blob: e10b6eca331e727f45465bae4b263085cb360b38 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
|
#ifndef HDR_TONEMAPPER
#define HDR_TONEMAPPER
#include "colortransfer.glsl"
// See https://www.itu.int/dms_pub/itu-r/opb/rep/R-REP-BT.2390-6-2019-PDF-E.pdf, section 5.4
//
// masteringWhite in PQ values, not in linear. maxOutLum as defined in the doc above
// we assume that masteringBlack == 0, and minLum == 0 to simplify the calculations
//
// The HDR tonemapping operates in non linear space (PQ or HLG), taking the
// non linear luminosity as input and returning a factor by which to scale
// the RGB signal so it fits within the outbut devices range.
//
// We're using the same algorithm for HLG, and do the equivalent mapping in
// HLG space.
float tonemapScaleForLuminosity(float y, float masteringWhite, float maxLum)
{
float p = y/masteringWhite;
float ks = 1.5*maxLum - 0.5;
if (p < ks)
return 1.;
float t = (p - ks)/(1 - ks);
float t2 = t*t;
float t3 = t*t2;
p = (2*t3 - 3*t2 + 1)*ks + (t3 - 2*t2 + t)*(1. - ks) + (-2*t3 + 3*t2)*maxLum;
// get the linear new luminosity
float newY = p*masteringWhite;
return newY/y;
}
#endif
|
