Frank Vannieuwkerke
Tool to convert RGB values to the HSI colorspace
Revision 0:168f892cb7cb, committed 2015-04-16
- Comitter:
- frankvnk
- Date:
- Thu Apr 16 15:44:58 2015 +0000
- Commit message:
- initial release
Changed in this revision
| rgb2hsi.h | Show annotated file Show diff for this revision Revisions of this file |
diff -r 000000000000 -r 168f892cb7cb rgb2hsi.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/rgb2hsi.h Thu Apr 16 15:44:58 2015 +0000
@@ -0,0 +1,49 @@
+/**************************************************************************************************************
+ ***** *****
+ ***** Name: rgb2hsi.h *****
+ ***** Date: 12/04/2015 *****
+ ***** Auth: Frank Vannieuwkerke *****
+ ***** Func: convert RGB color space values to HSI *****
+ ***** *****
+ ***** Source : http://www.had2know.com/technology/hsi-rgb-color-converter-equations.html *****
+ ***** *****
+ **************************************************************************************************************/
+
+#ifndef RGB2HSI_H
+#define RGB2HSI_H
+
+/** Convert RGB to HSI.
+*
+* @param rgb Input - Pointer to RGB array[3] (uint8_t 0..255).\n
+* rgb[0] = red, rgb[1] = green, rgb[2] = blue.\n
+* @param Hue Output - Pointer to Hue (float 0..360)\n
+* @param Saturation Output - Pointer to Saturation (float 0..1)\n
+* @param Intensity Output - Pointer to Intensity (float 0..1)\n
+*
+*/
+void rgb2hsi (uint8_t *rgb, float *Hue, float *Saturation, float *Intensity)
+{
+ float red = (float)rgb[0];
+ float green = (float)rgb[1];
+ float blue = (float)rgb[2];
+ *Intensity = (red + green + blue)/3;
+ if(*Intensity == 0) {
+ *Saturation = 0;
+ } else {
+ *Saturation = 1 - min(red,min(green,blue))/(*Intensity);
+ }
+
+ if((red == green) && (red == blue)) {
+ *Hue = 0;
+ } else {
+ *Hue = acos((red - (green/2) - (blue/2)) / sqrt((red*red) + (green*green) + (blue*blue) - (red*green) - (red*blue) - (green*blue)));
+ *Hue = *Hue * 180.0f / 3.14159265f;
+ if(blue > green)
+ *Hue = 360.0f - (*Hue);
+ }
+ *Hue = floor((*Hue)+0.5);
+ *Intensity = floor((*Intensity)+0.5f)/255;
+ *Saturation = floor(((*Saturation)*10000)+0.5f)/10000;
+}
+
+#endif