 	pixel_t* h_buf = new pixel_t[img.width() * img.height()];
 
 	// fill up h_buf
-	for (int y = 0; y < img.height(); y++) {
-		for (int x = 0; x < img.width(); x++) {
+	for (unsigned int y = 0; y < img.height(); y++) {
+		for (unsigned int x = 0; x < img.width(); x++) {
 			pixel_t* pixel = &h_buf[(y * img.width()) + x];
 			img.get_pixel(x, y, pixel->red, pixel->green, pixel->blue);
 		}

	bitmap_image img(input_bmp_path);

	if (!img) {
		printf("Error - Failed to open: %s \r\b", input_bmp_path);
		return 1;
	}


	printf("Copy from device:  %3.1f ms \n", stopTimer());

	// WRITE OUT UPDATED IMAGE
	for (unsigned int y = 0; y < img.height(); y++) {
		for (unsigned int x = 0; x < img.width(); x++) {
			const pixel_t* p = &h_buf[(y * img.width()) + x];
			img.set_pixel(x, y, p->red, p->green, p->blue);
		}
