Understanding File Formats

[Sombeech]

http://www.pcworld.com/article/id,138290/article.html

What file format to use, when and how to save your images, and understanding the JPEG format.

File Format Myth

Before we go too far, let me dispel a popular misconception. A lot of folks have heard about how saving JPEG photos can affect the image quality. Some people take that idea too far and worry that viewing a JPEG can be hazardous as well.

Not true.

Just looking at a JPEG file doesn't affect its image quality. You can open the file in a photo editor, view it, and close it again without affecting quality--just don't make any changes and click the Save button. If you don't plan to edit an image, you can safely leave it in JPEG format forever and the image quality will never degrade.

[waltny]

I just use the "save as" when I have an editted verison of a photo that I am going to save off for sharing.