When pictures are too dark...

[Toad]

...take them to your picture / graphics software and raise the gamma.
Use the gamma instead of the brightness (usually).

What you want to do is bring it up enough to reveal what's there in the dark, "unseen" black areas, but not too much or it will look "washed out".
Adding contrast can help if it does get the washed out look.

So many pictures that are posted in some forums are so dark they are useless. You've seen 'em, like, "Here's a picture of my new leaf springs." And you look and the picture is a black blob of blackness.

:-)

[pastor_bob]

Thanks for the info, Toad.