ImageFiltering.pde

/**
 * Image Filtering
 * This sketch performs some image filtering (threshold, blur) and contour detection
 * 
 * @author: Jordi Tost (@jorditost)
 * @url: https://github.com/jorditost/ImageFiltering/tree/master/ImageFiltering
 *
 * University of Applied Sciences Potsdam, 2014
 *
 * It requires the ControlP5 Processing library:
 * http://www.sojamo.de/libraries/controlP5/
 */
 
import gab.opencv.*;
import java.awt.Rectangle;
import processing.video.*;
import controlP5.*;

OpenCV opencv;
Capture video;
PImage src, preProcessedImage, processedImage, contoursImage;
ArrayList<Contour> contours;

float contrast = 1.35;
int brightness = 0;
int threshold = 75;
boolean useAdaptiveThreshold = false; // use basic thresholding
int thresholdBlockSize = 489;
int thresholdConstant = 45;
int blobSizeThreshold = 20;
int blurSize = 4;

// Control vars
ControlP5 cp5;
int buttonColor;
int buttonBgColor;

void setup() {
  frameRate(15);
  
  video = new Capture(this, 640, 480);
  video.start();
  
  opencv = new OpenCV(this, 640, 480);
  contours = new ArrayList<Contour>();
  
  size(840, 480, P2D);
  
  // Init Controls
  cp5 = new ControlP5(this);
  initControls();
  
  // Set thresholding
  toggleAdaptiveThreshold(useAdaptiveThreshold);
}

void draw() {
  
  // Read last captured frame
  if (video.available()) {
    video.read();
  }
  
  // Load the new frame of our camera in to OpenCV
  opencv.loadImage(video);
  src = opencv.getSnapshot();
  
  ///////////////////////////////
  // <1> PRE-PROCESS IMAGE
  // - Grey channel 
  // - Brightness / Contrast
  ///////////////////////////////
  
  // Gray channel
  opencv.gray();
  
  //opencv.brightness(brightness);
  opencv.contrast(contrast);
  
  // Save snapshot for display
  preProcessedImage = opencv.getSnapshot();
  
  ///////////////////////////////
  // <2> PROCESS IMAGE
  // - Threshold
  // - Noise Supression
  ///////////////////////////////
  
  // Adaptive threshold - Good when non-uniform illumination
  if (useAdaptiveThreshold) {
    
    // Block size must be odd and greater than 3
    if (thresholdBlockSize%2 == 0) thresholdBlockSize++;
    if (thresholdBlockSize < 3) thresholdBlockSize = 3;
    
    opencv.adaptiveThreshold(thresholdBlockSize, thresholdConstant);
    
  // Basic threshold - range [0, 255]
  } else {
    opencv.threshold(threshold);
  }

  // Invert (black bg, white blobs)
  opencv.invert();
  
  // Reduce noise - Dilate and erode to close holes
  opencv.dilate();
  opencv.erode();
  
  // Blur
  opencv.blur(blurSize);
  
  // Save snapshot for display
  processedImage = opencv.getSnapshot();
  
  ///////////////////////////////
  // <3> FIND CONTOURS  
  ///////////////////////////////
  
  // Passing 'true' sorts them by descending area.
  contours = opencv.findContours(true, true);
  
  // Save snapshot for display
  contoursImage = opencv.getSnapshot();
  
  // Draw
  pushMatrix();
    
    // Leave space for ControlP5 sliders
    translate(width-src.width, 0);
    
    // Display images
    displayImages();
    
    // Display contours in the lower right window
    pushMatrix();
      scale(0.5);
      translate(src.width, src.height);
  
      displayContours();
      displayContoursBoundingBoxes();
      
    popMatrix(); 
    
  popMatrix();
}

/////////////////////
// Display Methods
/////////////////////

void displayImages() {
  
  pushMatrix();
  scale(0.5);
  image(src, 0, 0);
  image(preProcessedImage, src.width, 0);
  image(processedImage, 0, src.height);
  image(src, src.width, src.height);
  popMatrix();
  
  stroke(255);
  fill(255);
  text("Source", 10, 25); 
  text("Pre-processed Image", src.width/2 + 10, 25); 
  text("Processed Image", 10, src.height/2 + 25); 
  text("Tracked Points", src.width/2 + 10, src.height/2 + 25);
}

void displayContours() {
 
  for (int i=0; i<contours.size(); i++) {
  
    Contour contour = contours.get(i);
    
    noFill();
    stroke(0, 255, 0);
    strokeWeight(3);
    contour.draw();
  }
}

void displayContoursBoundingBoxes() {
  
  for (int i=0; i<contours.size(); i++) {
    
    Contour contour = contours.get(i);
    Rectangle r = contour.getBoundingBox();
    
    if (//(contour.area() > 0.9 * src.width * src.height) ||
        (r.width < blobSizeThreshold || r.height < blobSizeThreshold))
      continue;
    
    stroke(255, 0, 0);
    fill(255, 0, 0, 150);
    strokeWeight(2);
    rect(r.x, r.y, r.width, r.height);
  }
}

//////////////////////////
// CONTROL P5 Functions
//////////////////////////

void initControls() {
  // Slider for contrast
  cp5.addSlider("contrast")
     .setLabel("contrast")
     .setPosition(20,50)
     .setRange(0.0,6.0)
     ;
     
  // Slider for threshold
  cp5.addSlider("threshold")
     .setLabel("threshold")
     .setPosition(20,110)
     .setRange(0,255)
     ;
  
  // Toggle to activae adaptive threshold
  cp5.addToggle("toggleAdaptiveThreshold")
     .setLabel("use adaptive threshold")
     .setSize(10,10)
     .setPosition(20,144)
     ;
     
  // Slider for adaptive threshold block size
  cp5.addSlider("thresholdBlockSize")
     .setLabel("a.t. block size")
     .setPosition(20,180)
     .setRange(1,700)
     ;
     
  // Slider for adaptive threshold constant
  cp5.addSlider("thresholdConstant")
     .setLabel("a.t. constant")
     .setPosition(20,200)
     .setRange(-100,100)
     ;
  
  // Slider for blur size
  cp5.addSlider("blurSize")
     .setLabel("blur size")
     .setPosition(20,260)
     .setRange(1,20)
     ;
     
  // Slider for minimum blob size
  cp5.addSlider("blobSizeThreshold")
     .setLabel("min blob size")
     .setPosition(20,290)
     .setRange(0,60)
     ;
     
  // Store the default background color, we gonna need it later
  buttonColor = cp5.getController("contrast").getColor().getForeground();
  buttonBgColor = cp5.getController("contrast").getColor().getBackground();
}

void toggleAdaptiveThreshold(boolean theFlag) {
  
  useAdaptiveThreshold = theFlag;
  
  if (useAdaptiveThreshold) {
    
    // Lock basic threshold
    setLock(cp5.getController("threshold"), true);
       
    // Unlock adaptive threshold
    setLock(cp5.getController("thresholdBlockSize"), false);
    setLock(cp5.getController("thresholdConstant"), false);
       
  } else {
    
    // Unlock basic threshold
    setLock(cp5.getController("threshold"), false);
       
    // Lock adaptive threshold
    setLock(cp5.getController("thresholdBlockSize"), true);
    setLock(cp5.getController("thresholdConstant"), true);
  }
}

void setLock(Controller theController, boolean theValue) {
  
  theController.setLock(theValue);
  
  if (theValue) {
    theController.setColorBackground(color(150,150));
    theController.setColorForeground(color(100,100));
  
  } else {
    theController.setColorBackground(color(buttonBgColor));
    theController.setColorForeground(color(buttonColor));
  }
}