Step 3

The following piece of code produces a one-dimensional array of pixels (stored in src_1d) from the image contained in src.

     PixelGrabber pg1 = new PixelGrabber(src,0,0,i_w,i_h,src_1d,0,i_w);
     try {
       pg1.grabPixels();
     } catch (InterruptedException e) {
       System.err.println("InterruptedException!");
       return;
     }
     if (pg1.status() & ImageObserver.ABORT) return;

src_1d will contain the pixel values required provided that the operation executes smoothly.
The method grabPixels() initiates the pixel acquisition process.