Index: work/gpstroke/Makefile
===================================================================
--- work/gpstroke/Makefile	(revision 7411)
+++ work/gpstroke/Makefile	(revision 7412)
@@ -1,9 +1,12 @@
-CFLAGS = -Wall -g -O3
+CFLAGS = -Wall -g
+# -O3
 LDFLAGS = -lm
 LIBS=pcb_draw.o gp.o c24lib/image/draw.o c24lib/image/image.o c24lib/image/pnm.o
 
-all: find_polyl find_line_indep cap
+all: find_polyl find_line_indep cap erode
 
+erode: erode.o $(LIBS)
+
 cap: cap.o $(LIBS)
 
 find_polyl: find_polyl.o $(LIBS)
Index: work/gpstroke/erode.c
===================================================================
--- work/gpstroke/erode.c	(nonexistent)
+++ work/gpstroke/erode.c	(revision 7412)
@@ -0,0 +1,94 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <math.h>
+#include <string.h>
+#include <time.h>
+#include "c24lib/image/image.h"
+#include "c24lib/image/draw.h"
+#include "c24lib/image/pnm.h"
+
+#include "pcb_draw.h"
+
+
+int stat[100];
+
+static inline void ray(image_t *i, double x, double y, double dx, double dy, int *out)
+{
+	pixel_t *p;
+	int h = 0, xx, yy;
+	do {
+		x += dx;
+		y += dy;
+		xx = round(x);
+		yy = round(y);
+		p = &image_pix(i, xx, yy);
+		h++;
+
+	} while(p->r == 0);
+
+	if (h < *out)
+		*out = h;
+}
+
+static inline int height(image_t *i, int cx, int cy)
+{
+	pixel_t *p;
+	double dx, dy;
+	int h = i->sx + i->sy;
+	p = &image_pix(i, cx, cy);
+	if (p->r != 0)
+		return 0;
+	for(dy = -1.0; dy <= 1.0; dy+=0.27)
+		for(dx = -1.0; dx <= 1.0; dx+=0.27)
+			ray(i, (double)cx, (double)cy, dx, dy, &h);
+	return h;
+}
+
+int main(int arc, char *argv[])
+{
+	image_t *ref;
+	int *hg;
+	int maxh = 0;
+	int x, y, n, cutoff, end;
+	char *ref_fn = "1.pnm";
+
+	if (argv[1] != NULL)
+		ref_fn = argv[1];
+
+	ref = pnm_load(ref_fn);
+
+	hg = calloc(sizeof(int), ref->sx * ref->sy);
+	for(y = 1; y < ref->sy-1; y++) {
+		for(x = 1; x < ref->sy-1; x++) {
+			int h = height(ref, x, y);
+			if (h > maxh)
+				maxh = h;
+			stat[h]++;
+			printf("%d", h);
+			hg[x + y*ref->sx] = h;
+		}
+		printf("\n");
+	}
+
+	cutoff = 0;
+	for(n = 1; n <= maxh; n++) {
+		printf("h=%d %d\n", n, stat[n]);
+		if ((n > 1) && (stat[n] < stat[n-1]/2) && (cutoff == 0)) {
+			cutoff = n-1;
+		}
+	}
+
+	printf("-- cutoff=%d\n", cutoff);
+	end = ref->sx * ref->sy;
+	for(n = 0; n < end; n++) {
+		if (hg[n] == cutoff)
+			ref->pixmap[n] = pixel_red;
+		else if (ref->pixmap[n].r != 255) {
+			ref->pixmap[n].r = 200;
+			ref->pixmap[n].g = 200;
+			ref->pixmap[n].b = 200;
+		}
+	}
+	pnm_save(ref, "OUT.pnm");
+}
+