Color Management Primer: Monitor Profiling

by Jay Kinghorn

In a digital photography workflow, your monitor is your window to the world. It is the tool you use for making critical decisions on tone and color and the benchmark you use for judging print quality and accuracy. It’s no wonder then that photographers are selective when purchasing a monitor. If money were no object, photographers would simply choose one of the top two or three monitors. The price of a new monitor is a major factor for most photographers. This forces photographers to strike a balance between cost, performance and accuracy when choosing between hundreds of different monitors. In the first half of this article, I’ll discuss the important criteria you’ll want to consider before purchasing your next monitor. In the second half, I’ll help you calibrate and profile your monitor for greatest accuracy, giving you confidence that what you see on screen is what you can expect in print.

Note: This is the second article in a four-part series on color management for digital photographers. Part 1 provides an overview of color management’s key concepts and its role in a digital photography workflow. Part 3 of the series will help you configure your color settings and color management options in popular image-processing applications. Part 4 focuses on color management and printing, helping close the gap between what you see on screen and what you see in your finished prints.

Selecting A Monitor For Digital Photography

Look at any monitor’s spec sheet and you’ll be confronted with myriad technical terms, arcane specifications and confusing sales copy. In this section, I’ll walk you through the commonly-used monitor specifications pointing out which will have the greatest impact in your digital photography workflow.

Cost

The unfortunate truth with monitors is you get what you pay for. While there are bargains to be found, a $200 monitor won’t be as accurate, calibrate as well, or display the subtleties in your work as well as a $2,000 monitor will. If you make your living as a photographer, retoucher or designer, you need to have a high-performing monitor. Your art, your livelihood and your reputation all depend on you being able to make good color decisions on the best equipment.

Even if you don’t make a living by selling your photos, your monitor will have an economic impact. A high-quality, well calibrated monitor will help minimize the number of test prints you’ll need to make when creating your portfolio or gallery prints. Over the life of the monitor, this savings may exceed the initial cost of the monitor.

This brings me to my first recommendation. Buy the very best monitor you can afford. Scrimp on your computer upgrades, a new camera body or flashy accessories. Your monitor is the most important investment in your digital photography workflow. It is the foundation upon which all other elements in the workflow depend. An inferior monitor will cost you time, money and image quality.

With that in mind, let’s look at ways you can stretch your dollars when purchasing a monitor, focusing on elements offering the biggest bang for their buck.

Display Technologies

At the turn of the century, in simpler days of digital photography, you really only had one monitor type to choose from, CRT (Cathode Ray Tube). These heavy, deep dish monitors took up a lot of space on your desk but could be calibrated very accurately because the red, green and blue components used to create the picture on screen could be adjusted independently to fine-tune the display.

These monitors have largely gone the way of the dinosaurs and have largely disappeared from the photographer’s desk except for a reticent few who refuse to give up their CRT monitors for newer LCD displays.

LCD (Liquid Crystal Displays) are smaller, lighter, brighter and have better contrast than their predecessors. Like many new technologies, early LCD monitors were not well suited for digital photography. They were difficult to profile, aged too quickly and didn’t maintain a stable brightness. However, the current crop of LCD monitors on the market provides exceptional quality at reasonable prices.

The primary downside to LCD displays is the inability to adjust the red, green and blue picture controls. Most LCD monitors use a single light source, typically a fluorescent bulb, making it impossible to control or fine-tune individual amounts of red, green or blue.

The newest generation of LCD monitors on the market use an LED (Light-Emitting Diode) light source instead of a fluorescent bulb. Unlike traditional LCDs, LED-based displays can adjust red, green and blue independently for the highest accuracy.

As these LCD/LED monitors gain wider acceptance, expect the price for these monitors to decrease quickly, making LCD/LED the dominant technology used for computer monitors. If you’re looking to purchase a monitor today, look for one with an LED backlight for improved calibration capabilities.

Brightness

One of the advantages of moving from CRT to LCD monitors is the increased brightness of the monitors makes it easier to read text on screen with less eyestrain and movies, video games and photos take on an extra brilliance. Unfortunately, bright monitors also make it more difficult to create a match between your monitor and printer. If your monitor is too bright, prints will appear too dark. As part of the calibration process, you will want to decrease the brightness of the monitor to match your print-viewing conditions. I’ll cover this in greater depth later in this article.

From a buying perspective, don’t pay more for a brighter screen. Virtually any LCD monitor on the market will have sufficient brightness for your purposes.

Contrast

Often marketed in tandem with a brightness measurement is a contrast range. Simply put, the contrast measurement is the ratio between the brightest white and the darkest black. Brightness and Contrast ratio are directly correlated as the brighter a monitor the greater the difference there will be between white and black.

Like a high brightness setting, a high contrast ratio can cause problems for digital photography. Most prints have a contrast ratio of less than 500:1, while it is not uncommon for today’s LCD monitors to have a contrast ratio of 1000:1 or higher. This creates a situation where the image on screen contains brighter whites and deeper shadows than is possible to reproduce in print.

The popularity of mobile devices, online photo sharing sites like this one, and televisions connected to the Internet, it is quite possible that many photographers will look to screens, instead of print as their primary output medium. For these photographers, having a wider contrast range will be beneficial as it will more closely match the contrast range of the original scene, particularly as High-Dynamic Range (HDR) imaging tools improve.

For the time being, I wouldn’t purchase a monitor based on a contrast range setting though it may factor into the decision making process at some point in the future.

Gray Balance

The most effective real-world test of a monitor, particularly after calibration, is how well it displays a gradient from black to white. Ideally, the gradient will transition smoothly throughout the tones without any banding or discoloration. Sounds simple, doesn’t it? Unfortunately, the weaknesses of many monitors are clearly visible with this test.

In Photoshop, create a new document 5×7-inches in size at 300 ppi. Use the Gradient tool (G) to draw a gradient from black to white across the length of the document. Zoom in to fill the screen and press Tab to hide your palettes. Does the gradient progress smoothly through the tones or are there uneven bands or steps between brightness levels? Is there any discoloration through the midtones? Take a close look at the shadows. Do tones become gradually darker or do they drop abruptly to black?

Smooth Grayscale

Inferior Grayscale

This analysis will give you valuable insight into the quality of a monitor and its effectiveness for digital photography. When removing a subtle color cast from an image, you need to have confidence that the color you see is an accurate representation of the photo. Otherwise, you may remove a color cast from the photo that was never present in the original image.

Gray balance is high on my list of criteria to use when selecting a monitor.

Screen Uniformity

Here’s another simple test you can use to check the quality of a monitor. Create a new 5×7 inch at 300 ppi document in Photoshop and fill it with white. Press Tab to hide the palettes and zoom into the document until it fills the screen. Can you see any dark spots or discoloration on the monitor? Are there any color casts or bands of color along the edges of the screen?

Slight discoloration along the edges of the screen is not uncommon and is manageable, but significant dark spots or colored areas should be a red flag. Either the monitor quality is sub-par or this particular monitor may be defective and should be returned to the manufacturer.

Angle of View

Early LCD monitors suffered from a shallow angle of view—the colors in your photos changed depending on your position relative to the monitor. Although the angle of view of a monitor is listed in the specifications, the numbers listed by the manufacturer should be treated with a dose of skepticism. The tests used to calculate the angle of view measurement don’t reflect the reality of sitting at a monitor judging the color of a photograph. If possible, display a photo on screen and shift your body position from side to side? Does the photo change in color, tone or contrast? Ideally, you want a monitor you can look at from slightly different angles and still see the same image. This is one of the characteristics of higher-quality monitors that is often lacking in less expensive models.

Color Gamut

As I introduced in the previous overview article, every device has a range of colors it can reproduce, called the color gamut. A device with a wider color gamut can display more saturated colors than one with a smaller color gamut. The color gamut of most monitors closely matches the sRGB colorspace. The past few years have seen an increase in the number of wide-gamut monitors capable of displaying a larger percentage of the Adobe 1998 color gamut, a larger color gamut than sRGB. A wide-gamut monitor makes it easier to perform corrections on heavily saturated colors or deep shadows, which often cannot be displayed on a normal-gamut monitor.

A wide-gamut monitor gives photos a vibrancy and clarity not seen on standard-gamut displays. If you’re spending big bucks for a top-of-the-line monitor, consider looking for a wide-gamut display. At the same time, I would be leery of an inexpensive wide-gamut display because the additional color gamut may come at the expense of gray balance. Make sure a wide-gamut display uses a high-bit internal LUT (Look-Up Table) to prevent banding or uneven color transitions.

Size and Resolution

When Apple introduced their 30-inch monitor, photographers began clamoring for extra large monitors for their studios. Today, several manufacturers offer large monitors but, does size truly matter?

The construction of LCD monitors makes it difficult to maintain even lighting across the display, as evidenced by the screen uniformity test discussed above. These difficulties are exacerbated by an oversized monitor. While some manufacturers have been able to create large monitors without uniformity problems, these displays tend to be very expensive.

A better solution for most photographers is to purchase two monitors, one high-quality display for performing color critical work, and a second less-expensive display for storing palettes, word processing, etc. This setup gives you a large area to work on with significantly less cost and allows you to purchase a higher quality monitor. This is the setup I use in my studio and I’ve been very happy with it. Ergonomically, I find two smaller screens much easier to navigate through than one large screen and it allows me to jump back and forth between two tasks quickly, like editing photos and responding to e-mail.

Corresponding to monitor size is monitor resolution. The monitor’s resolution, typically listed in pixels, is closer to the image size measurements used for digital photos. Higher resolution displays often appear sharper and display detail more effectively than low-resolution displays. Many older users find high-resolution displays to be somewhat problematic as the icon and text size used in many applications is fixed, making icons very small. Fortunately, you can always decrease the screen resolution on a high-resolution display and many applications include higher resolution icons and interfaces which are easier to read on high-resolution displays.

Advanced Features

This final category is a bit of a catch-all to include the features separating the good monitors from the best monitors. A monitor with some or all of these features is likely a high-quality display that will exceed all but the most discerning expectations.

An internal, high-bit LUT (Look-Up Table) allows adjustments during profiling to be made internally to the monitor’s hardware instead of to your computer’s video card. This improves gray balance and accuracy during calibration and profiling.

Some monitors are pre-tuned in the factory to the standard white point and gamma settings used for digital photography. This minimizes the adjustments made during calibration and profiling, resulting in better gray balance and overall accuracy.

One problem with LCD monitors has traditionally been the long time needed to reach a stable brightness. Many monitors continue to fluctuate slightly for up to an hour before they reach a stable brightness. A few manufacturers have solved this problem and guarantee stable brightness within 2-3 minutes of powering up the monitor.

Another hallmark of a high-quality monitor is built-in monitor calibration software that communicates directly with the monitor’s internal LUT. These monitors deliver high-quality, hassle-free calibrations because the calibration software is tuned specifically for the characteristics of the monitor.

The ultimate goal of these advanced features is to ensure your monitor is stable, repeatable and accurate. This minimizes the amount of correction necessary during the calibration and profiling process making for a more reliable monitor for performing critical color corrections.

Now that you’ve selected your monitor, let’s look at the tools and techniques used when calibrating your monitor for maximum accuracy.

Monitor Calibration

The purpose of calibrating your monitor is to compensate for any color and tone inaccuracies caused by the construction of the monitor or the interaction of the monitor with the video card in your computer. No monitor is perfect out of the box—every one will display color in slightly different ways. Monitor calibration measures, then compensates for, these differences by creating a custom ICC (International Color Consortium) profile.

The term “monitor calibration” actually refers to a two-step process, monitor calibration and profiling. The first component, calibration, changes the physical behavior of the monitor to match a known, desired state. On LCD monitors, this is essentially limited to adjusting the brightness of the backlight. Other corrections listed in the monitor’s on-screen display, such asRGB and white point adjustments, perform software corrections to the display without changing the physical behavior of the device. This differentiation is important because hardware adjustments, like altering brightness, do not negatively impact the quality of the image displayed, while software adjustments can cause problems, particularly with gray balance and the smoothness of transitions and gradients.

In profiling, the second portion of the monitor calibration process, a series of colored patches displayed on screen. The monitor calibration software then compares the measured colors against the actual color values stored in the software and builds a look-up table to compensate for the differences.

Together, the two-part process improves the accuracy of photos displayed on your monitor. The calibration process brings the monitor’s hardware controls to a known state, then the profiling portion uses software to correct any lingering inaccuracies. The resulting ICC profile is set as the default monitor profile in your operating system. Any color management-aware applications, like Lightroom, Photoshop or Aperture use this monitor profile to automatically adjust the RGB values of displayed colors. Once you create the profile, there is nothing more you need to do.

Display Compensation

This concept can be confusing to users new to color management. So, to help bring clarity, let’s look at an example. You and I both calibrate our monitors. The color management hardware and software determines your monitor is slightly blue and mine is slightly green. When you and I look at the same photo on screen, the monitor profile tells your video card to display less blue and mine to display less green. This ensures the photo looks the same on both our monitors despite their inherent differences.

What Settings Do I Choose?

With most monitor calibration packages, you will be asked to specify the white point, Gamma and luminance you would like to calibrate your monitor to. With some monitor calibration software packages you will find these options listed in the Advanced calibration modes, others will place these options on the initial screen. To help you make informed decisions, here is a summary of each option along with my recommended settings.

• White Point: The white point option determines the color of white used for the monitor. Similar in function to the white balance option on your camera, the white point specifies the color temperature the monitor should be calibrated to. Most photographers will want to set their white point to 6500K, a close match to daylight and close to your monitor’s native white point. Photographers and retouchers who frequently prepare images for reproduction on commercial printing presses may want to calibrate their monitor to 5500-5800K. This produces a warmer white, which is a closer match to the papers used for proofing and printing on printing presses.
• Gamma: The monitor’s gamma controls the tone response curve of the monitor, or, to put it more simply, the contrast through the midtones. For both Mac and Window users, I recommend starting with the Gamma 2.2 setting. Advanced profiling software packages may offer an L option, which has become a favorite of photographers because it is perceptually uniform, meaning changes in tone are distributed evenly throughout the tonal range. With other gamma settings, a change in 10 RGB units can produce uneven jumps in tone depending upon whether the change occurs in the shadows, midtones or highlights.
• Luminance: Recommending a specific luminance setting is a bit tricky. You need to set your luminance to match the brightness of the ambient lighting used for viewing prints. Since I’m not sitting at your desk next to you judging prints, I can’t give a firm recommendation. I suggest performing an initial calibration set to 110 cm2 (candelas/meter2), then comparing prints with their display on screen. You’ll want to look for a match in tone between your print and your monitor. Use the print as your reference and vary your monitor accordingly. You may need to calibrate your monitor several times to find the best match. I’ve had very good success with a luminance setting of 110 cm2, but some photographers working in brightly lit rooms will need to boost their luminance up to 200 cm2 for print matching.

Monitor Calibration Tools

Although there are several monitor calibration packages on the market, I’ve chosen to highlight three options I feel are easy to use and produce excellent profiles. Each of these options is designed for a different user group, so I suggest performing additional research online to solicit the opinions of other photographers who have similar needs as yours before making a decision.

Note: To perform an effective monitor calibration, you need to have a dedicated hardware and software package. The older, visual calibration packages are not accurate enough for digital photography. Your initial investment in a monitor calibration package will be quickly repaid through time, ink and paper savings.

i1 Display 2

X-Rite Eye-One Display : $176. The i1 Display 2 is the best entry-level monitor calibration package I’ve tested. The wizard interface is easy to use and the accompanying colorimeter creates good-quality profiles for a variety of monitors, including laptops.

The i1 Display is particularly attractive to schools and larger photo studios as the included EyeOne Match software can be installed on an unlimited number of computers allowing you to share a device with others in your photo club, photography class or workgroup.

ColorEyes Display Pro

ColorEyes Display Pro: $175 software only/$325 w/DTP-94 Colorimeter. For photographers looking for more sophisticated control over their monitor calibration, the ColorEyes Display Pro is hard to beat. After entering your desired settings into the software, the ColorEyes software takes over, adjusting brightness, contrast and white point automatically.

I recommend purchasing the Color Eyes Display Pro DTP-94 bundle, combining the Display Pro software with theDTP-94 colorimeter, which is widely considered to be the most accurate colorimeter for monitor calibration. If you already have a spectrophotometer or colorimeter, you can purchase the software separately and use your existing hardware.

One of the most useful features of the Color Eyes Display Pro software is the profile validation option, which calculates the accuracy of your existing monitor profile and allows you to track accuracy over time. This provides both a current snapshot of your monitor’s accuracy and allows you to monitor for changes in brightness or color accuracy over time. Should the accuracy of your monitor begin to decrease, it is a signal that your monitor may be due for replacement.

ColorMunki

ColorMunki Photo: $499. Photographers looking for a single solution for monitor calibration and print profiling should take a serious look at the ColorMunki Photo, a spectrophotometer that does double duty. The ColorMunki software is very easy to use, simplifying both the monitor calibration and printer profiling processes. The accuracy of both types of profiles is very good, rivaling more expensive, professional-level applications.

The primary knock on the ColorMunki Photo is the inability to define monitor luminance or white point. You can specify your preferred Gamma setting, but the ColorMunki software is hard-wired to predefined luminance and white point settings. Still, the monitor profiles are very good, particularly for the price.

Calibrating Your Monitor

With any of these calibration packages, the calibration process is very straightforward. Each program features a wizard interface to walk you through each step of the process. There are, however, a couple tips to make the process run more smoothly.

• Allow your monitor to warm up for at least an hour before calibrating. This ensures the monitor is at a stable brightness.
• Disable any features that dim your monitor to match the ambient light. This feature, most commonly found on newer Apple laptops, dims the screen to match ambient light conditions. Any change in brightness also changes the monitor’s color characteristics, invalidating your monitor profile.
• Check the Curves display included in the Profile Summary of most calibration packages. The Curves window shows how severe a correction was necessary to build your profile. Ideally, the curves should all appear as a straight line from lower left to top right. The farther the curve deviates from this ideal, the more severe the correction and the more likely you will see problems with accuracy in certain color regions or banding in smooth transitions like skies and skin tones.
• Recalibrate your monitor monthly. Your newly created monitor profile is a snapshot of your monitor’s color characteristics at the moment the profile was created. Any changes to the monitor’s settings, or drifts cause by aging, temperature or changes to the video card will cause the color characteristics of the monitor to change as well. Calibrating monthly will help ensure your monitor profile is an accurate representation of your monitor’s color characteristics. If you are printing frequently, you may prefer to calibrate weekly to ensure your monitor profile is as accurate as possible.

Monitor Recommendations

Your monitor is the cornerstone upon which the efficiency of your digital workflow is built. Carefully selecting the best monitor for your workflow and calibrating your monitor regularly are the best means of ensuring your workflow runs smoothly and your printing is hassle-free.

Given the large number of monitors currently on the market, it is impossible for me to make specific monitor recommendations to fit your needs, budget and workflow. One valuable resource you can use in your research is to search for your monitor within the ColorSync User Group archives. The ColorSync user group is a color management discussion group. Try searching for your monitor name (e.g. Eizo CG222W) and “ColorSync”. You’ll often find expert user experiences with your monitor and recommendations for other comparable monitors.

I am personally a big fan of the Eizo ColorEdge monitors. I’ve been using them for years and recommend them highly to clients. I have also heard rave reviews for the HP LP2480zx Dreamcolor display. You might also consider the NEC MultiSync 2690WUXi2, a 26” display with a wide color gamut. For more modestly priced displays, I’ve had good results with the Apple Cinema Displays, particularly those with a matte surface, and the slightly less expensive Samsung 245T.

What other resources do you use when shopping for monitors? Post your recommendations in the comments field below. In the next article, I’ll help you configure your color settings and color management policies in Photoshop, Lightroom, Aperture and other common image-editing applications.