Gamma.h

// Credits to the LPD8806 Advanced Sample

PROGMEM const prog_uchar _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,  1,  1,  1,  1,  1,  1,  1,  1,
    1,  1,  1,  1,  1,  1,  1,  1,  2,  2,  2,  2,  2,  2,  2,  2,
    2,  3,  3,  3,  3,  3,  3,  3,  3,  4,  4,  4,  4,  4,  4,  4,
    5,  5,  5,  5,  5,  6,  6,  6,  6,  6,  7,  7,  7,  7,  7,  8,
    8,  8,  8,  9,  9,  9,  9, 10, 10, 10, 10, 11, 11, 11, 12, 12,
   12, 13, 13, 13, 13, 14, 14, 14, 15, 15, 16, 16, 16, 17, 17, 17,
   18, 18, 18, 19, 19, 20, 20, 21, 21, 21, 22, 22, 23, 23, 24, 24,
   24, 25, 25, 26, 26, 27, 27, 28, 28, 29, 29, 30, 30, 31, 32, 32,
   33, 33, 34, 34, 35, 35, 36, 37, 37, 38, 38, 39, 40, 40, 41, 41,
   42, 43, 43, 44, 45, 45, 46, 47, 47, 48, 49, 50, 50, 51, 52, 52,
   53, 54, 55, 55, 56, 57, 58, 58, 59, 60, 61, 62, 62, 63, 64, 65,
   66, 67, 67, 68, 69, 70, 71, 72, 73, 74, 74, 75, 76, 77, 78, 79,
   80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95,
   96, 97, 98, 99,100,101,102,103,104,105,106,107,108,109,110,111,
  112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127
};

inline byte GammaCorretion(byte x) {
  return pgm_read_byte(&_GammaTable[x]);
}