I am trying to encode a classical image of size 512*512 gray image into the quantum image like NEQR (Novel enhanced quantum image representation), and GQIR (General quantum image representation), but I can't find any method to encode in quantum image by which I can apply quantum operation on quantum image to generate the quantum image encryption algorithm. Can anyone give me some hints about how to encode the classical image into a quantum image? It will be very beneficial for me.

Thanks and regards