Pictures become brighter when saved?

Hello everyone I 'am new to the forums so I hope that I am posting this in the right area. Well I am new to the whole mac world, so the first thing I did to my mac was calibrate the display, now for some reason when I find a picture online and I set it as my background, the picture get really bright from what the original looked like, same thing when I do screen shots. Does anyone know why or how to fix it?....I was thinking maybe it is something I did when calibrating the display?

Again I apologize if this is in the wrong section.

No one knows at all??

what browser are you using

Lou- I am using Mozilla Firefox

xingles- so are you saying that if could be the file type?....I will try CorelDRAW to convert it and see how that works.

Firefox didn't / doesn't always respect embedded image colour profiles correctly, so photos with embedded profiles will display differently in firefox than in applications that do respect colour profiles, such as Safari, Preview and Photoshop.

Check out this blog entry for more information and make sure you're using a version of Firefox that supports profiles:
Color profiles turned on for Firefox 3.1 - Mozilla Links

You need to make sure you are saving your files using the sRGB color space for viewing on the web. If you use aRGB the colors will be off in every browser.