Hidden frames

Upload frame(s):
Frame 1:
Frame 2:

Or give URL(s):
Frame 1:
Frame 2:

Visibility ratio: to

Select action:
Extract horizontally
Extract vertically

When inserting you need two indexed images with the same size and the same number of colors.
When enhancing you need one indexed image with a squarish palette.

Source code available at http://1190.bicyclesonthemoon.info/pro/insertframe.
Livensed under AGPL 3.