Imagen en escala de grises

- (UIImage *)grayscaleImage:(UIImage *)image {

	CIImage *ciImage = [[CIImage alloc] initWithImage:image];
	CIImage *grayscale = [ciImage imageByApplyingFilter:@"CIColorControls"
									withInputParameters: @{kCIInputSaturationKey : @0.0}];
	return [UIImage imageWithCIImage:grayscale];

}