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libvips/libvips/arithmetic/divide.c

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/* Divide two images
*
* Copyright: 1990, N. Dessipris.
*
* Author: Nicos Dessipris
* Written on: 02/05/1990
* Modified on:
* 29/4/93 JC
* - now works for partial images
* 1/7/93 JC
* - adapted for partial v2
* - ANSIfied
* 19/10/93 JC
* - coredump-inducing bug in complex*complex fixed
* 13/12/93
* - char * short bug fixed
* 12/6/95 JC
* - new im_multiply adapted to make new im_divide
* 27/9/04
* - updated for 1 band $op n band image -> n band image case
* 8/12/06
* - add liboil support
* 18/8/08
* - revise upcasting system
* - add gtkdoc comments
* 31/7/10
* - remove liboil support
* - avoid /0
* 6/11/11
* - rewrite as a class
* 22/2/12
* - avoid /0 for complex as well
* 6/4/12
* - fixed switch cases
* - fixed int operands with <1 result
*/
/*
Copyright (C) 1991-2005 The National Gallery
This library 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 2.1 of the License, or (at your option) any later version.
This library 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 library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA
*/
/*
These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
*/
/*
#define DEBUG
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <glib/gi18n-lib.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <vips/vips.h>
#include "binary.h"
typedef VipsBinary VipsDivide;
typedef VipsBinaryClass VipsDivideClass;
G_DEFINE_TYPE( VipsDivide, vips_divide, VIPS_TYPE_BINARY );
/* Complex divide.
*/
#ifdef USE_MODARG_DIV
/* This is going to be much slower */
#define CLOOP( TYPE ) { \
TYPE * restrict left = (TYPE *) in[0]; \
TYPE * restrict right = (TYPE *) in[1]; \
TYPE * restrict q = (TYPE *) out; \
int i; \
\
for( i = 0; i < sz; i++ ) { \
if( right[0] == 0.0 && \
right[1] == 0.0 ) { \
q[0] = 0.0; \
q[1] = 0.0; \
} \
else { \
double arg = atan2( left[1], left[0] ) - \
atan2( right[1], right[0] ); \
double mod = hypot( left[1], left[0] ) / \
hypot( right[1], right[0] ); \
\
q[0] = mod * cos( arg ); \
q[1] = mod * sin( arg ); \
} \
\
left += 2; \
right += 2; \
q += 2; \
} \
}
#else /* USE_MODARG_DIV */
#define CLOOP( TYPE ) { \
TYPE * restrict left = (TYPE *) in[0]; \
TYPE * restrict right = (TYPE *) in[1]; \
TYPE * restrict q = (TYPE *) out; \
int i; \
\
for( i = 0; i < sz; i++ ) { \
if( right[0] == 0.0 && \
right[1] == 0.0 ) { \
q[0] = 0.0; \
q[1] = 0.0; \
} \
else if( VIPS_FABS( right[0] ) > VIPS_FABS( right[1] ) ) { \
double a = right[1] / right[0]; \
double b = right[0] + right[1] * a; \
\
q[0] = (left[0] + left[1] * a) / b; \
q[1] = (left[1] - left[0] * a) / b; \
} \
else { \
double a = right[0] / right[1]; \
double b = right[1] + right[0] * a; \
\
q[0] = (left[0] * a + left[1]) / b; \
q[1] = (left[1] * a - left[0]) / b; \
} \
\
left += 2; \
right += 2; \
q += 2; \
} \
}
#endif /* USE_MODARG_DIV */
/* Real divide. Cast in to OUT before divide so we work for float output.
*/
#define RLOOP( IN, OUT ) { \
IN * restrict left = (IN *) in[0]; \
IN * restrict right = (IN *) in[1]; \
OUT * restrict q = (OUT *) out; \
\
for( x = 0; x < sz; x++ ) \
q[x] = right[x] == 0 ? 0 : (OUT) left[x] / (OUT) right[x]; \
}
static void
vips_divide_buffer( VipsArithmetic *arithmetic,
VipsPel *out, VipsPel **in, int width )
{
VipsImage *im = arithmetic->ready[0];
const int sz = width * vips_image_get_bands( im );
int x;
/* Keep types here in sync with vips_divide_format_table[]
* below.
*/
switch( vips_image_get_format( im ) ) {
case VIPS_FORMAT_CHAR: RLOOP( signed char, float ); break;
case VIPS_FORMAT_UCHAR: RLOOP( unsigned char, float ); break;
case VIPS_FORMAT_SHORT: RLOOP( signed short, float ); break;
case VIPS_FORMAT_USHORT: RLOOP( unsigned short, float ); break;
case VIPS_FORMAT_INT: RLOOP( signed int, float ); break;
case VIPS_FORMAT_UINT: RLOOP( unsigned int, float ); break;
case VIPS_FORMAT_FLOAT: RLOOP( float, float ); break;
case VIPS_FORMAT_DOUBLE: RLOOP( double, double ); break;
case VIPS_FORMAT_COMPLEX: CLOOP( float ); break;
case VIPS_FORMAT_DPCOMPLEX: CLOOP( double ); break;
default:
g_assert_not_reached();
}
}
/* Save a bit of typing.
*/
#define UC VIPS_FORMAT_UCHAR
#define C VIPS_FORMAT_CHAR
#define US VIPS_FORMAT_USHORT
#define S VIPS_FORMAT_SHORT
#define UI VIPS_FORMAT_UINT
#define I VIPS_FORMAT_INT
#define F VIPS_FORMAT_FLOAT
#define X VIPS_FORMAT_COMPLEX
#define D VIPS_FORMAT_DOUBLE
#define DX VIPS_FORMAT_DPCOMPLEX
/* Type promotion for division. Sign and value preserving. Make sure
* these match the case statement in divide_buffer() above.
*/
static VipsBandFormat vips_divide_format_table[10] = {
/* Band format: UC C US S UI I F X D DX */
/* Promotion: */ F, F, F, F, F, F, F, X, D, DX
};
static void
vips_divide_class_init( VipsDivideClass *class )
{
VipsObjectClass *object_class = (VipsObjectClass *) class;
VipsArithmeticClass *aclass = VIPS_ARITHMETIC_CLASS( class );
object_class->nickname = "divide";
object_class->description = _( "divide two images" );
aclass->process_line = vips_divide_buffer;
vips_arithmetic_set_format_table( aclass, vips_divide_format_table );
}
static void
vips_divide_init( VipsDivide *divide )
{
}
/**
* vips_divide:
* @left: input image
* @right: input image
* @out: (out): output image
* @...: %NULL-terminated list of optional named arguments
*
* This operation calculates @in1 / @in2 and writes the result to @out. If any
* pixels in @in2 are zero, the corresponding pixel in @out is also zero.
*
* If the images differ in size, the smaller image is enlarged to match the
* larger by adding zero pixels along the bottom and right.
*
* If the number of bands differs, one of the images
* must have one band. In this case, an n-band image is formed from the
* one-band image by joining n copies of the one-band image together, and then
* the two n-band images are operated upon.
*
* The two input images are cast up to the smallest common format (see table
* Smallest common format in
* <link linkend="libvips-arithmetic">arithmetic</link>), then the
* following table is used to determine the output type:
*
* <table>
* <title>vips_divide() type promotion</title>
* <tgroup cols='2' align='left' colsep='1' rowsep='1'>
* <thead>
* <row>
* <entry>input type</entry>
* <entry>output type</entry>
* </row>
* </thead>
* <tbody>
* <row>
* <entry>uchar</entry>
* <entry>float</entry>
* </row>
* <row>
* <entry>char</entry>
* <entry>float</entry>
* </row>
* <row>
* <entry>ushort</entry>
* <entry>float</entry>
* </row>
* <row>
* <entry>short</entry>
* <entry>float</entry>
* </row>
* <row>
* <entry>uint</entry>
* <entry>float</entry>
* </row>
* <row>
* <entry>int</entry>
* <entry>float</entry>
* </row>
* <row>
* <entry>float</entry>
* <entry>float</entry>
* </row>
* <row>
* <entry>double</entry>
* <entry>double</entry>
* </row>
* <row>
* <entry>complex</entry>
* <entry>complex</entry>
* </row>
* <row>
* <entry>double complex</entry>
* <entry>double complex</entry>
* </row>
* </tbody>
* </tgroup>
* </table>
*
* In other words, the output type is just large enough to hold the whole
* range of possible values.
*
* See also: vips_multiply(), vips_linear(), vips_pow().
*
* Returns: 0 on success, -1 on error
*/
int
vips_divide( VipsImage *left, VipsImage *right, VipsImage **out, ... )
{
va_list ap;
int result;
va_start( ap, out );
result = vips_call_split( "divide", ap, left, right, out );
va_end( ap );
return( result );
}
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