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HDR: Improve ACES tone mapping curve

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The previous one tended to over-expose the final image.
This commit is contained in:
Fernando García Liñán 2021-08-25 15:15:57 +02:00
parent 55410e9d35
commit aaf6bb9309
2 changed files with 29 additions and 14 deletions
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5
Shaders/HDR/exposure-include.frag
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@ -9,12 +9,11 @@ float log10(float x)
return one_over_log10 * log(x);
}
// Custom exposure curve based on the one proposed on
// 'Perceptual Effects in Real-time Tone Mapping'.
// Exposure curve from 'Perceptual Effects in Real-time Tone Mapping'.
// http://resources.mpi-inf.mpg.de/hdr/peffects/krawczyk05sccg.pdf
float keyValue(float L)
{
return 0.82 - 2.0 / (log10(L + 0.84) + 2.6);
return 1.03 - 2.0 / (log10(L + 1.0) + 2.0);
}
vec3 applyExposure(vec3 color, float avgLuminance, float threshold)

38
Shaders/HDR/postprocess.frag
View file

@ -15,6 +15,32 @@ uniform bool debug_ev100;
vec3 applyExposure(vec3 color, float avgLuminance, float threshold);
/**
* ACES tone mapping
* From 'Baking Lab' by MJP and David Neubelt
* Original by Stephen Hill
* https://github.com/TheRealMJP/BakingLab/blob/master/BakingLab/ACES.hlsl
* Licensed under the MIT license
*/
// sRGB => XYZ => D65_2_D60 => AP1 => RRT_SAT
const mat3 ACESInputMat = mat3(
0.59719, 0.07600, 0.02840,
0.35458, 0.90834, 0.13383,
0.04823, 0.01566, 0.83777);
// ODT_SAT => XYZ => D60_2_D65 => sRGB
const mat3 ACESOutputMat = mat3(
1.60475, -0.10208, -0.00327,
-0.53108, 1.10813, -0.07276,
-0.07367, -0.00605, 1.07602);
vec3 ACESFitted(vec3 color)
{
vec3 v = ACESInputMat * color;
vec3 a = v * (v + 0.0245786) - 0.000090537;
vec3 b = v * (0.983729 * v + 0.4329510) + 0.238081;
return clamp(ACESOutputMat * (a / b), 0.0, 1.0);
}
vec3 getDebugColor(float value)
{
float level = value*3.14159265/2.0;
@ -40,16 +66,6 @@ vec3 debugEV100(vec3 hdr, float avgLuminance)
return getDebugColor(norm);
}
const float a = 2.51;
const float b = 0.03;
const float c = 2.43;
const float d = 0.59;
const float e = 0.14;
vec3 ACESFilm(vec3 x)
{
return clamp((x*(a*x+b))/(x*(c*x+d)+e), 0.0, 1.0);
}
vec3 encodeSRGB(vec3 linearRGB)
{
vec3 a = 12.92 * linearRGB;
@ -71,7 +87,7 @@ void main()
}
// Tonemap
vec3 color = ACESFilm(exposedHdrColor);
vec3 color = ACESFitted(exposedHdrColor);
// Gamma correction
color = encodeSRGB(color);