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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/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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