Image processing to auto adjust colors in python ?

[goldtech]

Hi,

I'm processing thumbnails with python but one thing I need to do is to
auto-adjust an image for the "best" colors. I am using ffmpeg to get
thumbs three seconds into a video, sometimes  the image is too dark.
Normally I'd go into something like the windows program Irfan View and
do "Auto Adjust Colors", but I need a comand-line solution to
processes hundreds of images in a loop. I'm using Ubuntu and Python.
Is there an image precessing package i could use to do this?

thanks,

Lee G.