Render a lookup table with luminance data for eye response.

luminance_lut.pde

/*
  Render a lookup table with luminance data for eye response. 

  more about the luminance calculations: 

  http://ledshield.wordpress.com/2012/11/13/led-brightness-to-your-eye-gamma-correction-no/ 
  http://forum.arduino.cc/index.php/topic,147810.0.html
  
  if you can't use dithering it would be smart to add 1 to the output for FastLED 3.0
  since a value of 1 still is 0 due the inner workings of FastLED when dithering is turned off. 
  
*/

int [] luminanceLUT = new int[256];

boolean addOneForFastLED = false;

void setup()
{  
  println("const uint8_t luminanceLUT[] = {");

  for(int i = 0; i < 256; i++) 
  {   
      // brightness should be a value from 0 to 100
      float brightnessScale = map(i,0,255,0.0,100.0);
      float luminance;
      
      if(i>7) luminance = pow((brightnessScale+16.0)/116.0, 3);
      else    luminance = brightnessScale/903.3;
      
      //luminance is a value between 0 and 1
      luminanceLUT[i] = floor(luminance * 255);
      
      if(addOneForFastLED) luminanceLUT[i] = constrain(luminanceLUT[i] + 1,0,255);
      
      //String writeValue = "0x"+hex(luminanceLUT[i],2);
      String writeValue = ""+luminanceLUT[i];
      
      if(i!=255) writeValue = writeValue + ", ";
      
      writeValue = writeValue + printWhiteSpace(luminanceLUT[i]);
      
      if(i%16==0)  print("\t");
      if(i%16==15) println(writeValue);
      else         print(writeValue);
  }
  
  println("}");
  exit();
}

String printWhiteSpace(int val)
{   
    String whitespace = "";  
    
    if(val<10)        whitespace = "  ";
    else if(val<100)  whitespace = " ";
    else              whitespace = "";
        
    return whitespace;
}

/*   output of the script above (FastLED is false)

const uint8_t luminanceLUT[] = {
  0,   0,   0,   0,   0,   0,   0,   0,   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,   4,   4,   4,   4,   4,   5,   5,   5,   5,   5,   6,   6,   6,   6,   
  6,   7,   7,   7,   7,   8,   8,   8,   8,   9,   9,   9,   10,  10,  10,  11,  
  11,  11,  12,  12,  12,  13,  13,  13,  14,  14,  14,  15,  15,  16,  16,  16,  
  17,  17,  18,  18,  19,  19,  20,  20,  21,  21,  22,  22,  23,  23,  24,  24,  
  25,  25,  26,  26,  27,  28,  28,  29,  29,  30,  31,  31,  32,  33,  33,  34,  
  35,  35,  36,  37,  37,  38,  39,  40,  40,  41,  42,  43,  44,  44,  45,  46,  
  47,  48,  49,  49,  50,  51,  52,  53,  54,  55,  56,  57,  58,  59,  60,  61,  
  62,  63,  64,  65,  66,  67,  68,  69,  70,  71,  72,  73,  75,  76,  77,  78,  
  79,  80,  82,  83,  84,  85,  87,  88,  89,  90,  92,  93,  94,  96,  97,  99,  
  100, 101, 103, 104, 106, 107, 108, 110, 111, 113, 114, 116, 118, 119, 121, 122, 
  124, 125, 127, 129, 130, 132, 134, 135, 137, 139, 141, 142, 144, 146, 148, 149, 
  151, 153, 155, 157, 159, 161, 162, 164, 166, 168, 170, 172, 174, 176, 178, 180, 
  182, 185, 187, 189, 191, 193, 195, 197, 200, 202, 204, 206, 208, 211, 213, 215, 
  218, 220, 222, 225, 227, 230, 232, 234, 237, 239, 242, 244, 247, 249, 252, 255
}

*/