148 lines
3.0 KiB
C
148 lines
3.0 KiB
C
/* @(#) Turn Lab to XYZ colourspace.
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* @(#)
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* @(#) Usage:
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* @(#) im_Lab2XYZ( imagein, imageout )
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* @(#) IMAGE *imagein, *imageout;
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* @(#)
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* @(#) Float in, float out.
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* @(#)
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* @(#) Returns: -1 on error, else 0
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* Modified:
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* 15/11/94 JC
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* - ANSIfied
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* - sets Type of output
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* - better error messages
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* 16/11/94 JC
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* - partialed
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* - in-line conversion
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* 8/2/95 JC
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* - new im_wrapone function
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*/
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/*
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This file is part of VIPS.
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VIPS is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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/*
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These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif /*HAVE_CONFIG_H*/
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#include <vips/intl.h>
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#include <stdio.h>
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#include <math.h>
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#include <vips/vips.h>
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#ifdef WITH_DMALLOC
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#include <dmalloc.h>
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#endif /*WITH_DMALLOC*/
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/* Process a buffer of data.
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*/
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void
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imb_Lab2XYZ( float *p, float *q, int n, im_colour_temperature *temp )
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{
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int x;
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for( x = 0; x < n; x++ ) {
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float L, a, b;
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float X, Y, Z;
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double cby, tmp;
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L = p[0];
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a = p[1];
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b = p[2];
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p += 3;
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if( L < 8.0 ) {
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Y = (L * temp->Y0) / 903.3;
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cby = 7.787 * (Y / temp->Y0) + 16.0 / 116.0;
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}
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else {
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cby = (L + 16.0) / 116.0;
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Y = temp->Y0 * cby * cby * cby;
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}
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tmp = a / 500.0 + cby;
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if( tmp < 0.2069 )
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X = temp->X0 * (tmp - 0.13793) / 7.787;
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else
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X = temp->X0 * tmp * tmp * tmp;
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tmp = cby - b / 200.0;
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if( tmp < 0.2069 )
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Z = temp->Z0 * (tmp - 0.13793) / 7.787;
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else
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Z = temp->Z0 * tmp * tmp * tmp;
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/* Write.
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*/
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q[0] = X;
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q[1] = Y;
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q[2] = Z;
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q += 3;
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}
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}
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int
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im_Lab2XYZ_temp( IMAGE *in, IMAGE *out, double X0, double Y0, double Z0 )
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{
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im_colour_temperature *temp;
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/* Check input image.
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*/
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if( !(temp = IM_NEW( out, im_colour_temperature )) )
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return( -1 );
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if( in->Bands != 3 ||
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in->BandFmt != IM_BANDFMT_FLOAT ||
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in->Coding != IM_CODING_NONE ) {
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im_error( "im_Lab2XYZ", _( "not 3-band uncoded float" ) );
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return( -1 );
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}
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/* Prepare the output image.
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*/
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if( im_cp_desc( out, in ) )
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return( -1 );
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out->Type = IM_TYPE_XYZ;
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/* Process!
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*/
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temp->X0 = X0;
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temp->Y0 = Y0;
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temp->Z0 = Z0;
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if( im_wrapone( in, out,
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(im_wrapone_fn) imb_Lab2XYZ, temp, NULL ) )
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return( -1 );
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return( 0 );
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}
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int
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im_Lab2XYZ( IMAGE *in, IMAGE *out )
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{
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return( im_Lab2XYZ_temp( in, out, IM_D65_X0, IM_D65_Y0, IM_D65_Z0 ) );
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}
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