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/* im_msb
*
* Copyright: 2006, The Nottingham Trent University
*
* Author: Tom Vajzovic
*
* Written on: 2006-03-13
* 27/9/06
* - removed extra im_free() in im_copy() fallback
* 4/10/06
* - removed warning on uchar fallback: it happens a lot with nip2 and
* isn't very serious
* 1/2/10
* - revised, cleanups
* - gtkdoc
*/
/*
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
*/
/** HEADERS **/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H */
#include <vips/intl.h>
#include <vips/vips.h>
typedef struct _Msb {
size_t index;
size_t width;
size_t repeat;
} Msb;
static void
byte_select( unsigned char *in, unsigned char *out, int n, Msb *msb )
{
unsigned char *stop = out + n * msb->repeat;
for( in += msb->index; out < stop; in += msb->width, ++out )
*out = *in;
}
static void
byte_select_flip( unsigned char *in, unsigned char *out, int n, Msb *msb )
{
unsigned char *stop = out + n * msb->repeat;
for( in += msb->index; out < stop; in += msb->width, ++out )
*out = 0x80 ^ *in;
}
static void
msb_labq( unsigned char *in, unsigned char *out, int n )
{
unsigned char *stop = in + (n << 2);
for( ; in < stop; in += 4, out += 3 ) {
out[0] = in[0];
out[1] = 0x80 ^ in[1];
out[2] = 0x80 ^ in[2];
}
}
/**
* im_msb:
* @in: input image
* @out: output image
*
* Turn any integer image to 8-bit unsigned char by discarding all but the most
* significant byte.
* Signed values are converted to unsigned by adding 128.
*
* This operator also works for LABQ coding.
*
* See also: im_msb_band().
*
* Returns: 0 on success, -1 on error
*/
int
im_msb( IMAGE *in, IMAGE *out )
{
Msb *msb;
im_wrapone_fn func;
if( in->Coding == IM_CODING_NONE &&
in->BandFmt == IM_BANDFMT_UCHAR )
return( im_copy( in, out ) );
if( im_piocheck( in, out ) ||
!(msb = IM_NEW( out, Msb )) )
return( -1 );
if( in->Coding == IM_CODING_NONE ) {
if( im_check_int( "im_msb", in ) )
return( -1 );
msb->width = IM_IMAGE_SIZEOF_ELEMENT( in );
msb->index = im_amiMSBfirst() ? 0 : msb->width - 1;
msb->repeat = in->Bands;
if( vips_bandfmt_isuint( in->BandFmt ) )
func = (im_wrapone_fn) byte_select;
else
func = (im_wrapone_fn) byte_select_flip;
}
else if( IM_CODING_LABQ == in->Coding )
func = (im_wrapone_fn) msb_labq;
else {
im_error( "im_msb", "%s", _( "unknown coding" ) );
return( -1 );
}
if( im_cp_desc( out, in ) )
return( -1 );
out->BandFmt = IM_BANDFMT_UCHAR;
out->Coding = IM_CODING_NONE;
return( im_wrapone( in, out, func, msb, NULL ) );
}
/**
* im_msb_band:
* @in: input image
* @out: output image
* @band: select this band
*
* Turn any integer image to a single-band 8-bit unsigned char by discarding
* all but the most significant byte from the selected band.
* Signed values are converted to unsigned by adding 128.
*
* This operator also works for LABQ coding.
*
* See also: im_msb_band().
*
* Returns: 0 on success, -1 on error
*/
int
im_msb_band( IMAGE *in, IMAGE *out, int band )
{
Msb *msb;
im_wrapone_fn func;
if( band < 0 ) {
im_error( "im_msb_band", "%s", _( "bad arguments" ) );
return( -1 );
}
if( im_piocheck( in, out ) ||
!(msb = IM_NEW( out, Msb )) )
return( -1 );
if( in->Coding == IM_CODING_NONE ) {
if( im_check_int( "im_msb_band", in ) )
return( -1 );
if( band >= in->Bands ) {
im_error( "im_msb_band", "%s",
_( "image does not have that many bands" ) );
return( -1 );
}
msb->width = IM_IMAGE_SIZEOF_ELEMENT( in );
msb->index = im_amiMSBfirst() ?
msb->width * band : msb->width * (band + 1) - 1;
msb->repeat = 1;
if( vips_bandfmt_isuint( in->BandFmt ) )
func = (im_wrapone_fn) byte_select;
else
func = (im_wrapone_fn) byte_select_flip;
}
else if( IM_CODING_LABQ == in->Coding ) {
if( band > 2 ) {
im_error( "im_msb_band", "%s",
_( "image does not have that many bands" ) );
return( -1 );
}
msb->width = 4;
msb->repeat = 1;
msb->index = band;
if( band )
func = (im_wrapone_fn) byte_select_flip;
else
func = (im_wrapone_fn) byte_select;
}
else {
im_error( "im_msb", "%s", _( "unknown coding" ) );
return( -1 );
}
if( im_cp_desc( out, in ) )
return( -1 );
out->BandFmt = IM_BANDFMT_UCHAR;
out->Coding = IM_CODING_NONE;
out->Bands = 1;
return( im_wrapone( in, out, func, msb, NULL ) );
}
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