VBGamer

Does anyone know a fast way of doing this? If you don't know what I mean, I'll give an example. Mosiacing (probably not spelled right) is when you have an image or something, and the image becomes less detailed as it shows specific pixels which are inlarged. For instance, Final Fantasy 2 uses this when moving from one map to another, morphing the screen to be more blocky. Does anyone know a fast way of doing this?