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Fix gamma correction #1825

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Merged
merged 3 commits into from
Oct 6, 2025
Merged

Fix gamma correction #1825

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8ff90ff
corrected gamma function
jcam Oct 4, 2025
0574a91
uncorrect color temperature to work with new gamma
jcam Oct 5, 2025
c6fa806
Adjust gamma corrected expectation for self test
jcam Oct 5, 2025
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61 changes: 45 additions & 16 deletions src/cmnds/cmd_newLEDDriver.c
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Original file line number Diff line number Diff line change
Expand Up @@ -408,20 +408,23 @@ float led_gamma_correction (int color, float iVal) { // apply LED gamma and RGB
}

// apply LED gamma correction:
float ch_bright_min = g_cfg.led_corr.rgb_bright_min / 100;
if (color > 2) {
ch_bright_min = g_cfg.led_corr.cw_bright_min / 100;
}
float oVal = (powf (brightnessNormalized0to1, g_cfg.led_corr.led_gamma) * (1 - ch_bright_min) + ch_bright_min) * iVal;

// this gamma correction function does not properly calculate gamma
// float ch_bright_min = g_cfg.led_corr.rgb_bright_min / 100;
// if (color > 2) {
// ch_bright_min = g_cfg.led_corr.cw_bright_min / 100;
// }
// float oVal = (powf (brightnessNormalized0to1, g_cfg.led_corr.led_gamma) * (1 - ch_bright_min) + ch_bright_min) * iVal;

// color value adjusted to float 0-1, modified by brightness
float brightnessCorrectedColor = iVal / 255.0f * brightnessNormalized0to1;

// gamma correct the color value
float oVal = powf (brightnessCorrectedColor, g_cfg.led_corr.led_gamma) * 255.0f;

// apply RGB level correction:
if (color < 3) {
rgb_used_corr[color] = g_cfg.led_corr.rgb_cal[color];
// boost gain to get full brightness when one RGB base color is dominant:
float sum_other_colors = led_baseColors[0] + led_baseColors[1] + led_baseColors[2] - led_baseColors[color];
if (led_baseColors[color] > sum_other_colors) {
rgb_used_corr[color] += (1.0f - rgb_used_corr[color]) * (1.0f - sum_other_colors / led_baseColors[color]);
}
oVal *= rgb_used_corr[color];
}

Expand Down Expand Up @@ -832,14 +835,31 @@ float LED_GetTemperature0to1Range() {
}

void LED_SetTemperature(int tmpInteger, bool bApply) {
float f;
float ww,cw,max_cw_ww;

led_temperature_current = tmpInteger;

f = LED_GetTemperature0to1Range();
ww = LED_GetTemperature0to1Range();
cw = 1 - ww;

//normalize to have a local max of 100%
if (ww > cw)
max_cw_ww = ww;
else
max_cw_ww = cw;

ww = ww / max_cw_ww;
cw = cw / max_cw_ww;

//uncorrect for gamma to allow gamma correcting brightness later
if (g_cfg.led_corr.led_gamma >= 1 && g_cfg.led_corr.led_gamma <= 3) {
ww = powf(ww, 1 / g_cfg.led_corr.led_gamma);
cw = powf(cw, 1 / g_cfg.led_corr.led_gamma);
}

led_baseColors[3] = (255.0f) * cw;
led_baseColors[4] = (255.0f) * ww;

led_baseColors[3] = (255.0f) * (1-f);
led_baseColors[4] = (255.0f) * f;

if(bApply) {
if (CFG_HasFlag(OBK_FLAG_LED_AUTOENABLE_ON_ANY_ACTION)) {
Expand Down Expand Up @@ -1253,9 +1273,18 @@ void LED_SetFinalRGBW(byte r, byte g, byte b, byte w) {
led_baseColors[0] = r;
led_baseColors[1] = g;
led_baseColors[2] = b;

// half between Cool and Warm
led_baseColors[3] = w / 2;
led_baseColors[4] = w / 2;
float w_half = w / 2 / 255.0f;
LED_SetTemperature0to1Range(0.5f);

//uncorrect for gamma to allow gamma correcting brightness later
if (g_cfg.led_corr.led_gamma >= 1 && g_cfg.led_corr.led_gamma <= 3) {
w_half = powf(w_half, 1 / g_cfg.led_corr.led_gamma);
}

led_baseColors[3] = (255.0f) * w_half;
led_baseColors[4] = (255.0f) * w_half;

RGBtoHSV(led_baseColors[0] / 255.0f, led_baseColors[1] / 255.0f, led_baseColors[2] / 255.0f, &g_hsv_h, &g_hsv_s, &g_hsv_v);

Expand Down
2 changes: 1 addition & 1 deletion src/selftest/selftest_http_led.c
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Original file line number Diff line number Diff line change
Expand Up @@ -213,7 +213,7 @@ void Test_Http_LED_RGB() {
SELFTEST_ASSERT_JSON_VALUE_INTEGER("StatusSTS", "Dimmer", 100);
SELFTEST_ASSERT_JSON_VALUE_STRING("StatusSTS", "POWER", "ON");
// Tasmota colors are scalled by Dimmer in this case. Confirmed.
SELFTEST_ASSERT_JSON_VALUE_STRING("StatusSTS", "Color", "127,255,0");
SELFTEST_ASSERT_JSON_VALUE_STRING("StatusSTS", "Color", "55,255,0");
// check Tasmota HSBColor
/*
NOTE:
Expand Down