I use my Android phone on high res and they've never had an issue with my pics. Sometimes I crop them and again, no issues.
Where you need to be careful is linking them. For the gas stations, for example, you have to link the gas receipt as link 1, store purchase as link 2, etc and so on. My misunderstanding on my first ones with the linking got a shop rejected. I didn't link them correctly and they rejected it and wouldn't allow me to fix it even though I had all the correct pics.
Just out shopping around...