Sophia the more pixels the better. Then I can crop or whatever as required to fit and it won't compromise quality but it is not mandatory. All I require is sharp, well focused, pics; not fuzzy ones. If you took a good pic on your cell phone it will be printable as the pics added to articles are not large. You do not need a fancy, mega pixelled camera.
If you look through the conference pics in the Aug mag you will note some are better than others. A lot of the head shots were cropped from group pics and in a dark room so quality varied greatly. The printer does a good job of striking a happy medium when it comes to contrast. Some of the pics printed have been around 100kb, or less, and others up to 250kb as I resize big ones.