Understanding File Compression

Compression is Photoshop's way of reducing the size of a document file. Kind of like the ultimate weight-loss program… just click a button, and the file is half its original size. Photoshop employs two types of compress schemes: lossy and lossless. Lossy compression reduces the size of the file by removing color information… information that can never be restored to the saved document. Lossy compression schemes can achieve file reductions of 80 percent or greater.