172 lines
3.2 KiB
C
172 lines
3.2 KiB
C
/* Turn Lab to LCh
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*
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* 2/11/09
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* - gtkdoc
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* - cleanups
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* 18/9/12
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* - redone as a class
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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., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 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 <glib/gi18n-lib.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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#include "pcolour.h"
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typedef VipsColourTransform VipsLab2LCh;
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typedef VipsColourTransformClass VipsLab2LChClass;
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G_DEFINE_TYPE( VipsLab2LCh, vips_Lab2LCh, VIPS_TYPE_COLOUR_TRANSFORM );
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/**
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* vips_col_ab2h:
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* @a: CIE a
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* @b: CIE b
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*
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* Returns: Hue (degrees)
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*/
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double
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vips_col_ab2h( double a, double b )
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{
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double h;
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/* We have to get the right quadrant!
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*/
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if( a == 0 ) {
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if( b < 0.0 )
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h = 270;
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else if( b == 0.0 )
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h = 0;
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else
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h = 90;
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}
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else {
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double t = atan( b / a );
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if( a > 0.0 )
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if( b < 0.0 )
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h = VIPS_DEG( t + VIPS_PI * 2.0 );
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else
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h = VIPS_DEG( t );
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else
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h = VIPS_DEG( t + VIPS_PI );
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}
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return( h );
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}
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void
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vips_col_ab2Ch( float a, float b, float *C, float *h )
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{
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*h = vips_col_ab2h( a, b );
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#ifdef HAVE_HYPOT
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*C = hypot( a, b );
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#else
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*C = sqrt( a * a + b * b );
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#endif
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}
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static void
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vips_Lab2LCh_line( VipsColour *colour, VipsPel *out, VipsPel **in, int width )
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{
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float * restrict p = (float *) in[0];
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float * restrict q = (float *) out;
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int x;
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for( x = 0; x < width; x++ ) {
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float L = p[0];
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float a = p[1];
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float b = p[2];
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float C, h;
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p += 3;
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C = sqrt( a * a + b * b );
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h = vips_col_ab2h( a, b );
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q[0] = L;
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q[1] = C;
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q[2] = h;
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q += 3;
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}
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}
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static void
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vips_Lab2LCh_class_init( VipsLab2LChClass *class )
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{
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VipsObjectClass *object_class = (VipsObjectClass *) class;
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VipsColourClass *colour_class = VIPS_COLOUR_CLASS( class );
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object_class->nickname = "Lab2LCh";
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object_class->description = _( "transform Lab to LCh" );
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colour_class->process_line = vips_Lab2LCh_line;
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}
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static void
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vips_Lab2LCh_init( VipsLab2LCh *Lab2LCh )
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{
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VipsColour *colour = VIPS_COLOUR( Lab2LCh );
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colour->interpretation = VIPS_INTERPRETATION_LCH;
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}
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/**
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* vips_Lab2LCh: (method)
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* @in: input image
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* @out: (out): output image
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* @...: %NULL-terminated list of optional named arguments
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*
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* Turn Lab to LCh.
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*
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* Returns: 0 on success, -1 on error
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*/
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int
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vips_Lab2LCh( VipsImage *in, VipsImage **out, ... )
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{
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va_list ap;
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int result;
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va_start( ap, out );
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result = vips_call_split( "Lab2LCh", ap, in, out );
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va_end( ap );
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return( result );
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}
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