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/* @(#) Function to perform black level correction given black image
* @(#) designed for PAD camera single field black to apply in blocks
* @(#) as each is reused for higher resolution pels (eg: 6 8 for Progres)
* @(#) IM_BANDFMT_UCHAR images only. Always writes UCHAR.
* @(#) int im_clamp(in, w, out, hstep, vstep)
* @(#) IMAGE *in, *w, *out; int hstep, vstep;
* @(#) - Compute clip(image - (black)) ie subtract black no negatives
* @(#) scales for low res Progres images to replicate black value
* @(#) Returns 0 on success and -1 on error
* fiddle at your peril - nasty code
* Copyright: 1993 KM
* 20/8/93
*/
/*
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., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 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 <glib/gi18n-lib.h>
#include <stdio.h>
#include <stdlib.h>
#include <vips/vips.h>
#include <vips/vips7compat.h>
#include <vips/internal.h>
int
im_clamp( IMAGE *in, IMAGE *out, IMAGE *black, int hstep, int vstep )
{ PEL *p, *blk, *bline, *bexp;
PEL *q, *outbuf;
int rep;
int x, y, bnd;
int temp, blacky, newblacky;
if( im_iocheck( in, out ) )
return( -1 );
if( in->Bbits != 8 ||
in->Coding != IM_CODING_NONE || in->BandFmt != IM_BANDFMT_UCHAR ) {
im_error( "im_clamp", "%s", _( "bad input format" ) );
return( -1 );
}
if( black->Bbits != 8 ||
black->Coding != IM_CODING_NONE || black->BandFmt != IM_BANDFMT_UCHAR ) {
im_error( "im_clamp", "%s", _( "bad black format" ) );
return( -1 );
}
/* Set up the output header.
*/
if( im_cp_desc( out, in ) )
return( -1 );
if( im_setupout( out ) )
return( -1 );
/* Make buffer for expanded black line
*/
if( !(bline = (PEL *) im_malloc( out, black->Bands * hstep * in->Xsize )) )
return( -1 );
/* Make buffer we write to.
*/
if( !(outbuf = (PEL *) im_malloc( out, out->Bands * out->Xsize )) )
return( -1 );
blacky = -1;
p = (PEL *) in->data;
for( y = 0; y < in->Ysize; y++ ) {
/* calc corresponding black line - get new one if different */
newblacky = (vstep * black->Ysize - in->Ysize + y)/vstep;
if( newblacky != blacky){
blacky = newblacky;
/* time to expand a new black line */
blk = (PEL *) (black->data +
black->Xsize * black->Bands * blacky);
for(bexp = bline, x = 0; x < black->Xsize; x++){
for(rep = 0; rep < hstep; rep++)
for(q=blk, bnd = 0; bnd < in->Bands; bnd++)
*bexp++ = *q++;
blk += black->Bands;
}
}
/* correct a line of image */
bexp = bline;
q = outbuf;
for( x = 0; x < (out->Bands * out->Xsize); x++ ) {
temp = ((int) *p++ - *bexp++);
if( temp < 0 ) temp = 0;
*q++ = (PEL)temp;
}
if( im_writeline( y, out, outbuf ) )
return( -1 );
} /* end of a line */
return( 0 );
}
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