"Spatial frequencies" isn't wrong, but can be a false friend and lead you astray.

The 'problem' with doubled images like these is that you can all too easily over-emphasize a particular direction. Branches running parallel to the doubling direction don't look doubled, while those perpendicular are doubled most strongly. It is easy to end up with a dull bunch of stripes. One of the things I admire in these photos is the way that Meatyard has avoided that, and has retained an interesting formal scheme in the midst of what looks like chaos.