Gray.c

unsigned char* copyGrayImage(unsigned char* img, int w, int h) {

  unsigned char* imgCpy = (unsigned char*) malloc ( sizeof(unsigned char) * w * h);

	int i,j;
	
	if (imgCpy != NULL)
		for (j = 0 ; j < h ; j++) 
			for (i = 0 ; i < w ; i++) 
				imgCpy[j*w+i] = (	0.3*img[j*w*3+i*3+RED] + 
									0.59*img[j*w*3+i*3+GREEN] + 
									0.11*img[j*w*3+i*3+BLUE]);
				
	return imgCpy;
}