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Simple RGB/HSV conversion in C++
// Copyright (c) 2014, Jan Winkler <winkler@cs.uni-bremen.de>
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
// * Neither the name of Universität Bremen nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
/* Author: Jan Winkler */
#include <iostream>
#include <cstdlib>
#include <cmath>
using namespace std;
/*! \brief Convert RGB to HSV color space
Converts a given set of RGB values `r', `g', `b' into HSV
coordinates. The input RGB values are in the range [0, 1], and the
output HSV values are in the ranges h = [0, 360], and s, v = [0,
1], respectively.
\param fR Red component, used as input, range: [0, 1]
\param fG Green component, used as input, range: [0, 1]
\param fB Blue component, used as input, range: [0, 1]
\param fH Hue component, used as output, range: [0, 360]
\param fS Hue component, used as output, range: [0, 1]
\param fV Hue component, used as output, range: [0, 1]
*/
void RGBtoHSV(float& fR, float& fG, float fB, float& fH, float& fS, float& fV) {
float fCMax = max(max(fR, fG), fB);
float fCMin = min(min(fR, fG), fB);
float fDelta = fCMax - fCMin;
if(fDelta > 0) {
if(fCMax == fR) {
fH = 60 * (fmod(((fG - fB) / fDelta), 6));
} else if(fCMax == fG) {
fH = 60 * (((fB - fR) / fDelta) + 2);
} else if(fCMax == fB) {
fH = 60 * (((fR - fG) / fDelta) + 4);
}
if(fCMax > 0) {
fS = fDelta / fCMax;
} else {
fS = 0;
}
fV = fCMax;
} else {
fH = 0;
fS = 0;
fV = fCMax;
}
if(fH < 0) {
fH = 360 + fH;
}
}
/*! \brief Convert HSV to RGB color space
Converts a given set of HSV values `h', `s', `v' into RGB
coordinates. The output RGB values are in the range [0, 1], and
the input HSV values are in the ranges h = [0, 360], and s, v =
[0, 1], respectively.
\param fR Red component, used as output, range: [0, 1]
\param fG Green component, used as output, range: [0, 1]
\param fB Blue component, used as output, range: [0, 1]
\param fH Hue component, used as input, range: [0, 360]
\param fS Hue component, used as input, range: [0, 1]
\param fV Hue component, used as input, range: [0, 1]
*/
void HSVtoRGB(float& fR, float& fG, float& fB, float& fH, float& fS, float& fV) {
float fC = fV * fS; // Chroma
float fHPrime = fmod(fH / 60.0, 6);
float fX = fC * (1 - fabs(fmod(fHPrime, 2) - 1));
float fM = fV - fC;
if(0 <= fHPrime && fHPrime < 1) {
fR = fC;
fG = fX;
fB = 0;
} else if(1 <= fHPrime && fHPrime < 2) {
fR = fX;
fG = fC;
fB = 0;
} else if(2 <= fHPrime && fHPrime < 3) {
fR = 0;
fG = fC;
fB = fX;
} else if(3 <= fHPrime && fHPrime < 4) {
fR = 0;
fG = fX;
fB = fC;
} else if(4 <= fHPrime && fHPrime < 5) {
fR = fX;
fG = 0;
fB = fC;
} else if(5 <= fHPrime && fHPrime < 6) {
fR = fC;
fG = 0;
fB = fX;
} else {
fR = 0;
fG = 0;
fB = 0;
}
fR += fM;
fG += fM;
fB += fM;
}
int main(int argc, char** argv) {
float fR = 0, fG = 0, fB = 0, fH = 0, fS = 0, fV = 0;
fH = 146.0;
fS = 0.19;
fV = 0.66;
HSVtoRGB(fR, fG, fB, fH, fS, fV);
/*fR = 136.0;
fG = 168.0;
fB = 150.0;
RGBtoHSV(fR, fG, fB, fH, fS, fV);*/
cout << "[RGB] "
<< "Float: (" << fR << ", " << fG << ", " << fB << ")" << endl
<< " Integer: (" << (255 * fR) << ", " << (255 * fG) << ", " << (255 * fB) << ")" << endl;
cout << "[HSV] (" << fH << ", " << fS << ", " << fV << ")" << endl;
return EXIT_SUCCESS;
}
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