added gamma correction

Author: felixthecat8a

keywords.txt

@@ -15,6 +15,7 @@ setHex	KEYWORD2
 getColorHex	KEYWORD2
 setHSV	KEYWORD2
 setCMYK KEYWORD2
+setGammaCorrection  KEYWORD2
 off KEYWORD2
 setWhite    KEYWORD2
 setPink KEYWORD2

library.properties

@@ -1,5 +1,5 @@
 name=LCD_BacklightRGB
-version=1.5.7
+version=1.6.0
 author=Felix Ochoa
 maintainer=Felix Ochoa
 sentence=An Arduino library for an 18-pin RGB LCD Display

src/BacklightRGB.cpp

@@ -19,13 +19,15 @@ BacklightRGB::BacklightRGB(uint8_t redPin, uint8_t greenPin, uint8_t bluePin) {
   _redPin = redPin; _greenPin = greenPin; _bluePin = bluePin;
   _COMMON_ANODE = true;
   _brightness = 255;
+  _gammaEnabled = false;
   _currentColor[0] = _currentColor[1] = _currentColor[2] = 0;
 }
 
 BacklightRGB::BacklightRGB(uint8_t redPin, uint8_t greenPin, uint8_t bluePin, bool COMMON_ANODE) {
   _redPin = redPin; _greenPin = greenPin; _bluePin = bluePin;
   _COMMON_ANODE = COMMON_ANODE;
   _brightness = 255;
+  _gammaEnabled = false;
   _currentColor[0] = _currentColor[1] = _currentColor[2] = 0;
 }
 
@@ -104,6 +106,9 @@ void BacklightRGB::setHex(uint32_t hexColor, uint8_t brightness) {
 uint8_t BacklightRGB::setColor(uint8_t color) {
   color = constrain(color, 0, 255);
   color = color * _brightness / 255;
+  if (_gammaEnabled) {
+    color = _gammaTable[color];
+  }
   if (_COMMON_ANODE) {
     color = 255 - color;
   }
@@ -176,3 +181,26 @@ void BacklightRGB::setCMYK(float cyan, float magenta, float yellow, float key) {
   int blue  = roundf((1 - yellow) * (1 - black) * 255);
   setRGB(red, green, blue);
 }
+
+void BacklightRGB::setGammaCorrection(bool enabled) {
+  _gammaEnabled = enabled;
+}
+
+const uint8_t BacklightRGB::_gammaTable[256] = {
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
+  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2,
+  2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5,
+  5, 6, 6, 6, 7, 7, 7, 8, 8, 9, 9, 10, 10, 10, 11, 11,
+  12, 12, 13, 13, 14, 15, 15, 16, 16, 17, 18, 19, 19, 20, 21, 22,
+  23, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37,
+  38, 40, 41, 42, 43, 44, 46, 47, 48, 50, 51, 52, 54, 55, 56, 58,
+  59, 61, 62, 64, 65, 67, 68, 70, 71, 73, 74, 76, 78, 79, 81, 83,
+  84, 86, 88, 90, 91, 93, 95, 97, 99,100,102,104,106,108,110,112,
+  114,116,118,120,122,124,126,128,130,132,134,136,138,141,143,145,
+  147,149,152,154,156,159,161,163,166,168,170,173,175,178,180,183,
+  185,188,190,193,195,198,201,203,206,209,211,214,217,220,222,225,
+  228,231,234,237,239,242,245,248,251,254,255,255,255,255,255,255,
+  255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
+  255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255
+};

src/BacklightRGB.h

@@ -19,12 +19,13 @@
  */
 class BacklightRGB {
     private:
-    bool _COMMON_ANODE;     ///< True if common anode RGB LED
+    bool _COMMON_ANODE;         ///< True if common anode RGB LED
     uint8_t _redPin;            ///< Pin connected to the red LED.
     uint8_t _greenPin;          ///< Pin connected to the green LED.
     uint8_t _bluePin;           ///< Pin connected to the blue LED.
-    uint8_t _brightness;  ///< Brightness value (0 to 255).
+    uint8_t _brightness;        ///< Brightness value (0 to 255).
     uint8_t _currentColor[3];   ///< Array storing the current RGB values.
+    bool _gammaEnabled;         ///< Set true to enable gamma correction.
 
     /**
      * @brief Adjusts the intensity of a color component based on brightness.
@@ -41,6 +42,20 @@ class BacklightRGB {
      */
     inline void showRGB(uint8_t red, uint8_t green, uint8_t blue);
 
+    /**
+     * @brief Precomputed gamma correction lookup table.
+     *
+     * This table maps 8-bit linear brightness values (0–255) to perceptual values
+     * corrected for human vision using a gamma of approximately 2.2.
+     *
+     * When gamma correction is enabled via setGammaCorrection(true), this table is
+     * used to adjust each color channel before output.
+     *
+     * Index: input brightness (0–255)
+     * Value: corrected brightness (0–255)
+     */
+    static const uint8_t _gammaTable[256];
+
     public:
     /**
      * @brief Constructor to initialize RGB pins.
@@ -139,7 +154,6 @@ class BacklightRGB {
     //const int* getRGB() const;
     const uint8_t* getRGB() const;
 
-
     /**
      * @brief Gets the current color as a 24-bit hexadecimal value.
      * @return 24-bit integer representing the color (0xRRGGBB).
@@ -163,6 +177,12 @@ class BacklightRGB {
      */
     void setCMYK(float cyan, float magenta, float yellow, float key);
 
+    /**
+     * @brief Set whether to apply gamma correction to RGB output.
+     *
+     * @param enabled True to apply gamma correction using a lookup table.
+     */
+    void setGammaCorrection(bool enabled);
 };
 
 #endif