typedef struct ppm_t {
	unsigned char *rgb;
	unsigned int x, y, d;
	} ppm_t;

// read ppm from filename and return a ppm_t structure with its contents
ppm_t *ppmread (char *filename);

// write the image in filename
int ppmwrite (char *filename, ppm_t *image);

// deallocate all memory allocated to ppm_t image. The image must have been allocated either through ppmread
// or ppmalloc
void ppmfree (ppm_t *image);

// allocate a blank ppm_t image with x rows, y columns, where each color can be as high as depth (expected to be 255)
ppm_t *ppmalloc (int x, int y, int depth);