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During my playful experiments with Fourier Transforms, I discovered that you can overlay an image on top of a Fourier transformed image, and freely convert back and forth from Fourier to regular space. Each transform would descramble the previously FFT’d image. So in short, you can hide the FFT of one image in another image.
Here’s the message I want to hide:
I’ve put it in the bottom half of the picture so it will still be intelligible after being transformed. Here’s the FFT of my secret message:
My first test overlaid the FFT over a color wheel, but it’s still a bit obvious:
If we scroll the FFT over to the corners and scale down the brightness, it’s much harder to spot when overlaid with the zucchini-in-a-bottle image:
You can barely spot it. Some information is lost when the image is saved in the .tif format, but after we scale the brightness back up, we get this:
Here’s my whole shake tree for both the test image and the final masterfully masterfool zucchini-hiding-a-secret image. Cheers!