LaneDetection

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see https://github.com/naokishibuya/car-finding-lane-lines

Color Filter

Source Code

ColorFilter

package org.rcdukes.video;

import org.opencv.core.Core;
import org.opencv.core.Mat;
import org.opencv.core.Scalar;

/**
 * filter colors in a given range
 * 
 * @author wf
 *
 */
public class ColorFilter {
  private Scalar minColor;
  private Scalar maxColor;

  /**
   * set minimum color with relative rgb values
   * 
   * @param r
   *          - red from 0.0 to 1.0
   * @param g
   *          - green from 0.0 to 1.0
   * @param b
   *          - blue from 0.0 to 1.0
   */
  public void setMinColorRGB(double r, double g, double b) {
    this.minColor = new Scalar(b * 255, g * 255, r * 255);
  }
  
  /**
   * set the minimum rgb color
   * @param r red from 0 to 255
   * @param g green from 0 to 255
   * @param b blue from 0 to 255
   */
  public void setMinColorRGB(int r, int g, int b) {
    this.minColor=new Scalar(b,g,r);
  }

  /**
   * set maximum color with rgb values
   * 
   * @param r
   * @param g
   * @param b
   */
  public void setMaxColorRGB(double r, double g, double b) {
    this.maxColor = new Scalar(b * 255, g * 255, r * 255);
  }
  
  /**
   * set the maximum rgb color
   * @param r red from 0 to 255
   * @param g green from 0 to 255
   * @param b blue from 0 to 255
   */
  public void setMaxColorRGB(int r, int g, int b) {
    this.maxColor=new Scalar(b,g,r);
  }

  /**
   * filter by the min and max Colors (if set)
   * 
   * @param image
   *          - the image to filter
   * @return - an image with colors in the given range or the original if not
   *         both minColor and maxColor have been set
   */
  public Mat filter(Mat image) {
    Mat imgColorFiltered = image;
    if (minColor != null && maxColor != null) {
      // https://docs.opencv.org/3.4/da/d97/tutorial_threshold_inRange.html
      // https://stackoverflow.com/questions/36693348/java-opencv-core-inrange-input-parameters
      Mat imgColorMask = new Mat();
      Core.inRange(image, minColor, maxColor, imgColorMask);
      imgColorFiltered = new Mat();
      Core.bitwise_and(image, image, imgColorFiltered, imgColorMask);
    }
    return imgColorFiltered;
  }
}

JUnit Test

 @Test
  public void testColorFilter() throws Exception {
    ColorFilter cf=new ColorFilter();
    cf.setMinColorRGB( 65,  85,  85);
    cf.setMaxColorRGB(140, 140, 140);
    Mat frame = getTestImage();
    Mat gray=new Mat();
    Imgproc.cvtColor(frame, gray, Imgproc.COLOR_BGR2GRAY);
    assertEquals(2458261,Core.countNonZero(gray));
    Mat colorFiltered = cf.filter(frame);
    assertEquals(colorFiltered.width(), frame.width());
    Mat cfGray=new Mat();
    Imgproc.cvtColor(colorFiltered, cfGray, Imgproc.COLOR_BGR2GRAY);
    assertEquals(173768,Core.countNonZero(cfGray));
    if (show) {
      ImageUtils.show(getTestImage());
      ImageUtils.show(gray);
      ImageUtils.show(colorFiltered); 
    }
  }