70 lines
1.7 KiB
GLSL
70 lines
1.7 KiB
GLSL
// Based on https://github.com/Filoppi/PumboAutoHDR
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/*
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[configuration]
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[OptionRangeFloat]
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GUIName = HDR Display Max Nits
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OptionName = HDR_DISPLAY_MAX_NITS
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MinValue = 80
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MaxValue = 2000
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StepAmount = 1
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DefaultValue = 400
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[OptionRangeFloat]
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GUIName = Shoulder Start Alpha
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OptionName = AUTO_HDR_SHOULDER_START_ALPHA
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MinValue = 0
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MaxValue = 1
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StepAmount = 0.01
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DefaultValue = 0
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[OptionRangeFloat]
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GUIName = Shoulder Pow
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OptionName = AUTO_HDR_SHOULDER_POW
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MinValue = 1
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MaxValue = 10
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StepAmount = 0.05
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DefaultValue = 2.5
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[/configuration]
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*/
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float luminance(float3 color)
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{
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return dot(color, float3(0.2126f, 0.7152f, 0.0722f));
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}
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void main()
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{
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float4 color = Sample();
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// Nothing to do here, we are in SDR
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if (!OptionEnabled(hdr_output) || !OptionEnabled(linear_space_output))
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{
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SetOutput(color);
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return;
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}
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const float hdr_paper_white = hdr_paper_white_nits / hdr_sdr_white_nits;
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// Restore the original SDR (0-1) brightness (we might or might not restore it later)
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color.rgb /= hdr_paper_white;
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// Find the color luminance (it works better than average)
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float sdr_ratio = luminance(color.rgb);
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const float auto_hdr_max_white = max(HDR_DISPLAY_MAX_NITS / (hdr_paper_white_nits / hdr_sdr_white_nits), hdr_sdr_white_nits) / hdr_sdr_white_nits;
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if (sdr_ratio > AUTO_HDR_SHOULDER_START_ALPHA && AUTO_HDR_SHOULDER_START_ALPHA < 1.0)
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{
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const float auto_hdr_shoulder_ratio = 1.0 - (max(1.0 - sdr_ratio, 0.0) / (1.0 - AUTO_HDR_SHOULDER_START_ALPHA));
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const float auto_hdr_extra_ratio = pow(auto_hdr_shoulder_ratio, AUTO_HDR_SHOULDER_POW) * (auto_hdr_max_white - 1.0);
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const float auto_hdr_total_ratio = sdr_ratio + auto_hdr_extra_ratio;
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color.rgb *= auto_hdr_total_ratio / sdr_ratio;
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}
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color.rgb *= hdr_paper_white;
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SetOutput(color);
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}
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