Utility.java

package app;

import org.opencv.core.Mat;
import org.opencv.imgproc.Imgproc;

public class Utility {
    
    /**
	 * Converts a color image into shades of grey.
	 * @param input The image on which to perform the desaturate.
	 * @param output The image in which to store the output.
	 */
	static public void desaturate(Mat input, Mat output) {
		switch (input.channels()) {
			case 1:
				// If the input is already one channel, it's already desaturated
				input.copyTo(output);
				break;
			case 3:
				Imgproc.cvtColor(input, output, Imgproc.COLOR_BGR2GRAY);
				break;
			case 4:
				Imgproc.cvtColor(input, output, Imgproc.COLOR_BGRA2GRAY);
				break;
			default:
				throw new IllegalArgumentException("Input to desaturate must have 1, 3, or 4 channels");
		}
	}
}