libvips/libsrc/colour/im_Yxy2XYZ.c

103 lines
2.0 KiB
C

/* @(#) Turn Yxy to XYZ colourspace.
* @(#)
* @(#) Usage:
* @(#) im_Yxy2XYZ( imagein, imageout )
* @(#) IMAGE *imagein, *imageout;
* @(#)
* @(#) Float in, float out.
* @(#)
* @(#) Returns: -1 on error, else 0
* Modified:
* 29/5/02 JC
* - from lab2xyz
*/
/*
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 <math.h>
#include <vips/vips.h>
#ifdef WITH_DMALLOC
#include <dmalloc.h>
#endif /*WITH_DMALLOC*/
/* Process a buffer of data.
*/
void
imb_Yxy2XYZ( float *p, float *q, int n )
{
int i;
for( i = 0; i < n; i++ ) {
float Y = p[0];
float x = p[1];
float y = p[2];
double total;
float X, Z;
p += 3;
total = Y / y;
X = x * total;
Z = (X - x * X - x * Y) / x;
q[0] = X;
q[1] = Y;
q[2] = Z;
q += 3;
}
}
int
im_Yxy2XYZ( IMAGE *in, IMAGE *out )
{
if( in->Bands != 3 || in->BandFmt != IM_BANDFMT_FLOAT ||
in->Coding != IM_CODING_NONE ) {
im_errormsg( "im_Yxy2XYZ: 3-band uncoded float input only" );
return( -1 );
}
if( im_cp_desc( out, in ) )
return( -1 );
out->Type = IM_TYPE_XYZ;
if( im_wrapone( in, out,
(im_wrapone_fn) imb_Yxy2XYZ, NULL, NULL ) )
return( -1 );
return( 0 );
}