Monitors Part Two

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This reserved article originally appeared in CHROMiX ColorNews Issue 28 on August 2, 2007.

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Monitors, Revisited

by CHROMiX's Patrick Herold

Click here to go to Monitors, Part One

In the last installment of the CHROMiX ColorNews, we looked at the overall process of how color gets from your computer into your monitor; sort of a look at the hardware involved.

In "Monitors Part 2," we'll look through the software side of things - the blistering array of settings that are available to you in a typical monitor calibration program.

White Point

The idea behind White Point is to set the color of your screen's white to whatever white you think is "normal". The most common recommendation these days is 6500 Kelvin. You can choose a different color aim if you are trying to match your monitor to a particular output with a different white point. This is where a "custom" white point setting would come into play. Many people match their monitor color to the color temperature of their light booth or other lighting situation. 5000 Kelvin is technically the color temperature of normal daylight, which most profiling systems take as the standard - but that does not mean you should set your monitor to that. Most people see 5000 as too red. We discussed white point options in more detail in ColorNews issue #24 if you would like to read more about this:

Editor's note:
More detail on why our eyes see white differently at different brightness levels can be found here:

Native White

Native White point deserves some explanation. In the last article, we saw how LCD monitors are lit by a "backlight" of some kind. The natural color of this backlight (without any LCD filtering going on in front of it) is often very close to what you want to achieve, all by itself. Typical LCD native white points run anywhere between 5900 to 6700 or so.

With a CRT, the idea was to use the monitor's own adjustments to the red, green & blue guns to bring the white point close to what you're aiming at, and then the computer's video card would not have to make large adjustments to bring the color into line. Since users are used to this feature, LCD manufacturers have probably incorporated into the screen setup buttons some way to adjust the screen color. But this is really just artificially dimming the LCD array in front of the backlight, and it's questionable how uniform this sort of "correction" is.

An alternative method to try when calibrating an LCD monitor is to leave the "on-board" monitor color adjustments alone so that the monitor is left to produce its native white. Then let the calibration software do the adjusting in the video card to bring all the colors around to what you're aiming for.

However, it's a double-edged sword. If the video card has to yank the color around quite a bit, then banding is more likely.


2.2 is the almost universal standard now. If you are working in an ICC controlled application like Photoshop, then the gamma is irrelevant since it is corrected for in the monitor profile. A gamma setting of 2.2 might also help to reduce banding.


The Luminance setting you choose depends a lot on your viewing environment. General guidelines are 100 - 120 for a moderately lit room, 100 or less for a dim room. If you are trying to adjust your screen to match your printer output, then adjust your luminance so that a white screen will be as bright as a blank piece of paper.

If you plan to use your on-board monitor controls to adjust the RGB of an LCD display, you will want to adjust your luminance at the same time. These two effect each other. If your software does not have the colors and the luminance readout on the same page, then you'll want to skip back and forth a bit until you have the RGB the way you want, and the luminance the way you want.

Matrix vs. Lookup Tables

Your monitor profiling software will offer you a choice between making a matrix profile or a look-up table profile. A matrix profile consists of a simple mathematical formula that describes the shape of the gamut. This results in a very small file size, and these profiles can be smoother in transitions (less banding), but perhaps less accurate hue-wise.

Look-up table profiles (or LUTS) define color using a table or grid describing the behavior of precise points of color in the monitor. These create larger file sizes, and can accurately handle monitors that have sudden spikes of color (as many LCD's do).

In general terms, older CRT's and some of the upper end LCD screens can be profiled very successfully using matrix profiles, and you can turn to a matrix profile if you are willing to sacrifice a bit of color accuracy for a reduction in banding on your LCD monitor. Otherwise, it is generally recommended that you choose to make LUT profiles for the average, modern LCD.

8-bit vs. 16-bit profiles

The 16-bit option gives more precision in profiles and should be used whenever possible.

Version 2 vs. Version 4 profiles

Version 4 profiles conform to the most recent specifications of the ICC, and this option should be chosen in most cases. But if you are using a program that does not recognize Version 4 profiles, you have the option to make and use a Version 2 profile.

What is DDC?

If you have a DDC-capable monitor and a DDC-compatible video card, and a DDC feature in your calibration software, then you can have Direct Digital Communication between the three. DDC will automatically take care of adjusting the brightness, contrast and color controls that you would normally adjust on the front of your monitor. Not only does this make profiling easier and faster, but it can keep your profiling more consistent, and can produce finer adjustments that are available from within your monitor's on-screen controls.

What about these new LED-backlit displays?

I knew you were going to ask me about those. There is a new technology that uses Light-Emitting Diodes as backlights for LCD monitors (instead of fluorescent tubes). LED's show great promise, in that they are long-lasting, can use less power, and still get quite bright. Some LED LCD's use only "white" LED's for the backlighting. Those with separate red, green and blue LED's can be "tune-able" to a specific white point. When you have control over the actual color temperature of the light source itself, this makes for another way to avoid having to depend on the video card to make big changes in the color. That's the theory anyway. It's a little too soon for us to tell you to rush out and buy one. A lot is going to depend on how these LEDs are used in specific models.

Finally, here are a few interesting tidbits concerning LCD monitors that you should be aware of:

Thanks for reading,

-Patrick Herold CHROMiX

Click here to go to Monitors, Part One

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