Mystery of the stairs

I have observed that the Pillars of creation image from the Hubble space telescope is stair case shaped on the top right. Today I actually found explanation for that!

It seems that there are actually 4 cameras in there and that one of them captures a larger view compared to the other three. The view from the larger camera is then shrunk to produce a normal picture, resulting in the stair shape.

See here for more details.