I'm sorry, but are there your sample images? Or are there the sample images from a reviewer website?
It's ok since you chose to believe in these pictures. And yes, based on these reviewer pictures, the galaxy mini s4 is better than the Lumia 920.
But base on what I can see in Lumia 920 sub forums, I chose to disbelieve this reviewer pictures. I'm still having my Lumia 920. If your want, I can take another sample to compare with your galaxy mini s4 (if you have any).
Glad I can help.
P.S: About the Lumia 930. Please take another research on why does Lumia 930 have up to 20MP.