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fix(system): round rgb_to_luminance so white maps to 255 #1006

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Merged
mairas merged 1 commit into from
Jun 16, 2026
Merged

fix(system): round rgb_to_luminance so white maps to 255 #1006

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5 changes: 4 additions & 1 deletion src/sensesp/system/crgb.h
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
#ifndef SENSESP_SYSTEM_CRGB_H_
#define SENSESP_SYSTEM_CRGB_H_

#include <cmath>
#include <cstdint>

namespace sensesp {
Expand Down Expand Up @@ -123,7 +124,9 @@ inline uint8_t apply_brightness(uint8_t value, uint8_t brightness) {
* @return Luminance value (0-255)
*/
inline uint8_t rgb_to_luminance(uint8_t r, uint8_t g, uint8_t b) {
return static_cast<uint8_t>(0.2126 * r + 0.7152 * g + 0.0722 * b);
// Round to nearest: the weights sum to just under 1.0 in floating point, so
// truncation would map pure white (255,255,255) to 254 instead of 255.
return static_cast<uint8_t>(std::lround(0.2126 * r + 0.7152 * g + 0.0722 * b));
}

/**
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