source: other-projects/is-sheet-music-encore/trunk/image-identification/src/Main.java@ 33069

import org.opencv.core.*;
import org.opencv.core.Point;
import org.opencv.highgui.HighGui;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.imgproc.Imgproc;
import static org.opencv.imgcodecs.Imgcodecs.imwrite;


//REFERENCES:
//https://docs.opencv.org/3.4.3/d9/db0/tutorial_hough_lines.html


public class Main {

    private Scalar meanOfProcessed;

    public static void main(String[] args) {
        System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
/*
        // write your code here
        System.out.println("Welcome to OpenCV " + Core.VERSION);
        Mat m = new Mat(5, 10, CvType.CV_8UC1, new Scalar(0));
        System.out.println("OpenCV Mat: " + m);
        Mat mr1 = m.row(1);
        mr1.setTo(new Scalar(1));
        Mat mc5 = m.col(0);
        mc5.setTo(new Scalar(8));
        System.out.println("OpenCV Mat data:\n" + m.dump());
 */
    try {
            //Variables
            Mat edgesDetected = new Mat();
            Mat edgesDetectedRGB = new Mat();
            Mat edgesDetectedRGBProb;
            Mat justEdges;



            String default_file = "Test.png";
            String filename = ((args.length > 0) ? args[0] : default_file);

            // Load an image
            Mat original = Imgcodecs.imread(filename, Imgcodecs.IMREAD_GRAYSCALE);
            // Edge detection
            Imgproc.Canny(original, edgesDetected, 50, 200, 3, false);
            //Copy edges to the images that will display the results in BGR
            Imgproc.cvtColor(edgesDetected, edgesDetectedRGB, Imgproc.COLOR_GRAY2BGR);
            edgesDetectedRGBProb = edgesDetectedRGB.clone();

            justEdges = edgesDetectedRGBProb.clone();



            // Standard Hough Line Transform
            Mat lines = new Mat(); // will hold the results of the detection
            Imgproc.HoughLines(edgesDetected, lines, 1, Math.PI / 180, 150); // runs the actual detection
            // Draw the lines
            for (int x = 0; x < lines.rows(); x++) {
                double rho = lines.get(x, 0)[0],
                        theta = lines.get(x, 0)[1];
                double a = Math.cos(theta), b = Math.sin(theta);
                double x0 = a * rho, y0 = b * rho;
                Point pt1 = new Point(Math.round(x0 + 1000 * (-b)), Math.round(y0 + 1000 * (a)));
                Point pt2 = new Point(Math.round(x0 - 1000 * (-b)), Math.round(y0 - 1000 * (a)));
                Imgproc.line(edgesDetectedRGB, pt1, pt2, new Scalar(0, 0, 255), 3, Imgproc.LINE_AA, 0);
            }



            // Probabilistic Line Transform
            Mat linesP = new Mat(); // will hold the results of the detection
            Imgproc.HoughLinesP(edgesDetected, linesP, 1, Math.PI / 180, 50, 50, 10); // runs the actual detection
            // Draw the lines
            for (int x = 0; x < linesP.rows(); x++) {
                double[] l = linesP.get(x, 0);
                Imgproc.line(edgesDetectedRGBProb, new Point(l[0], l[1]), new Point(l[2], l[3]), new Scalar(0, 0, 255), 3, Imgproc.LINE_AA, 0);
            }

            //save output
            imwrite(filename+"_HoughLineP", edgesDetectedRGBProb);
            String processedFile = filename+"_HoughLineP";
            //Load an image
            Mat processed = Imgcodecs.imread(processedFile, Imgcodecs.IMREAD_COLOR);
            System.out.println(Core.mean(processed));
            String meanOfProcessed = (Core.mean(processed).toString());
            //OUTPUTS [ BLUE , GREEN , RED, ALPHA?
            //Core.mean GETS scalar of image (array of BGR) and calculates the average for each
            //https://docs.opencv.org/java/2.4.2/org/opencv/core/Core.html#mean(org.opencv.core.Mat)

            //With this logic, then if can say if the RED in the array is between 'x' and 'y' then its sheet music
            System.out.println(meanOfProcessed); //PRINTS AS EXPECTED

            //CONVERT STRING TO ARRAY OR FIND ANOTHER WAY OF GETTING TO RED VALUE
            //SAVE AS VARIABLE : RedValue.
            //IF redValue > 'x' and redValue < 'y' THEN it is sheet music



            // Show results
            //HighGui.imshow("Source", original);
            //HighGui.imshow("Detected Lines (in red) - Standard Hough Line Transform", edgesDetectedRGB);
            HighGui.imshow("Detected Lines (in red) - Probabilistic Line Transform", edgesDetectedRGBProb);
            //HighGui.imshow("Just Edges", justEdges);
            // Wait and Exit
            HighGui.waitKey();
            System.exit(0);
        }
        catch(Exception e){
         System.err.println(e);
        }
    }
}