f, 0.254152094330827000f, 0.258182852921596000f, + 0.262250657529696000f, 0.266355604802862000f, 0.270497791013066000f, 0.274677312060385000f, + 0.278894263476810000f, 0.283148740429992000f, 0.287440837726918000f, 0.291770649817536000f, + 0.296138270798321000f, 0.300543794415777000f, 0.304987314069886000f, 0.309468922817509000f, + 0.313988713375718000f, 0.318546778125092000f, 0.323143209112951000f, 0.327778098056542000f, + 0.332451536346179000f, 0.337163615048330000f, 0.341914424908661000f, 0.346704056355030000f, + 0.351532599500439000f, 0.356400144145944000f, 0.361306779783510000f, 0.366252595598840000f, + 0.371237680474149000f, 0.376262122990906000f, 0.381326011432530000f, 0.386429433787049000f, + 0.391572477749723000f, 0.396755230725627000f, 0.401977779832196000f, 0.407240211901737000f, + 0.412542613483904000f, 0.417885070848138000f, 0.423267669986072000f, 0.428690496613907000f, + 0.434153636174749000f, 0.439657173840919000f, 0.445201194516228000f, 0.450785782838223000f, + 0.456411023180405000f, 0.462076999654407000f, 0.467783796112159000f, 0.473531496148010000f, + 0.479320183100827000f, 0.485149940056070000f, 0.491020849847836000f, 0.496932995060870000f, + 0.502886458032569000f, 0.508881320854934000f, 0.514917665376521000f, 0.520995573204354000f, + 0.527115125705813000f, 0.533276404010505000f, 0.539479489012107000f, 0.545724461370187000f, + 0.552011401512000000f, 0.558340389634268000f, 0.564711505704929000f, 0.571124829464873000f, + 0.577580440429651000f, 0.584078417891164000f, 0.590618840919337000f, 0.597201788363763000f, + 0.603827338855338000f, 0.610495570807865000f, 0.617206562419651000f, 0.623960391675076000f, + 0.630757136346147000f, 0.637596873994033000f, 0.644479681970582000f, 0.651405637419824000f, + 0.658374817279448000f, 0.665387298282272000f, 0.672443156957688000f, 0.679542469633094000f, + 0.686685312435314000f, 0.693871761291990000f, 0.701101891932973000f, 0.708375779891687000f, + 0.715693500506481000f, 0.723055128921969000f, 0.730460740090354000f, 0.737910408772731000f, + 0.745404209540387000f, 0.752942216776078000f, 0.760524504675292000f, 0.768151147247507000f, + 0.775822218317423000f, 0.783537791526194000f, 0.791297940332630000f, 0.799102738014409000f, + 0.806952257669252000f, 0.814846572216101000f, 0.822785754396284000f, 0.830769876774655000f, + 0.838799011740740000f, 0.846873231509858000f, 0.854992608124234000f, 0.863157213454102000f, + 0.871367119198797000f, 0.879622396887832000f, 0.887923117881966000f, 0.896269353374266000f, + 0.904661174391149000f, 0.913098651793419000f, 0.921581856277295000f, 0.930110858375424000f, + 0.938685728457888000f, 0.947306536733200000f, 0.955973353249286000f, 0.964686247894465000f, + 0.973445290398413000f, 0.982250550333117000f, 0.991102097113830000f, 1.000000000000000000f, +}; diff --git a/src/core/SkSRGB.h b/src/core/SkSRGB.h new file mode 100644 index 0000000000..de80596de4 --- /dev/null +++ b/src/core/SkSRGB.h @@ -0,0 +1,50 @@ +/* + * Copyright 2016 Google Inc. + * + * Use of this source code is governed by a BSD-style license that can be + * found in the LICENSE file. + */ + +#ifndef SkSRGB_DEFINED +#define SkSRGB_DEFINED + +#include "SkNx.h" + +/** Components for building our canonical sRGB -> linear and linear -> sRGB transformations. + * + * Current best practices: + * - for sRGB -> linear, lookup R,G,B in sk_linear_from_srgb; + * - for linear -> sRGB, call sk_linear_to_srgb() for R,G,B, clamp to 255, and round; + * - the alpha channel is linear in both formats, needing at most *(1/255.0f) or *255.0f. + * + * sk_linear_to_srgb()'s output requires rounding; it does not round for you. + * + * Given inputs in [0,1], sk_linear_to_srgb() will not underflow 0 but may overflow 255. + * The overflow is small enough that you can safely either clamp then round or round then clamp. + * (If you don't trust the inputs are in [0,1], you'd better clamp both sides immediately.) + * + * sk_linear_to_srgb() will run a little faster than usual when compiled with SSE4.1+. + */ + +extern const float sk_linear_from_srgb[256]; + +static inline Sk4f sk_linear_to_srgb(const Sk4f& x) { + // Approximation of the sRGB gamma curve (within 1 when scaled to 8-bit pixels). + // For 0.00000f <= x < 0.00349f, 12.92 * x + // For 0.00349f <= x <= 1.00000f, 0.679*(x.^0.5) + 0.423*x.^(0.25) - 0.101 + // Note that 0.00349 was selected because it is a point where both functions produce the + // same pixel value when rounded. + auto rsqrt = x.rsqrt(), + sqrt = rsqrt.invert(), + ftrt = rsqrt.rsqrt(); + + auto lo = (12.92f * 255.0f) * x; + + auto hi = (-0.101115084998961f * 255.0f) + + (+0.678513029959381f * 255.0f) * sqrt + + (+0.422602055039580f * 255.0f) * ftrt; + + return (x < 0.00349f).thenElse(lo, hi); +} + +#endif//SkSRGB_DEFINED diff --git a/src/opts/SkColorXform_opts.h b/src/opts/SkColorXform_opts.h index 74aa53ce7a..9904b3ef93 100644 --- a/src/opts/SkColorXform_opts.h +++ b/src/opts/SkColorXform_opts.h @@ -10,8 +10,8 @@ #include "SkNx.h" #include "SkColorPriv.h" +#include "SkSRGB.h" -extern const float sk_linear_from_srgb[256]; extern const float sk_linear_from_2dot2[256]; namespace SK_OPTS_NS { @@ -26,26 +26,6 @@ static Sk4f linear_to_2dot2(const Sk4f& x) { return 255.0f * x2.invert() * x32 * x64.invert(); } -static Sk4f linear_to_srgb(const Sk4f& x) { - // Approximation of the sRGB gamma curve (within 1 when scaled to 8-bit pixels). - // For 0.00000f <= x < 0.00349f, 12.92 * x - // For 0.00349f <= x <= 1.00000f, 0.679*(x.^0.5) + 0.423*x.^(0.25) - 0.101 - // Note that 0.00349 was selected because it is a point where both functions produce the - // same pixel value when rounded. - auto rsqrt = x.rsqrt(), - sqrt = rsqrt.invert(), - ftrt = rsqrt.rsqrt(); - - auto hi = (-0.101115084998961f * 255.0f) + - (+0.678513029959381f * 255.0f) * sqrt + - (+0.422602055039580f * 255.0f) * ftrt; - - auto lo = (12.92f * 255.0f) * x; - - auto mask = (x < 0.00349f); - return mask.thenElse(lo, hi); -} - static Sk4f clamp_0_to_255(const Sk4f& x) { // The order of the arguments is important here. We want to make sure that NaN // clamps to zero. Note that max(NaN, 0) = 0, while max(0, NaN) = NaN. @@ -154,12 +134,12 @@ static void color_xform_RGB1_2dot2_to_2dot2(uint32_t* dst, const uint32_t* src, static void color_xform_RGB1_srgb_to_srgb(uint32_t* dst, const uint32_t* src, int len, const float matrix[16]) { - color_xform_RGB1<sk_linear_from_srgb, linear_to_srgb>(dst, src, len, matrix); + color_xform_RGB1<sk_linear_from_srgb, sk_linear_to_srgb>(dst, src, len, matrix); } static void color_xform_RGB1_2dot2_to_srgb(uint32_t* dst, const uint32_t* src, int len, const float matrix[16]) { - color_xform_RGB1<sk_linear_from_2dot2, linear_to_srgb>(dst, src, len, matrix); + color_xform_RGB1<sk_linear_from_2dot2, sk_linear_to_srgb>(dst, src, len, matrix); } } // namespace SK_OPTS_NS diff --git a/tests/SRGBTest.cpp b/tests/SRGBTest.cpp new file mode 100644 index 0000000000..89930b5c05 --- /dev/null +++ b/tests/SRGBTest.cpp @@ -0,0 +1,34 @@ +/* + * 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 "SkSRGB.h" +#include "Test.h" +#include <math.h> + +static uint8_t linear_to_srgb(float l) { + return (uint8_t)roundf(sk_linear_to_srgb(Sk4f{l})[0]); +} + +DEF_TEST(sk_linear_to_srgb, r) { + // Should map 0 -> 0 and 1 -> 1. + REPORTER_ASSERT(r, 0 == linear_to_srgb(0.0f)); + REPORTER_ASSERT(r, 255 == linear_to_srgb(1.0f)); + + // Should be monotonic between 0 and 1. + // We don't bother checking denorm values. + uint8_t prev = 0; + for (float f = FLT_MIN; f <= 1.0f; ) { + uint8_t srgb = linear_to_srgb(f); + + REPORTER_ASSERT(r, srgb >= prev); + prev = srgb; + + union { float flt; uint32_t bits; } pun = { f }; + pun.bits++; + f = pun.flt; + } +} |