80 lines
1.8 KiB
C
80 lines
1.8 KiB
C
/* hsv2rgb.c
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* Integer only conversion functions between HSV and RGB
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*/
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#include "hsv2rgb.h"
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// TODO fix these buggy macros
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#define max(x,y) ((x>y) ? x:y)
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#define min(x,y) ((x>y) ? y:x)
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#define min3(x,y,z) (min(min(x,y),z))
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#define max3(x,y,z) (max(max(x,y),z))
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rgb_color hsv2rgb(hsv_color hsv)
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{
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// From : http://qscribble.blogspot.fr/2008/06/integer-conversion-from-hsl-to-rgb.html
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int h = hsv.h;
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int s = hsv.s;
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int v = hsv.v;
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rgb_color rgb = {0, 0, 0};
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if (v == 0)
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return rgb;
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// sextant = 0 .. 5
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int sextant = (h*6)/256;
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// f = 0 .. 42
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int f = h - (sextant*256)/6;
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int p = (v * (256 - s))/256;
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int q = (v * (256*43 - s*f))/(256*43);
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int t = (v * (256*43 - s*(43-f)))/(256*43);
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// Corrige les erreurs dues aux arrondis
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p = max(min(p, 255), 0);
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q = max(min(q, 255), 0);
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t = max(min(t, 255), 0);
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switch(sextant){
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case 0: rgb.r = v; rgb.g = t; rgb.b = p; break;
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case 1: rgb.r = q; rgb.g = v; rgb.b = p; break;
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case 2: rgb.r = p; rgb.g = v; rgb.b = t; break;
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case 3: rgb.r = p; rgb.g = q; rgb.b = v; break;
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case 4: rgb.r = t; rgb.g = p; rgb.b = v; break;
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default:rgb.r = v; rgb.g = p; rgb.b = q; break;
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}
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return rgb;
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}
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hsv_color rgb2hsv(rgb_color rgb)
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{
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// From : http://www.ruinelli.ch/rgb-to-hsv
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hsv_color hsv = {0, 0, 0};
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int min, max, delta;
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min = min3(rgb.r, rgb.g, rgb.b);
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max = max3(rgb.r, rgb.g, rgb.b);
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if(max==0) {
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hsv.h = 0;
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hsv.s = 0;
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hsv.v = 0;
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return hsv;
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}
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hsv.v = max;
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delta = max - min;
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hsv.s = (delta)*255 / max;
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if(rgb.r == max)
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hsv.h = (rgb.g - rgb.b)*42/delta; // between yellow & magenta
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else if(rgb.g == max)
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hsv.h = 120 + (rgb.b - rgb.r)*42/delta; // between cyan & yellow
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else
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hsv.h = 240 + (rgb.r - rgb.g)*42/delta; // between magenta & cyan
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return hsv;
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} |