When to Use PNG. Use PNG when you need smaller file sizes with no loss in quality. PNG files are usually smaller than TIFFs, in my experience. PNG also supports alpha transparency (soft edges) and was developed to be a Web graphics replacement for GIF. Note that if you want to retain full transparency, you will need to save your PNG file as PNG-24 and not PNG-8. PNG-8 is useful for reducing the file size of PNG files when you don't need transparency, but it has the same color palette limitations as GIF files.