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experimental: preview with gamma correction

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.... actually we undo gamma adjustments, because screens (laptop, pad, etc) will apply their own gamma corrections.

Activate in LED settings: "Use Gamma correction for preview"

Colors in WLED are sometimes gamma corrected, sometimes not. This change tries to make the best out of the color mess, but its still not working properly in all configurations.
This commit is contained in:
Frank
2023-08-04 22:03:53 +02:00
parent 477cb11b36
commit f010adfe24
9 changed files with 531 additions and 489 deletions
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19
wled00/colors.cpp
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@@ -347,6 +347,24 @@ static const byte gammaT[256] = {
245, 247, 250, 252, 255 };
#endif
// WLEDMM begin
static uint8_t gammaTinv[256] = { 0 };
static void calcInvGammaTable(float gamma)
{
float gammaInv = 1.0f / 2.4f; // surprise surprise: WLED palettes use a fixed gamma of 2.4 !!!
//float gammaInv = 1.0f / gamma; // if we go by the book, 1.0/gamma will revert gamma corrections
for (size_t i = 0; i < 256; i++) {
gammaTinv[i] = (int)(powf((float)i / 255.0f, gammaInv) * 255.0f + 0.5f);
}
}
uint8_t unGamma8(uint8_t value) {
if (!gammaCorrectCol || (value == 0) || (value == 255)) return value;
if ((gammaCorrectVal <= 1.0f) || (gammaCorrectVal > 3.0f)) return value;
if (gammaTinv[255] == 0) calcInvGammaTable(gammaCorrectVal);
return gammaTinv[value];
}
// wleDMM end
uint8_t gamma8_cal(uint8_t b, float gamma)
{
return (int)(powf((float)b / 255.0f, gamma) * 255.0f + 0.5f);
@@ -360,6 +378,7 @@ void calcGammaTable(float gamma)
gammaT[i] = gamma8_cal(i, gamma);
}
#endif
calcInvGammaTable(gamma); // WLEDMM
}
// used for individual channel or brightness gamma correction