diff options
Diffstat (limited to 'src/core/SkSRGB.h')
-rw-r--r-- | src/core/SkSRGB.h | 50 |
1 files changed, 0 insertions, 50 deletions
diff --git a/src/core/SkSRGB.h b/src/core/SkSRGB.h deleted file mode 100644 index de80596de4..0000000000 --- a/src/core/SkSRGB.h +++ /dev/null @@ -1,50 +0,0 @@ -/* - * 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 |