There are a number of reasons why Mac users would want to ditch PNG as the default file format for screen captures.
Not all users can view PNGs, especially users running older versions of Windows and Internet Explorer. Also, some desktop applications won't import them. And some people just plain don't like them – they'd rather use JPGs or GIFs exclusively. Who are we to argue with personal preference?
One of the strengths of Mac OS X is the ease with which you can generate a screenshot. Command-Shift-3 gives you a shot of the entire desktop, and Command-Shift-4 lets you grab a specific portion of your desktop with the Finder's marquee tool. The screenshots appear on your desktop.
Extend that ease of use by capturing in a file format of your choosing.
Terry Harmer's ScreenMat is a free download for Mac OS X 10.3.9 or later. The app lets you pick the defualt file format for your screen captures – choose from PDF, JPG, GIF or PNG.
If you want to go a little farther down the customization road, check out OnyX from Titanium Software. It's an extended GUI for the Mac OS X command line, and it gives you a powerful set of customization tools for the Finder. The default file formats for screenshots can be set as PNG, JPG, PDF, GIF, TIFF, BMP and a few other file types. You can also set a default directory to dump your captures in.
That's only the tip of the OnyX iceberg. The app offers extensive customization options for the core set of OS X apps. We'll give you a full walk-through soon. OnyX is a free download for 10.4.3 or later, and it's available as a Universal Binary.
