src/px/pf3.c

/* Copyright (c) 1993 Regents of the University of California */

#ifndef lint
static char SCCSid[] = "$SunId$ LBL";
#endif

/*
 *  pf3.c - routines for gaussian and box filtering
 *
 *     8/13/86
 */

#include  "standard.h"

#include  "color.h"

#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 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 */

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 = 150*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)/sqrt(d);
        for (x = 1; x < gtabsiz; x++)
                if ((gausstable[x] = exp(-x*0.1)/sqrt(x*0.1)) > gausstable[0])
                        gausstable[x] = gausstable[0];
        if (obarsize == 0)
                return;
                                        /* compute integral of filter */
        gaussN = PI*sqrt(d)*exp(-d);            /* plateau */
        for (d = sqrt(d)+0.05; d <= 1.25*CHECKRAD; d += 0.1)
                gaussN += 0.1*2.0*PI*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;
        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 : (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++) {
                        if (x < 0) continue;
                        if (x >= xres) break;
                        d = x_c < 1.0 ? x_c*x - c : (double)(x - xcent);
                        if (d < -0.5) continue;
                        if (d >= 0.5) break;
                        wsum++;
                        addcolor(csum, scan[x]);
                }
        }
        if (wsum > 1)
                scalecolor(csum, 1.0/wsum);
}


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;
        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++) {
                        if (x < 0) continue;
                        if (x >= xres) break;
                        dx = (x_c*(x+.5) - (c+.5))/rad;
                        weight = lookgauss(dx*dx + dy*dy);
                        wsum += weight;
                        copycolor(ctmp, scan[x]);
                        scalecolor(ctmp, weight);
                        addcolor(csum, ctmp);
                }
        }
        scalecolor(csum, 1.0/wsum);
}


dothresh(xcent, ycent, ccent, rcent)    /* gaussian threshold filter */
int  xcent, ycent;
int  ccent, rcent;
{
        double  d;
        int  r, y;
        register int  c, x;
        register float  *gscan;
#define pval gscan
                                        /* compute ring sums */
        bzero((char *)ringsum, (orad+1)*sizeof(float));
        bzero((char *)ringwt, (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++) {
                        if (ccent+c < 0) continue;
                        if (ccent+c >= ncols) break;
                        x = ringndx[c*c + r*r];
                        if (x < 0) continue;
                        ringsum[x] += gscan[ccent+c];
                        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 : (double)(y - ycent);
                if (d < -0.5) continue;
                if (d >= 0.5) break;
                for (x = xcent+1-xbrad; x <= xcent+xbrad; x++) {
                        if (x < 0) continue;
                        if (x >= xres) break;
                        d = x_c < 1.0 ? x_c*x - ccent : (double)(x - xcent);
                        if (d < -0.5) continue;
                        if (d >= 0.5) break;
                        pval = scanin[y%barsize][x];
                        sumans(x, y, rcent, ccent, pickfilt(bright(pval)));
                }
        }
#undef pval
}


double
pickfilt(p0)                    /* find filter multiplier for p0 */
double  p0;
{
        double  m = 1.0;
        double  t, num, denom, avg, wsum;
        double  maxm = orad/rad/CHECKRAD;
        double  mlimit[2];
        int  ilimit = 4/TEPS;
        register int  i;
                                /* iterative search for m */
        mlimit[0] = 1.0; mlimit[1] = maxm;
        do {
                                        /* compute grey weighted average */
                i = 1.25*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 */
                        return(maxm);
                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  dy, dx;
        COLOR  pval, ctmp;
        int  ksiz, r;
        double  pc, pr, norm;
        register int  i, c;
        register COLOR  *scan;

        copycolor(pval, scanin[py%barsize][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;
                dy = (pr - (r+.5))/(m*rad);
                for (c = ccent-ksiz; c <= ccent+ksiz; c++) {
                        if (c < 0) continue;
                        if (c >= ncols) break;
                        dx = (pc - (c+.5))/(m*rad);
                        norm += warr[i++] = lookgauss(dx*dx + dy*dy);
                }
        }
        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++) {
                        if (c < 0) continue;
                        if (c >= ncols) break;
                        copycolor(ctmp, pval);
                        dx = norm*warr[i++];
                        scalecolor(ctmp, dx);
                        addcolor(scan[c], ctmp);
                }
        }
}
Revision:	2.10
Committed:	Thu Jul 15 18:32:06 1993 UTC (30 years, 9 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.9:	+32 -14 lines
Log Message:	corrected test criteria using exclusive average and improved convergence of algorithm in pickfilt()
#	User	Rev	Content
1	greg	2.10	/* Copyright (c) 1993 Regents of the University of California */
2	greg	1.1
3			#ifndef lint
4			static char SCCSid[] = "$SunId$ LBL";
5			#endif
6
7			/*
8			* pf3.c - routines for gaussian and box filtering
9			*
10			* 8/13/86
11			*/
12
13	greg	2.7	#include "standard.h"
14	greg	1.1
15			#include "color.h"
16
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			extern char *progname;
47
48	greg	2.5	float gausstable; / gauss lookup table */
49	greg	1.1
50	greg	2.7	float ringsum; / sum of ring values */
51			short ringwt; / weight (count) of ring values */
52			short ringndx; / ring index table */
53			float warr; / array of pixel weights */
54
55			double pickfilt();
56
57	greg	2.6	#define lookgauss(x) gausstable[(int)(10.*(x)+.5)]
58	greg	1.1
59
60			initmask() /* initialize gaussian lookup table */
61			{
62	greg	2.7	int gtabsiz;
63			double gaussN;
64	greg	2.5	double d;
65	greg	1.1	register int x;
66
67	greg	2.7	gtabsiz = 150*CHECKRAD;
68			gausstable = (float )malloc(gtabsizsizeof(float));
69			if (gausstable == NULL)
70			goto memerr;
71			d = x_cy_r0.25/(rad*rad);
72	greg	2.5	gausstable[0] = exp(-d)/sqrt(d);
73	greg	2.7	for (x = 1; x < gtabsiz; x++)
74	greg	2.5	if ((gausstable[x] = exp(-x0.1)/sqrt(x0.1)) > gausstable[0])
75			gausstable[x] = gausstable[0];
76	greg	2.7	if (obarsize == 0)
77			return;
78			/* compute integral of filter */
79			gaussN = PIsqrt(d)exp(-d); /* plateau */
80			for (d = sqrt(d)+0.05; d <= 1.25*CHECKRAD; d += 0.1)
81			gaussN += 0.12.0PIexp(-dd);
82			/* normalize filter */
83			gaussN = x_cy_r/(radrad*gaussN);
84			for (x = 0; x < gtabsiz; x++)
85			gausstable[x] *= gaussN;
86			/* create ring averages table */
87			ringndx = (short )malloc((2oradorad+1)sizeof(short));
88			if (ringndx == NULL)
89			goto memerr;
90			for (x = 2oradorad+1; --x > orad*orad; )
91			ringndx[x] = -1;
92			do
93	greg	2.8	ringndx[x] = sqrt((double)x);
94	greg	2.7	while (x--);
95			ringsum = (float )malloc((orad+1)sizeof(float));
96			ringwt = (short )malloc((orad+1)sizeof(short));
97			warr = (float )malloc(obarsizeobarsize*sizeof(float));
98			if (ringsum == NULL \| ringwt == 0 \| warr == NULL)
99			goto memerr;
100			return;
101			memerr:
102			fprintf(stderr, "%s: out of memory in initmask\n", progname);
103			quit(1);
104	greg	1.1	}
105
106
107			dobox(csum, xcent, ycent, c, r) /* simple box filter */
108			COLOR csum;
109			int xcent, ycent;
110			int c, r;
111			{
112	greg	2.6	int wsum;
113			double d;
114			int y;
115	greg	1.1	register int x;
116	greg	2.2	register COLOR *scan;
117	greg	2.7
118	greg	1.1	wsum = 0;
119			setcolor(csum, 0.0, 0.0, 0.0);
120	greg	2.7	for (y = ycent+1-ybrad; y <= ycent+ybrad; y++) {
121	greg	2.4	if (y < 0) continue;
122			if (y >= yres) break;
123			d = y_r < 1.0 ? y_r*y - r : (double)(y - ycent);
124	greg	2.7	if (d < -0.5) continue;
125			if (d >= 0.5) break;
126	greg	1.1	scan = scanin[y%barsize];
127	greg	2.7	for (x = xcent+1-xbrad; x <= xcent+xbrad; x++) {
128	greg	2.4	if (x < 0) continue;
129			if (x >= xres) break;
130			d = x_c < 1.0 ? x_c*x - c : (double)(x - xcent);
131	greg	2.7	if (d < -0.5) continue;
132			if (d >= 0.5) break;
133	greg	1.1	wsum++;
134			addcolor(csum, scan[x]);
135			}
136			}
137			if (wsum > 1)
138			scalecolor(csum, 1.0/wsum);
139			}
140
141
142			dogauss(csum, xcent, ycent, c, r) /* gaussian filter */
143			COLOR csum;
144			int xcent, ycent;
145			int c, r;
146			{
147	greg	2.6	double dy, dx, weight, wsum;
148			COLOR ctmp;
149			int y;
150	greg	1.1	register int x;
151	greg	2.2	register COLOR *scan;
152	greg	1.1
153			wsum = FTINY;
154			setcolor(csum, 0.0, 0.0, 0.0);
155	greg	1.2	for (y = ycent-yrad; y <= ycent+yrad; y++) {
156	greg	2.4	if (y < 0) continue;
157			if (y >= yres) break;
158	greg	1.2	dy = (y_r*(y+.5) - (r+.5))/rad;
159	greg	1.1	scan = scanin[y%barsize];
160	greg	1.2	for (x = xcent-xrad; x <= xcent+xrad; x++) {
161	greg	2.4	if (x < 0) continue;
162			if (x >= xres) break;
163	greg	1.2	dx = (x_c*(x+.5) - (c+.5))/rad;
164	greg	2.6	weight = lookgauss(dxdx + dydy);
165	greg	1.1	wsum += weight;
166			copycolor(ctmp, scan[x]);
167			scalecolor(ctmp, weight);
168			addcolor(csum, ctmp);
169			}
170			}
171			scalecolor(csum, 1.0/wsum);
172	greg	2.7	}
173
174
175			dothresh(xcent, ycent, ccent, rcent) /* gaussian threshold filter */
176			int xcent, ycent;
177			int ccent, rcent;
178			{
179			double d;
180			int r, y;
181			register int c, x;
182			register float *gscan;
183			#define pval gscan
184			/* compute ring sums */
185			bzero((char )ringsum, (orad+1)sizeof(float));
186			bzero((char )ringwt, (orad+1)sizeof(short));
187			for (r = -orad; r <= orad; r++) {
188			if (rcent+r < 0) continue;
189	greg	2.8	if (rcent+r >= nrows) break;
190	greg	2.7	gscan = greybar[(rcent+r)%obarsize];
191			for (c = -orad; c <= orad; c++) {
192			if (ccent+c < 0) continue;
193			if (ccent+c >= ncols) break;
194			x = ringndx[cc + rr];
195			if (x < 0) continue;
196			ringsum[x] += gscan[ccent+c];
197			ringwt[x]++;
198			}
199			}
200			/* filter each subpixel */
201			for (y = ycent+1-ybrad; y <= ycent+ybrad; y++) {
202			if (y < 0) continue;
203			if (y >= yres) break;
204			d = y_r < 1.0 ? y_r*y - rcent : (double)(y - ycent);
205			if (d < -0.5) continue;
206			if (d >= 0.5) break;
207			for (x = xcent+1-xbrad; x <= xcent+xbrad; x++) {
208			if (x < 0) continue;
209			if (x >= xres) break;
210			d = x_c < 1.0 ? x_c*x - ccent : (double)(x - xcent);
211			if (d < -0.5) continue;
212			if (d >= 0.5) break;
213			pval = scanin[y%barsize][x];
214			sumans(x, y, rcent, ccent, pickfilt(bright(pval)));
215			}
216			}
217			#undef pval
218			}
219
220
221			double
222			pickfilt(p0) /* find filter multiplier for p0 */
223			double p0;
224			{
225			double m = 1.0;
226	greg	2.10	double t, num, denom, avg, wsum;
227			double maxm = orad/rad/CHECKRAD;
228			double mlimit[2];
229	greg	2.9	int ilimit = 4/TEPS;
230	greg	2.7	register int i;
231			/* iterative search for m */
232	greg	2.10	mlimit[0] = 1.0; mlimit[1] = maxm;
233	greg	2.7	do {
234			/* compute grey weighted average */
235			i = 1.25CHECKRADrad*m + .5;
236	greg	2.8	if (i > orad) i = orad;
237	greg	2.7	avg = wsum = 0.0;
238			while (i--) {
239	greg	2.8	t = (i+.5)/(m*rad);
240	greg	2.7	t = lookgauss(t*t);
241			avg += t*ringsum[i];
242			wsum += t*ringwt[i];
243			}
244	greg	2.10	if (avg < 1e-20) /* zero inclusive average */
245			return(1.0);
246	greg	2.7	avg /= wsum;
247			/* check threshold */
248	greg	2.10	denom = m*m/gausstable[0] - p0/avg;
249			if (denom <= FTINY) /* zero exclusive average */
250			return(maxm);
251			num = p0/avg - 1.0;
252			if (num < 0.0) num = -num;
253			t = num/denom;
254			if (t <= thresh) {
255			if (m <= mlimit[0]+REPS \|\| (thresh-t)/thresh <= TEPS)
256			break;
257			} else {
258			if (m >= mlimit[1]-REPS \|\| (t-thresh)/thresh <= TEPS)
259			break;
260			}
261			t = m; /* remember current m */
262	greg	2.7	/* next guesstimate */
263	greg	2.10	m = sqrt(gausstable[0]*(num/thresh + p0/avg));
264			if (m < t) { /* bound it */
265			if (m <= mlimit[0]+FTINY)
266			m = 0.5*(mlimit[0] + t);
267			mlimit[1] = t;
268			} else {
269			if (m >= mlimit[1]-FTINY)
270			m = 0.5*(mlimit[1] + t);
271			mlimit[0] = t;
272			}
273	greg	2.7	} while (--ilimit > 0);
274			return(m);
275			}
276
277
278			sumans(px, py, rcent, ccent, m) /* sum input pixel to output */
279			int px, py;
280			int rcent, ccent;
281			double m;
282			{
283			double dy, dx;
284			COLOR pval, ctmp;
285			int ksiz, r;
286			double pc, pr, norm;
287			register int i, c;
288			register COLOR *scan;
289
290			copycolor(pval, scanin[py%barsize][px]);
291			pc = x_c*(px+.5);
292			pr = y_r*(py+.5);
293			ksiz = CHECKRADmrad + 1;
294			if (ksiz > orad) ksiz = orad;
295			/* compute normalization */
296			norm = 0.0;
297			i = 0;
298			for (r = rcent-ksiz; r <= rcent+ksiz; r++) {
299			if (r < 0) continue;
300			if (r >= nrows) break;
301			dy = (pr - (r+.5))/(m*rad);
302			for (c = ccent-ksiz; c <= ccent+ksiz; c++) {
303			if (c < 0) continue;
304			if (c >= ncols) break;
305			dx = (pc - (c+.5))/(m*rad);
306			norm += warr[i++] = lookgauss(dxdx + dydy);
307			}
308			}
309			norm = 1.0/norm;
310			if (x_c < 1.0) norm *= x_c;
311			if (y_r < 1.0) norm *= y_r;
312			/* sum pixels */
313			i = 0;
314			for (r = rcent-ksiz; r <= rcent+ksiz; r++) {
315			if (r < 0) continue;
316			if (r >= nrows) break;
317			scan = scoutbar[r%obarsize];
318			for (c = ccent-ksiz; c <= ccent+ksiz; c++) {
319			if (c < 0) continue;
320			if (c >= ncols) break;
321			copycolor(ctmp, pval);
322			dx = norm*warr[i++];
323			scalecolor(ctmp, dx);
324			addcolor(scan[c], ctmp);
325			}
326			}
327	greg	1.1	}