Index: cap.c
===================================================================
--- cap.c	(revision 7382)
+++ cap.c	(revision 7383)
@@ -72,6 +72,22 @@
 	return diff;
 }
 
+static inline void pcb_shadow(image_t *dst, const image_t *src)
+{
+	int n;
+	pixel_t *d = dst->pixmap;
+	const pixel_t *s = src->pixmap;
+	for(n = 0; n < dst->sx * dst->sy; n++,d++,s++) {
+		if ((s->r != 255) && (s->g != 255) && (s->b != 255)) {
+			d->r = 200;
+			d->g = 240;
+			d->b = 240;
+		}
+		else
+			*d = pixel_white;
+	}
+}
+
 static inline void pcb_draw(image_t *img, pcb_t *p)
 {
 	int n;
@@ -165,7 +181,7 @@
 		fprintf(f,"stroke %d %d %d %d %d\n", p->str[n].x1, p->str[n].y1, p->str[n].x2, p->str[n].y2, p->str[n].th);
 	fclose(f);
 
-	pcb_clear(img);
+	pcb_shadow(img, ref);
 	pcb_draw(img, data);
 	snprintf(s, sizeof(s), "/tmp/stroke_%04d_%02d.pnm", population_id, individual_id);
 	pnm_save(img, s);