typedef struct RGBint RGBint;
struct RGBint {
	int maxcol;
	int width;
	int height;
	int *r;
	int *g;
	int *b;
};

RGBint *readppm(Biobuf *b);
RGBint *free_rgb(RGBint *rgb);
char *import_ppm(Aux *aux, char *fname);