Make Finder Desktop Icon Sizes Huge
The Mac OS X desktop is attractive, highly functional, and very customizable, but by default the maximum icon size is 128×128 as adjusted through the normal Mac icon size settings.
While 128 x 128 pixels is pretty large, if you have a huge monitor, or you’re visually impaired, you may want larger icons so that they’re easier to see. This is where the command line comes in, where you can use a defaults write command to force the Mac OS X desktop to display icons as large as 1024 x 1024 pixels!
To do this yourself, launch the Terminal and type the following commands:
defaults write com.apple.finder DesktopViewOptions -dict IconSize -integer 256
Newer versions of OS X are slightly different with a very minor change in the syntax:
defaults write com.apple.Finder DesktopViewOptions -dict IconSize -integer 256
See the difference? The change is the capitalization of ‘Finder’ in the defaults write directive.
You can set 256 to whatever number you want, as high as 1024, just be aware that it can get a little ridiculous, and 512×512 pixel icons will take up the vast majority of your screen.
Next, kill the Finder to relaunch it and see the changes
To get an idea of how big 512×512 pixels is, here’s a sample Finder icon enlarged to full size at that resolution:
Reverting the changes is a matter of setting the integer variable to a smaller number.
To return to the default largest setting, either adjust the Finder Icon size in Finder Preferences, or run a defaults command like this:
defaults write com.apple.finder DesktopViewOptions -dict IconSize -integer 128;killall Finder
This continues to work in most versions of OS X, including Snow Leopard, Mountain Lion, Mavericks, and likely Yosemite too. Just remember to capitalize the com.apple.finder to be com.apple.Finder