Maybe your color control goes crazy in 8-bit color. Try changing the output mode to something that's not surface

My apologies, but I'd need specific instructions. xD I have no idea what you're on about. :x Not the most tech savvy person around.

in dosbox configuration change output to one of the other choices. In your start menu should be an option to edit the config.

Erm...do what now who?

I click on options and it opens up a text with a bunch of gibberish.

-edited-

Okay, I figured out how to change it, and tried all of them. The brightness is still REALLY low for all of them.

Did you try the controls on your monitor? some of them save their settings per resolution.

What would I change? I know that the brightness/contrast is maxed.

is it maxed for this resolution?

I just know that it's at 100. It doesn't say anything about resolutions.

what is your operating system, graphic card, monitor type?

check what happens if you set in dosbox's config
fullresolution=0x0
with different output types

Windows 7 x64, ATI Radeon HD 4200, monitor says "generic Non-PnP monitor". It's a pretty old, crappy emachines monitor.

Putting it to 0x0 just keeps it at the normal size, while having black all around it to technically make it full screen. I'd like it to actually be full-screen.

try different outputs now

It's still a little dark, but for the most part, that solved the problem. Thank you for your assistance.

is monitor flat or now? what model exactly? how old is it?
try to change its drivers to windows' default Plug and Play Monitor