Yes, I've loaded some on my computer, and I can modify them there. It's
just that the phone's camera function acts as if I can modify
the exposure at the time the photo is being taken, but in fact does not.
If it could, that would cure the dark image problem. Post-modifying the
images to lighten them helps, but one can never recover the full dynamic
range of an image that was more or less underexposed (that is, if you
brighten it after the fact, it is granier and noiser than an image that
had the proper exposure to begin with).

I appreciate the other respondant's comments that it is a phone first and
a camera a distant second. True. :)

-Bill