+CanonImage *file_read_image(FILE *f);
+int main_test(void);
+
+#define MAX_PAGES 100
+extern CanonImage *page_images[MAX_PAGES];
+extern int npages;
+
+
+typedef struct {
+ unsigned long rgb; /* on screen */
+ char c; /* canonical */
+} CanonColourInfo;
+
+extern const CanonColourInfo canoncolourinfos[];
+
+CanonImage *alloc_canon_image(int w, int h);
+
+#ifdef DEBUG_RECTANGLES
+# define CANIMG_DEBUG_RECTANGLE_1LINE(im,w,h) \
+ fprintf(debug, "%4d ",y); \
+ r= fwrite(im->d + y*w, 1,w, debug); \
+ eassert(r==w); \
+ fputc('\n',debug);
+#else
+# define CANIMG_DEBUG_RECTANGLE_1LINE(im,y,h) /* nothing */
+#endif
+
+#define CANONICALISE_IMAGE(im,w,h, COMPUTE_RGB) do{ \
+ /* compute_rgb should be a number of statements, or \
+ * a block, which assigns to \
+ * unsigned long rgb; \
+ * given the values of \
+ * int x,y; \
+ * all of which are anamorphic. Result is stored in im. \
+ */ \
+ (im)= alloc_canon_image((w), (h)); \
+ \
+ int x,y,r; \
+ for (y=0; y<(h); y++) { \
+ for (x=0; x<(w); x++) { \
+ const CanonColourInfo *cci; \
+ unsigned long rgb; \
+ COMPUTE_RGB; \
+ for (cci=canoncolourinfos; cci->c; cci++) \
+ if (cci->rgb == rgb) { \
+ (im)->d[y*(w) + x]= cci->c; \
+ break; \
+ } \
+ } \
+ CANIMG_DEBUG_RECTANGLE_1LINE((im),(w),(h)) \
+ } \
+ debug_flush(); \
+ }while(0)