selective inversion tutorial

How to selectively invert a photo in Picnik:

1. Go to the Create tab and add a rectangle shape
2. Size the rectangle over the part of your image you want to invert
3. Set the rectangle's color to white
-- here's the cool part --
4. Set the "Advanced Blend Mode" to "Difference"

You can do this with any shape and even invert inverts to make cookie cut-outs by layering shapes on top of shapes!