Colors.cpp

00001 #include <math.h>
00002 #include "Colors.h"
00003 
00004 void HSBtoRGB(float hue, float saturation, float brightness, uint8_t *pr, uint8_t *pg, uint8_t *pb)
00005 {
00006     uint8_t r = 0, g = 0, b = 0;
00007     if (saturation == 0) {
00008         r = g = b = (uint8_t) (brightness * 255.0f + 0.5f);
00009     } else {
00010         float h = (hue - (float)floor(hue)) * 6.0f;
00011         float f = h - (float)floor(h);
00012         float p = brightness * (1.0f - saturation);
00013         float q = brightness * (1.0f - saturation * f);
00014         float t = brightness * (1.0f - (saturation * (1.0f - f)));
00015         switch ((int) h) {
00016             case 0:
00017                 r = (int) (brightness * 255.0f + 0.5f);
00018                 g = (int) (t * 255.0f + 0.5f);
00019                 b = (int) (p * 255.0f + 0.5f);
00020                 break;
00021             case 1:
00022                 r = (int) (q * 255.0f + 0.5f);
00023                 g = (int) (brightness * 255.0f + 0.5f);
00024                 b = (int) (p * 255.0f + 0.5f);
00025                 break;
00026             case 2:
00027                 r = (int) (p * 255.0f + 0.5f);
00028                 g = (int) (brightness * 255.0f + 0.5f);
00029                 b = (int) (t * 255.0f + 0.5f);
00030                 break;
00031             case 3:
00032                 r = (int) (p * 255.0f + 0.5f);
00033                 g = (int) (q * 255.0f + 0.5f);
00034                 b = (int) (brightness * 255.0f + 0.5f);
00035                 break;
00036             case 4:
00037                 r = (int) (t * 255.0f + 0.5f);
00038                 g = (int) (p * 255.0f + 0.5f);
00039                 b = (int) (brightness * 255.0f + 0.5f);
00040                 break;
00041             case 5:
00042                 r = (int) (brightness * 255.0f + 0.5f);
00043                 g = (int) (p * 255.0f + 0.5f);
00044                 b = (int) (q * 255.0f + 0.5f);
00045                 break;
00046         }
00047     }
00048     *pr = r;
00049     *pg = g;
00050     *pb = b;
00051 }
00052 
00053 float* RGBtoHSB(uint8_t r, uint8_t g, uint8_t b, float* hsbvals)
00054 {
00055     float hue, saturation, brightness;
00056     if (!hsbvals) {
00057         hsbvals = new float[3];
00058     }
00059     uint8_t cmax = (r > g) ? r : g;
00060     if (b > cmax) cmax = b;
00061     uint8_t cmin = (r < g) ? r : g;
00062     if (b < cmin) cmin = b;
00063 
00064     brightness = ((float) cmax) / 255.0f;
00065     if (cmax != 0)
00066         saturation = ((float) (cmax - cmin)) / ((float) cmax);
00067     else
00068         saturation = 0;
00069     if (saturation == 0)
00070         hue = 0;
00071     else {
00072         float redc = ((float) (cmax - r)) / ((float) (cmax - cmin));
00073         float greenc = ((float) (cmax - g)) / ((float) (cmax - cmin));
00074         float bluec = ((float) (cmax - b)) / ((float) (cmax - cmin));
00075         if (r == cmax)
00076             hue = bluec - greenc;
00077         else if (g == cmax)
00078             hue = 2.0f + redc - bluec;
00079         else
00080             hue = 4.0f + greenc - redc;
00081         hue = hue / 6.0f;
00082         if (hue < 0)
00083             hue = hue + 1.0f;
00084     }
00085     hsbvals[0] = hue;
00086     hsbvals[1] = saturation;
00087     hsbvals[2] = brightness;
00088     return hsbvals;
00089 }