PART II - Monitor Profiling

When we left off in Part I , we had reached the point where we could define a color within a color space, but were thwarted in our attempt to have that color look the same to different viewers using different computer monitors (think of that TV store where all the TVs are tuned to the same channel but they all look slightly, or, in some cases, vastly different).

This is where monitor calibration and profiling comes to the rescue.

My apologies to Dilbert….I changed two words in the first frame.

Simply put, calibration and profiling is an attempt to standardize the appearance of computer monitors in order to avoid the “TV Store” phenomena and have a given color look the same on all properly calibrated and profiled monitors. Does it work? More or less yes. Perfection is hard to come by since different monitors have different color gamuts; meaning that some monitors can actually display more colors than others. If the monitor is unable to display a specific color it will have to somehow ‘squeeze it’ into the range of colors it can display. In addition to that, different quality monitors have different ranges of brightness and contrast that they can achieve, as well as different levels of accuracy and consistency when it comes to their displays. BUT….while calibration and profiling may not be perfect, it’s as good as we can get and it works reasonably well.

The bad news is that properly calibrating and profiling your monitor requires a device (colorimeter or spectrophotometer). Such devices are made by several companies, including Datacolor and X-Rite, but they can set you back anywhere from about $150-$1500. However, the lower price range devices work quite well and a very reasonable calibration device can be had for about $200. While there are some non-hardware based calibration methods they, unfortunately, do not work nearly as well as device based calibration. To get started with a color managed workflow, monitor calibration is your most important step and yields the ‘biggest bang for the buck’.

Profiling your monitor actually consists of two steps, a calibration step and a profiling step. Both steps are done by the same device which is hung over the top of the monitor, gently touching the screen, as shown below. An easy way to think about calibration is that it sets the baseline attributes of the monitor to a standard state. This includes the monitor’s color temperature, gamma, brightness and contrast. Once the baseline standard is achieved and the monitor has known attributes, then the colors that are displayed can be properly adjusted.

Does that seem a little confusing? Think of it like this….if you were to look at a color swatch of fabric in a dark room with no light what would you see? Right - you wouldn’t see a thing. You would have no idea what the color of the fabric is. We need light to reflect off the fabric in order to see the color (I realize this analogy is not totally accurate because monitors display color using transmitted light as opposed to reflected light…..but just go with it for now). However, the way the color looks will depend to some extent on how bright the lights in the room are and what the color temperature of the room lighting is. If we look at the swatch under incandescent lighting it will appear to be warmer in tone than if we look at it under ‘cooler’, whiter light, in which case the swatch will look more blueish. A dim light will make the color look duller while a brighter light will make it look more vibrant. So we need some type of standard lighting to look at the color swatch with. That is what monitor calibration is sort of like. It attempts to set all monitors to a standard brightness, a standard color temperature etc for viewing, so, to continue the analogy, all viewers will essentially be looking at the fabric color under similar baseline lighting conditions.

There is some argument (when isn’t there) as to what the best standard settings for use in photography are, particularly in the case of color temperature. For the most part there seem to be two camps, those that advocate setting your monitor’s color temperature to 5000K and those that advocate 6500K (I personally use 6500K). The best monitor brightness setting for matching your screen to your inkjet printer output is 80-100 cd/m2. At this setting your monitor will likely look quite a bit duller or dimmer than it did ‘out of the box’ (this, incidentally, is the most common reason that one’s prints might look too dark - the monitor is set at too high a brightness level). The gamma should be set to 2.2 (the gamma setting is somewhat akin to contrast and determines how light the lights are and how dark the darks are). But don’t worry about all this……the profiling device will do all the work of adjusting the settings for you, but you do have to tell it (in software - I once tried talking to it but it didn’t help :) what settings you want it to calibrate the monitor to……so just remember a color temperature of 6500K (or maybe 5000K if you belong to that camp), a brightness level of 80-100 cd/m2, and a gamma of 2.2.

Once the monitor is correctly calibrated it can then be profiled. During profiling, the device’s software displays a series of pre-defined color and gray-scale patches on screen, which are read by the hardware. The device measures these patches to see how they are being displayed by the monitor. The software knows what the colors should be displayed as (they are pre-defined) and how the monitor is actually displaying them (by what the device measures) and can then make a ‘correction table’ of sorts. This correction table is called an icc profile, and the software places the profile in a specific folder within the operating system. For Windows systems, the profile is located in the C:\Windows\System32\spool\drivers\color folder and for Mac OSX it is placed in either the Mac HD/Library/ColorSync/Profiles or the Mac HD/Users/<username>/Library/ColorSync/Profiles folders.

Now, when a color ‘comes into’ the monitor, like when you use Photoshop or Lightroom to view a photo (assuming that the photo has a color profile associated with it-more on this later), the icc profile basically says……OK, I know what this color is because it is defined by the color space and the RGB values and I know that at baseline I would display it in this specific way, but to display the color properly it needs to be tweaked. Let me look up in my table how I should tweak it to make it display correctly on this monitor……it then makes the tweak and has the monitor display it with the tweak applied. Does that make sense?

For completeness sake, I should mention that some more expensive monitors have a different hardware based method of profiling that may dispense with the software ‘look up’ correction profiles, but, in essence, they end up accomplishing the same thing and can be thought of in the same way.

I should also note that in order for all this to happen you have to tell your monitor that you don’t want it to use either the generic profile that came with the monitor software or the generic profile that the operating system assigns it. You need to tell it that you would rather use the profile that you generated with your profiling device. To do that you have to know what the device named the profile (it tells you and even lets you give it your own name if you would like) and you have to know how to give the monitor those directions. Here is a brief rundown of how to give those directions to the monitor for both Windows and Mac.

So there you have it…..the most important series of steps for instituting a color managed workflow.

In the third part of this series I will discuss printer profiling.

Comments or questions? Just click on comments link below and I will do my best to answer them.

Basic Color Management For Photographers - Part II

PART II - Monitor Profiling