Reverse transformation

In theory, since FF is sample based and not pixel based, I think any transformation you do can be undone, it's just a matter of knowing exactly what the transformation was, and doing the exact opposite of it.

What if you take a perlin noise and apply it as offset for an image, can you then apply the reverse distortion by inverting the noise?

Edit: No... I don't know why, but it just seems to distort it even further.

http://www.filterforge.com/filters/1762.html

This one is reversable.

Yes, it is a bit of an tricky problem for solving procedurally.

When you offset something, the starting point will no longer "know" where it was offset to. You will have to look for the point in all the possible places it could have gone. Which means scripting it.

Here is a simple situation with a horizontally offset image:

I wrote a script that looks at every pixel in that horizontal row to find the one that is closest to the origin point. This point is then used for the Lookup component to reverse the offset.

Now, since you have to search 600 different points to locate a closest match for horizontal offset (for a 600x600 image), you can see that it goes pretty slow. And it isn't all that accurate either, since there is no in-between pixel checking.

Anyways, this approach works and can certainly be improved upon.

Reverse Offset.ffxml

Purposely using just the Reverse Offset (leaving out the original Offset) to distort the image gives this result. Notice the self-overlapping areas in the image. Only if it didn't take 25 minutes to render this...