I've been suffering a little while with images that appear great on Macintosh but that look super dark on Windows. I always knew the problem was with gamma correction, but I hadn't hunkered down to deal with it. I looked around at a number of image applications and couldn't find anything that would do a reasonable job on a batch of images.

Then I remembered ImageMagick, which works on the command line, corrects for gamma, and is free. It works like a charm, I just:

mogrify -gamma 1.6 *.jpg

On my image directory before I upload it and now they look a little bright on Mac but just fine on Windows.

I could embed the image profile in each image, but that isn't supported by all viewers and browsers. So if I'm just making some copies to drop on the web, which are already seriously compressed, I'm not bothered about making a small color correction for Windows.