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Issue 2837: Fixed CIECAM02 clipping issues

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This commit is contained in:
torger 2015-07-29 17:53:19 +02:00
parent 6bb0d15ff0
commit fca16a697a
1 changed files with 49 additions and 3 deletions
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52
rtengine/curves.cc
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@ -1827,6 +1827,10 @@ void PerceptualToneCurve::Apply(float &r, float &g, float &b, PerceptualToneCurv
r = g = b = 65535.f;
return;
}
if (ar <= 0.f && ag <= 0.f && ab <= 0.f) {
r = g = b = 0;
return;
}
// ProPhoto constants for luminance, that is xyz_prophoto[1][]
const float Yr = 0.2880402f;
@ -1846,6 +1850,18 @@ void PerceptualToneCurve::Apply(float &r, float &g, float &b, PerceptualToneCurv
Color::Prophotoxyz(r,g,b,x,y,z);
XYZ = (cmsCIEXYZ){ .X = x * 100.0f/65535, .Y = y * 100.0f/65535, .Z = z * 100.0f/65535 };
cmsCIECAM02Forward(h02[thread_idx], &XYZ, &JCh);
if (!isfinite(JCh.J) || !isfinite(JCh.C) || !isfinite(JCh.h)) {
// this can happen for dark noise colors or colors outside human gamut. Then we just return the curve's result.
if (!state.isProphoto) {
float newr = state.Prophoto2Working[0][0]*r + state.Prophoto2Working[0][1]*g + state.Prophoto2Working[0][2]*b;
float newg = state.Prophoto2Working[1][0]*r + state.Prophoto2Working[1][1]*g + state.Prophoto2Working[1][2]*b;
float newb = state.Prophoto2Working[2][0]*r + state.Prophoto2Working[2][1]*g + state.Prophoto2Working[2][2]*b;
r = newr;
g = newg;
b = newb;
}
return;
}
float cmul = state.cmul_contrast; // chroma scaling factor
@ -1896,12 +1912,42 @@ void PerceptualToneCurve::Apply(float &r, float &g, float &b, PerceptualToneCurv
cmul *= dark_scale_factor;
}
{ // to avoid strange CIECAM02 chroma errors on close-to-shadow-clipping colors we reduce chroma scaling towards 1.0 for black colors
float dark_scale_factor = 1.0 / cmul;
const float lolim = 4;
const float hilim = 7;
if (JCh.J < lolim) {
// do nothing, keep scale factor
} else if (JCh.J < hilim) {
// S-curve transition
float x = (JCh.J - lolim) / (hilim - lolim);
if (x < 0.5) {
x = 0.5 * powf(2*x, 2);
} else {
x = 0.5 + 0.5 * (1-powf(1-2*(x-0.5), 2));
}
dark_scale_factor = dark_scale_factor*(1.0-x) + 1.0*x;
} else {
dark_scale_factor = 1.0;
}
cmul *= dark_scale_factor;
}
JCh.C *= cmul;
cmsCIECAM02Reverse(h02[thread_idx], &JCh, &XYZ);
if (!isfinite(XYZ.X) || !isfinite(XYZ.Y) || !isfinite(XYZ.Z)) {
// can happen for colors on the rim of being outside gamut, that worked without chroma scaling but not with. Then we return only the curve's result.
if (!state.isProphoto) {
float newr = state.Prophoto2Working[0][0]*r + state.Prophoto2Working[0][1]*g + state.Prophoto2Working[0][2]*b;
float newg = state.Prophoto2Working[1][0]*r + state.Prophoto2Working[1][1]*g + state.Prophoto2Working[1][2]*b;
float newb = state.Prophoto2Working[2][0]*r + state.Prophoto2Working[2][1]*g + state.Prophoto2Working[2][2]*b;
r = newr;
g = newg;
b = newb;
}
return;
}
Color::xyz2Prophoto(XYZ.X,XYZ.Y,XYZ.Z,r,g,b);
if (!isfinite(r)) r = 1.0;
if (!isfinite(g)) g = 1.0;
if (!isfinite(b)) b = 1.0;
r *= 655.35;
g *= 655.35;
b *= 655.35;