Mountain Lion’s Displays preference is scaled down in comparison to Displays preferences of old. But it offers most of the same options (and with a few Mac models, some additions).
If you’re using a single display you’ll see two tabs: Display and Color. In the Display tab, you’ll see entries for Resolution, Brightness, and—on recent MacBook models—AirPlay Mirroring.
Resolution: If you have a Mac without a retina display, you have two options within the Resolution area. The first, 'Best for built-in display', allows the operating system to choose the default resolution for your Mac. With my 13-inch MacBook Air, for example, the resolution is 1440 by 900 pixels. A 15-inch MacBook Pro with retina display has a default resolution of 2880 by 1800 pixels.
“Whoa, slow down buckaroo!” you hoot. “What’s this resolution thing you’re talking about?”
Display resolution is the number of dots (or pixels) in a display, routinely described in terms of width-by-height dimensions. So my MacBook Air has rows of 1440 pixels running across the display and columns of 900 pixels running up and down.
The higher the display resolution gets, the more detailed the screen’s items become. But those items also appear smaller on a higher-resolution display. For example, suppose that a window extends across an area of 640 by 480 pixels. If the total display resolution of your monitor is 1024 by 768 pixels, that window will take up a fair amount of room on the display. But if your monitor's total display resolution is much higher—say, 2880 by 1800 pixels, as it would be on the retina-display MacBook Pro I mentioned earlier—that 640-by-480-pixel window will occupy a much smaller amount of the monitor's overall screen space.
If your Mac’s native resolution is not to your liking, you can change it. To do so, select the Scaled option, and a list of available resolutions will appear below it. Click one, and the Mac’s display will switch to that resolution. If you choose a lower resolution, the objects on your Mac’s screen should appear larger, for the reason I just gave. And as I hinted, those objects will also show less detail and will seem fuzzier than before.
If you have a retina-display MacBook Pro, your Mac’s resolution options will be a bit different. When you choose Scaled on a 13-inch MacBook Pro with retina display, for example, you’ll see scaled options that equal 680 by 1050, 1440 by 900, 1280 by 800, and 1024 by 640 pixels.
Brightness: The Brightness slider serves the same purpose as the brightness keys on your Mac’s keyboard (F1 and F2 on the top row of keys): It lets you adjust the display’s brightness up or down.
On laptops and recent iMacs, below the slider, you'll see an 'Automatically adjust brightness' option. This option enables or disables the Mac’s ambient light sensor—a sensor that detects how bright the area is around the Mac and adjusts the display’s brightness accordingly. With the sensor enabled, your Mac’s display won’t be overpoweringly bright in a very dark room, as it doesn’t need to be for you to see it; but in a very bright room, where the display may be washed out, the sensor will pump up the brightness.
AirPlay Mirroring: Unless you have an iMac (Mid 2011 or newer), a Mac mini (Mid 2011 or newer), a MacBook Air (Mid 2011 or newer), or a MacBook Pro (Early 2011 or newer), you won’t see this option in the Displays preference. If you do have one of these Macs, this feature will allow you to wirelessly project what’s on your Mac’s screen to a second- or third-generation Apple TV (the small black one, not the larger gray model). To use AirPlay Mirroring, simply click its pop-up menu and choose the Apple TV you’d like to project the Mac’s image to. We’ll discuss the finer points of AirPlay Mirroring in another column.
Regrettably, selecting a system preference option won’t change your Mac’s countenance from silver to purple. Rather, the Color tab allows you to change the color tone of your Mac’s display (technically, you can change its white point and gamma).
In the Color tab, you’ll see a few items listed under 'Display profile'. The one currently selected (if you haven’t changed it) is the default profile—the one that the OS believes is best suited for your Mac. Try clicking some of the other profiles just to see what happens. As you do, you’ll find that the screen's color and tone change: The display will appear brighter or dimmer, and the the color duller or more vibrant. Compare these profiles to the default. If you find one that you prefer, using it isn't a crime.
Note, however, that it changes the color of everything on your Mac’s display, including any photos you have. This can be a problem when you print photos, as you may adjust them for a particular profile that looks great on your display but not so good when printed.
I'm going to skip any discussion of the Open Profile button in this tab because it’s for geeks only. But let’s not leave without taking a look at the Calibrate button.
When you click Calibrate, the Display Calibrator application opens. Within this application, you can tweak the look of your display. In its standard mode, you can choose from a couple of gamma settings and white points; but you probably won't find them terribly useful, as most people don’t care for the look they get by changing these options in this way.
If you enable Expert Mode in the first screen and then click Continue, however, the Display Calibrator Assistant will walk you through a variety of options that can yield a display you’ll be happier with—particularly if you’re using a third-party monitor with your Mac and you’re unhappy with its native look. I needn’t hold your hand through the process. Just follow the instructions and see what you come up with. Nothing you do will harm the Mac’s native display settings. Experiment. If you find something you like, great; if not, just choose the default display profile to return the display to its original look.
About multiple displays
If you are new to the Mac (as most readers of this column undoubtedly are), it’s likely that you use a single monitor—either the one that’s integrated into your MacBook or iMac, or one you’ve attached to a Mac mini. But the Mac supports more than one monitor via some kind of additional display port. This may seem like overkill, but I find a multiple-monitor setup indispensable. I keep the application I’m working with on the main monitor, and I place tool palettes or secondary applications on the second monitor.
I mention this not to brag about how the other half lives, but rather to explain that when you attach more than one monitor to your Mac, the Displays preference changes. Instead of two tabs you’ll see at least three. The second one is called Arrangement and it governs how the monitors are set up.
This is an advanced topic, and I won’t cover it until we’ve addressed more of the Mac’s basics. In the meantime, if you do have more than one monitor, click the Arrangement tab and then click the small question mark icon. Doing so will open the Mac’s Help Viewer, which will provide you with more details on configuring multiple displays and projectors attached to your Mac.
Next week: Presenting the printing primer