mirror of
https://github.com/opencv/opencv.git
synced 2024-11-30 06:10:02 +08:00
136 lines
4.3 KiB
C++
136 lines
4.3 KiB
C++
///////////////////////////////////////////////////////////////////////////
|
|
//
|
|
// Copyright (c) 2003, Industrial Light & Magic, a division of Lucas
|
|
// Digital Ltd. LLC
|
|
//
|
|
// 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 Industrial Light & Magic 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.
|
|
//
|
|
///////////////////////////////////////////////////////////////////////////
|
|
|
|
|
|
//-----------------------------------------------------------------------------
|
|
//
|
|
// CIE (x,y) chromaticities, and conversions between
|
|
// RGB tiples and CIE XYZ tristimulus values.
|
|
//
|
|
//-----------------------------------------------------------------------------
|
|
|
|
#include <ImfChromaticities.h>
|
|
|
|
namespace Imf {
|
|
|
|
|
|
Chromaticities::Chromaticities (const Imath::V2f &red,
|
|
const Imath::V2f &green,
|
|
const Imath::V2f &blue,
|
|
const Imath::V2f &white)
|
|
:
|
|
red (red),
|
|
green (green),
|
|
blue (blue),
|
|
white (white)
|
|
{
|
|
// empty
|
|
}
|
|
|
|
|
|
Imath::M44f
|
|
RGBtoXYZ (const Chromaticities chroma, float Y)
|
|
{
|
|
//
|
|
// For an explanation of how the color conversion matrix is derived,
|
|
// see Roy Hall, "Illumination and Color in Computer Generated Imagery",
|
|
// Springer-Verlag, 1989, chapter 3, "Perceptual Response"; and
|
|
// Charles A. Poynton, "A Technical Introduction to Digital Video",
|
|
// John Wiley & Sons, 1996, chapter 7, "Color science for video".
|
|
//
|
|
|
|
//
|
|
// X and Z values of RGB value (1, 1, 1), or "white"
|
|
//
|
|
|
|
float X = chroma.white.x * Y / chroma.white.y;
|
|
float Z = (1 - chroma.white.x - chroma.white.y) * Y / chroma.white.y;
|
|
|
|
//
|
|
// Scale factors for matrix rows
|
|
//
|
|
|
|
float d = chroma.red.x * (chroma.blue.y - chroma.green.y) +
|
|
chroma.blue.x * (chroma.green.y - chroma.red.y) +
|
|
chroma.green.x * (chroma.red.y - chroma.blue.y);
|
|
|
|
float Sr = (X * (chroma.blue.y - chroma.green.y) -
|
|
chroma.green.x * (Y * (chroma.blue.y - 1) +
|
|
chroma.blue.y * (X + Z)) +
|
|
chroma.blue.x * (Y * (chroma.green.y - 1) +
|
|
chroma.green.y * (X + Z))) / d;
|
|
|
|
float Sg = (X * (chroma.red.y - chroma.blue.y) +
|
|
chroma.red.x * (Y * (chroma.blue.y - 1) +
|
|
chroma.blue.y * (X + Z)) -
|
|
chroma.blue.x * (Y * (chroma.red.y - 1) +
|
|
chroma.red.y * (X + Z))) / d;
|
|
|
|
float Sb = (X * (chroma.green.y - chroma.red.y) -
|
|
chroma.red.x * (Y * (chroma.green.y - 1) +
|
|
chroma.green.y * (X + Z)) +
|
|
chroma.green.x * (Y * (chroma.red.y - 1) +
|
|
chroma.red.y * (X + Z))) / d;
|
|
|
|
//
|
|
// Assemble the matrix
|
|
//
|
|
|
|
Imath::M44f M;
|
|
|
|
M[0][0] = Sr * chroma.red.x;
|
|
M[0][1] = Sr * chroma.red.y;
|
|
M[0][2] = Sr * (1 - chroma.red.x - chroma.red.y);
|
|
|
|
M[1][0] = Sg * chroma.green.x;
|
|
M[1][1] = Sg * chroma.green.y;
|
|
M[1][2] = Sg * (1 - chroma.green.x - chroma.green.y);
|
|
|
|
M[2][0] = Sb * chroma.blue.x;
|
|
M[2][1] = Sb * chroma.blue.y;
|
|
M[2][2] = Sb * (1 - chroma.blue.x - chroma.blue.y);
|
|
|
|
return M;
|
|
}
|
|
|
|
|
|
Imath::M44f
|
|
XYZtoRGB (const Chromaticities chroma, float Y)
|
|
{
|
|
return RGBtoXYZ (chroma, Y).inverse();
|
|
}
|
|
|
|
|
|
} // namespace Imf
|