src/px/pf3.c

#ifndef lint
static const char RCSid[] = "$Id: pf3.c,v 2.19 2018/07/26 23:50:40 greg Exp $";
#endif
/*
 *  pf3.c - routines for gaussian and box filtering
 *
 *     8/13/86
 */

#include  "pfilt.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 */

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 */

#define  lookgauss(x)           gausstable[(int)(20.*(x)+.5)]

static double pickfilt(double  p0);
static void sumans(int  px, int  py, int  rcent, int  ccent, double  m);


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

        gtabsiz = 444*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*0.05 <= d)
                        gausstable[x] = gausstable[0];
                else
                        gausstable[x] = exp(-x*0.05);
        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);
}


void
dobox(                  /* simple box filter */
        COLOR  csum,
        int  xcent,
        int  ycent,
        int  c,
        int  r
)
{
        int  wsum;
        double  d;
        int  y;
        int  x, offs;
        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);
        }
}


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


void
dothresh(       /* gaussian threshold filter */
        int  xcent,
        int  ycent,
        int  ccent,
        int  rcent
)
{
        double  d;
        int  r, y, offs;
        int  c, x;
        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])));
                }
        }
}


static double
pickfilt(                       /* 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;
        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);
}


static void
sumans(         /* sum input pixel to output */
        int  px,
        int  py,
        int  rcent,
        int  ccent,
        double  m
)
{
        double  dy2, dx;
        COLOR  pval, ctmp;
        int  ksiz, r, offs;
        double  pc, pr, norm;
        int  i, c;
        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 != 0) & !wrapfilt)
                                continue;
                        copycolor(ctmp, pval);
                        dx = norm*warr[i++];
                        scalecolor(ctmp, dx);
                        addcolor(scan[c+offs], ctmp);
                }
        }
}
Revision:	2.20
Committed:	Thu Dec 7 21:15:54 2023 UTC (16 months, 3 weeks ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.19:	+1 -6 lines
Log Message:	refactor: Cleaned up and simplified #include's
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	greg	2.20	static const char RCSid[] = "$Id: pf3.c,v 2.19 2018/07/26 23:50:40 greg Exp $";
3	greg	1.1	#endif
4			/*
5			* pf3.c - routines for gaussian and box filtering
6			*
7			* 8/13/86
8			*/
9
10	schorsch	2.18	#include "pfilt.h"
11	greg	1.1
12	greg	2.14	#define RSCA 1.13 /* square-radius multiplier: sqrt(4/PI) */
13	greg	2.9	#define TEPS 0.2 /* threshold proximity goal */
14	greg	2.10	#define REPS 0.1 /* radius proximity goal */
15	greg	1.1
16	greg	2.5	float gausstable; / gauss lookup table */
17	greg	1.1
18	greg	2.7	float ringsum; / sum of ring values */
19			short ringwt; / weight (count) of ring values */
20			short ringndx; / ring index table */
21			float warr; / array of pixel weights */
22
23	greg	2.19	#define lookgauss(x) gausstable[(int)(20.*(x)+.5)]
24	greg	2.7
25	schorsch	2.18	static double pickfilt(double p0);
26			static void sumans(int px, int py, int rcent, int ccent, double m);
27	greg	1.1
28
29	greg	2.19	void
30	schorsch	2.18	initmask(void) /* initialize gaussian lookup table */
31	greg	1.1	{
32	greg	2.7	int gtabsiz;
33			double gaussN;
34	greg	2.5	double d;
35	greg	2.19	int x;
36	greg	1.1
37	greg	2.19	gtabsiz = 444CHECKRADCHECKRAD;
38	greg	2.7	gausstable = (float )malloc(gtabsizsizeof(float));
39			if (gausstable == NULL)
40			goto memerr;
41			d = x_cy_r0.25/(rad*rad);
42	greg	2.14	gausstable[0] = exp(-d);
43	greg	2.7	for (x = 1; x < gtabsiz; x++)
44	greg	2.19	if (x*0.05 <= d)
45	greg	2.5	gausstable[x] = gausstable[0];
46	greg	2.14	else
47	greg	2.19	gausstable[x] = exp(-x*0.05);
48	greg	2.7	if (obarsize == 0)
49			return;
50			/* compute integral of filter */
51	greg	2.14	gaussN = PIdexp(-d); /* plateau */
52			for (d = sqrt(d)+0.05; d <= RSCA*CHECKRAD; d += 0.1)
53			gaussN += 0.12.0PIdexp(-d*d);
54	greg	2.7	/* normalize filter */
55			gaussN = x_cy_r/(radrad*gaussN);
56			for (x = 0; x < gtabsiz; x++)
57			gausstable[x] *= gaussN;
58			/* create ring averages table */
59			ringndx = (short )malloc((2oradorad+1)sizeof(short));
60			if (ringndx == NULL)
61			goto memerr;
62			for (x = 2oradorad+1; --x > orad*orad; )
63			ringndx[x] = -1;
64			do
65	greg	2.8	ringndx[x] = sqrt((double)x);
66	greg	2.7	while (x--);
67			ringsum = (float )malloc((orad+1)sizeof(float));
68			ringwt = (short )malloc((orad+1)sizeof(short));
69			warr = (float )malloc(obarsizeobarsize*sizeof(float));
70	schorsch	2.17	if ((ringsum == NULL) \| (ringwt == 0) \| (warr == NULL))
71	greg	2.7	goto memerr;
72			return;
73			memerr:
74			fprintf(stderr, "%s: out of memory in initmask\n", progname);
75			quit(1);
76	greg	1.1	}
77
78
79	greg	2.19	void
80	schorsch	2.18	dobox( /* simple box filter */
81			COLOR csum,
82			int xcent,
83			int ycent,
84			int c,
85			int r
86			)
87	greg	1.1	{
88	greg	2.6	int wsum;
89			double d;
90			int y;
91	greg	2.19	int x, offs;
92			COLOR *scan;
93	greg	2.7
94	greg	1.1	wsum = 0;
95			setcolor(csum, 0.0, 0.0, 0.0);
96	greg	2.7	for (y = ycent+1-ybrad; y <= ycent+ybrad; y++) {
97	greg	2.4	if (y < 0) continue;
98			if (y >= yres) break;
99	greg	2.13	d = y_r < 1.0 ? y_r*y - (r+.5) : (double)(y - ycent);
100	greg	2.7	if (d < -0.5) continue;
101			if (d >= 0.5) break;
102	greg	1.1	scan = scanin[y%barsize];
103	greg	2.7	for (x = xcent+1-xbrad; x <= xcent+xbrad; x++) {
104	greg	2.12	offs = x < 0 ? xres : x >= xres ? -xres : 0;
105			if (offs && !wrapfilt)
106			continue;
107	greg	2.13	d = x_c < 1.0 ? x_c*x - (c+.5) : (double)(x - xcent);
108	greg	2.7	if (d < -0.5) continue;
109			if (d >= 0.5) break;
110	greg	1.1	wsum++;
111	greg	2.12	addcolor(csum, scan[x+offs]);
112	greg	1.1	}
113			}
114	greg	2.14	if (wsum > 1) {
115			d = 1.0/wsum;
116			scalecolor(csum, d);
117			}
118	greg	1.1	}
119
120
121	greg	2.19	void
122	schorsch	2.18	dogauss( /* gaussian filter */
123			COLOR csum,
124			int xcent,
125			int ycent,
126			int c,
127			int r
128			)
129	greg	1.1	{
130	greg	2.6	double dy, dx, weight, wsum;
131			COLOR ctmp;
132			int y;
133	greg	2.19	int x, offs;
134			COLOR *scan;
135	greg	1.1
136			wsum = FTINY;
137			setcolor(csum, 0.0, 0.0, 0.0);
138	greg	1.2	for (y = ycent-yrad; y <= ycent+yrad; y++) {
139	greg	2.4	if (y < 0) continue;
140			if (y >= yres) break;
141	greg	1.2	dy = (y_r*(y+.5) - (r+.5))/rad;
142	greg	1.1	scan = scanin[y%barsize];
143	greg	1.2	for (x = xcent-xrad; x <= xcent+xrad; x++) {
144	greg	2.12	offs = x < 0 ? xres : x >= xres ? -xres : 0;
145			if (offs && !wrapfilt)
146			continue;
147	greg	1.2	dx = (x_c*(x+.5) - (c+.5))/rad;
148	greg	2.6	weight = lookgauss(dxdx + dydy);
149	greg	1.1	wsum += weight;
150	greg	2.12	copycolor(ctmp, scan[x+offs]);
151	greg	1.1	scalecolor(ctmp, weight);
152			addcolor(csum, ctmp);
153			}
154			}
155	greg	2.14	weight = 1.0/wsum;
156			scalecolor(csum, weight);
157	greg	2.7	}
158
159
160	greg	2.19	void
161	schorsch	2.18	dothresh( /* gaussian threshold filter */
162			int xcent,
163			int ycent,
164			int ccent,
165			int rcent
166			)
167	greg	2.7	{
168			double d;
169	greg	2.12	int r, y, offs;
170	greg	2.19	int c, x;
171			float *gscan;
172	greg	2.7	/* compute ring sums */
173	schorsch	2.16	memset((char )ringsum, '\0', (orad+1)sizeof(float));
174			memset((char )ringwt, '\0', (orad+1)sizeof(short));
175	greg	2.7	for (r = -orad; r <= orad; r++) {
176			if (rcent+r < 0) continue;
177	greg	2.8	if (rcent+r >= nrows) break;
178	greg	2.7	gscan = greybar[(rcent+r)%obarsize];
179			for (c = -orad; c <= orad; c++) {
180	greg	2.12	offs = ccent+c < 0 ? ncols :
181			ccent+c >= ncols ? -ncols : 0;
182			if (offs && !wrapfilt)
183			continue;
184	greg	2.7	x = ringndx[cc + rr];
185			if (x < 0) continue;
186	greg	2.12	ringsum[x] += gscan[ccent+c+offs];
187	greg	2.7	ringwt[x]++;
188			}
189			}
190			/* filter each subpixel */
191			for (y = ycent+1-ybrad; y <= ycent+ybrad; y++) {
192			if (y < 0) continue;
193			if (y >= yres) break;
194	greg	2.13	d = y_r < 1.0 ? y_r*y - (rcent+.5) : (double)(y - ycent);
195	greg	2.7	if (d < -0.5) continue;
196			if (d >= 0.5) break;
197			for (x = xcent+1-xbrad; x <= xcent+xbrad; x++) {
198	greg	2.12	offs = x < 0 ? xres : x >= xres ? -xres : 0;
199			if (offs && !wrapfilt)
200			continue;
201	greg	2.13	d = x_c < 1.0 ? x_c*x - (ccent+.5) : (double)(x - xcent);
202	greg	2.7	if (d < -0.5) continue;
203			if (d >= 0.5) break;
204	greg	2.12	sumans(x, y, rcent, ccent,
205			pickfilt((*ourbright)(scanin[y%barsize][x+offs])));
206	greg	2.7	}
207			}
208			}
209
210
211	schorsch	2.18	static double
212			pickfilt( /* find filter multiplier for p0 */
213			double p0
214			)
215	greg	2.7	{
216			double m = 1.0;
217	greg	2.10	double t, num, denom, avg, wsum;
218			double mlimit[2];
219	greg	2.14	int ilimit = 4.0/TEPS;
220	greg	2.19	int i;
221	greg	2.7	/* iterative search for m */
222	greg	2.11	mlimit[0] = 1.0; mlimit[1] = orad/rad/CHECKRAD;
223	greg	2.7	do {
224			/* compute grey weighted average */
225	greg	2.14	i = RSCACHECKRADrad*m + .5;
226	greg	2.8	if (i > orad) i = orad;
227	greg	2.7	avg = wsum = 0.0;
228			while (i--) {
229	greg	2.8	t = (i+.5)/(m*rad);
230	greg	2.7	t = lookgauss(t*t);
231			avg += t*ringsum[i];
232			wsum += t*ringwt[i];
233			}
234	greg	2.10	if (avg < 1e-20) /* zero inclusive average */
235			return(1.0);
236	greg	2.7	avg /= wsum;
237			/* check threshold */
238	greg	2.10	denom = m*m/gausstable[0] - p0/avg;
239	greg	2.11	if (denom <= FTINY) { /* zero exclusive average */
240			if (m >= mlimit[1]-REPS)
241			break;
242			m = mlimit[1];
243			continue;
244			}
245	greg	2.10	num = p0/avg - 1.0;
246			if (num < 0.0) num = -num;
247			t = num/denom;
248			if (t <= thresh) {
249			if (m <= mlimit[0]+REPS \|\| (thresh-t)/thresh <= TEPS)
250			break;
251			} else {
252			if (m >= mlimit[1]-REPS \|\| (t-thresh)/thresh <= TEPS)
253			break;
254			}
255			t = m; /* remember current m */
256	greg	2.7	/* next guesstimate */
257	greg	2.10	m = sqrt(gausstable[0]*(num/thresh + p0/avg));
258			if (m < t) { /* bound it */
259			if (m <= mlimit[0]+FTINY)
260			m = 0.5*(mlimit[0] + t);
261			mlimit[1] = t;
262			} else {
263			if (m >= mlimit[1]-FTINY)
264			m = 0.5*(mlimit[1] + t);
265			mlimit[0] = t;
266			}
267	greg	2.7	} while (--ilimit > 0);
268			return(m);
269			}
270
271
272	schorsch	2.18	static void
273			sumans( /* sum input pixel to output */
274			int px,
275			int py,
276			int rcent,
277			int ccent,
278			double m
279			)
280	greg	2.7	{
281	greg	2.14	double dy2, dx;
282	greg	2.7	COLOR pval, ctmp;
283	greg	2.12	int ksiz, r, offs;
284	greg	2.7	double pc, pr, norm;
285	greg	2.19	int i, c;
286			COLOR *scan;
287	greg	2.12	/*
288			* This normalization method fails at the picture borders because
289			* a different number of input pixels contribute there.
290			*/
291			scan = scanin[py%barsize] + (px < 0 ? xres : px >= xres ? -xres : 0);
292			copycolor(pval, scan[px]);
293	greg	2.7	pc = x_c*(px+.5);
294			pr = y_r*(py+.5);
295			ksiz = CHECKRADmrad + 1;
296			if (ksiz > orad) ksiz = orad;
297			/* compute normalization */
298			norm = 0.0;
299			i = 0;
300			for (r = rcent-ksiz; r <= rcent+ksiz; r++) {
301			if (r < 0) continue;
302			if (r >= nrows) break;
303	greg	2.14	dy2 = (pr - (r+.5))/(m*rad);
304			dy2 *= dy2;
305	greg	2.7	for (c = ccent-ksiz; c <= ccent+ksiz; c++) {
306	greg	2.12	if (!wrapfilt) {
307			if (c < 0) continue;
308			if (c >= ncols) break;
309			}
310	greg	2.7	dx = (pc - (c+.5))/(m*rad);
311	greg	2.14	norm += warr[i++] = lookgauss(dx*dx + dy2);
312	greg	2.7	}
313			}
314			norm = 1.0/norm;
315			if (x_c < 1.0) norm *= x_c;
316			if (y_r < 1.0) norm *= y_r;
317			/* sum pixels */
318			i = 0;
319			for (r = rcent-ksiz; r <= rcent+ksiz; r++) {
320			if (r < 0) continue;
321			if (r >= nrows) break;
322			scan = scoutbar[r%obarsize];
323			for (c = ccent-ksiz; c <= ccent+ksiz; c++) {
324	greg	2.12	offs = c < 0 ? ncols : c >= ncols ? -ncols : 0;
325	greg	2.19	if ((offs != 0) & !wrapfilt)
326	greg	2.12	continue;
327	greg	2.7	copycolor(ctmp, pval);
328			dx = norm*warr[i++];
329			scalecolor(ctmp, dx);
330	greg	2.12	addcolor(scan[c+offs], ctmp);
331	greg	2.7	}
332			}
333	greg	1.1	}