libvips/libvips/arithmetic/subtract.c

269 lines
7.0 KiB
C

/* Subtract two images
*
* Copyright: 1990, N. Dessipris.
*
* Author: Nicos Dessipris
* Written on: 02/05/1990
* Modified on:
* 29/4/93 J.Cupitt
* - now works for partial images
* 1/7/93 JC
* - adapted for partial v2
* 9/5/95 JC
* - simplified: now just handles 10 cases (instead of 50), using
* im_clip2*() to help
* - now uses im_wrapmany() rather than im_generate()
* 12/6/95 JC
* - new im_add() adapted to make this
* 31/5/96 JC
* - what was this SWAP() stuff? failed for small - big!
* 22/8/03 JC
* - cast up more quickly to help accuracy
* 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
* - remove separate complex case, just double size
* 31/7/10
* - remove liboil
* 23/8/11
* - rewrite as a class from add.c
*/
/*
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 <vips/intl.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <vips/vips.h>
#include "binary.h"
typedef VipsBinary VipsSubtract;
typedef VipsBinaryClass VipsSubtractClass;
G_DEFINE_TYPE( VipsSubtract, vips_subtract, VIPS_TYPE_BINARY );
#define LOOP( 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] = left[x] - right[x]; \
}
static void
vips_subtract_buffer( VipsArithmetic *arithmetic,
VipsPel *out, VipsPel **in, int width )
{
VipsImage *im = arithmetic->ready[0];
/* Complex just doubles the size.
*/
const int sz = width * vips_image_get_bands( im ) *
(vips_band_format_iscomplex( vips_image_get_format( im ) ) ?
2 : 1);
int x;
/* Keep types here in sync with bandfmt_subtract[]
* below.
*/
switch( vips_image_get_format( im ) ) {
case VIPS_FORMAT_CHAR: LOOP( signed char, signed short ); break;
case VIPS_FORMAT_UCHAR: LOOP( unsigned char, signed short ); break;
case VIPS_FORMAT_SHORT: LOOP( signed short, signed int ); break;
case VIPS_FORMAT_USHORT:LOOP( unsigned short, signed int ); break;
case VIPS_FORMAT_INT: LOOP( signed int, signed int ); break;
case VIPS_FORMAT_UINT: LOOP( unsigned int, signed int ); break;
case VIPS_FORMAT_FLOAT:
case VIPS_FORMAT_COMPLEX:
LOOP( float, float );
break;
case VIPS_FORMAT_DOUBLE:
case VIPS_FORMAT_DPCOMPLEX:
LOOP( double, 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 subtraction. Sign and value preserving. Make sure these
* match the case statement in vips_subtract_buffer() above.
*/
static const VipsBandFormat vips_subtract_format_table[10] = {
/* UC C US S UI I F X D DX */
S, S, I, I, I, I, F, X, D, DX
};
static void
vips_subtract_class_init( VipsSubtractClass *class )
{
VipsObjectClass *object_class = (VipsObjectClass *) class;
VipsArithmeticClass *aclass = VIPS_ARITHMETIC_CLASS( class );
object_class->nickname = "subtract";
object_class->description = _( "subtract two images" );
aclass->process_line = vips_subtract_buffer;
vips_arithmetic_set_format_table( aclass, vips_subtract_format_table );
}
static void
vips_subtract_init( VipsSubtract *subtract )
{
}
/**
* vips_subtract:
* @in1: input image
* @in2: 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 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>VipsSubtract 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>short</entry>
* </row>
* <row>
* <entry>char</entry>
* <entry>short</entry>
* </row>
* <row>
* <entry>ushort</entry>
* <entry>int</entry>
* </row>
* <row>
* <entry>short</entry>
* <entry>int</entry>
* </row>
* <row>
* <entry>uint</entry>
* <entry>int</entry>
* </row>
* <row>
* <entry>int</entry>
* <entry>int</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_add(), vips_linear().
*
* Returns: 0 on success, -1 on error
*/
int
vips_subtract( VipsImage *left, VipsImage *right, VipsImage **out, ... )
{
va_list ap;
int result;
va_start( ap, out );
result = vips_call_split( "subtract", ap, left, right, out );
va_end( ap );
return( result );
}