There are limitation of the complexity.
Even making as simple as a paper texture it takes compositing a flood fill into a fractal noise, some displacement and blending it with another flood fill.
For a layer of tree foliage, it would take to generate the "cropping" with a series of fractal noises not to make it look too obvious or at least to look somewhat similar to leaves -next to eachother with no overlapping.
Do the same several time, to generate the "shades" of lighter and darker ones and then maybe place them atop eachother?
No, that wouldn't be enough.
A tree is a "foam" of particles -leaf- within a more-or less spherical shape.
So, what would be the input for the filter besides the shape of the filtered object?
Some blurring added in to that to create a lousy 3D feel with diffuse lighting. That would only result in a single solid spherical shape with no depth.
So instead of generating a single 3D, first that would take to be cut to smaller chunks.
Twice, with inverted colour direction -as you can see through the first layer of leaves and see the "back" of the sphere from the inside.
Then, when all chunks are separated, could be breaking down the shading to separate generated layers of leaves.
Maybe the original fill could also add in an overlay effect -which would also take the ridiculous amount of compositing, displacement and tweaking to look somewhat conveying in the result.
All in all it's a bit more complex than a
camouflage filter.
