RGBtoHSV.h

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// -*- mode: c++; indent-tabs-mode: nil; c-basic-offset: 4; coding: iso-8859-1; -*-

/*
ACT-CV - Machine Vision for Cognitive Modeling
Copyright (c) 2008 Marc Halbruegge

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

#ifndef __RGBTOHSV_H
#define __RGBTOHSV_H

struct HSV {
    float h;
    unsigned char s;
    unsigned char v;
};

// RGB nach HSV
#ifndef MIN
#define MIN(a,b) (a<b?a:b)
#endif

#ifndef MAX
#define MAX(a,b) (a>b?a:b)
#endif

void RGBtoHSV(unsigned char r, unsigned char g, unsigned char b,
            float &h, unsigned char &s, unsigned char &v ){
    unsigned char min, max;
    float delta;
    min = MIN(MIN( r, g), b );    
    max = MAX(MAX( r, g), b );
    v = max;              // v
    delta = static_cast<float>(max - min);
    if( max != 0 ) {
        s = (unsigned char) ((delta /(float) max) * 255);       // s
    } else {
        s = 0;
    }

    if (s==0) { // either max=0 oder max=min
        h = 0; //rot
        return;
    }

    if(r == max) {
        h = ( g - b ) / delta;      // between yellow & magenta
    } else if(g == max) {
        h = 2 + ( b - r ) / delta;  // between cyan & yellow
    } else {
        h = 4 + ( r - g ) / delta;  // between magenta & cyan
    }

    h *= 60;              // degrees
    if (h < 0) h += 360;
}

void RGBtoHSV(unsigned char r, unsigned char g, unsigned char b,
    struct HSV &hsv) {
    RGBtoHSV(r,g,b,hsv.h,hsv.s,hsv.v);
}

void RGBtoHSV(unsigned int rgb,
    struct HSV &hsv) {
    RGBtoHSV((rgb&0xff0000)>>16,
             (rgb&0x00ff00)>>8,
             (rgb&0x0000ff),
             hsv.h,hsv.s,hsv.v);
}

#endif