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[client] egl: make it possible to configure HDR to SDR mapping

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This commit is contained in:
Geoffrey McRae
2023-10-20 15:26:27 +11:00
parent 844a37a276
commit 78df2073ff
4 changed files with 73 additions and 18 deletions
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6
client/renderers/EGL/shader/desktop_rgb.frag
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@@ -21,6 +21,8 @@ uniform int scaleAlgo;
uniform float nvGain;
uniform int cbMode;
uniform bool isHDR;
uniform bool mapHDRtoSDR;
uniform float mapHDRGain;
void main()
{
@@ -40,8 +42,8 @@ void main()
}
}
if (isHDR)
color.rgb = mapToSDR(color.rgb);
if (isHDR && mapHDRtoSDR)
color.rgb = mapToSDR(color.rgb, mapHDRGain);
if (cbMode > 0)
color = cbTransform(color, cbMode);

18
client/renderers/EGL/shader/hdr.h
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@@ -13,14 +13,11 @@
*/
// Configuration ---------------------------------------------------------------
const float peakLuminance = 250.0; // Peak playback screen luminance in nits
const float knee = 0.75; // Compressor knee position
const float ratio = 4.0; // Compressor ratio: 1 = disabled, <1 = expander
const float maxCLL = 10000.0; // Maximum content light level in nits
// -----------------------------------------------------------------------------
// Precalculated values
const float gain = maxCLL / peakLuminance;
const float compressor = 1.0 / ratio;
// PQ constants
@@ -43,10 +40,11 @@ float midGain(vec3 pixel)
min(pixel.r, pixel.g)); // min = b
}
vec3 compress(vec3 pixel)
vec3 compress(vec3 pixel, float gain)
{
float gain = maxGain(pixel);
return pixel * (gain < knee ? gain : knee + max(gain - knee, 0.0) * compressor) / gain;
float maxGain = maxGain(pixel);
return pixel * (maxGain < knee ? maxGain :
knee + max(maxGain - knee, 0.0) * compressor) / maxGain;
}
vec3 fixClip(vec3 pixel)
@@ -67,7 +65,7 @@ vec3 fixClip(vec3 pixel)
}
// Returns luminance in nits
vec3 pq2lin(vec3 pq)
vec3 pq2lin(vec3 pq, float gain)
{
vec3 p = pow(pq, vec3(m2inv));
vec3 d = max(p - c1, vec3(0.0)) / (c2 - c3 * p);
@@ -101,8 +99,8 @@ vec3 bt2020to709(vec3 bt2020)
bt2020.r * -0.0182 + bt2020.g * -0.1006 + bt2020.b * 1.1187);
}
vec3 mapToSDR(vec3 color)
vec3 mapToSDR(vec3 color, float gain)
{
vec3 lin = bt2020to709(pq2lin(color.rgb));
return lin2srgb(compress(lin));
vec3 lin = bt2020to709(pq2lin(color.rgb, gain));
return lin2srgb(compress(lin, gain));
}