Add findLines() function based on HoughLinesP.

Add Line class as result for findLines() including angle calculation
in double precision.
Add example of usage of findLines()

Author: atduskgreg

examples/HoughLineDetection/HoughLineDetection.pde

@@ -1,63 +1,38 @@
 import gab.opencv.*;
-import org.opencv.imgproc.Imgproc;
-import org.opencv.core.Mat;
-import java.awt.geom.Line2D;
 
 OpenCV opencv;
-
-ArrayList<Line2D> lines;
+ArrayList<Line> lines;
 
 void setup() {
   PImage src = loadImage("film_scan.jpg");
   src.resize(0, 800);
   size(src.width, src.height, P2D);
 
   opencv = new OpenCV(this, src);
-  opencv.findSobelEdges(1, 0);
-  opencv.threshold(20);
-
-  lines = findLines(opencv.getGray(), 200, 120, 5);
-  
-  for(Line2D l : lines){
-    println(Math.toDegrees(angleOf(l)));
-  }
-  
-  noLoop();
-}
-
-double angleOf(Line2D l){
-   Line2D vertical = new Line2D.Double(0,0, 0,1);
-   
-   return angleBetween(l, vertical);
-}
+  opencv.findCannyEdges(20, 75);
 
-double angleBetween(Line2D line1, Line2D line2) {
-  double angle1 = Math.atan2(line1.getY1() - line1.getY2(), 
-  line1.getX1() - line1.getX2());
-  double angle2 = Math.atan2(line2.getY1() - line2.getY2(), 
-  line2.getX1() - line2.getX2());
-  return angle1-angle2;
-}
-
-ArrayList<Line2D> findLines(Mat m, int threshold, double minLength, double maxGap) {
-  ArrayList<Line2D> result = new ArrayList<Line2D>();
-
-  Mat lineMat = new Mat();
-  Imgproc.HoughLinesP(m, lineMat, 1, PI/180.0, threshold, minLength, maxGap);
-  for (int i = 0; i < lineMat.width(); i++) {
-    double[] coords = lineMat.get(0, i);
-    result.add(new Line2D.Double(coords[0], coords[1], coords[2], coords[3]));
-  }
-
-  return result;
+  // Find lines with Hough line detection
+  // Arguments are: threshold, minLengthLength, maxLineGap
+  lines = opencv.findLines(100, 30, 20);
 }
 
 void draw() {
   image(opencv.getOutput(), 0, 0);
-  stroke(0, 255, 0);
-  strokeWeight(2);
-  for (Line2D line : lines) {
-    line((float)line.getX1(), (float)line.getY1(), (float)line.getX2(), (float)line.getY2());
+  strokeWeight(3);
+  
+  for (Line line : lines) {
+    // lines include angle in radians, measured in double precision
+    // so we can select out vertical and horizontal lines
+    // They also include "start" and "end" PVectors with the position
+    if (line.angle >= radians(0) && line.angle < radians(1)) {
+      stroke(0, 255, 0);
+      line(line.start.x, line.start.y, line.end.x, line.end.y);
+    }
+
+    if (line.angle > radians(89) && line.angle < radians(91)) {
+      stroke(255, 0, 0);
+      line(line.start.x, line.start.y, line.end.x, line.end.y);
+    }
   }
 }
 

readme.md

@@ -16,15 +16,15 @@ OpenCV for Processing is in the early stages of development. Currently it only s
 
 _NB: When running on the Mac, make sure you have Processing set to 64-bit mode in the Preferences_
 
-See [here](https://github.com/atduskgreg/OpenCVPro/releases) for the latest release.
+See [here](https://github.com/atduskgreg/opencv-processing/releases) for the latest release.
 
 ### Examples
 
 #### LiveCamTest
 
 Access a live camera and do image processing on the result, specifically face detection.
 
-Code: [LiveCamTest.pde](https://github.com/atduskgreg/OpenCVPro/blob/master/examples/LiveCamTest/LiveCamTest.pde)
+Code: [LiveCamTest.pde](https://github.com/atduskgreg/opencv-processing/blob/master/examples/LiveCamTest/LiveCamTest.pde)
 
 _Note: There's a bug that prevents live camera access in current versions of Processing 2.0 on machines with a Retina display._
 
@@ -34,79 +34,87 @@ Detect faces in images.
 
 <a href="http://www.flickr.com/photos/unavoidablegrain/8634017624/" title="Screen Shot 2013-04-08 at 1.22.18 PM by atduskgreg, on Flickr"><img src="http://farm9.staticflickr.com/8543/8634017624_35f7ef05ce.jpg" width="500" height="358" alt="Screen Shot 2013-04-08 at 1.22.18 PM"></a>
 
-Code: [FaceDetection.pde](https://github.com/atduskgreg/OpenCVPro/blob/master/examples/FaceDetection/FaceDetection.pde)
+Code: [FaceDetection.pde](https://github.com/atduskgreg/opencv-processing/blob/master/examples/FaceDetection/FaceDetection.pde)
 
 #### BrightnessContrast
 
 Adjust the brightness and contrast of color and gray images.
 
 <a href="http://www.flickr.com/photos/unavoidablegrain/9155239258/" title="brightness and contrast by atduskgreg, on Flickr"><img src="http://farm3.staticflickr.com/2841/9155239258_41a7df36c6.jpg" width="500" height="358" alt="brightness and contrast"></a>
 
-Code: [BrightnessContrast.pde](https://github.com/atduskgreg/OpenCVPro/blob/master/examples/BrightnessContrast/BrightnessContrast.pde)
+Code: [BrightnessContrast.pde](https://github.com/atduskgreg/opencv-processing/blob/master/examples/BrightnessContrast/BrightnessContrast.pde)
 
 #### FilterImages
 
 Basic filtering operations on images: threshold, blur, and adaptive thresholds.
 
 <a href="http://www.flickr.com/photos/unavoidablegrain/8643666252/" title="Screen Shot 2013-04-12 at 1.42.30 PM by atduskgreg, on Flickr"><img src="http://farm9.staticflickr.com/8240/8643666252_be0da1c751.jpg" width="500" height="358" alt="Screen Shot 2013-04-12 at 1.42.30 PM"></a>
 
-Code: [FilterImages.pde](https://github.com/atduskgreg/OpenCVPro/blob/master/examples/FilterImages/FilterImages.pde)
+Code: [FilterImages.pde](https://github.com/atduskgreg/opencv-processing/blob/master/examples/FilterImages/FilterImages.pde)
 
 #### FindContours
 
 Find contours in images and calculate polygon approximations of the contours (i.e., the closest straight line that fits the contour).
 
 <a href="http://www.flickr.com/photos/unavoidablegrain/9024663015/" title="contours with polygon approximations by atduskgreg, on Flickr"><img src="http://farm4.staticflickr.com/3719/9024663015_f419b117b1.jpg" width="500" height="208" alt="contours with polygon approximations"></a>
 
-Code: [FindContours.pde](https://github.com/atduskgreg/OpenCVPro/blob/master/examples/FindContours/FindContours.pde)
+Code: [FindContours.pde](https://github.com/atduskgreg/opencv-processing/blob/master/examples/FindContours/FindContours.pde)
 
 #### FindEdges
 
 Three different edge-detection techniques: Canny, Scharr, and Sobel.
 
 <a href="http://www.flickr.com/photos/unavoidablegrain/8635989723/" title="Screen Shot 2013-04-10 at 2.03.59 AM by atduskgreg, on Flickr"><img src="http://farm9.staticflickr.com/8109/8635989723_170b69dca0.jpg" width="500" height="358" alt="Screen Shot 2013-04-10 at 2.03.59 AM"></a>
 
-Code: [FindEdges.pde](https://github.com/atduskgreg/OpenCVPro/blob/master/examples/FindEdges/FindEdges.pde)
+Code: [FindEdges.pde](https://github.com/atduskgreg/opencv-processing/blob/master/examples/FindEdges/FindEdges.pde)
+
+#### FindLines
+
+Find straight lines in the image using Hough line detection.
+
+<a href="http://www.flickr.com/photos/unavoidablegrain/9263329608/" title="Hough line detection by atduskgreg, on Flickr"><img src="http://farm4.staticflickr.com/3781/9263329608_735ce228bb.jpg" width="486" height="500" alt="Hough line detection"></a>
+
+Code: [HoughLineDetection.pde](https://github.com/atduskgreg/opencv-processing/blob/master/examples/HoughLineDetection/HoughLineDetection.pde)
 
 #### BrightestPoint
 
 Find the brightest point in an image.
 
 <a href="http://www.flickr.com/photos/unavoidablegrain/9199572469/" title="finding the brightest point by atduskgreg, on Flickr"><img src="http://farm8.staticflickr.com/7407/9199572469_4a25c83062.jpg" width="500" height="366" alt="finding the brightest point"></a>
 
-Code: [BrightestPoint.pde](https://github.com/atduskgreg/OpenCVPro/blob/master/examples/BrightestPoint/BrightestPoint.pde)
+Code: [BrightestPoint.pde](https://github.com/atduskgreg/opencv-processing/blob/master/examples/BrightestPoint/BrightestPoint.pde)
 
 #### RegionOfInterest
 
 Assign a sub-section (or Region of Interest) of the image to be processed. Video of this example in action here: [Region of Interest demo on Vimeo](https://vimeo.com/69009345).
 
 <a href="http://www.flickr.com/photos/unavoidablegrain/9077805277/" title="region of interest by atduskgreg, on Flickr"><img src="http://farm4.staticflickr.com/3795/9077805277_084d87a3a5.jpg" width="500" height="358" alt="region of interest"></a>
 
-Code: [RegionOfInterest.pde](https://github.com/atduskgreg/OpenCVPro/blob/master/examples/RegionOfInterest/RegionOfInterest.pde)
+Code: [RegionOfInterest.pde](https://github.com/atduskgreg/opencv-processing/blob/master/examples/RegionOfInterest/RegionOfInterest.pde)
 
 #### ImageDiff
 
 Find the difference between two images in order to subtract the background or detect a new object in a scene.
 
 <a href="http://www.flickr.com/photos/unavoidablegrain/8640005799/" title="Screen Shot 2013-04-11 at 2.10.35 PM by atduskgreg, on Flickr"><img src="http://farm9.staticflickr.com/8114/8640005799_44b48e01ae.jpg" width="500" height="409" alt="Screen Shot 2013-04-11 at 2.10.35 PM"></a>
 
-Code: [ImageDiff.pde](https://github.com/atduskgreg/OpenCVPro/blob/master/examples/ImageDiff/ImageDiff.pde)
+Code: [ImageDiff.pde](https://github.com/atduskgreg/opencv-processing/blob/master/examples/ImageDiff/ImageDiff.pde)
 
 #### DilationAndErosion
 
 Thin (erode) and expand (dilate) an image in order to close holes. These are known as "morphological" operations.
 
 <a href="http://www.flickr.com/photos/unavoidablegrain/9075875005/" title="dilation and erosion by atduskgreg, on Flickr"><img src="http://farm3.staticflickr.com/2818/9075875005_8f7cde3ed7.jpg" width="496" height="500" alt="dilation and erosion"></a>
 
-Code: [DilationAndErosion.pde](https://github.com/atduskgreg/OpenCVPro/blob/master/examples/DilationAndErosion/DilationAndErosion.pde)
+Code: [DilationAndErosion.pde](https://github.com/atduskgreg/opencv-processing/blob/master/examples/DilationAndErosion/DilationAndErosion.pde)
 
 #### BackgroundSubtraction
 
 Detect moving objects in a scene. Use background subtraction to distinguish background from foreground and contour tracking to track the foreground objects.
 
 <a href="http://www.flickr.com/photos/unavoidablegrain/9220336868/" title="Background Subtraction by atduskgreg, on Flickr"><img src="http://farm8.staticflickr.com/7292/9220336868_bed3498528.jpg" width="500" height="369" alt="Background Subtraction"></a>
 
-Code: [BackgroundSubtraction.pde](https://github.com/atduskgreg/OpenCVPro/blob/master/examples/BackgroundSubtraction/BackgroundSubtraction.pde)
+Code: [BackgroundSubtraction.pde](https://github.com/atduskgreg/opencv-processing/blob/master/examples/BackgroundSubtraction/BackgroundSubtraction.pde)
 
 
 #### WorkingWithColorImages
@@ -115,62 +123,62 @@ Demonstration of what you can do color images in OpenCV (threshold, blur, etc) a
 
 <a href="http://www.flickr.com/photos/unavoidablegrain/9136033334/" title="color operations: threshold and blur by atduskgreg, on Flickr"><img src="http://farm6.staticflickr.com/5451/9136033334_3345dfa057.jpg" width="500" height="358" alt="color operations: threshold and blur"></a>
 
-Code: [WorkingWithColorImages.pde](https://github.com/atduskgreg/OpenCVPro/blob/master/examples/WorkingWithColorImages/WorkingWithColorImages.pde)
+Code: [WorkingWithColorImages.pde](https://github.com/atduskgreg/opencv-processing/blob/master/examples/WorkingWithColorImages/WorkingWithColorImages.pde)
 
 #### ColorChannels ####
 
 Separate a color image into red, green, blue or hue, saturation, and value channels in order to work with the channels individually.
 
 <a href="http://www.flickr.com/photos/unavoidablegrain/9246157901/" title="ColorChannels by atduskgreg, on Flickr"><img src="http://farm3.staticflickr.com/2847/9246157901_08ccf19e7d.jpg" width="488" height="500" alt="ColorChannels"></a>
 
-Code: [ColorChannels](https://github.com/atduskgreg/OpenCVPro/blob/master/examples/ColorChannels/ColorChannels.pde)
+Code: [ColorChannels](https://github.com/atduskgreg/opencv-processing/blob/master/examples/ColorChannels/ColorChannels.pde)
 
 #### FindHistogram
 
 Demonstrates use of the findHistogram() function and the Histogram class to get and draw histograms for grayscale and individual color channels.
 
 <a href="http://www.flickr.com/photos/unavoidablegrain/9174190443/" title="gray, red, green, blue histograms by atduskgreg, on Flickr"><img src="http://farm8.staticflickr.com/7287/9174190443_224a740ce8.jpg" width="500" height="355" alt="gray, red, green, blue histograms"></a>
 
-Code: [FindHistogram.pde](https://github.com/atduskgreg/OpenCVPro/blob/master/examples/FindHistogram/FindHistogram.pde)
+Code: [FindHistogram.pde](https://github.com/atduskgreg/opencv-processing/blob/master/examples/FindHistogram/FindHistogram.pde)
 
 #### HueRangeSelection
 
 Detect objects based on their color. Demonstrates the use of HSV color space as well as range-based image filtering.
 
 <a href="http://www.flickr.com/photos/unavoidablegrain/9193745547/" title="Hue-based color detection by atduskgreg, on Flickr"><img src="http://farm4.staticflickr.com/3799/9193745547_8f09e55a39.jpg" width="500" height="397" alt="Hue-based color detection"></a>
 
-Code: [HueRangeSelection.pde](https://github.com/atduskgreg/OpenCVPro/blob/master/examples/HueRangeSelection/HueRangeSelection.pde)
+Code: [HueRangeSelection.pde](https://github.com/atduskgreg/opencv-processing/blob/master/examples/HueRangeSelection/HueRangeSelection.pde)
 
 #### CalibrationDemo (in progress)
 
 An example of the process involved in calibrating a camera. Currently only detects the corners in a chessboard pattern.
 
 <a href="http://www.flickr.com/photos/unavoidablegrain/8706849024/" title="Screen Shot 2013-05-04 at 2.03.23 AM by atduskgreg, on Flickr"><img src="http://farm9.staticflickr.com/8267/8706849024_f2d938ec51.jpg" width="500" height="382" alt="Screen Shot 2013-05-04 at 2.03.23 AM"></a>
 
-Code: [CalibrationDemo.pde](https://github.com/atduskgreg/OpenCVPro/blob/master/examples/CalibrationDemo/CalibrationDemo.pde)
+Code: [CalibrationDemo.pde](https://github.com/atduskgreg/opencv-processing/blob/master/examples/CalibrationDemo/CalibrationDemo.pde)
 
 #### HistogramSkinDetection
 
 A more advanced example. Detecting skin in an image based on colors in a region of color space. Warning: uses un-wrapped OpenCV objects and functions.
 
 <a href="http://www.flickr.com/photos/unavoidablegrain/8707167599/" title="Screen Shot 2013-05-04 at 2.25.18 PM by atduskgreg, on Flickr"><img src="http://farm9.staticflickr.com/8135/8707167599_d38fbdfe30.jpg" width="500" height="171" alt="Screen Shot 2013-05-04 at 2.25.18 PM"></a>
 
-Code: [HistogramSkinDetection.pde](https://github.com/atduskgreg/OpenCVPro/blob/master/examples/HistogramSkinDetection/HistogramSkinDetection.pde)
+Code: [HistogramSkinDetection.pde](https://github.com/atduskgreg/opencv-processing/blob/master/examples/HistogramSkinDetection/HistogramSkinDetection.pde)
 
 #### DepthFromStereo
 
 An advanced example. Calculates depth information from a pair of stereo images. Warning: uses un-wrapped OpenCV objects and functions.
 
 <a href="http://www.flickr.com/photos/unavoidablegrain/8642493130/" title="Screen Shot 2013-04-12 at 2.27.30 AM by atduskgreg, on Flickr"><img src="http://farm9.staticflickr.com/8260/8642493130_f99dd76f3d.jpg" width="500" height="404" alt="Screen Shot 2013-04-12 at 2.27.30 AM"></a>
 
-Code: [DepthFromStereo.pde](https://github.com/atduskgreg/OpenCVPro/blob/master/examples/DepthFromStereo/DepthFromStereo.pde)
+Code: [DepthFromStereo.pde](https://github.com/atduskgreg/opencv-processing/blob/master/examples/DepthFromStereo/DepthFromStereo.pde)
 
 #### MarkerDetection
 
 An in-depth advanced example. Detect a CV marker in an image, warp perspective, and detect the number stored in the marker. Many steps in the code. Uses many un-wrapped OpenCV objects and functions.
 
 <a href="http://www.flickr.com/photos/unavoidablegrain/8642309968/" title="Screen Shot 2013-04-12 at 12.20.17 AM by atduskgreg, on Flickr"><img src="http://farm9.staticflickr.com/8522/8642309968_257e397db2.jpg" width="500" height="225" alt="Screen Shot 2013-04-12 at 12.20.17 AM"></a>
 
-Code: [MarkerDetection.pde](https://github.com/atduskgreg/OpenCVPro/blob/master/examples/MarkerDetection/MarkerDetection.pde)
+Code: [MarkerDetection.pde](https://github.com/atduskgreg/opencv-processing/blob/master/examples/MarkerDetection/MarkerDetection.pde)
 
 

resources/build.properties

@@ -149,12 +149,12 @@ source.repository=https://github.com/atduskgreg/OpenCVPro
 # This is used to compare different versions of the same library, and check if 
 # an update is available.
 
-library.version=5
+library.version=6
 
 
 # The version as the user will see it. 
 
-library.prettyVersion=0.4
+library.prettyVersion=0.4.1
 
 
 library.copyright=(c) 2013

src/gab/opencv/Histogram.java

@@ -7,7 +7,7 @@ public class Histogram {
 	private Mat mat;
 	private PApplet parent;
 
-	Histogram(PApplet parent, Mat mat){
+	public Histogram(PApplet parent, Mat mat){
 		this.mat = mat;
 		this.parent = parent;
 	}

src/gab/opencv/Line.java

@@ -0,0 +1,34 @@
+package gab.opencv;
+
+import processing.core.*;
+
+public class Line {
+	public PVector start, end;
+	public double angle;
+	public double x1, y1, x2, y2;
+	
+	public Line(double x1, double y1, double x2, double y2){
+		this.x1 = x1;
+		this.y1 = y1;
+		this.x2 = x2;
+		this.y2 = y2;
+		
+		start = new PVector((float)x1, (float)y1);
+		end = new PVector((float)x2, (float)y2);
+		
+		// measure the angle between this line
+		// and a vertical line oriented up
+		angle = angleBetween(x1, y1, x2, y2, 0, 0, 0, -1);
+	}
+	
+	public double angleFrom(Line other){
+		return angleBetween(x1, y1, x2, y2, other.x1, other.y1, other.x2, other.y2);
+	}
+	
+	
+	public static double angleBetween(double x1, double y1, double x2, double y2, double x3, double y3, double x4, double y4){
+		double angle1 = Math.atan2(y1 - y2, x1 - x2);
+		double angle2 = Math.atan2(y3 - y4, x3 - x4);
+		return angle1-angle2;
+	}
+}

src/gab/opencv/OpenCV.java

@@ -32,6 +32,7 @@
 import gab.opencv.Contour;
 import gab.opencv.ContourComparator;
 import gab.opencv.Histogram;
+import gab.opencv.Line;
 
 import java.awt.Rectangle;
 
@@ -520,6 +521,19 @@ public ArrayList<Contour> findContours(){
 		return findContours(true, false);
 	}
 
+	public ArrayList<Line> findLines(int threshold, double minLineLength, double maxLineGap){
+		ArrayList<Line> result = new ArrayList<Line>();
+		
+		Mat lineMat = new Mat();
+		Imgproc.HoughLinesP(getCurrentMat(), lineMat, 1, PConstants.PI/180.0, threshold, minLineLength, maxLineGap);
+		for (int i = 0; i < lineMat.width(); i++) {
+			double[] coords = lineMat.get(0, i);
+		    result.add(new Line(coords[0], coords[1], coords[2], coords[3]));
+		}
+		
+		return result;
+	}
+	
 	public ArrayList<Contour> findContours(boolean findHoles, boolean sort){
 		ArrayList<Contour> result = new ArrayList<Contour>();