[Saphire]

I never bother changing that setting I keep it as Standard. I think it safer to leave as standard just in case.

This is what it says in the help file for the settings.

Format OptionsSpecifies the format of your JPEG file. Baseline (“Standard”) uses a format recognized by most web browsers. Baseline Optimized creates a file with optimized color and a slightly smaller file size. Progressive displays a series of increasingly detailed versions of the image (you specify how many) as it downloads.Note: Not all web browsers support optimized and Progressive JPEG images.