void identify_rgbimage(const RgbImage *base, Rect portion,
char result[MAXIMGIDENT], const char *what);
RgbImage *alloc_rgb_image(int w, int h);
+void fwrite_ppmraw(FILE *f, const RgbImage *ri);
#define RI_PIXEL(ri,x,y) ((ri)->data + ((y)*(ri)->w + (x)) * 3)