Features That Affect Display Quality
If you're a photographer or designer and you're shopping for a new display, you're probably running into unfamiliar jargon like "wide gamut" and "4K" that complicates the buying process. But in many ways today's displays are better than ever. Read on to sort out the specs that are meaningful, and learn to demystify your choices as you narrow your search for a great monitor.
Not everything in this article is typically listed on the specifications for a display. Monitor spec sheets tend to include both useful specifications and completely irrelevant specs you should ignore. For important specs that are missing, you may have to dig deeper or look for independent reviews of the monitor. (One source of reviews is TFT Central.)
Resolution: Is 4K the New Standard?
In the world of displays, the term resolution has two meanings, and those meanings have different benefits.
Resolution has traditionally meant the width and height of the monitor in pixels, or the pixel dimensions. Knowing the width and height in pixels also tells you the total number of pixels, which indicates how much room you have to spread out your work on the screen. If you're always zooming and scrolling on your current display because your work is crowded out by the number of windows and panels in your software, your next display probably needs to have larger pixel dimensions. Figure 1 shows how the difference in pixel dimensions can affect what you see on your screen.
Figure 1 When a display has larger pixel dimensions at the same number of pixels per inch, you can fit more controls on the screen at once, seeing text and images larger and more clearly with less zooming.
The other meaning of resolution is how precisely the display can show detail; in other words, how small the pixels are, indicated as pixels per inch (ppi). Displays are often believed to be only 72 ppi, but that hasn't been true for many years. Most recent desktop and laptop displays actually range from 90 to 120 ppi.
Some new displays use HiDPI resolution to achieve a ppi value much closer to that of print, usually between 150 and 300 ppi. (Apple calls its version a Retina display.) HiDPI screens bring the screen experience closer to print by displaying sharper type and graphics than conventional displays can, by increasing the number of pixels to add detail, instead of adding work area. HiDPI displays have been available only on notebooks, tablets, and smartphone screen sizes; they're not yet common on desktop-sized displays. So-called 4K displays are HiDPI monitors at desktop sizes, but at the time of writing HiDPI display technology is so new that many of these monitors have low refresh rates, and they lack the color performance and features of the better conventional displays that creatives use today. Your next monitor might not be a 4K display, but 4K may well be standard a few years from now.
Aspect Ratio: Are Widescreen Displays an Improvement?
Widescreen displays have taken over the display market, partly because the HDTV standard uses a cinema-like aspect ratio of 16:9 (16 units across by 9 units down). The older CRT-based displays used a 4:3 aspect ratio. But 16:9 displays sometimes aren't ideal for creative work because a vertically oriented document can't be shown as large as a horizontal document when the long side is sized to fit the screen. If a 16:9 display of the right width just isn't "tall" enough for your vertical photos or pages, check out some alternatives. Displays with a 16:10 aspect ratio are available for a little more height (see Figure 2), or you can seek out one of the 4:3 aspect ratio displays that are now less common.
Figure 2 A 16:10 aspect ratio display departs from the current trend toward 16:9 displays, but for creative work 16:10 might be better for vertical documents, while providing more vertical space for tools.
Panel Type: Does the Technology Matter?
As a graphics professional, you should look for a display that has an in-plane switching (IPS) LCD panel. You don't really have to know how in-plane switching works; what's important is that an IPS panel produces better color reproduction with wider viewing angles than the twisted nematic (TN) and vertical alignment (VA) types of LCD panels used on most consumer-oriented displays.
Contrast Ratio: Can It Help Make Your Images Snap?
Some companies proudly tout the contrast ratio of their display, but you can't use that number to compare displays. No industry criteria exist for measuring and reporting contrast ratios, so that number isn't a meaningful specification for comparing different monitors. For one thing, the stated contrast ratio is often calculated before taking the steps to calibrate or profile the display, but what matters to a graphics professional is the contrast ratio after calibration and profiling.
Brightness: Isn't Brighter Better?
High maximum brightness is another specification promoted as a virtue. High brightness is great for televisions and projectors, but not a priority in photography or design—especially for print projects. No paper can match the maximum brightness of most displays. To help match the displayed image to a print, a calibrated display will usually be set to a luminance level in the range of 90 to 140 candelas per square meter, which is typically in the bottom half of many displays' brightness range. Higher brightness isn't even useful for overpowering reflections on a glossy display, because the monitor will be too bright to reproduce black accurately. For many creatives, higher maximum brightness is not useful. (If you're having a problem with glare, you need better control of the lighting in your workspace.)
Color Depth: Is 10-Bits-Per-Channel Color the Way to Go?
Most displays take 8 bits of data per RGB channel from the graphics card. Some displays marketed to creative professionals advertise 10 bits per channel (bpc) of color reproduction. To take full advantage of 10 bpc color, your application, your operating system, its graphics drivers, the display connector, and the display must all support 10 bpc color. If any link in that chain doesn't support 10 bpc, you won't get 10 bpc color. If you're seriously interested in 10 bpc color, right now that means you need a Windows computer with a 10 bpc graphics card connected with a DisplayPort or Dual-Link Digital Visual Interface (DVI) connector to a 10 bpc display. (As of the date of this article, OS X 10.9 Mavericks doesn't support 10 bpc displays.)
Don't confuse the bits per channel rating of the display with the number of bits per channel in an image file or with having a 64-bit CPU. These measurements are not related.
Connectors: Isn't VGA Still Good Enough?
Many monitors are equipped with connections for DisplayPort, Mini DisplayPort, DVI, HDMI (High-Definition Multimedia Interface), and VGA (Visual Graphics Array). High-end monitors tend to include DisplayPort to handle high resolutions and in some cases 10 bpc color and internal calibration, so DisplayPort is currently the most useful connector for creative professionals. Low-end monitors might have only HDMI and VGA. HDMI is useful for connecting multimedia equipment such as a DVD or Blu-ray disc player, but can be used to connect a computer if DisplayPort isn't available. DVI and VGA are older and more limited standards, with a shrinking presence on today's computers.
The connector on your display doesn't have to match the connector on your computer, because it isn't hard to find adapters or cables with different connectors on each end. On Macs, the Thunderbolt port also works as a Mini DisplayPort video connector that can drive large displays.
Color Gamut: Should You Go Wide?
The color gamut of a display is the range of colors it can reproduce. Most displays can reproduce a gamut approximately the size of the standard sRGB gamut. Some wide gamut displays can reproduce a range of colors as large as the Adobe RGB (1998) gamut. You might benefit from a wide gamut display if you do color-critical work, often reproduced on CMYK presses or fine-art printers that can easily reproduce a larger color gamut than sRGB (see Figure 3).
Figure 3 High-end displays can display the Adobe RGB color gamut. More common displays may cover sRGB.
A wide gamut display is more expensive than an sRGB display, so before buying a wide gamut display make sure it's worth the extra cost. Wide gamut displays are marketed to creatives, but as with some other specs we've seen, bigger isn't always better. Wide gamut displays are a small percentage of the monitor market, and most software is written assuming a standard gamut. So while properly configured professional photo and graphic arts software can reproduce color most accurately on a wide gamut monitor, some applications (including some web browsers) display color incorrectly on wide-gamut monitors. For this and other reasons, a wide gamut monitor will serve you best if you understand how color management and color profiles work. (You can learn color management basics from my video "Color Management for Photographers and Designers: Learn by Video.")
If your work is reproduced on devices that exceed sRGB, a wide gamut monitor may be worthwhile—if you understand how to get the most out of it and also how to get around its limitations. If your work is reproduced mostly within gamuts approximating sRGB, such as web design or HD video, your money is better spent on an accurate sRGB monitor than on a wide gamut monitor.
Aren't Calibration and Profiling the Same Thing?
If your work relies on seeing color on your display that's consistent with your final output, you should be keeping your display calibrated and profiled on a regular basis. This means running a high-quality display calibrator and profiler—eyeballing monitor adjustments isn't precise enough.
With any monitor, you start by selecting a standard graphic arts specification that you want the display to meet; for example, your commercial printer might tell you to match a D65 white point at a luminance of 120 candelas per square meter. After you run the profiler, OS X or Windows automatically uses the newly generated color profile to make the display perform as closely as it can to the standard you picked (see Figure 4).
Figure 4 If color reproduction performance is a priority, you need to understand how to calibrate and profile your display.
Calibration and profiling are not the same thing; they're different parts of the process of getting the display to match the standard you chose. The first pass, calibration, adjusts the display itself to bring it as close as possible to the standard. But calibration usually doesn't get the display all the way to the standard, so the second pass, profiling, works out any remaining difference between the standard and the display's current performance, recording that difference in the display's profile.
With most monitors, each time you profile it you make one or more manual adjustments before letting the hardware profiler measure the screen; then, when the profiler is done, most of the work of correcting the display happens in its profile.
Some high-end monitors can work with a compatible calibrator that does almost all of the calibration adjustments automatically by talking directly to the monitor. Most of the work of correcting the display is done inside the display hardware itself, using a look-up table (LUT). This process, sometimes called internal calibration, typically produces better color performance.
In some displays that have internal calibration, you can store more than one calibration setting. This approach helps solve the problem I mentioned earlier of wide-gamut monitors incorrectly displaying colors in non-graphics software; for example, you can create calibrations for both wide-gamut and sRGB, switching between them as needed.
If you're considering a wide-gamut monitor, get one that's capable of internal calibration with a compatible calibrator as well as multiple switchable calibrations. You'll get the best performance out of a wide-gamut display, with less work.
Uniformity: Is That a Hot Spot or Not?
To achieve the best display performance, it isn't enough for a monitor to match a specific luminance level where the display profiler measured it—you need the same luminance at every point on the display. Cheap displays may have poor uniformity, with luminance varying across the panel. When you're trying to make critical decisions in an image-editing application such as Adobe Photoshop, poor uniformity may mislead you as you compare the brightness of different areas of the image.
Now that we've discussed features that affect display quality, let's take a look at a few features that can help smooth your desktop workflow.
Pivot: Wide Becomes Tall
If you work with a lot of vertically oriented content, it may be handy to have a display that you can physically rotate on its stand between horizontal and vertical orientations. You'll probably have to change a setting in your operating system that rotates the monitor image to match the orientation of the display itself, as shown in Figure 5.
Figure 5 If you rotate your display, be sure to rotate the screen image in your operating system too.
Even if a display can't be rotated on its own stand, most can be mounted vertically on another stand or on the wall, as you see with flight status displays in airports.
Multiple Inputs: Share and Enjoy
Many displays let you plug in more than one video input and switch between the inputs, which is convenient if you want to share a monitor between your main workstation and your laptop, for example, or a DVD/Blu-ray Disc player. Others may let you display multiple devices simultaneously, using a picture-in-picture feature like many televisions have.
USB Hub: Plug and Play
Having multiple USB ports is now common on displays, and these ports are handy for plugging in devices like your mouse, keyboard, flash drive, camera card reader, and of course your calibrator/profiler. Note that USB 3 ports are more future-proof than the older, slower USB 2 ports.
Some displays let you coordinate their USB ports with a specific input port, which is great when using multiple computers with the monitor. For example, suppose you have a mouse and keyboard plugged into the monitor's USB ports and both your desktop and laptop computers are plugged into the display's video inputs. When you switch the active video from the desktop to the laptop, the USB mouse and keyboard will now control the laptop.
Can't You Just Use an HDTV?
You might wonder whether an inexpensive HDTV would make a good display. After all, they come in a wide variety of sizes, have multiple inputs, and are generally more affordable than computer displays. So why not?
The problem is that televisions may be perfectly adequate monitors for general office applications, but TVs typically are set up at the factory to provide a vibrant entertainment experience for the living room—they're not designed to represent color accurately for professional graphics work.
Also, even as HDTVs reach sizes of 60 or 70 diagonal inches, they still use the 1920 × 1080 pixel resolution of HDTV (except for the currently rare 4K TVs). That's because large TVs are meant to be seen from across a living room. Using a 27-inch TV instead of a 24-inch computer display doesn't give you any more work area—just larger pixels that look coarser at a desktop distance. But getting a 27-inch computer display instead of a 24-inch display typically will bump up the pixels to 2560 × 1440, giving you an actual increase in work area and probably a better panel.
While buying a professional graphics display can involve a long list of considerations, it all boils down to what you can expect to find within your budget.
With a limited budget, you can find affordable displays that use an IPS panel for good color, and with at least as many pixels as an HDTV offers. These monitors can provide consistent color as long as you use a good profiling device to generate an accurate color profile for your operating system to use.
In the price range above roughly $500, you can find IPS-panel displays with additional resolution for an expanded work area, and convenience features such as multiple switchable inputs and pivoting. At around $1,000, features for color-critical workflows begin to appear, such as wide gamut and maybe internal calibration. As prices pass $1,000, wide gamut and internal calibration become more common.
In many cases, what you pay for is an extra measure of quality control. Like other high-tech components, LCD panels don't all come out of the factory at the same level of quality. Each panel is graded based on criteria such as how many dead pixels it has, the quality and consistency of its color and tonal reproduction, and the uniformity of backlight. Some display makers accept only the highest-quality panels; others take rejected panels and sell them at a lower price. So while you may read that a $600 display uses the same LCD panel as a $1,200 display, that doesn't necessarily mean that the displays perform the same, or that the $1,200 display is overpriced. The $1,200 display might use a higher grade of that panel, calibrate it more rigorously at the factory, or drive it with better electronics.
The good news in all of this detail? Graphics professionals have more and better choices today. LCD technology has matured to the point where you can get a good-quality IPS panel even on a modest budget. And with a better budget, you can enjoy color and tonal reproduction that rivals or exceeds the best of the old CRT displays.