/*Drew Cogbill
 ex40.12 and Image 4_2
 [computation08]*/

//2D Array
float[][] kernel = { { -1, -1.4, -1 }, 
                     { -2, 4, 2 }, 
                     { -1, 0, 0.9 } };
                     
PImage img = loadImage("trista.jpg"); 
  size(img.width, img.height);

img.loadPixels();  
PImage edgeImg = createImage(img.width, img.height, RGB); 
for (int y = 1; y < img.height-1; y++) {  
  for (int x = 1; x < img.width-1; x++) { 
    float redsum = 0; 
    float greensum = 0;
    float bluesum = 0;
    for (int ky = -1; ky <= 1; ky++) { 
      for (int kx = -1; kx <= 1; kx++) { 
        int pos = (y + ky)*width + (x + kx); 
        float redval = red(img.pixels[pos]); 
        float greenval = green(img.pixels[pos]); 
        float blueval = blue(img.pixels[pos]); 
        redsum += kernel[ky+1][kx+1] * redval; 
        greensum += kernel[ky+1][kx+1] * greenval;
        bluesum += kernel[ky+1][kx+1] * blueval; 
      } 
    } 
    edgeImg.pixels[y*img.width + x] = color(redsum, greensum, bluesum); 
  } 
} 

edgeImg.updatePixels(); 
image(edgeImg, 0, 0);