This effect was generated in Filter Forge, a Photoshop plugin that allows you to create your own filters.
This snippet demonstrates an effect similar to Photoshop's pixelize. The difference here is that a single point sample is taken as apposed to an average.
==v2.0===
-Improved speed and simplicity
*Props to matrix and ThreeDee for their contributions to the fraction control.
mosaic tile tiled tiling curve profile offset square pixel pixelize snippet uber zev