Mac Dual Screen Tutorial Part II

In Part I I showed you how to get a Mac set up with dual monitors. In this tutorial, I will show you how to make your new found desktop real estate look cool.
Mac with dual monitors
Photoshop or similar
Math skills and knowledge of display resolutions

Windows and Mac handles dual monitors differently. Mac keeps each screen separate, and allows different resolutions on the two monitors. A background used for dual screen computers is typically a standard resolution with the width multiplied by two. This will not work on Macs with unmatched resolutions, without some modification.

Find a dual monitor desktop (via InterfaceLIFT) with the height resolution closest to the larger of the two monitors. For example, I have an iMac with 1440×900 resolution, and a Dell monitor at 1280×1024. Therefore I would get the 2560×1024 file.
Take the widths of the two monitors and add them. In my example the total width is 2720 pixels (1440 + 1280 = 2720) Create a new document in PS with that width, and a height of the largest monitor (1024 in my case.) We’ll call this dump.psd.
Insert your picture into dump.psd. Scale it up until the width is the same as your document. (Scaling proportionally isn’t necessary, but a stretched image might not look as good. You may have to sacrifice the top or bottom of your image to get the width correct.)
New open two new documents in PS. Call these Name right.psd and Name left.psd Make sure they are both the same DPI. Make them the sizes of your two monitors (observing the right and left notation.) At this point, if snapping isn’t turned on, do it now (View > Snap and View > Show > Smart Guides in PS.)
Select all (Cmd + A or Edit > Select All) in the dump.psd, and copy.
Paste into each of the Name documents. On the left document, use the move tool to line up the left edge of the image with the left of the document. Do the opposite in the right document. In the shorter document, make sure the top of the image is at the top of the document (assuming that the tops of your monitors are lined up in System Preferences > Displays > Arrangement.)
Save both Name documents (you can keep them PSD or use JPG, or really any traditional image format. Mac OS can display most of them.)
Now just open System Preferences > Desktop and Screensaver > Desktop and drag your two image files into the image wells. Make sure you get them on the right monitors. This shouldn’t matter, but make sure they are set to Fill Screen. You should now have a panoramic desktop picture that spans both monitors seamlessly (except for the monitor bezel, or course.)
The process for matched monitors is actually easier, just create two documents of the monitor size, and line up the image the same way (left edge in left document, and vice-versa.)

About Edward Carlson

Broadcast television engineer working in Los Angeles, CA.
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