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-rw-r--r--sharpyuv/sharpyuv_gamma.c310
1 files changed, 308 insertions, 2 deletions
diff --git a/sharpyuv/sharpyuv_gamma.c b/sharpyuv/sharpyuv_gamma.c
index 20ab2da6..09028428 100644
--- a/sharpyuv/sharpyuv_gamma.c
+++ b/sharpyuv/sharpyuv_gamma.c
@@ -12,6 +12,7 @@
#include "sharpyuv/sharpyuv_gamma.h"
#include <assert.h>
+#include <float.h>
#include <math.h>
#include "src/webp/types.h"
@@ -97,7 +98,7 @@ static WEBP_INLINE uint32_t FixedPointInterpolation(int v, uint32_t* tab,
return result;
}
-uint32_t SharpYuvGammaToLinear(uint16_t v, int bit_depth) {
+static uint32_t ToLinearSrgb(uint16_t v, int bit_depth) {
const int shift = GAMMA_TO_LINEAR_TAB_BITS - bit_depth;
if (shift > 0) {
return kGammaToLinearTabS[v << shift];
@@ -105,9 +106,314 @@ uint32_t SharpYuvGammaToLinear(uint16_t v, int bit_depth) {
return FixedPointInterpolation(v, kGammaToLinearTabS, -shift, 0);
}
-uint16_t SharpYuvLinearToGamma(uint32_t value, int bit_depth) {
+static uint16_t FromLinearSrgb(uint32_t value, int bit_depth) {
return FixedPointInterpolation(
value, kLinearToGammaTabS,
(GAMMA_TO_LINEAR_BITS - LINEAR_TO_GAMMA_TAB_BITS),
bit_depth - GAMMA_TO_LINEAR_BITS);
}
+
+////////////////////////////////////////////////////////////////////////////////
+
+#define CLAMP(x, low, high) \
+ (((x) < (low)) ? (low) : (((high) < (x)) ? (high) : (x)))
+#define MIN(a, b) (((a) < (b)) ? (a) : (b))
+#define MAX(a, b) (((a) > (b)) ? (a) : (b))
+
+static WEBP_INLINE float Roundf(float x) {
+ if (x < 0)
+ return (float)ceil((double)(x - 0.5f));
+ else
+ return (float)floor((double)(x + 0.5f));
+}
+
+static WEBP_INLINE float Powf(float base, float exp) {
+ return (float)pow((double)base, (double)exp);
+}
+
+static WEBP_INLINE float Log10f(float x) { return (float)log10((double)x); }
+
+static float ToLinear709(float gamma) {
+ if (gamma < 0.f) {
+ return 0.f;
+ } else if (gamma < 4.5f * 0.018053968510807f) {
+ return gamma / 4.5f;
+ } else if (gamma < 1.f) {
+ return Powf((gamma + 0.09929682680944f) / 1.09929682680944f, 1.f / 0.45f);
+ }
+ return 1.f;
+}
+
+static float FromLinear709(float linear) {
+ if (linear < 0.f) {
+ return 0.f;
+ } else if (linear < 0.018053968510807f) {
+ return linear * 4.5f;
+ } else if (linear < 1.f) {
+ return 1.09929682680944f * Powf(linear, 0.45f) - 0.09929682680944f;
+ }
+ return 1.f;
+}
+
+static float ToLinear470M(float gamma) {
+ return Powf(CLAMP(gamma, 0.f, 1.f), 2.2f);
+}
+
+static float FromLinear470M(float linear) {
+ return Powf(CLAMP(linear, 0.f, 1.f), 1.f / 2.2f);
+}
+
+static float ToLinear470Bg(float gamma) {
+ return Powf(CLAMP(gamma, 0.f, 1.f), 2.8f);
+}
+
+static float FromLinear470Bg(float linear) {
+ return Powf(CLAMP(linear, 0.f, 1.f), 1.f / 2.8f);
+}
+
+static float ToLinearSmpte240(float gamma) {
+ if (gamma < 0.f) {
+ return 0.f;
+ } else if (gamma < 4.f * 0.022821585529445f) {
+ return gamma / 4.f;
+ } else if (gamma < 1.f) {
+ return Powf((gamma + 0.111572195921731f) / 1.111572195921731f, 1.f / 0.45f);
+ }
+ return 1.f;
+}
+
+static float FromLinearSmpte240(float linear) {
+ if (linear < 0.f) {
+ return 0.f;
+ } else if (linear < 0.022821585529445f) {
+ return linear * 4.f;
+ } else if (linear < 1.f) {
+ return 1.111572195921731f * Powf(linear, 0.45f) - 0.111572195921731f;
+ }
+ return 1.f;
+}
+
+static float ToLinearLog100(float gamma) {
+ // The function is non-bijective so choose the middle of [0, 0.01].
+ const float mid_interval = 0.01f / 2.f;
+ return (gamma <= 0.0f) ? mid_interval
+ : Powf(10.0f, 2.f * (MIN(gamma, 1.f) - 1.0f));
+}
+
+static float FromLinearLog100(float linear) {
+ return (linear < 0.01f) ? 0.0f : 1.0f + Log10f(MIN(linear, 1.f)) / 2.0f;
+}
+
+static float ToLinearLog100Sqrt10(float gamma) {
+ // The function is non-bijective so choose the middle of [0, 0.00316227766f[.
+ const float mid_interval = 0.00316227766f / 2.f;
+ return (gamma <= 0.0f) ? mid_interval
+ : Powf(10.0f, 2.5f * (MIN(gamma, 1.f) - 1.0f));
+}
+
+static float FromLinearLog100Sqrt10(float linear) {
+ return (linear < 0.00316227766f) ? 0.0f
+ : 1.0f + Log10f(MIN(linear, 1.f)) / 2.5f;
+}
+
+static float ToLinearIec61966(float gamma) {
+ if (gamma <= -4.5f * 0.018053968510807f) {
+ return Powf((-gamma + 0.09929682680944f) / -1.09929682680944f, 1.f / 0.45f);
+ } else if (gamma < 4.5f * 0.018053968510807f) {
+ return gamma / 4.5f;
+ }
+ return Powf((gamma + 0.09929682680944f) / 1.09929682680944f, 1.f / 0.45f);
+}
+
+static float FromLinearIec61966(float linear) {
+ if (linear <= -0.018053968510807f) {
+ return -1.09929682680944f * Powf(-linear, 0.45f) + 0.09929682680944f;
+ } else if (linear < 0.018053968510807f) {
+ return linear * 4.5f;
+ }
+ return 1.09929682680944f * Powf(linear, 0.45f) - 0.09929682680944f;
+}
+
+static float ToLinearBt1361(float gamma) {
+ if (gamma < -0.25f) {
+ return -0.25f;
+ } else if (gamma < 0.f) {
+ return Powf((gamma - 0.02482420670236f) / -0.27482420670236f, 1.f / 0.45f) /
+ -4.f;
+ } else if (gamma < 4.5f * 0.018053968510807f) {
+ return gamma / 4.5f;
+ } else if (gamma < 1.f) {
+ return Powf((gamma + 0.09929682680944f) / 1.09929682680944f, 1.f / 0.45f);
+ }
+ return 1.f;
+}
+
+static float FromLinearBt1361(float linear) {
+ if (linear < -0.25f) {
+ return -0.25f;
+ } else if (linear < 0.f) {
+ return -0.27482420670236f * Powf(-4.f * linear, 0.45f) + 0.02482420670236f;
+ } else if (linear < 0.018053968510807f) {
+ return linear * 4.5f;
+ } else if (linear < 1.f) {
+ return 1.09929682680944f * Powf(linear, 0.45f) - 0.09929682680944f;
+ }
+ return 1.f;
+}
+
+static float ToLinearPq(float gamma) {
+ if (gamma > 0.f) {
+ const float pow_gamma = Powf(gamma, 32.f / 2523.f);
+ const float num = MAX(pow_gamma - 107.f / 128.f, 0.0f);
+ const float den = MAX(2413.f / 128.f - 2392.f / 128.f * pow_gamma, FLT_MIN);
+ return Powf(num / den, 4096.f / 653.f);
+ }
+ return 0.f;
+}
+
+static float FromLinearPq(float linear) {
+ if (linear > 0.f) {
+ const float pow_linear = Powf(linear, 653.f / 4096.f);
+ const float num = 107.f / 128.f + 2413.f / 128.f * pow_linear;
+ const float den = 1.0f + 2392.f / 128.f * pow_linear;
+ return Powf(num / den, 2523.f / 32.f);
+ }
+ return 0.f;
+}
+
+static float ToLinearSmpte428(float gamma) {
+ return Powf(MAX(gamma, 0.f), 2.6f) / 0.91655527974030934f;
+}
+
+static float FromLinearSmpte428(float linear) {
+ return Powf(0.91655527974030934f * MAX(linear, 0.f), 1.f / 2.6f);
+}
+
+// Conversion in BT.2100 requires RGB info. Simplify to gamma correction here.
+static float ToLinearHlg(float gamma) {
+ if (gamma < 0.f) {
+ return 0.f;
+ } else if (gamma <= 0.5f) {
+ return Powf((gamma * gamma) * (1.f / 3.f), 1.2f);
+ }
+ return Powf((expf((gamma - 0.55991073f) / 0.17883277f) + 0.28466892f) / 12.0f,
+ 1.2f);
+}
+
+static float FromLinearHlg(float linear) {
+ linear = Powf(linear, 1.f / 1.2f);
+ if (linear < 0.f) {
+ return 0.f;
+ } else if (linear <= (1.f / 12.f)) {
+ return sqrtf(3.f * linear);
+ }
+ return 0.17883277f * logf(12.f * linear - 0.28466892f) + 0.55991073f;
+}
+
+uint32_t SharpYuvGammaToLinear(uint16_t v, int bit_depth,
+ SharpYuvTransferFunctionType transfer_type) {
+ float v_float, linear;
+ if (transfer_type == kSharpYuvTransferFunctionSrgb) {
+ return ToLinearSrgb(v, bit_depth);
+ }
+ v_float = (float)v / ((1 << bit_depth) - 1);
+ switch (transfer_type) {
+ case kSharpYuvTransferFunctionBt709:
+ case kSharpYuvTransferFunctionBt601:
+ case kSharpYuvTransferFunctionBt2020_10Bit:
+ case kSharpYuvTransferFunctionBt2020_12Bit:
+ linear = ToLinear709(v_float);
+ break;
+ case kSharpYuvTransferFunctionBt470M:
+ linear = ToLinear470M(v_float);
+ break;
+ case kSharpYuvTransferFunctionBt470Bg:
+ linear = ToLinear470Bg(v_float);
+ break;
+ case kSharpYuvTransferFunctionSmpte240:
+ linear = ToLinearSmpte240(v_float);
+ break;
+ case kSharpYuvTransferFunctionLinear:
+ return v;
+ case kSharpYuvTransferFunctionLog100:
+ linear = ToLinearLog100(v_float);
+ break;
+ case kSharpYuvTransferFunctionLog100_Sqrt10:
+ linear = ToLinearLog100Sqrt10(v_float);
+ break;
+ case kSharpYuvTransferFunctionIec61966:
+ linear = ToLinearIec61966(v_float);
+ break;
+ case kSharpYuvTransferFunctionBt1361:
+ linear = ToLinearBt1361(v_float);
+ break;
+ case kSharpYuvTransferFunctionSmpte2084:
+ linear = ToLinearPq(v_float);
+ break;
+ case kSharpYuvTransferFunctionSmpte428:
+ linear = ToLinearSmpte428(v_float);
+ break;
+ case kSharpYuvTransferFunctionHlg:
+ linear = ToLinearHlg(v_float);
+ break;
+ default:
+ assert(0);
+ linear = 0;
+ break;
+ }
+ return (uint32_t)Roundf(linear * ((1 << 16) - 1));
+}
+
+uint16_t SharpYuvLinearToGamma(uint32_t v, int bit_depth,
+ SharpYuvTransferFunctionType transfer_type) {
+ float v_float, linear;
+ if (transfer_type == kSharpYuvTransferFunctionSrgb) {
+ return FromLinearSrgb(v, bit_depth);
+ }
+ v_float = (float)v / ((1 << 16) - 1);
+ switch (transfer_type) {
+ case kSharpYuvTransferFunctionBt709:
+ case kSharpYuvTransferFunctionBt601:
+ case kSharpYuvTransferFunctionBt2020_10Bit:
+ case kSharpYuvTransferFunctionBt2020_12Bit:
+ linear = FromLinear709(v_float);
+ break;
+ case kSharpYuvTransferFunctionBt470M:
+ linear = FromLinear470M(v_float);
+ break;
+ case kSharpYuvTransferFunctionBt470Bg:
+ linear = FromLinear470Bg(v_float);
+ break;
+ case kSharpYuvTransferFunctionSmpte240:
+ linear = FromLinearSmpte240(v_float);
+ break;
+ case kSharpYuvTransferFunctionLinear:
+ return v;
+ case kSharpYuvTransferFunctionLog100:
+ linear = FromLinearLog100(v_float);
+ break;
+ case kSharpYuvTransferFunctionLog100_Sqrt10:
+ linear = FromLinearLog100Sqrt10(v_float);
+ break;
+ case kSharpYuvTransferFunctionIec61966:
+ linear = FromLinearIec61966(v_float);
+ break;
+ case kSharpYuvTransferFunctionBt1361:
+ linear = FromLinearBt1361(v_float);
+ break;
+ case kSharpYuvTransferFunctionSmpte2084:
+ linear = FromLinearPq(v_float);
+ break;
+ case kSharpYuvTransferFunctionSmpte428:
+ linear = FromLinearSmpte428(v_float);
+ break;
+ case kSharpYuvTransferFunctionHlg:
+ linear = FromLinearHlg(v_float);
+ break;
+ default:
+ assert(0);
+ linear = 0;
+ break;
+ }
+ return (uint16_t)Roundf(linear * ((1 << bit_depth) - 1));
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-05-26 15:55:23 +0000