libvips/libsrc/arithmetic/im_invert.c

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/* @(#) Invert a UCHAR image. Very simple new-style VIPS routine. See
* @(#) im_exptra() for the next level of complexity. This function is not
* @(#) as quick as it could be - it is intended to be an example rather than
* @(#) to be useful. This should really be written with im_wrapone().
* @(#)
* @(#) int
* @(#) im_invert( IMAGE *in, IMAGE *out )
* @(#)
* @(#) All functions return 0 on success and -1 on error
* @(#)
*
* Copyright: 1990, N. Dessipris.
*
* Author: Nicos Dessipris
* Written on: 12/02/1990
* Modified on :
* 7/7/93 JC
* - memory leaks fixed
* - adapted for partial v2
* - ANSIfied
* 22/2/95 JC
* - tidied up again
*/
/*
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 <vips/vips.h>
#ifdef WITH_DMALLOC
#include <dmalloc.h>
#endif /*WITH_DMALLOC*/
/* Invert a REGION. We are given the REGION we should write to, the REGION we
* should use for input, and the IMAGE we are processing. On entry to
* invert_gen(), or points to the memory we should write to and ir is blank.
*/
static int
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invert_gen( REGION *or, void *seq, void *a, void *b )
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{
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REGION *ir = (REGION *) seq;
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/* Left, right, top and bottom for the output region.
*/
int le = or->valid.left;
int to = or->valid.top;
int bo = IM_RECT_BOTTOM( &or->valid );
int x, y;
/* Ask for the section of the input image we need to produce this
* section of the output image.
*/
if( im_prepare( ir, &or->valid ) )
return( -1 );
/* Loop over output, writing input.
*/
for( y = to; y < bo; y++ ) {
/* Point p and q at the start of the line of pels we must
* process this loop.
*/
PEL *p = (PEL *) IM_REGION_ADDR( ir, le, y );
PEL *q = (PEL *) IM_REGION_ADDR( or, le, y );
/* Loop along the line, processing pels.
* IM_REGION_N_ELEMENTS(region) gives
* the number of band elements across a region. By looping to
* IM_REGION_N_ELEMENTS() rather than ir->valid.width, we work
* for any number of bands.
*/
for( x = 0; x < IM_REGION_N_ELEMENTS( or ); x++ )
q[x] = 255 - p[x];
}
return( 0 );
}
/* Invert IMAGE in to IMAGE out. Any number of bands, unsigned char pels
* only. See im_exptra() for an example of a VIPS function which can process
* any input image type.
*/
int
im_invert( IMAGE *in, IMAGE *out )
{
/* Check args.
*/
if( in->Coding != IM_CODING_NONE ) {
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im_error( "im_invert", "%s", _( "not uncoded" ) );
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return( -1 );
}
if( in->BandFmt != IM_BANDFMT_UCHAR ) {
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im_error( "im_invert", "%s", _( "not UCHAR" ) );
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return( -1 );
}
if( im_piocheck( in, out ) )
return( -1 );
/* Prepare the output header.
*/
if( im_cp_desc( out, in ) )
return( -1 );
/* Set demand hints. Like most one-to-one operations, we work best
* with long, thin strips.
*/
if( im_demand_hint( out, IM_THINSTRIP, in, NULL ) )
return( -1 );
/* Generate into out. im_start_one() and im_stop_one() are simple
* convenience functions provided by VIPS which do the necessary
* region creation and destruction for one-image-in
* style functions. See im_add(), im_start_many() and im_stop_many()
* for convenience functions for multiple inputs.
*/
if( im_generate( out,
im_start_one, invert_gen, im_stop_one, in, NULL ) )
return( -1 );
return( 0 );
}