topical media & game development

topical media & game development
[] readme course(s) preface I 1 2 II 3 4 III 5 6 7 IV 8 9 10 V 11 12 afterthought(s) appendix reference(s) example(s) resource(s) _
#javascript-processing-example-topic-image-convolution.htm / htm

  <!DOCTYPE html>
  <html><head>
  <script src="javascript-processing-example-processing.js"></script>
  <script src="javascript-processing-example-init.js"></script>
  <link rel="stylesheet" href="javascript-processing-example-style.css">
  </head><body><h1><a href="http://ejohn.org/blog/processingjs/">Processing.js</a></h1>
  <h2>Convolution</h2>
  
  <p>by <a href="http://www.shiffman.net/">Daniel Shiffman</a>.  
  
  Applys a convolution matrix to a portion of the index.  
  Move mouse to apply filter to different parts of the image.</p>
  
  <p><a href="http://processing.org/learning/topics/convolution.html"><b>Original Processing.org Example:</b> Convolution</a><br>
  <script type="application/processing">
  PImage img;
  int w = 10;
  
  // It's possible to convolve the image with 
  // many different matrices
  
    float[][] matrix = { { -1, -1, -1 },
                         { -1,  9, -1 },
                         { -1, -1, -1 } }; 
  
  void setup() {
    size(33, 22);
    frameRate(30);
    img = loadImage("cait.jpg");
  }
  
  void draw() {
    // We're only going to process a portion of the image
    // so let's set the whole image as the background first
    image(img,0,0);
    // Where is the small rectangle we will process
    int xstart = constrain(mouseX-w/2,0,img.width);
    int ystart = constrain(mouseY-w/2,0,img.height);
    int xend = constrain(mouseX+w/2,0,img.width);
    int yend = constrain(mouseY+w/2,0,img.height);
    int matrixsize = 3;
    loadPixels();
    // Begin our loop for every pixel
    for (int x = xstart; x < xend; x++) {
      for (int y = ystart; y < yend; y++ ) {
        color c = convolution(x,y,matrix,matrixsize,img);
        int loc = x + y*img.width;
        pixels[loc] = c;
      }
    }
    updatePixels();
  }
  
  color convolution(int x, int y, float[][] matrix,int matrixsize, PImage img)
  {
    float rtotal = 0.0;
    float gtotal = 0.0;
    float btotal = 0.0;
    int offset = matrixsize / 2;
    for (int i = 0; i < matrixsize; i++){
      for (int j= 0; j < matrixsize; j++){
        // What pixel are we testing
        int xloc = x+i-offset;
        int yloc = y+j-offset;
        int loc = xloc + img.width*yloc;
        // Make sure we haven't walked off our image, we could do better here
        loc = constrain(loc,0,img.pixels.length-1);
        // Calculate the convolution
        rtotal += (red(img.pixels[loc]) * matrix[i][j]);
        gtotal += (green(img.pixels[loc]) * matrix[i][j]);
        btotal += (blue(img.pixels[loc]) * matrix[i][j]);
      }
    }
    // Make sure RGB is within range
    rtotal = constrain(rtotal,0,255);
    gtotal = constrain(gtotal,0,255);
    btotal = constrain(btotal,0,255);
    // Return the resulting color
    return color(rtotal,gtotal,btotal);
  }
  </script><canvas width="33" height="22"></canvas></p>
  <div style="overflow: hidden; height: 0px; width: 0px;"><img src="javascript-processing-example-cait.jpg" id="cait.jpg"><img src="javascript-processing-example-sunflower.jpg" id="sunflower.jpg"></div>
  
  <pre><b>// All Examples Written by <a href="http://reas.com/">Casey Reas</a> and <a href="http://benfry.com/">Ben Fry</a>
  // unless otherwise stated.</b>
  PImage img;
  int w = 80;
  
  // It's possible to convolve the image with 
  // many different matrices
  
    float[][] matrix = { { -1, -1, -1 },
                         { -1,  9, -1 },
                         { -1, -1, -1 } }; 
  
  void setup() {
    size(200, 200);
    frameRate(30);
    img = loadImage("end.jpg");
  }
  
  void draw() {
    // We're only going to process a portion of the image
    // so let's set the whole image as the background first
    image(img,0,0);
    // Where is the small rectangle we will process
    int xstart = constrain(mouseX-w/2,0,img.width);
    int ystart = constrain(mouseY-w/2,0,img.height);
    int xend = constrain(mouseX+w/2,0,img.width);
    int yend = constrain(mouseY+w/2,0,img.height);
    int matrixsize = 3;
    loadPixels();
    // Begin our loop for every pixel
    for (int x = xstart; x &lt; xend; x++) {
      for (int y = ystart; y &lt; yend; y++ ) {
        color c = convolution(x,y,matrix,matrixsize,img);
        int loc = x + y*img.width;
        pixels[loc] = c;
      }
    }
    updatePixels();
  }
  
  color convolution(int x, int y, float[][] matrix,int matrixsize, PImage img)
  {
    float rtotal = 0.0;
    float gtotal = 0.0;
    float btotal = 0.0;
    int offset = matrixsize / 2;
    for (int i = 0; i &lt; matrixsize; i++){
      for (int j= 0; j &lt; matrixsize; j++){
        // What pixel are we testing
        int xloc = x+i-offset;
        int yloc = y+j-offset;
        int loc = xloc + img.width*yloc;
        // Make sure we haven't walked off our image, we could do better here
        loc = constrain(loc,0,img.pixels.length-1);
        // Calculate the convolution
        rtotal += (red(img.pixels[loc]) * matrix[i][j]);
        gtotal += (green(img.pixels[loc]) * matrix[i][j]);
        btotal += (blue(img.pixels[loc]) * matrix[i][j]);
      }
    }
    // Make sure RGB is within range
    rtotal = constrain(rtotal,0,255);
    gtotal = constrain(gtotal,0,255);
    btotal = constrain(btotal,0,255);
    // Return the resulting color
    return color(rtotal,gtotal,btotal);
  }</pre>
  
  </body></html>
[] readme course(s) preface I 1 2 II 3 4 III 5 6 7 IV 8 9 10 V 11 12 afterthought(s) appendix reference(s) example(s) resource(s) _
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