244 lines
6.0 KiB
C
244 lines
6.0 KiB
C
/* Convert colours in various ways.
|
|
*
|
|
* Written: January 1990
|
|
* Modified .. innumerable times
|
|
* Code by: DS, JC, J-Ph.L.
|
|
* 18/7/93 JC
|
|
* - final tidies before v7 release
|
|
* - ANSIfied
|
|
* - code for samples removed
|
|
* 5/5/94 JC
|
|
* - nint() -> rint() to make ANSI easier
|
|
* 14/3/96 JC
|
|
* - new display characterisation
|
|
* - speed-up to im_col_XYZ2rgb() and im_col_rgb2XYZ()
|
|
* 4/3/98 JC
|
|
* - new display profile for ultra2
|
|
* - new sRGB profile
|
|
* 17/8/98 JC
|
|
* - error_exit() removed, now clips
|
|
* 26/11/03 Andrey Kiselev
|
|
* - tiny clean-up for calcul_tables()
|
|
* - some reformatting
|
|
* 23/7/07
|
|
* - tiny cleanup for make_hI() prevents cond jump on ui in valgrind
|
|
* 14/3/08
|
|
* - more tiny cond jump valgrind fixes
|
|
* 23/10/09
|
|
* - gtkdoc comments
|
|
*/
|
|
|
|
/*
|
|
|
|
This file is part of VIPS.
|
|
|
|
VIPS is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU Lesser 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 Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public License
|
|
along with this program; if not, write to the Free Software
|
|
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
|
|
|
|
*/
|
|
|
|
/*
|
|
|
|
These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
|
|
|
|
*/
|
|
|
|
#ifdef HAVE_CONFIG_H
|
|
#include <config.h>
|
|
#endif /*HAVE_CONFIG_H*/
|
|
#include <vips/intl.h>
|
|
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
#include <ctype.h>
|
|
#include <math.h>
|
|
|
|
#include <vips/vips.h>
|
|
#include <vips/internal.h>
|
|
|
|
/**
|
|
* vips_pythagoras:
|
|
* @L1: Input coordinate 1
|
|
* @a1: Input coordinate 1
|
|
* @b1: Input coordinate 1
|
|
* @L2: Input coordinate 2
|
|
* @a2: Input coordinate 2
|
|
* @b2: Input coordinate 2
|
|
*
|
|
* Pythagorean distance between two points in colour space. Lab/XYZ/UCS etc.
|
|
*/
|
|
float
|
|
vips_pythagoras( float L1, float a1, float b1, float L2, float a2, float b2 )
|
|
{
|
|
float dL = L1 - L2;
|
|
float da = a1 - a2;
|
|
float db = b1 - b2;
|
|
|
|
return( sqrt( dL * dL + da * da + db * db ) );
|
|
}
|
|
|
|
/* Functions to convert from Lab to uniform colour space and back.
|
|
*/
|
|
|
|
/**
|
|
* im_col_dE00:
|
|
* @L1: Input coordinate 1
|
|
* @a1: Input coordinate 1
|
|
* @b1: Input coordinate 1
|
|
* @L2: Input coordinate 2
|
|
* @a2: Input coordinate 2
|
|
* @b2: Input coordinate 2
|
|
*
|
|
* CIEDE2000, from:
|
|
*
|
|
* Luo, Cui, Rigg, "The Development of the CIE 2000 Colour-Difference
|
|
* Formula: CIEDE2000", COLOR research and application, pp 340
|
|
*
|
|
* Returns: CIE dE2000 colour difference.
|
|
*/
|
|
float
|
|
im_col_dE00( float L1, float a1, float b1,
|
|
float L2, float a2, float b2 )
|
|
{
|
|
/* Code if you want XYZ params and the colour temp used in the reference
|
|
|
|
float
|
|
im_col_dE00( float X1, float Y1, float Z1,
|
|
float X2, float Y2, float Z2 )
|
|
{
|
|
const double X0 = 94.811;
|
|
const double Y0 = 100.0;
|
|
const double Z0 = 107.304;
|
|
|
|
#define f(I) ((I) > 0.008856 ? \
|
|
cbrt( (I), 1.0 / 3.0 ) : 7.7871 * (I) + (16.0 / 116.0))
|
|
|
|
double nX1 = f( X1 / X0 );
|
|
double nY1 = f( Y1 / Y0 );
|
|
double nZ1 = f( Z1 / Z0 );
|
|
|
|
double L1 = 116 * nY1 - 16;
|
|
double a1 = 500 * (nX1 - nY1);
|
|
double b1 = 200 * (nY1 - nZ1);
|
|
|
|
double nX2 = f( X2 / X0 );
|
|
double nY2 = f( Y2 / Y0 );
|
|
double nZ2 = f( Z2 / Z0 );
|
|
|
|
double L2 = 116 * nY2 - 16;
|
|
double a2 = 500 * (nX2 - nY2);
|
|
double b2 = 200 * (nY2 - nZ2);
|
|
*/
|
|
|
|
/* Chroma and mean chroma (C bar)
|
|
*/
|
|
double C1 = sqrt( a1 * a1 + b1 * b1 );
|
|
double C2 = sqrt( a2 * a2 + b2 * b2 );
|
|
double Cb = (C1 + C2) / 2;
|
|
|
|
/* G
|
|
*/
|
|
double Cb7 = Cb * Cb * Cb * Cb * Cb * Cb * Cb;
|
|
double G = 0.5 * (1 - sqrt( Cb7 / (Cb7 + pow( 25, 7 )) ));
|
|
|
|
/* L', a', b', C', h'
|
|
*/
|
|
double L1d = L1;
|
|
double a1d = (1 + G) * a1;
|
|
double b1d = b1;
|
|
double C1d = sqrt( a1d * a1d + b1d * b1d );
|
|
double h1d = im_col_ab2h( a1d, b1d );
|
|
|
|
double L2d = L2;
|
|
double a2d = (1 + G) * a2;
|
|
double b2d = b2;
|
|
double C2d = sqrt( a2d * a2d + b2d * b2d );
|
|
double h2d = im_col_ab2h( a2d, b2d );
|
|
|
|
/* L' bar, C' bar, h' bar
|
|
*/
|
|
double Ldb = (L1d + L2d) / 2;
|
|
double Cdb = (C1d + C2d) / 2;
|
|
double hdb = fabs( h1d - h2d ) < 180 ?
|
|
(h1d + h2d) / 2 :
|
|
fabs( h1d + h2d - 360 ) / 2;
|
|
|
|
/* dtheta, RC
|
|
*/
|
|
double hdbd = (hdb - 275) / 25;
|
|
double dtheta = 30 * exp( -(hdbd * hdbd) );
|
|
double Cdb7 = Cdb * Cdb * Cdb * Cdb * Cdb * Cdb * Cdb;
|
|
double RC = 2 * sqrt( Cdb7 / (Cdb7 + pow( 25, 7 )) );
|
|
|
|
/* RT, T.
|
|
*/
|
|
double RT = -sin( IM_RAD( 2 * dtheta ) ) * RC;
|
|
double T = 1 -
|
|
0.17 * cos( IM_RAD( hdb - 30 ) ) +
|
|
0.24 * cos( IM_RAD( 2 * hdb ) ) +
|
|
0.32 * cos( IM_RAD( 3 * hdb + 6 ) ) -
|
|
0.20 * cos( IM_RAD( 4 * hdb - 63 ) );
|
|
|
|
/* SL, SC, SH
|
|
*/
|
|
double Ldb50 = Ldb - 50;
|
|
double SL = 1 + (0.015 * Ldb50 * Ldb50) / sqrt( 20 + Ldb50 * Ldb50);
|
|
double SC = 1 + 0.045 * Cdb;
|
|
double SH = 1 + 0.015 * Cdb * T;
|
|
|
|
/* hue difference ... careful!
|
|
*/
|
|
double dhd = fabs( h1d - h2d ) < 180 ?
|
|
h1d - h2d :
|
|
360 - (h1d - h2d);
|
|
|
|
/* dLd, dCd dHd
|
|
*/
|
|
double dLd = L1d - L2d;
|
|
double dCd = C1d - C2d;
|
|
double dHd = 2 * sqrt( C1d * C2d ) * sin( IM_RAD( dhd / 2 ) );
|
|
|
|
/* Parametric factors for viewing parameters.
|
|
*/
|
|
const double kL = 1.0;
|
|
const double kC = 1.0;
|
|
const double kH = 1.0;
|
|
|
|
/* Normalised terms.
|
|
*/
|
|
double nL = dLd / (kL * SL);
|
|
double nC = dCd / (kC * SC);
|
|
double nH = dHd / (kH * SH);
|
|
|
|
/* dE00!!
|
|
*/
|
|
double dE00 = sqrt( nL * nL + nC * nC + nH * nH + RT * nC * nH );
|
|
|
|
/*
|
|
printf( "X1 = %g, Y1 = %g, Z1 = %g\n", X1, Y1, Z1 );
|
|
printf( "X2 = %g, Y2 = %g, Z2 = %g\n", X2, Y2, Z2 );
|
|
printf( "L1 = %g, a1 = %g, b1 = %g\n", L1, a1, b1 );
|
|
printf( "L2 = %g, a2 = %g, b2 = %g\n", L2, a2, b2 );
|
|
printf( "L1d = %g, a1d = %g, b1d = %g, C1d = %g, h1d = %g\n",
|
|
L1d, a1d, b1d, C1d, h1d );
|
|
printf( "L2d = %g, a2d = %g, b2d = %g, C2d = %g, h2d = %g\n",
|
|
L2d, a2d, b2d, C2d, h2d );
|
|
printf( "G = %g, T = %g, SL = %g, SC = %g, SH = %g, RT = %g\n",
|
|
G, T, SL, SC, SH, RT );
|
|
printf( "dE00 = %g\n", dE00 );
|
|
*/
|
|
|
|
return( dE00 );
|
|
}
|