Magnify shader

A long time ago I remember someone posting a shader that had a few effects similar to the tools found in Photoshop like magnify. Does anyone remember who made this or have a working version they could upload?

do you think about distordion_2d shader and its fisheye effect ?

This is probably what I am thinking about ;)

here it is

Distortions_2D.fx (8.8 kB)