|
Chris, compression has to do with the relationship of a jpeg file's image quality and the amount of computer file space it takes to store it, or bandwidth to transmit it. It doesn't have anything to do with the actual pixel or print dimensions of a file. A tif file from your camera uses no compression at all and gives the best quality, but takes up the largest amount of storage.
When you store a file as a jpeg in Photoshop, and you choose the absolute lowest quality/highest compression setting, the number of megabytes the file takes up will be dramatically less. Unfortunately the appearance of the file can be dramatically worse too. It can look all fuzzy and lumpy (the best words I can think of to describe what over-enthusiastic jpeg compression looks like. Try it and you'll see what I mean.
Somewhere in the middle of the quality/file size continuum usually works best for web images. No noticeable degradation in quality (at least at computer screeen resolution) and a lot less storage space taken up on the server.
|