src/px/pf3.c

#ifndef lint
static const char RCSid[] = "$Id: pf3.c,v 2.16 2003/06/30 14:59:12 schorsch Exp $";
#endif
/*
 *  pf3.c - routines for gaussian and box filtering
 *
 *     8/13/86
 */

#include  "standard.h"

#include  <string.h>

#include  "color.h"

#define  RSCA           1.13    /* square-radius multiplier: sqrt(4/PI) */
#define  TEPS           0.2     /* threshold proximity goal */
#define  REPS           0.1     /* radius proximity goal */

extern double  CHECKRAD;        /* radius over which gaussian is summed */

extern double  rad;             /* output pixel radius for filtering */

extern double  thresh;          /* maximum contribution for subpixel */

extern int  nrows;              /* number of rows for output */
extern int  ncols;              /* number of columns for output */

extern int  xres, yres;         /* resolution of input */

extern double  x_c, y_r;        /* conversion factors */

extern int  xrad;               /* x search radius */
extern int  yrad;               /* y search radius */
extern int  xbrad;              /* x box size */
extern int  ybrad;              /* y box size */

extern int  barsize;            /* size of input scan bar */
extern COLOR  **scanin;         /* input scan bar */
extern COLOR  *scanout;         /* output scan line */
extern COLOR  **scoutbar;       /* output scan bar (if thresh > 0) */
extern float  **greybar;        /* grey-averaged input values */
extern int  obarsize;           /* size of output scan bar */
extern int  orad;               /* output window radius */

extern int  wrapfilt;           /* wrap filter horizontally? */

extern char  *progname;

float  *gausstable;             /* gauss lookup table */

float  *ringsum;                /* sum of ring values */
short  *ringwt;                 /* weight (count) of ring values */
short  *ringndx;                /* ring index table */
float  *warr;                   /* array of pixel weights */

extern double  (*ourbright)();  /* brightness computation function */

double  pickfilt();

#define  lookgauss(x)           gausstable[(int)(10.*(x)+.5)]


initmask()                      /* initialize gaussian lookup table */
{
        int  gtabsiz;
        double  gaussN;
        double  d;
        register int  x;

        gtabsiz = 111*CHECKRAD*CHECKRAD;
        gausstable = (float *)malloc(gtabsiz*sizeof(float));
        if (gausstable == NULL)
                goto memerr;
        d = x_c*y_r*0.25/(rad*rad);
        gausstable[0] = exp(-d);
        for (x = 1; x < gtabsiz; x++)
                if (x*0.1 <= d)
                        gausstable[x] = gausstable[0];
                else
                        gausstable[x] = exp(-x*0.1);
        if (obarsize == 0)
                return;
                                        /* compute integral of filter */
        gaussN = PI*d*exp(-d);                  /* plateau */
        for (d = sqrt(d)+0.05; d <= RSCA*CHECKRAD; d += 0.1)
                gaussN += 0.1*2.0*PI*d*exp(-d*d);
                                        /* normalize filter */
        gaussN = x_c*y_r/(rad*rad*gaussN);
        for (x = 0; x < gtabsiz; x++)
                gausstable[x] *= gaussN;
                                        /* create ring averages table */
        ringndx = (short *)malloc((2*orad*orad+1)*sizeof(short));
        if (ringndx == NULL)
                goto memerr;
        for (x = 2*orad*orad+1; --x > orad*orad; )
                ringndx[x] = -1;
        do
                ringndx[x] = sqrt((double)x);
        while (x--);
        ringsum = (float *)malloc((orad+1)*sizeof(float));
        ringwt = (short *)malloc((orad+1)*sizeof(short));
        warr = (float *)malloc(obarsize*obarsize*sizeof(float));
        if ((ringsum == NULL) | (ringwt == 0) | (warr == NULL))
                goto memerr;
        return;
memerr:
        fprintf(stderr, "%s: out of memory in initmask\n", progname);
        quit(1);
}


dobox(csum, xcent, ycent, c, r)                 /* simple box filter */
COLOR  csum;
int  xcent, ycent;
int  c, r;
{
        int  wsum;
        double  d;
        int  y;
        register int  x, offs;
        register COLOR  *scan;
        
        wsum = 0;
        setcolor(csum, 0.0, 0.0, 0.0);
        for (y = ycent+1-ybrad; y <= ycent+ybrad; y++) {
                if (y < 0) continue;
                if (y >= yres) break;
                d = y_r < 1.0 ? y_r*y - (r+.5) : (double)(y - ycent);
                if (d < -0.5) continue;
                if (d >= 0.5) break;
                scan = scanin[y%barsize];
                for (x = xcent+1-xbrad; x <= xcent+xbrad; x++) {
                        offs = x < 0 ? xres : x >= xres ? -xres : 0;
                        if (offs && !wrapfilt)
                                continue;
                        d = x_c < 1.0 ? x_c*x - (c+.5) : (double)(x - xcent);
                        if (d < -0.5) continue;
                        if (d >= 0.5) break;
                        wsum++;
                        addcolor(csum, scan[x+offs]);
                }
        }
        if (wsum > 1) {
                d = 1.0/wsum;
                scalecolor(csum, d);
        }
}


dogauss(csum, xcent, ycent, c, r)               /* gaussian filter */
COLOR  csum;
int  xcent, ycent;
int  c, r;
{
        double  dy, dx, weight, wsum;
        COLOR  ctmp;
        int  y;
        register int  x, offs;
        register COLOR  *scan;

        wsum = FTINY;
        setcolor(csum, 0.0, 0.0, 0.0);
        for (y = ycent-yrad; y <= ycent+yrad; y++) {
                if (y < 0) continue;
                if (y >= yres) break;
                dy = (y_r*(y+.5) - (r+.5))/rad;
                scan = scanin[y%barsize];
                for (x = xcent-xrad; x <= xcent+xrad; x++) {
                        offs = x < 0 ? xres : x >= xres ? -xres : 0;
                        if (offs && !wrapfilt)
                                continue;
                        dx = (x_c*(x+.5) - (c+.5))/rad;
                        weight = lookgauss(dx*dx + dy*dy);
                        wsum += weight;
                        copycolor(ctmp, scan[x+offs]);
                        scalecolor(ctmp, weight);
                        addcolor(csum, ctmp);
                }
        }
        weight = 1.0/wsum;
        scalecolor(csum, weight);
}


dothresh(xcent, ycent, ccent, rcent)    /* gaussian threshold filter */
int  xcent, ycent;
int  ccent, rcent;
{
        double  d;
        int  r, y, offs;
        register int  c, x;
        register float  *gscan;
                                        /* compute ring sums */
        memset((char *)ringsum, '\0', (orad+1)*sizeof(float));
        memset((char *)ringwt, '\0', (orad+1)*sizeof(short));
        for (r = -orad; r <= orad; r++) {
                if (rcent+r < 0) continue;
                if (rcent+r >= nrows) break;
                gscan = greybar[(rcent+r)%obarsize];
                for (c = -orad; c <= orad; c++) {
                        offs = ccent+c < 0 ? ncols :
                                        ccent+c >= ncols ? -ncols : 0;
                        if (offs && !wrapfilt)
                                continue;
                        x = ringndx[c*c + r*r];
                        if (x < 0) continue;
                        ringsum[x] += gscan[ccent+c+offs];
                        ringwt[x]++;
                }
        }
                                        /* filter each subpixel */
        for (y = ycent+1-ybrad; y <= ycent+ybrad; y++) {
                if (y < 0) continue;
                if (y >= yres) break;
                d = y_r < 1.0 ? y_r*y - (rcent+.5) : (double)(y - ycent);
                if (d < -0.5) continue;
                if (d >= 0.5) break;
                for (x = xcent+1-xbrad; x <= xcent+xbrad; x++) {
                        offs = x < 0 ? xres : x >= xres ? -xres : 0;
                        if (offs && !wrapfilt)
                                continue;
                        d = x_c < 1.0 ? x_c*x - (ccent+.5) : (double)(x - xcent);
                        if (d < -0.5) continue;
                        if (d >= 0.5) break;
                        sumans(x, y, rcent, ccent,
                        pickfilt((*ourbright)(scanin[y%barsize][x+offs])));
                }
        }
}


double
pickfilt(p0)                    /* find filter multiplier for p0 */
double  p0;
{
        double  m = 1.0;
        double  t, num, denom, avg, wsum;
        double  mlimit[2];
        int  ilimit = 4.0/TEPS;
        register int  i;
                                /* iterative search for m */
        mlimit[0] = 1.0; mlimit[1] = orad/rad/CHECKRAD;
        do {
                                        /* compute grey weighted average */
                i = RSCA*CHECKRAD*rad*m + .5;
                if (i > orad) i = orad;
                avg = wsum = 0.0;
                while (i--) {
                        t = (i+.5)/(m*rad);
                        t = lookgauss(t*t);
                        avg += t*ringsum[i];
                        wsum += t*ringwt[i];
                }
                if (avg < 1e-20)                /* zero inclusive average */
                        return(1.0);
                avg /= wsum;
                                        /* check threshold */
                denom = m*m/gausstable[0] - p0/avg;
                if (denom <= FTINY) {           /* zero exclusive average */
                        if (m >= mlimit[1]-REPS)
                                break;
                        m = mlimit[1];
                        continue;
                }
                num = p0/avg - 1.0;
                if (num < 0.0) num = -num;
                t = num/denom;
                if (t <= thresh) {
                        if (m <= mlimit[0]+REPS || (thresh-t)/thresh <= TEPS)
                                break;
                } else {
                        if (m >= mlimit[1]-REPS || (t-thresh)/thresh <= TEPS)
                                break;
                }
                t = m;                  /* remember current m */
                                        /* next guesstimate */
                m = sqrt(gausstable[0]*(num/thresh + p0/avg));
                if (m < t) {            /* bound it */
                        if (m <= mlimit[0]+FTINY)
                                m = 0.5*(mlimit[0] + t);
                        mlimit[1] = t;
                } else {
                        if (m >= mlimit[1]-FTINY)
                                m = 0.5*(mlimit[1] + t);
                        mlimit[0] = t;
                }
        } while (--ilimit > 0);
        return(m);
}


sumans(px, py, rcent, ccent, m)         /* sum input pixel to output */
int  px, py;
int  rcent, ccent;
double  m;
{
        double  dy2, dx;
        COLOR  pval, ctmp;
        int  ksiz, r, offs;
        double  pc, pr, norm;
        register int  i, c;
        register COLOR  *scan;
        /*
         * This normalization method fails at the picture borders because
         * a different number of input pixels contribute there.
         */
        scan = scanin[py%barsize] + (px < 0 ? xres : px >= xres ? -xres : 0);
        copycolor(pval, scan[px]);
        pc = x_c*(px+.5);
        pr = y_r*(py+.5);
        ksiz = CHECKRAD*m*rad + 1;
        if (ksiz > orad) ksiz = orad;
                                                /* compute normalization */
        norm = 0.0;
        i = 0;
        for (r = rcent-ksiz; r <= rcent+ksiz; r++) {
                if (r < 0) continue;
                if (r >= nrows) break;
                dy2 = (pr - (r+.5))/(m*rad);
                dy2 *= dy2;
                for (c = ccent-ksiz; c <= ccent+ksiz; c++) {
                        if (!wrapfilt) {
                                if (c < 0) continue;
                                if (c >= ncols) break;
                        }
                        dx = (pc - (c+.5))/(m*rad);
                        norm += warr[i++] = lookgauss(dx*dx + dy2);
                }
        }
        norm = 1.0/norm;
        if (x_c < 1.0) norm *= x_c;
        if (y_r < 1.0) norm *= y_r;
                                                /* sum pixels */
        i = 0;
        for (r = rcent-ksiz; r <= rcent+ksiz; r++) {
                if (r < 0) continue;
                if (r >= nrows) break;
                scan = scoutbar[r%obarsize];
                for (c = ccent-ksiz; c <= ccent+ksiz; c++) {
                        offs = c < 0 ? ncols : c >= ncols ? -ncols : 0;
                        if (offs && !wrapfilt)
                                continue;
                        copycolor(ctmp, pval);
                        dx = norm*warr[i++];
                        scalecolor(ctmp, dx);
                        addcolor(scan[c+offs], ctmp);
                }
        }
}
Revision:	2.17
Committed:	Sun Jul 27 22:12:03 2003 UTC (20 years, 9 months ago) by schorsch
Content type:	text/plain
Branch:	MAIN
Changes since 2.16:	+2 -2 lines
Log Message:	Added grouping parens to reduce ambiguity warnings.
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	schorsch	2.17	static const char RCSid[] = "$Id: pf3.c,v 2.16 2003/06/30 14:59:12 schorsch Exp $";
3	greg	1.1	#endif
4			/*
5			* pf3.c - routines for gaussian and box filtering
6			*
7			* 8/13/86
8			*/
9
10	greg	2.7	#include "standard.h"
11	greg	1.1
12	schorsch	2.16	#include <string.h>
13
14	greg	1.1	#include "color.h"
15
16	greg	2.14	#define RSCA 1.13 /* square-radius multiplier: sqrt(4/PI) */
17	greg	2.9	#define TEPS 0.2 /* threshold proximity goal */
18	greg	2.10	#define REPS 0.1 /* radius proximity goal */
19	greg	1.1
20	greg	2.7	extern double CHECKRAD; /* radius over which gaussian is summed */
21
22	greg	1.1	extern double rad; /* output pixel radius for filtering */
23
24	greg	2.7	extern double thresh; /* maximum contribution for subpixel */
25
26	greg	1.1	extern int nrows; /* number of rows for output */
27			extern int ncols; /* number of columns for output */
28
29			extern int xres, yres; /* resolution of input */
30
31			extern double x_c, y_r; /* conversion factors */
32
33	greg	2.7	extern int xrad; /* x search radius */
34			extern int yrad; /* y search radius */
35			extern int xbrad; /* x box size */
36			extern int ybrad; /* y box size */
37	greg	1.1
38			extern int barsize; /* size of input scan bar */
39			extern COLOR *scanin; / input scan bar */
40			extern COLOR scanout; / output scan line */
41	greg	2.7	extern COLOR *scoutbar; / output scan bar (if thresh > 0) */
42			extern float *greybar; / grey-averaged input values */
43			extern int obarsize; /* size of output scan bar */
44			extern int orad; /* output window radius */
45	greg	1.1
46	greg	2.12	extern int wrapfilt; /* wrap filter horizontally? */
47
48	greg	1.1	extern char *progname;
49
50	greg	2.5	float gausstable; / gauss lookup table */
51	greg	1.1
52	greg	2.7	float ringsum; / sum of ring values */
53			short ringwt; / weight (count) of ring values */
54			short ringndx; / ring index table */
55			float warr; / array of pixel weights */
56
57	greg	2.12	extern double (ourbright)(); / brightness computation function */
58
59	greg	2.7	double pickfilt();
60
61	greg	2.6	#define lookgauss(x) gausstable[(int)(10.*(x)+.5)]
62	greg	1.1
63
64			initmask() /* initialize gaussian lookup table */
65			{
66	greg	2.7	int gtabsiz;
67			double gaussN;
68	greg	2.5	double d;
69	greg	1.1	register int x;
70
71	greg	2.15	gtabsiz = 111CHECKRADCHECKRAD;
72	greg	2.7	gausstable = (float )malloc(gtabsizsizeof(float));
73			if (gausstable == NULL)
74			goto memerr;
75			d = x_cy_r0.25/(rad*rad);
76	greg	2.14	gausstable[0] = exp(-d);
77	greg	2.7	for (x = 1; x < gtabsiz; x++)
78	greg	2.14	if (x*0.1 <= d)
79	greg	2.5	gausstable[x] = gausstable[0];
80	greg	2.14	else
81			gausstable[x] = exp(-x*0.1);
82	greg	2.7	if (obarsize == 0)
83			return;
84			/* compute integral of filter */
85	greg	2.14	gaussN = PIdexp(-d); /* plateau */
86			for (d = sqrt(d)+0.05; d <= RSCA*CHECKRAD; d += 0.1)
87			gaussN += 0.12.0PIdexp(-d*d);
88	greg	2.7	/* normalize filter */
89			gaussN = x_cy_r/(radrad*gaussN);
90			for (x = 0; x < gtabsiz; x++)
91			gausstable[x] *= gaussN;
92			/* create ring averages table */
93			ringndx = (short )malloc((2oradorad+1)sizeof(short));
94			if (ringndx == NULL)
95			goto memerr;
96			for (x = 2oradorad+1; --x > orad*orad; )
97			ringndx[x] = -1;
98			do
99	greg	2.8	ringndx[x] = sqrt((double)x);
100	greg	2.7	while (x--);
101			ringsum = (float )malloc((orad+1)sizeof(float));
102			ringwt = (short )malloc((orad+1)sizeof(short));
103			warr = (float )malloc(obarsizeobarsize*sizeof(float));
104	schorsch	2.17	if ((ringsum == NULL) \| (ringwt == 0) \| (warr == NULL))
105	greg	2.7	goto memerr;
106			return;
107			memerr:
108			fprintf(stderr, "%s: out of memory in initmask\n", progname);
109			quit(1);
110	greg	1.1	}
111
112
113			dobox(csum, xcent, ycent, c, r) /* simple box filter */
114			COLOR csum;
115			int xcent, ycent;
116			int c, r;
117			{
118	greg	2.6	int wsum;
119			double d;
120			int y;
121	greg	2.12	register int x, offs;
122	greg	2.2	register COLOR *scan;
123	greg	2.7
124	greg	1.1	wsum = 0;
125			setcolor(csum, 0.0, 0.0, 0.0);
126	greg	2.7	for (y = ycent+1-ybrad; y <= ycent+ybrad; y++) {
127	greg	2.4	if (y < 0) continue;
128			if (y >= yres) break;
129	greg	2.13	d = y_r < 1.0 ? y_r*y - (r+.5) : (double)(y - ycent);
130	greg	2.7	if (d < -0.5) continue;
131			if (d >= 0.5) break;
132	greg	1.1	scan = scanin[y%barsize];
133	greg	2.7	for (x = xcent+1-xbrad; x <= xcent+xbrad; x++) {
134	greg	2.12	offs = x < 0 ? xres : x >= xres ? -xres : 0;
135			if (offs && !wrapfilt)
136			continue;
137	greg	2.13	d = x_c < 1.0 ? x_c*x - (c+.5) : (double)(x - xcent);
138	greg	2.7	if (d < -0.5) continue;
139			if (d >= 0.5) break;
140	greg	1.1	wsum++;
141	greg	2.12	addcolor(csum, scan[x+offs]);
142	greg	1.1	}
143			}
144	greg	2.14	if (wsum > 1) {
145			d = 1.0/wsum;
146			scalecolor(csum, d);
147			}
148	greg	1.1	}
149
150
151			dogauss(csum, xcent, ycent, c, r) /* gaussian filter */
152			COLOR csum;
153			int xcent, ycent;
154			int c, r;
155			{
156	greg	2.6	double dy, dx, weight, wsum;
157			COLOR ctmp;
158			int y;
159	greg	2.12	register int x, offs;
160	greg	2.2	register COLOR *scan;
161	greg	1.1
162			wsum = FTINY;
163			setcolor(csum, 0.0, 0.0, 0.0);
164	greg	1.2	for (y = ycent-yrad; y <= ycent+yrad; y++) {
165	greg	2.4	if (y < 0) continue;
166			if (y >= yres) break;
167	greg	1.2	dy = (y_r*(y+.5) - (r+.5))/rad;
168	greg	1.1	scan = scanin[y%barsize];
169	greg	1.2	for (x = xcent-xrad; x <= xcent+xrad; x++) {
170	greg	2.12	offs = x < 0 ? xres : x >= xres ? -xres : 0;
171			if (offs && !wrapfilt)
172			continue;
173	greg	1.2	dx = (x_c*(x+.5) - (c+.5))/rad;
174	greg	2.6	weight = lookgauss(dxdx + dydy);
175	greg	1.1	wsum += weight;
176	greg	2.12	copycolor(ctmp, scan[x+offs]);
177	greg	1.1	scalecolor(ctmp, weight);
178			addcolor(csum, ctmp);
179			}
180			}
181	greg	2.14	weight = 1.0/wsum;
182			scalecolor(csum, weight);
183	greg	2.7	}
184
185
186			dothresh(xcent, ycent, ccent, rcent) /* gaussian threshold filter */
187			int xcent, ycent;
188			int ccent, rcent;
189			{
190			double d;
191	greg	2.12	int r, y, offs;
192	greg	2.7	register int c, x;
193			register float *gscan;
194			/* compute ring sums */
195	schorsch	2.16	memset((char )ringsum, '\0', (orad+1)sizeof(float));
196			memset((char )ringwt, '\0', (orad+1)sizeof(short));
197	greg	2.7	for (r = -orad; r <= orad; r++) {
198			if (rcent+r < 0) continue;
199	greg	2.8	if (rcent+r >= nrows) break;
200	greg	2.7	gscan = greybar[(rcent+r)%obarsize];
201			for (c = -orad; c <= orad; c++) {
202	greg	2.12	offs = ccent+c < 0 ? ncols :
203			ccent+c >= ncols ? -ncols : 0;
204			if (offs && !wrapfilt)
205			continue;
206	greg	2.7	x = ringndx[cc + rr];
207			if (x < 0) continue;
208	greg	2.12	ringsum[x] += gscan[ccent+c+offs];
209	greg	2.7	ringwt[x]++;
210			}
211			}
212			/* filter each subpixel */
213			for (y = ycent+1-ybrad; y <= ycent+ybrad; y++) {
214			if (y < 0) continue;
215			if (y >= yres) break;
216	greg	2.13	d = y_r < 1.0 ? y_r*y - (rcent+.5) : (double)(y - ycent);
217	greg	2.7	if (d < -0.5) continue;
218			if (d >= 0.5) break;
219			for (x = xcent+1-xbrad; x <= xcent+xbrad; x++) {
220	greg	2.12	offs = x < 0 ? xres : x >= xres ? -xres : 0;
221			if (offs && !wrapfilt)
222			continue;
223	greg	2.13	d = x_c < 1.0 ? x_c*x - (ccent+.5) : (double)(x - xcent);
224	greg	2.7	if (d < -0.5) continue;
225			if (d >= 0.5) break;
226	greg	2.12	sumans(x, y, rcent, ccent,
227			pickfilt((*ourbright)(scanin[y%barsize][x+offs])));
228	greg	2.7	}
229			}
230			}
231
232
233			double
234			pickfilt(p0) /* find filter multiplier for p0 */
235			double p0;
236			{
237			double m = 1.0;
238	greg	2.10	double t, num, denom, avg, wsum;
239			double mlimit[2];
240	greg	2.14	int ilimit = 4.0/TEPS;
241	greg	2.7	register int i;
242			/* iterative search for m */
243	greg	2.11	mlimit[0] = 1.0; mlimit[1] = orad/rad/CHECKRAD;
244	greg	2.7	do {
245			/* compute grey weighted average */
246	greg	2.14	i = RSCACHECKRADrad*m + .5;
247	greg	2.8	if (i > orad) i = orad;
248	greg	2.7	avg = wsum = 0.0;
249			while (i--) {
250	greg	2.8	t = (i+.5)/(m*rad);
251	greg	2.7	t = lookgauss(t*t);
252			avg += t*ringsum[i];
253			wsum += t*ringwt[i];
254			}
255	greg	2.10	if (avg < 1e-20) /* zero inclusive average */
256			return(1.0);
257	greg	2.7	avg /= wsum;
258			/* check threshold */
259	greg	2.10	denom = m*m/gausstable[0] - p0/avg;
260	greg	2.11	if (denom <= FTINY) { /* zero exclusive average */
261			if (m >= mlimit[1]-REPS)
262			break;
263			m = mlimit[1];
264			continue;
265			}
266	greg	2.10	num = p0/avg - 1.0;
267			if (num < 0.0) num = -num;
268			t = num/denom;
269			if (t <= thresh) {
270			if (m <= mlimit[0]+REPS \|\| (thresh-t)/thresh <= TEPS)
271			break;
272			} else {
273			if (m >= mlimit[1]-REPS \|\| (t-thresh)/thresh <= TEPS)
274			break;
275			}
276			t = m; /* remember current m */
277	greg	2.7	/* next guesstimate */
278	greg	2.10	m = sqrt(gausstable[0]*(num/thresh + p0/avg));
279			if (m < t) { /* bound it */
280			if (m <= mlimit[0]+FTINY)
281			m = 0.5*(mlimit[0] + t);
282			mlimit[1] = t;
283			} else {
284			if (m >= mlimit[1]-FTINY)
285			m = 0.5*(mlimit[1] + t);
286			mlimit[0] = t;
287			}
288	greg	2.7	} while (--ilimit > 0);
289			return(m);
290			}
291
292
293			sumans(px, py, rcent, ccent, m) /* sum input pixel to output */
294			int px, py;
295			int rcent, ccent;
296			double m;
297			{
298	greg	2.14	double dy2, dx;
299	greg	2.7	COLOR pval, ctmp;
300	greg	2.12	int ksiz, r, offs;
301	greg	2.7	double pc, pr, norm;
302			register int i, c;
303			register COLOR *scan;
304	greg	2.12	/*
305			* This normalization method fails at the picture borders because
306			* a different number of input pixels contribute there.
307			*/
308			scan = scanin[py%barsize] + (px < 0 ? xres : px >= xres ? -xres : 0);
309			copycolor(pval, scan[px]);
310	greg	2.7	pc = x_c*(px+.5);
311			pr = y_r*(py+.5);
312			ksiz = CHECKRADmrad + 1;
313			if (ksiz > orad) ksiz = orad;
314			/* compute normalization */
315			norm = 0.0;
316			i = 0;
317			for (r = rcent-ksiz; r <= rcent+ksiz; r++) {
318			if (r < 0) continue;
319			if (r >= nrows) break;
320	greg	2.14	dy2 = (pr - (r+.5))/(m*rad);
321			dy2 *= dy2;
322	greg	2.7	for (c = ccent-ksiz; c <= ccent+ksiz; c++) {
323	greg	2.12	if (!wrapfilt) {
324			if (c < 0) continue;
325			if (c >= ncols) break;
326			}
327	greg	2.7	dx = (pc - (c+.5))/(m*rad);
328	greg	2.14	norm += warr[i++] = lookgauss(dx*dx + dy2);
329	greg	2.7	}
330			}
331			norm = 1.0/norm;
332			if (x_c < 1.0) norm *= x_c;
333			if (y_r < 1.0) norm *= y_r;
334			/* sum pixels */
335			i = 0;
336			for (r = rcent-ksiz; r <= rcent+ksiz; r++) {
337			if (r < 0) continue;
338			if (r >= nrows) break;
339			scan = scoutbar[r%obarsize];
340			for (c = ccent-ksiz; c <= ccent+ksiz; c++) {
341	greg	2.12	offs = c < 0 ? ncols : c >= ncols ? -ncols : 0;
342			if (offs && !wrapfilt)
343			continue;
344	greg	2.7	copycolor(ctmp, pval);
345			dx = norm*warr[i++];
346			scalecolor(ctmp, dx);
347	greg	2.12	addcolor(scan[c+offs], ctmp);
348	greg	2.7	}
349			}
350	greg	1.1	}