title: FishEye Picture Effect (Barrel Distortion) Algorithm (with Java)?
body: <p>I'm looking for the algorithm (bitmap pixel manipulation) to simulate the fisheye lens (Barrel Distortion) from normal pictures. So far I've found implementation involving external libraries like OpenCV, OpenGL or jhlabs. Since I'm taking a class in Digital Image Processing and I'm making a course assessment project, I'm not sure whether using any external lib will earn me a good grade. So would anyone give me the reference to such algorithm?</p>
  
  <p>Ps. I'm asked to implement it in Java, but example from any language would do.</p>