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