128 lines
3.4 KiB
C
128 lines
3.4 KiB
C
/* @(#) Function to perform black level correction given black image
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* @(#) designed for PAD camera single field black to apply in blocks
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* @(#) as each is reused for higher resolution pels (eg: 6 8 for Progres)
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* @(#) IM_BANDFMT_UCHAR images only. Always writes UCHAR.
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* @(#) int im_clamp(in, w, out, hstep, vstep)
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* @(#) IMAGE *in, *w, *out; int hstep, vstep;
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* @(#) - Compute clip(image - (black)) ie subtract black no negatives
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* @(#) scales for low res Progres images to replicate black value
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* @(#) Returns 0 on success and -1 on error
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* fiddle at your peril - nasty code
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* Copyright: 1993 KM
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* 20/8/93
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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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 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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#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 <stdio.h>
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#include <stdlib.h>
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#include <vips/vips.h>
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#include <vips/internal.h>
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#ifdef WITH_DMALLOC
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#include <dmalloc.h>
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#endif /*WITH_DMALLOC*/
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int
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im_clamp( in, out,black, hstep, vstep )
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IMAGE *in, *black, *out;
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int hstep, vstep;
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{ PEL *p, *blk, *bline, *bexp;
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PEL *q, *outbuf;
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int rep;
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int x, y, bnd;
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int temp, blacky, newblacky;
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if( im_iocheck( in, out ) )
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return( -1 );
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if( in->Bbits != 8 ||
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in->Coding != IM_CODING_NONE || in->BandFmt != IM_BANDFMT_UCHAR ) {
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im_error( "im_clamp", _( "bad input format" ) );
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return( -1 );
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}
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if( black->Bbits != 8 ||
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black->Coding != IM_CODING_NONE || black->BandFmt != IM_BANDFMT_UCHAR ) {
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im_error( "im_clamp", _( "bad black format" ) );
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return( -1 );
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}
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/* Set up the output header.
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*/
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if( im_cp_desc( out, in ) )
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return( -1 );
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if( im_setupout( out ) )
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return( -1 );
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/* Make buffer for expanded black line
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*/
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if( !(bline = (PEL *) im_malloc( out, black->Bands * hstep * in->Xsize )) )
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return( -1 );
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/* Make buffer we write to.
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*/
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if( !(outbuf = (PEL *) im_malloc( out, out->Bands * out->Xsize )) )
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return( -1 );
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blacky = -1;
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p = (PEL *) in->data;
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for( y = 0; y < in->Ysize; y++ ) {
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/* calc corresponding black line - get new one if different */
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newblacky = (vstep * black->Ysize - in->Ysize + y)/vstep;
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if( newblacky != blacky){
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blacky = newblacky;
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/* time to expand a new black line */
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blk = (PEL *) (black->data +
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black->Xsize * black->Bands * blacky);
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for(bexp = bline, x = 0; x < black->Xsize; x++){
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for(rep = 0; rep < hstep; rep++)
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for(q=blk, bnd = 0; bnd < in->Bands; bnd++)
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*bexp++ = *q++;
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blk += black->Bands;
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}
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}
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/* correct a line of image */
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bexp = bline;
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q = outbuf;
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for( x = 0; x < (out->Bands * out->Xsize); x++ ) {
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temp = ((int) *p++ - *bexp++);
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if( temp < 0 ) temp = 0;
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*q++ = (PEL)temp;
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}
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if( im_writeline( y, out, outbuf ) )
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return( -1 );
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} /* end of a line */
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return( 0 );
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}
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