Clean Java OpenCV Code With Chained Calls!

ImageProcessChain.java

package processor.computer_vision;

import java.util.ArrayList;
import java.util.List;
import java.util.function.Consumer;

import org.opencv.core.Core;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.core.Scalar;
import org.opencv.core.Size;
import org.opencv.imgproc.Imgproc;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Execute chain of commands on image that modify the Mat object in-place
 */
public class ImageProcessChain implements Consumer<Mat> {

	private static final Logger logger = LoggerFactory.getLogger(ImageProcessChain.class);

	private final List<Consumer<Mat>> CHAIN = new ArrayList<>();

	@Override
	/**
	 * Execute the chain of processinng functions on target Image
	 */
	public void accept(Mat image) {
		CHAIN.forEach(function -> {
			function.accept(image);
		});
	}

	public ImageProcessChain sharpen() {
		CHAIN.add(mat -> {
			Mat kernel = Mat.ones(3, 3, CvType.CV_32F);
			Core.multiply(kernel, new Scalar(-1), kernel);
			kernel.put(1, 1, new float[]{9.0f});
			Imgproc.filter2D(mat, mat, -1, kernel);
			logger.debug("executed sharpen on mat " + System.identityHashCode(mat));
			kernel.release();
		});
		logger.debug("added sharpen to chain");
		return this;
	}
	
	public ImageProcessChain addBlackBoxPadding(int pixels) {
		CHAIN.add(mat -> {
			Core.copyMakeBorder(mat, mat, pixels, pixels, pixels, pixels, Core.BORDER_CONSTANT);
			logger.debug("executed add black box on mat " + System.identityHashCode(mat));
		});
		logger.debug("added pad to chain");
		return this;
	}

	public ImageProcessChain blur(int blurSize) {
		CHAIN.add(mat -> {
			Imgproc.GaussianBlur(mat, mat, new Size(blurSize, blurSize), 0);
			logger.debug("executed blur on mat " + System.identityHashCode(mat));
		});
		logger.debug("added blur to chain");
		return this;
	}

	public ImageProcessChain bgrToHsv() {
		CHAIN.add(mat -> {
			Imgproc.cvtColor(mat, mat, Imgproc.COLOR_BGR2HSV);
			logger.debug("executed bgr to hsv on mat " + System.identityHashCode(mat));
		});
		logger.debug("added bgr to hsv to chain");
		return this;
	}

	public ImageProcessChain bgrToGray() {
		CHAIN.add(mat -> {
			Imgproc.cvtColor(mat, mat, Imgproc.COLOR_BGR2GRAY);
			logger.debug("executed bgr to gray on mat " + System.identityHashCode(mat));
		});
		logger.debug("added bgr to gray to chain");
		return this;
	}

	/**
	 * @param threshold an int between 0 and 255
	 */
	public ImageProcessChain binaryThreshold(int threshold) {
		CHAIN.add(mat -> {
			Imgproc.threshold(mat, mat, threshold, 255, Imgproc.THRESH_BINARY);
			logger.debug("executed binary threshold on mat " + System.identityHashCode(mat));
		});
		logger.debug("added binary threshold to chain");
		return this;
	}

	public ImageProcessChain scharrEdgeDetect(double scale) {
		CHAIN.add(mat -> {
			int delta = 0;
			int ddepth = CvType.CV_16S;
			Mat gradX = new Mat();
			Mat gradY = new Mat();
			Imgproc.Scharr(mat, gradX, ddepth, 1, 0, scale, delta, Core.BORDER_DEFAULT);
			Imgproc.Scharr(mat, gradY, ddepth, 0, 1, scale, delta, Core.BORDER_DEFAULT);
			Core.convertScaleAbs(gradX, gradX);
			Core.convertScaleAbs(gradY, gradY);
			Core.addWeighted(gradX, 0.5, gradY, 0.5, 0, mat);
			gradX.release();
			gradY.release();
			logger.debug("executed scharr edge detect on mat " + System.identityHashCode(mat));
		});
		logger.debug("added scharr edge detectto chain");
		return this;
	}

	/**
	 * compute gradients (Scharr edge detect) with default scale = 1
	 */
	public ImageProcessChain scharrEdgeDetect() {
		CHAIN.add(mat -> {
			double scale = 1.0;
			int delta = 0;
			int ddepth = CvType.CV_16S;
			Mat gradX = new Mat();
			Mat gradY = new Mat();
			Imgproc.Scharr(mat, gradX, ddepth, 1, 0, scale, delta, Core.BORDER_DEFAULT);
			Imgproc.Scharr(mat, gradY, ddepth, 0, 1, scale, delta, Core.BORDER_DEFAULT);
			Core.convertScaleAbs(gradX, gradX);
			Core.convertScaleAbs(gradY, gradY);
			Core.addWeighted(gradX, 0.5, gradY, 0.5, 0, mat);
			gradX.release();
			gradY.release();
			logger.debug("executed scharr edge detect on mat " + System.identityHashCode(mat));
		});
		logger.debug("added scharr edge detect to chain");
		return this;
	}

	public ImageProcessChain canny(int lowerThresh, int upperThresh) {
		CHAIN.add(mat -> {
			Imgproc.Canny(mat, mat, lowerThresh, upperThresh);
			logger.debug("executed canny on mat " + System.identityHashCode(mat));
		});
		logger.debug("added canny edge detect to chain");
		return this;
	}

	public  ImageProcessChain erode(int pixels) {
		CHAIN.add(mat -> {
			Imgproc.erode(mat, mat, Imgproc.getStructuringElement(Imgproc.MORPH_ELLIPSE,  new Size(pixels, pixels)));
			logger.debug("executed erode on mat " + System.identityHashCode(mat));
		});
		logger.debug("added erode to chain");
		return this;
	}

	public  ImageProcessChain dilate(int pixels) {
		CHAIN.add(mat -> {
			Imgproc.dilate(mat, mat, Imgproc.getStructuringElement(Imgproc.MORPH_ELLIPSE,  new Size(pixels, pixels)));
			logger.debug("executed dilate on mat " + System.identityHashCode(mat));
		});
		logger.debug("added dilate to chain");
		return this;
	}

	public ImageProcessChain inRange(Scalar lowerThresh, Scalar upperThresh) {
		CHAIN.add(mat -> {
			Core.inRange(mat, lowerThresh, upperThresh, mat);
			logger.debug("executed in range on mat " + System.identityHashCode(mat));
		});
		logger.debug("added in range to chain");
		return this;
	}

}