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Display Calibration 201: The Science Behind Tuning Your Monitor
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1. The Two Reasons To Calibrate Your Monitor

In Display Calibration 101: Step-By-Step With Datacolor's Spyder4Elite, we discussed one specific way to dial in your monitor; that is, to use the Spyder4Elite package to create a software look-up table (or LUT). This approach is both easy and relatively accessible, requiring very little knowledge of or training in the principles of display calibration and imaging science. 

But many readers commented that they wanted to learn more about adjusting their display's controls to achieve the same results. There are many tools available that can help you do this, and they'll be the subject of future articles. In fact, our next installment will cover the use of the CalPC package from SpectraCal. Today though, we’d like to lay a little groundwork so you know exactly what you’re in for.

There are two main reasons to calibrate any display. One is to match it to the other devices in the production chain like cameras and printers. In a photo studio, it’s crucial that the camera, printer, and monitor all conform to the same color and gamma profile. That way, what the photographer sees through the lens is what he sees on paper and on the screen. The second reason, the one we’ll be exploring here, is to match your display to a particular standard.

Why match a standard? It’s simple, really. Nearly every game or movie you view on your computer is mastered to the Rec. 709 video standard. This is nothing more than a specific set of parameters for color gamut, white point, and gamma. It covers other areas too, but for the purposes of display calibration, we only need to worry about those three. We’ll discuss what those parameters are and their importance in the first four sections. But calibrating your display to that standard ensures that you see exactly what the content creator saw.

There’s one more thing we’d like you to keep in mind as you move through the next few pages: the priorities of imaging science, a science of perception. How can one create a two-dimensional picture on a video display that naturally and accurately represents three-dimensional reality? Accepting the limitations of that display, we have to know how human beings perceive color, light, and detail.

To that end, imaging science as we know it is based on four elements. They are, in order of importance: dynamic range, color saturation, color accuracy, and resolution. Simply put, standards like Rec. 709 are intended to maximize those four elements. When all four are satisfied, you're looking at the most realistic image possible.

As we move on, we’ll go behind the scenes in the four major areas addressed by display calibration: levels, gamma, grayscale, and color. Understanding those principles means you’ll know exactly what’s happening when you move that brightness or RGB slider. And you’ll be able to identify your own display’s deficiencies and how to correct them. It's a wild ride, but we think you'll find it rewarding.

2. Levels: The Key To Contrast And Detail

We’ve established that dynamic range is the most important element in image quality. Just like audio, the greater the difference between the extremes (soft and loud, light and dark), the greater the realism and sense of depth. And in a rare bit of good fortune, this is the one thing a user can achieve with a monitor that doesn’t require a meter or fancy software! What we’re talking about are black and white levels, or, as they’re more commonly known, brightness and contrast.

At some point in history, a not-so-clever television engineer decided that the controls affecting dynamic range should be called brightness and contrast rather than black level and white level. This has created confusion as to what these adjustments are actually for. It’s actually quite simple, though. Brightness is black level and contrast is white level.

Now, what are we doing when we change those controls? Black level/brightness refers to the minimum level of light a display will produce. White level refers to the maximum level of light. Obviously, by minimizing black and maximizing white, you'll achieve the highest contrast ratio and the greatest dynamic range possible for a given display. The trick is to set the levels properly, while retaining all of the image's detail.

To illustrate the importance of setting black and white levels correctly, let’s check out an actual photograph. We modified the original in Photoshop by using the Levels dialog to manipulate the black and white levels. This is functionally the same as adjusting the brightness and contrast controls on your monitor. No adjustments were made to color.

Here’s a shot of singer Gavin Rossdale performing with Bush.

This is a pretty detailed photograph. You can clearly see the definition in his arms, his hair, and his jeans. Plus you can see the audience far in the background. And check out the subtle outline of his right hand against the guitar’s body.

Here’s the histogram.

Nearly the entire brightness range is represented, except for a few steps at the dark end. And there are one or two steps at the bright end that get crushed. This image is straight from the camera with no post-processing.

Here’s the same shot with the black level set too low.

The audience and Gavin’s hair get obliterated. His right hand now blends into the guitar’s pick guard. And his jeans have far fewer wrinkles than before. This is what we mean when we use the term crush or clip in reference to black. The darkest information is crushed together and shadow detail is lost. Where there were perhaps 50 gradations of black, there is now only one. While an artist may purposely modify an image like this for extra impact, the fact is that some of the original information was lost.

Now let’s see what happens when you set white level too high.

Gavin’s face and right arm turn into formless white shapes, and we lose the dimension we saw in the original. The many shades of white that created detail in his face are now blended together. Since the audience in the background is also brighter, the sense of depth is significantly reduced. It’s harder to tell just how far away they are.

Here’s the same photo with the black level set too high.

You can still see the detail, but now there’s a hazy look to the photo, as if a filter was put in place. Any sense of image depth is drastically reduced.

Our final example shows the effect of setting the white level too low.

Again, the detail is all there, but the photo looks dim and underexposed. This and the previous image retain all of their detail. However, by reducing the dynamic range, the vibrancy and impact are significantly lower.

We’ll show you how easy it is to fix these problems with a couple of test patterns you can download from the Internet. Setting black level and white level properly doesn’t require instruments or software. And it’s one of the best things you can do to improve your monitor’s image. By maximizing dynamic range, you’re well on your way to better pictures!

To fully take advantage of a display’s dynamic range, we also need to understand what’s happening to the points in between black and white. This is where the discussion turns toward gamma.

3. Gamma: The Key To Maximum Image Depth

You’ve seen us devote a fair amount of space in monitor reviews to the measurement of gamma. Here we have the opportunity to explain that concept in greater detail.

What is gamma, exactly? Each brightness point between zero and 100 percent has to have a certain value (luminance) in order to match the gamma of the camera that created the image. One might think this relationship is linear. For example, a 50-percent signal equals 50-percent light output. But this is not the case. Look at the table below.

Signal Level
Y (cd/m2)
0%
0.40
10%
2.02
20%
7.36
30%
17.35
40%
31.73
50%
52.06
60%
76.90
70%
108.99
80%
145.97
90%
190.37
100%
239.68

This is a series of measurements from a monitor that tracks a 2.2 gamma value very closely. The minimum black level is .39 cd/m2 and the max white is 239.67 cd/m2. If the display’s gamma were linear, a 50-percent signal should result in a light level of 119.84 cd/m2. The actual value is less than half that figure at only 52.01 cd/m2. Why? We need a short history lesson to find the answer.

The first displays used cathode ray tubes to create their images. Electrons were fired at an array of chemical phosphors, which in turn produced light. As it turned out, the intensity of light produced did not vary in a linear fashion. As in the table above, it was logarithmic. Obviously, cameras and other recording devices had to match this output curve. And they still do to this day, even though the CRT is no longer with us. Nearly all imaging devices, whether they are input- or output-oriented, are engineered to a gamma of 2.2. While there are variations, 2.2 is the accepted norm for video and still photography. If your monitor tracks 2.2, it will match the incoming signal from pretty much any source.

How do we measure this? It’s easy to gather the data when we measure grayscale. The patterns are windows that represent signal intensity from 0 to 100 percent. For each measurement, we record a Y (luminance) value. Then our software calculates the difference between the measured and target values. From that difference, a gamma number is generated. The closer this number is to 2.2, the better.

This window pattern is just like the one generated by our Accupel DVG-5000. The center square is 100 percent brightness and the background is 0 percent. When we measure gamma, the window varies from 0 to 100 in 10 percent increments.

Let’s look at the table again, but this time with the gamma values and Y targets.

Signal Level
Y (cd/m2)
Target Y
Gamma
0%
0.40
0.00
2.20
10%
2.02
1.53
2.08
20%
7.36
7.02
2.17
30%
17.35
17.13
2.19
40%
31.73
32.25
2.22
50%
52.06
52.69
2.22
60%
76.9
77.38
2.21
70%
108.99
108.89
2.20
80%
145.97
146.33
2.21
90%
190.37
189.88
2.18
100%
239.68
239.68
2.20

When the value is higher than 2.2, it means that output level is too dark. If the value is below 2.2, then the output is too bright. By comparing the actual measurements to the targets, you can see how far off you are. This display (a Samsung S27B970D) is pretty close to perfect.

This is the graphical representation we use in our reviews. It’s easy to see where even the tiniest errors are.

So how does this relate to a monitor’s calibration controls? It's actually fairly simple, since the vast majority of computer monitors with gamma controls only include presets. There’s no way to edit the gamma curve itself. What do we mean?

With presets, you have only one gamma curve available, which you can move up and down. The shape doesn’t change, only its relationship to 2.2. If you start with flat tracking, as illustrated above, you only need to find the preset that gets you closest to 2.2. If the tracking isn’t flat, like the chart below, there isn’t much to do except get at close to 2.2 as possible.

In this example, the gamma is OK until around 60 percent, where it starts to dip. Then it takes a huge dive at 90 percent. The only way to correct this is with multi-point gamma control, which lets you edit each brightness point individually. Unfortunately, these are quite rare on computer monitors (and on displays in general). We’ve only seen them on a few high-end televisions and projectors.

Here’s Gavin again,. This time, we’re simulating altered gamma by using the Curves editor in Photoshop.

By setting the gamma too high, we’ve reduced shadow detail almost to the point of clipping. Of course, you can do this to create a certain effect, but you’ve changed the original image and reduced much of the shadow detail to a minimum. It’s there, just very hard to see.

Now we’ll set the gamma too low.

This is similar to setting the white level too high. Detail in the bright areas is very difficult to discern and the whole picture looks over-exposed.

It’s obvious from the photos that poor gamma can have nearly the same effect on image quality as incorrect levels. That’s why it’s so important to a monitor’s perceived contrast that gamma be correct. You can have deep blacks, bright whites, and a fantastic contrast ratio. But if the gamma is off, much of that dynamic range is wasted.

Now we’ll move into grayscale, which, as we’ll see, is at the center of everything when it comes to color.

4. Grayscale: Why White Is The Color Of Everything

The one calibration control that every monitor has is color temperature. And to alleviate any confusion over terminology right now, let’s establish that color temperature, grayscale, white balance, and white point are all the same thing.

Fixed-pixel displays produce color, and white, using red, green, and blue sub-pixels. How does white come from that? Let’s look at the CIE chart to find out.

This is the CIE chart we use in our monitor reviews. The square inside the gamut triangle represents the white point, where the three primary colors combine to produce white. Of course, the color of white is open to interpretation and that’s where we need to apply a standard. For the purposes of video and computer imaging, that standard is a color temperature of 6500 kelvins or D65.

Where did this value come from? 6500 K is the approximate color temperature of the mid-day sun, and white objects viewed under this light will take on a particular color. You can try this yourself by taking a piece of white paper and viewing it under different kinds of light. Fluorescent lighting looks a little green, while tungsten appears orange or yellow. And even sunlight at different times of day will change your perception of white.

Of course color temperature doesn’t just apply to white. For the purposes of calibration it does, but think about how lighting affects the color of any object. Remember the last time you bought paint for your home and it looked different in the store than it did on your wall? The color temperature of the light shining on that paint can drastically alter your perceptions.

So what happens when you adjust the color temp on your monitor? While we are only adjusting the white point, this procedure has an additional benefit. Correcting a display’s color temperature also aligns the secondary colors (cyan, magenta, and yellow) more closely to their targets.

It may be a little hard to see in the photo below, but look closely at cyan and magenta.

All we did to this monitor was correct the color temp from its default state to D65. You can see that cyan and magenta are now much closer to their targets than before. Why is yellow not affected? That is an anomaly of this particular monitor, an AOC Q2963PM. It’s not a flaw. It’s just the way that screen reacts to calibration.

Let’s bring Gavin out again. Here is the unedited shot for reference.

This is typical stage lighting that gives a natural and even look to the performer. Notice that the all-important flesh tones look exactly as they should.

Now we’ll make the color temp too warm; in other words, below D65.

This is done by editing the color balance in Photoshop. We simply turned up the red as one would do with the red slider on their monitor. It looks as if a red filter has been placed over the spotlight. It doesn’t look awful, but it’s not what we saw at the concert, is it?

Here’s the effect of having too much green.

Gavin looks very unnatural here. Green is the most obvious kind of error because the human eye is more sensitive to that color than any other. We doubt anyone would want their photos to look this way on purpose.

The last example shows the most common color temperature error.

This doesn’t look too bad, right? That’s because blue makes things appear brighter. Again, this is science coming into play. If your display is going to be off, blue errors impact image quality less severely than red or green. If you look at our monitor reviews, almost all screens measure a little too blue out of the box.

We have our feet wet with color adjustment via the RGB controls and white point. Now let’s look at color gamuts and how they’re implemented and measured.

5. Gamut: What Color Is Your Monitor?

If you read the explanations of color gamut in our monitor reviews, or in Display Calibration 101: Step-By-Step With Datacolor's Spyder4Elite, then you know that color gamut is another standard by which displays are matched to each other, as well as to cameras and printers. While it is possible to have a screen with a built-in color management system, it’s far more common to create a look-up table, called an ICC profile, that reconciles differences between a monitor’s actual color gamut and the target values.

Below we have a different representation of the CIE chart.

We chose this one because it shows the two gamuts currently available on computer monitors: Adobe RGB 1998 and sRGB. As you can see in the graphics, they are subsets of the full chart, which portrays the spectrum of color visible to the human eye. How close a display comes to these gamuts is a very important part of our testing.

There are other standards besides these two. The most common one is Rec. 709, which is used by high-definition televisions and projectors. Why don’t we show it on the chart? Because it’s identical to sRGB. They are indeed interchangeable. The other standard we’ll mention briefly is Rec. 2020, which is still a proposed spec and not currently in use on any production displays.

This is the proposed color gamut for ultra-high definition screens at both 4K and 8K resolutions. When this gamut is actually used in a monitor, you’ll need appropriate content to match it. And that is unlikely to happen without major upgrades in optical disc storage capacity and bandwidth, since it requires a minimum of 30 bits per pixel to encode.

How does this apply to our discussion? All fixed-pixel displays use three primary colors, red, green, and blue, to display an image. In the case of an eight-bit panel, 2563 gives us a possible 16,777,216 colors. Obviously, the positions of those primaries on the CIE chart are of paramount importance. Assuming that the camera used conforms to the standard, the only way we’ll see the same image is if our monitor conforms to the same standard.

That’s simple enough to understand, but what about the secondary colors?

In between the primary color points are the secondary ones: cyan, magenta, yellow. These are created by mixing two of the primaries in a particular ratio. The technical term is phasing and it’s important that a display does this correctly. A screen can have spot-on primaries, however, if the secondaries are off, visible color errors will result. Previously, we saw that adjusting the white point can help align secondaries. And most of the time, this is the only thing we can do to improve a display’s color accuracy.

Now we’ll get into some actual application of all this science. We’re going to explain just how we calibrate a monitor using its built-in controls only. This is exactly what we do for our reviews.

6. Application: How To Adjust Levels

Hopefully, all of this talk of science and theory is inspiring you to try calibrating your own display. If you have the basic tools available, you can do this by following the steps we’ll outline in the next four pages. As stated in the beginning, you’ll be adjusting the monitor’s controls only. This method does not use a software look-up table. You can also create an ICC profile for use with your graphics apps. We’ll show you how on page nine.

We suggest you follow the steps here in the order we give them. Since there are nearly always interactions between controls, this procedure minimizes the need to go back and forth to dial in your display.

First, you should go through a little pre-flight drill.

  1. Warm up your monitor for at least 30 minutes before you start. That way, the backlight will be stable and you’ll get the most accurate measurements.
  2. Find a picture mode that is neither too bright nor too dark. Usually one marked Standard is a good bet.
  3. Set the Color Temp to User or Custom so you have access to the RGB sliders.
  4. If there is a Gamma preset, choose 2.2.
  5. Now you’re ready to begin.

First up are the level adjustments; Brightness and Contrast. These can be set by using a couple of test patterns. There are many available that will work. Here are a couple of samples.

This is one of the grayscale step patterns generated by our Accupel. You can also find this pattern online. In fact, we downloaded this very graphic. You should see 11 brightness steps. Fifty percent is in the middle.

Here is a PLUGE pattern.

PLUGE is a traditional term for patterns used to set levels. The acronym stands for Picture Line Up Generating Equipment. Definitely a throwback to the analog era! You should be able to see four vertical bars in the center of the field. They start with the darkest on the left and become brighter as you go right.

This pattern is good for setting contrast.

We’ll explain how to use all of these patterns in a moment. The important part is the section on the right side. There are a total of 33 bars ranging from 0 to 100 percent, or in RGB terms, 0 to 255.

Finally, we have another pattern that’s even better for setting contrast.

In this pattern, you should see eight concentric squares that vary in brightness. If you can’t see all eight squares, that color is clipping.

The common theme in all of the patterns is that they have bars a few brightness steps apart from one another. By viewing these bars, it’s easy to see when you’ve set the controls too far in one direction because one or more of them blend together. This is what we mean when we use the term clipping.

Start with the first pattern, the grayscale steps. Lower the Brightness control until the darkest two bars become one. On most monitors, they’ll never actually blend because they’re quite far apart in brightness.

Now try the same exercise with the second pattern. On some monitors, the darkest bar will disappear. When this happens, turn Brightness back up until the bar is just visible. If you can turn your Brightness control all the way down without clipping any bars, then you should set the control with a meter instead. Display a 100 percent window pattern like this one.

Measure the window with your meter and adjust brightness until it’s at the value you want. We always use 200 cd/m2 but your preference may vary based on your room lighting conditions.

Now display the third pattern. Raise the Contrast control until the rightmost two bars blend together. That’s your clipping point. If you can raise it all the way and the bars are still visible, try the fourth pattern with the colored squares. This one is more precise because you can see the clipping point of each primary color. If one color clips, you’ll lose grayscale accuracy because the monitor has literally “run out” of that color. We’ve noted in all our monitor reviews that the Contrast control’s default setting is usually at its highest possible point. Raising it even one click often clips at least one color and sometimes all of them.

This is pretty easy to do, even without a meter. Most monitors will let you set the brightness anywhere in their range without clipping blacks. You just have to decide how bright you want your screen to be for your particular workspace. And contrast is generally fine at its default setting.

Since the final values of your level adjustments determine the measurement parameters for gamma, it’s important to do this step first. As we’ve already demonstrated, poor gamma has an obvious negative impact on image quality.

7. Application: How To Adjust Gamma

If your monitor doesn’t have any gamma adjustments, you can skip this step. Hopefully, your gamma is accurate! Otherwise, make sure your preset is 2.2, and ready your meter and software.

To measure gamma, you’ll need to take readings from gray window patterns that range from at least 20 to 100 percent. We measure from 0 to 100 for our reviews. A package like CalMAN automates this process so all you have to do is click one button. If you are controlling your patterns manually, you’ll have to change them between each measurement. Start at the bottom and work your way up. Your software should give you a graph and the raw numbers.

A graph like this one from CalMAN makes it easy to see how close your display is to 2.2. In this example, there are slight dips at 10 and 90 percent. Dips mean that particular point is too bright. Here are the raw numbers from this measurement run.

Signal Level
Y (cd/m2)
Target Y
Gamma
0%
0.40
0.00
2.20
10%
2.02
1.53
2.08
20%
7.36
7.02
2.17
30%
17.35
17.13
2.19
40%
31.73
32.25
2.22
50%
52.06
52.69
2.22
60%
76.9
77.38
2.21
70%
108.99
108.89
2.20
80%
145.97
146.33
2.21
90%
190.37
189.88
2.18
100%
239.68
239.68
2.20

If it were possible to improve on this result, you would have to adjust each point until the Y value matched the target. This example is as good as it gets. But how would you make those tweaks with just presets available? Using multi-point gamma control. We haven’t seen a computer monitor with this feature, but we have used them on a few high-end TVs and projectors.

If you get results like our sample, then you’re ready to move on. If not, try the other presets to see if you can get closer to 2.2. Not every display returns a value of 2.2 just because the preset is labeled that way. You’ll have to do a full measurement run of each gamma option to find the best configuration.

We have our monitor set for maximum dynamic range and correct gamma. Now it’s time to adjust the grayscale.

8. Application: How To Adjust Color Temperature

Assuming you’ve selected the User or Custom color temp preset, we can now adjust the RGB controls. You will need the meter again for this one. In fact, you’ve likely already gathered the data you need during the gamma adjustment step. If you’re using CalMAN, you might have a graph like ours.

There are two data sets here, the RGB levels for each brightness step and the Delta E error. Delta E is a value that expresses the amount of error for a particular color; in this case, white. We believe three is the point where these errors are visible, so we aim to calibrate our review monitors to a lower value. In the example, you can see that 0 and 10 percent have a little too much blue and the rest of the steps have too much green. We like this graph because you can see exactly what’s happening at every measurement point.

How do we fix this? Every monitor we’ve reviewed has only one set of RGB sliders, so we have to figure out what brightness level is most affected by those sliders. We always begin with an 80-percent window, and as it turns out, that is always the right brightness level for our adjustments.

Display an 80-percent window, place your meter on it, and set your software for continuous readings. That way, you can adjust the sliders in real-time and observe their effect on the white point. Here are the indicators we like to use from CalMAN:

The upper portion is a bulls-eye that makes it very easy to see which way you need to manipulate the controls to get the dot into the square. Below that are RGB Levels, which are also very easy to use. The goal here is to get all three bars lined up at 100.

Now, there’s just one challenge to this.

You’ll notice that the RGB sliders start at their highest settings, meaning your only option is to lower them. We would prefer they start in the middle, but most computer monitors are set up this way. Not to worry, though. If you need raise Red, just lower Green and Blue in equal amounts instead. That’s what we did for this monitor, HP's E271i.

Once you’ve adjusted your 80-percent window to perfection, take another full measurement run. In most cases, you’ll find that all levels are greatly improved and will have errors of less than three Delta E. If this is not the case, you may need to adjust a different signal level. While this is rare, it does occasionally happen. Adjust the window pattern that gives you the best overall average Delta E.

Here’s a sample of the final results.

This tells us everything about grayscale and gamma in one screen. The max white and min black numbers are in the upper-left, along with average gamma, Delta E, and contrast ratio. The gamma chart is in the mid-left. The upper-right has the RGB levels, followed by Delta E for every brightness step. And at the bottom is all the raw data. If your results look like this, you have a really good monitor. This one is a Samsung S27B970D.

If you’ve made it this far, you’re pretty much done unless your monitor has a color management system, or you’d like to create an ICC profile. We’ll explain how that works on the next page.

9. Application: How To Adjust Color

We always measure color gamut and luminance in our monitor reviews, even though those parameters are not adjustable in most cases. To do this, you would need a color management system (CMS), and that is just not available on many displays. In fact, our only experience with this feature is from a few high-end projectors and TVs. If you have color gamut presets, they can help you achieve more accurate color. Choose the one that most closely matches your task (sRGB/Rec. 709 for most situations or Adobe RGB 1998 for photo editing). Then measure to see if it indeed meets the spec.

Let’s go through a brief anatomy lesson.

Here is the chart you’ve seen in all our monitor reviews. This one is from an AOC Q2963PM. At the top is the saturation sweep. The color saturation level is simply the distance from the white point on the CIE chart. You can see the targets moving out from white in a straight line towards each primary and secondary color. The farther a point is from center, the greater the saturation until you hit 100 percent at the edge of the gamut triangle. Rather than just measuring the 100-percent saturation level, we measure 20, 40, 60, and 80 percent too. Many monitors can generate a good-looking chart if only the 100-percent saturation is measured. This is a much more precise way of measuring color gamut.

The middle portion of the chart shows gamut luminance. This is the third dimension to color that is not shown on the CIE chart. We believe this has a greater impact on perceived color accuracy than the points on the gamut triangle. The shorter bars mean better performance. This monitor is superb.

The bottom chart is the Delta E information. Again, scoring below three means the error is not visible. Our chart shows the errors for each color, at each saturation level.

If you have one of the very rare displays with a color management system, we’ll give you a brief rundown of how to adjust it. Bear in mind that no two systems are quite the same, and some don’t work properly. Any use of a CMS should be done carefully, with instruments, and with the understanding that it may not actually improve your monitor.

A traditional CMS has three adjustments for each primary and secondary color: Hue, Saturation, and Lightness. Obviously, each one has a different effect. Let’s look at a blank CIE chart once again.

When you adjust the hue for green, for example, it moves that color point either towards cyan or towards yellow. If you adjust the hue of a secondary color, it moves closer to one of the primaries that make it up. For example, magenta moves between blue and red.

Adjusting saturation moves the color closer to, or further from, the gamut triangle. Just like our bulls-eye chart for adjusting grayscale, you can manipulate the hue and saturation controls to bring a color point into the target square.

Now let’s consider the lightness control.

In a CMS, lightness is just another term for luminance. To adjust this, you dial in the color points to the CIE chart first. Then, starting with red, adjust lightness until the bars pictured above are as close to zero as possible. It sounds simple, and it can be. The likelihood is that all three controls will interact and you’ll have to go back and forth until you get the best result. Adjusting a CMS can be very time-consuming. The basic procedure, however, involves adjusting hue and saturation for each color, and then going back to adjust lightness.

Creating An ICC Profile

Most monitors have chromaticity data embedded in their firmware, but this assumes it was measured correctly at the factory. And we know from experience no two monitors are identical. The best way to create an ICC profile is to measure the primaries yourself. We use QuickMonitorProfile, a free download, to do this for our reviews.

Once you’ve gathered the CIE coordinates for each primary color, you have everything you need to create the profile. All you need to do is select Custom in the Chromaticity coordinates drop-down, and then enter the x and y values for each color. Once you save it, you can call it up at any time in the future.

10. Calibrate Your Monitor For A Better Picture

Since we spread the calibration steps out among all the science, let’s sum up with a quick walk-through.

  1. Warm up your monitor for at least 30 minutes before taking any measurements. You want to be sure the backlight is completely stable.
  2. Choose a picture mode that provides a good starting point for levels, gamma, grayscale, and color, giving you all of the adjustments you need.
  3. Set levels with PLUGE and step patterns, taking care not to clip at the darkest and lightest extremes of the brightness scale. You may want to use your meter to determine a maximum light level. We always use 200 cd/m2.
  4. Set your gamma control to 2.2, if you have one. And set the color temp to user or custom to unlock the RGB sliders.
  5. Verify the gamma is close to or right on 2.2. If not, change the preset until it is.
  6. Using an 80-percent white window pattern, adjust the RGB sliders using your meter and software. We like bulls-eye and bar charts but you can use whatever method you prefer to set your white point to 6500K or D65.
  7. Measure your color gamut using window patterns. Record the CIE coordinates so you can create an ICC profile. Some software packages will do this for you. If you have a monitor with selectable color gamuts, choose the one that best suits your purpose. sRGB/Rec. 709 is perfect for games, movies, and general computing. Adobe RGB 1998 is the choice for photo editing as long as your camera records the same gamut.
  8. Verify your results with a final measurement run. Then, you’re done!

The main advantage to this method compared to a software look-up table is consistency. With LUTs, it can be very easy to chase one’s tail trying to dial in color, especially when you throw in the additional variable of ICC profiles. Every application does things a little differently, and a subtle change in color on your monitor might mean big changes later when you go to print. When your display is set up correctly using its own controls, there is no need for a LUT, and you can use a single ICC profile that is either on or off depending on the application. When we create graphics for reviews, for example, we don’t use a profile, since everything is created for the Web.

If you're trying to figure out which monitor to buy, creating your own benchmarks is easy if you just follow our steps. Then you know exactly what areas of performance are weak or strong. Just as we cover brightness, gamma, grayscale, and color, you too can test these parameters to see what display is right for you.

If this article has raised questions, be assured that there is more help on the way. Our next focus will be on a subset of the CalMAN package we use here at Tom’s called CalPC. SpectraCal has several bundles with value-priced meters and a client module that generates patterns for around $300. And if you already have a meter, you can buy their software for $149 online.

We hope you now have a better understanding of the principles behind monitor calibration and how the built-in controls can be used to make your display better. By following the same procedures we use in our reviews, anyone with the basic tools at their disposal can achieve the same results we do.