Feature selection - QR code localization
The idea would be to find  

1) Rotational independent and 
2) Shift invariant features. 

Simply speaking the Fourier transform is a rotational and translational (shift) independent feature. 
There are SIFT features used in computer vision that can extract such features. This is something you can try. 

Since you are using QR codes,I think edge magnitude maps would be better than images because you could use image processing techniques to suppress the  noise in the background and highlight the edges on the QR code. You could even look at autoencoder and CNN related feature extraction.