What should be the dimensions of a Fourier Transformed image?
Here is a third different output. So I have tried to perform an FFT with Matlab, on four versions of your image:


the grayscale version of the colored image,
the red, green, and blue channels.


I do get  the following, with $512\times256$ size, in a $\log$ scale.



If as suggested by @Peter K. you zero-pad below, with $512\times512$ size, one gets:



Looks like  the FFT of the Red component, padded.
If you have the opportunity to do other tests, we can settle this riddle