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/* $Id: hipass.c,v 1.1.1.1 1998/10/12 20:47:50 root Exp $ */
/*
* Copyright (c) 1990-1996 Sam Leffler
* Copyright (c) 1991-1996 Silicon Graphics, Inc.
* HylaFAX is a trademark of Silicon Graphics
*
* Permission to use, copy, modify, distribute, and sell this software and
* its documentation for any purpose is hereby granted without fee, provided
* that (i) the above copyright notices and this permission notice appear in
* all copies of the software and related documentation, and (ii) the names of
* Sam Leffler and Silicon Graphics may not be used in any advertising or
* publicity relating to the software without the specific, prior written
* permission of Sam Leffler and Silicon Graphics.
*
* THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
* EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
* WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
*
* IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
* ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
* OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
* WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
* LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
* OF THIS SOFTWARE.
*/
/*
* hipass -
* Hi pass filter rows using a 3x3 kernel.
*
* Paul Haeberli - 1989
*
*/
#include "stdio.h"
#include "hipass.h"
highpass *newhp(getfunc,xsize,ysize,mag)
int (*getfunc)();
int xsize, ysize;
float mag;
{
highpass *hp;
int i;
hp = (highpass *)malloc(sizeof(highpass));
hp->getfunc = getfunc;
hp->xsize = xsize;
hp->ysize = ysize;
hp->y = 0;
hp->extrapval = 1024*mag;
for(i=0; i<3; i++)
hp->blurrows[i] = (short *)malloc(xsize*sizeof(short));
for(i=0; i<2; i++)
hp->pastrows[i] = (short *)malloc(xsize*sizeof(short));
hp->acc = (short *)malloc(xsize*sizeof(short));
if(xsize<3 || ysize<3 || hp->extrapval == 0)
hp->active = 0;
else {
hp->active = 1;
}
return hp;
}
freehp(hp)
highpass *hp;
{
int i;
for(i=0; i<3; i++)
free(hp->blurrows[i]);
for(i=0; i<2; i++)
free(hp->pastrows[i]);
free(hp->acc);
free(hp);
}
/*
* extrap -
* Extrapolate from the blurred image beyond the original
*
*/
static extrap(pix,acc,div,n,extrapval)
unsigned short *pix;
short *acc;
int div, n;
int extrapval;
{
int delta, val;
int mul, ext;
mul = div;
div = div*256;
ext = extrapval;
while(n--) {
delta = (*pix * mul)-*acc++;
val = *pix+(ext*delta)/div;
if(val<0)
val = 0;
if(val>255)
val = 255;
*pix++ = val;
}
}
/*
* xblur -
* Blur a row in the x direction
*
*/
static xblur(sptr,cptr,n)
unsigned short *sptr, *cptr;
int n;
{
short acc;
if (n<3) {
fprintf(stderr,"xblur: n may not be less than 3\n");
exit(1);
}
acc = cptr[0] + cptr[1];
*sptr++ = (3*acc+1)>>1;
acc += cptr[2];
n-=3;
while(n--) {
*sptr++ = acc;
acc -= cptr[0];
acc += cptr[3];
cptr++;
}
*sptr++ = acc;
acc -= cptr[0];
*sptr++ = (3*acc+1)>>1;
}
hpgetrow(hp,buf,y)
highpass *hp;
short *buf;
int y;
{
short *temp;
int iy;
if(y == 0)
hp->y = 0;
if(hp->y != y) {
fprintf(stderr,"hpgetrow: y error\n");
exit(1);
}
if(hp->active) {
if (y == 0) {
memset(hp->acc,0,hp->xsize*sizeof(short));
for(iy=0; iy<2; iy++) {
temp = hp->pastrows[0];
hp->pastrows[0] = hp->pastrows[1];
hp->pastrows[1] = temp;
hp->getfunc(hp->pastrows[1],iy);
xblur(hp->blurrows[iy],hp->pastrows[1],hp->xsize);
addsrow(hp->acc,hp->blurrows[iy],hp->xsize);
}
copyrow(hp->pastrows[0],buf,hp->xsize);
extrap(buf,hp->acc,6,hp->xsize,hp->extrapval);
} else if (y == hp->ysize-1) {
copyrow(hp->pastrows[1],buf,hp->xsize);
extrap(buf,hp->acc,6,hp->xsize,hp->extrapval);
} else {
temp = hp->pastrows[0];
hp->pastrows[0] = hp->pastrows[1];
hp->pastrows[1] = temp;
hp->getfunc(hp->pastrows[1],y+1);
xblur(hp->blurrows[2],hp->pastrows[1],hp->xsize);
addsrow(hp->acc,hp->blurrows[2],hp->xsize);
copyrow(hp->pastrows[0],buf,hp->xsize);
extrap(buf,hp->acc,9,hp->xsize,hp->extrapval);
subsrow(hp->acc,hp->blurrows[0],hp->xsize);
temp = hp->blurrows[0];
hp->blurrows[0] = hp->blurrows[1];
hp->blurrows[1] = hp->blurrows[2];
hp->blurrows[2] = temp;
}
} else {
hp->getfunc(buf,y);
}
hp->y++;
}
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