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/*=========================================================================
Program: GDCM (Grassroots DICOM). A DICOM library
Copyright (c) 2006-2011 Mathieu Malaterre
All rights reserved.
See Copyright.txt or http://gdcm.sourceforge.net/Copyright.html for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notice for more information.
=========================================================================*/
#include "gdcmSurfaceHelper.h"
#include <cmath>
namespace gdcm
{
std::vector< float > SurfaceHelper::RGBToXYZ(const std::vector<float> & RGB)
{
std::vector< float > XYZ(3);
float tmp[3];
tmp[0] = RGB[0];
tmp[1] = RGB[1];
tmp[2] = RGB[2];
const float A = 1.0f / 12.92f;
const float B = 1.0f / 1.055f;
if ( tmp[0] > 0.04045f ) tmp[0] = powf( ( tmp[0] + 0.055f ) * B, 2.4f);
else tmp[0] *= A;
if ( tmp[1] > 0.04045f ) tmp[1] = powf( ( tmp[1] + 0.055f ) * B, 2.4f);
else tmp[1] *= A;
if ( tmp[2] > 0.04045f ) tmp[2] = powf( ( tmp[2] + 0.055f ) * B, 2.4f);
else tmp[2] *= A;
tmp[0] *= 100;
tmp[1] *= 100;
tmp[2] *= 100;
//Observer. = 2°, Illuminant = D65
XYZ[0] = (tmp[0] * 0.4124f + tmp[1] * 0.3576f + tmp[2] * 0.1805f);
XYZ[1] = (tmp[0] * 0.2126f + tmp[1] * 0.7152f + tmp[2] * 0.0722f);
XYZ[2] = (tmp[0] * 0.0193f + tmp[1] * 0.1192f + tmp[2] * 0.9505f);
return XYZ;
}
std::vector< float > SurfaceHelper::XYZToRGB(const std::vector<float> & XYZ)
{
std::vector< float > RGB(3);
float tmp[3];
tmp[0] = XYZ[0];
tmp[1] = XYZ[1];
tmp[2] = XYZ[2];
// Divide by 100
tmp[0] *= 0.01f; //X from 0 to 95.047 (Observer = 2°, Illuminant = D65)
tmp[1] *= 0.01f; //Y from 0 to 100.000
tmp[2] *= 0.01f; //Z from 0 to 108.883
RGB[0] = (tmp[0] * 3.2406f + tmp[1] * -1.5372f + tmp[2] * -0.4986f);
RGB[1] = (tmp[0] * -0.9689f + tmp[1] * 1.8758f + tmp[2] * 0.0415f);
RGB[2] = (tmp[0] * 0.0557f + tmp[1] * -0.2040f + tmp[2] * 1.0570f);
const float A = 1.0f / 2.4f;
if ( RGB[0] > 0.0031308f ) RGB[0] = 1.055f * powf( RGB[0], A) - 0.055f;
else RGB[0] *= 12.92f;
if ( RGB[1] > 0.0031308f ) RGB[1] = 1.055f * powf( RGB[1], A) - 0.055f;
else RGB[1] *= 12.92f;
if ( RGB[2] > 0.0031308f ) RGB[2] = 1.055f * powf( RGB[2], A) - 0.055f;
else RGB[2] *= 12.92f;
return RGB;
}
std::vector< float > SurfaceHelper::XYZToCIELab(const std::vector<float> & XYZ)
{
std::vector< float > CIELab(3);
float tmp[3];
tmp[0] = (XYZ[0] / 95.047f); //ref_X = 95.047 Observer= 2°, Illuminant= D65
tmp[1] = (XYZ[1] * 0.01f); //ref_Y = 100.000
tmp[2] = (XYZ[2] / 108.883f); //ref_Z = 108.883
const float A = 1.0f / 3.0f;
const float B = 16.0f / 116.0f;
if ( tmp[0] > 0.008856f ) tmp[0] = powf(tmp[0], A);
else tmp[0] = (7.787f * tmp[0] + B);
if ( tmp[1] > 0.008856f ) tmp[1] = powf(tmp[1], A);
else tmp[1] = (7.787f * tmp[1] + B);
if ( tmp[2] > 0.008856f ) tmp[2] = powf(tmp[2], A);
else tmp[2] = (7.787f * tmp[2] + B);
CIELab[0] = ( 116 * tmp[1] ) - 16;
CIELab[1] = 500 * ( tmp[0] - tmp[1] );
CIELab[2] = 200 * ( tmp[1] - tmp[2] );
return CIELab;
}
std::vector< float > SurfaceHelper::CIELabToXYZ(const std::vector<float> & CIELab)
{
std::vector< float > XYZ(3);
float tmp[3];
tmp[1] = (( CIELab[0] + 16 ) / 116.0f);
tmp[0] = (CIELab[1] * 0.002f + tmp[1]);
tmp[2] = (tmp[1] - CIELab[2] * 0.005f);
// Compute t
const float A = tmp[0]*tmp[0]*tmp[0];
const float B = tmp[1]*tmp[1]*tmp[1];
const float C = tmp[2]*tmp[2]*tmp[2];
const float D = 16.0f / 116.0f;
// Compute f(t)
if ( B > 0.008856f) tmp[1] = B;
else tmp[1] = ( tmp[1] - D ) / 7.787f;
if ( A > 0.008856f) tmp[0] = A;
else tmp[0] = ( tmp[0] - D ) / 7.787f;
if ( C > 0.008856f) tmp[2] = C;
else tmp[2] = ( tmp[2] - D ) / 7.787f;
XYZ[0] = (tmp[0] * 95.047f); //ref_X = 95.047 Observer= 2°, Illuminant= D65
XYZ[1] = (tmp[1] * 100.0f); //ref_Y = 100.000
XYZ[2] = (tmp[2] * 108.883f); //ref_Z = 108.883
return XYZ;
}
}
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