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Introduction
Congratulations on taking the first step in achieving predictable color between your display and printed output! If you're a little apprehensive about the process that follows, take heart... it's a learning curve that's worth the effort if you're serious about photography.

As you read through this article, keep in mind that the subject of color is quite complex. We take for granted what is truly a miracle of physiological engineering; our ability to see. Mimicking human vision with electronic devices like the display you're reading from, is no small feat. It is however, a series of compromises between the way humans and machines 'see' color.

The information I am presenting here barely scratches the surface on the subject of color, but should be sufficient to allow for a successful calibration on your display, and prepare you for learning and understanding additional information about color as you move along the learning process. And too, it will help in future discussions with us regarding color issues.

Calibrating a display is the first step in achieving predictable print output from your digital files, but there is more to calibration and color management than meets the eye. In order to get the best result, and take full advantage of it, you'll need a basic understanding of color theory. This article provides that basic knowledge.

You may jump directly to the Calibration Setup Summary if desired. The summary provides basic steps without detail or explanation. Jumping to the summary is not encouraged unless you are already familiar with the concepts discussed in this article. But hey, some of us like living on the edge... so jump if you're inclined.

Overview: Calibration and Characterization
Although routinely referred to as simply 'calibration', the procedure for calibrating a display is actually composed of two parts, although they appear as one seamless operation. An understanding of the two parts is necessary if the results are to be fully understood.

The two parts are Calibration and Characterization. Calibration is the part of the process that brings the display into a 'known' state. During calibration, you are entering certain preferences and actively adjusting controls on the display for brightness, contrast, color temperature, etc. in order to come as close as possible to the desired state.

Once calibration is finished, characterization begins. The EyeOne device 'reads' a series of color patches from the face of the freshly calibrated display, comparing the values it 'sees' against what they actually should be. This results in a ICC profile describing the differences.

The ICC profile is called up by ICC-aware applications, such as Photoshop, in order to display color properly. This is done by compensating for the remaining differences between the calibrated display and what is known to be accurate.

It is important to note that non ICC aware programs, including the Windows operating system and images displayed within web browsers, do not call upon the profile. Because of this, colors displayed in non ICC aware programs are not presented as accurately as those that do.

Non ICC aware applications present color according to the underlying calibration of the display, so while the profile is not used to fine-tune presentation of color, images do benefit from the initial calibration of the display.

Any changes made to the display after calibration and characterization, such as adjusting brightness or contrast, effectively voids both calibration and the profile that is created during characterization. Once a display is profiled, do not change any of its settings unless you are prepared to repeat the entire process of calibration and characterization.

Display Calibration
It is common for first time users to run through the process a couple of times while becoming familiar with the procedure.

The input you provide during calibration affects the end result. Some input is based on preferences where there is no single right or wrong answer. White Balance (color temperature) and Luminance (brightness) are two of them - another reason why you may need to calibrate more than once while experimenting with these subjective/preferential settings.

The previous paragraph hints at something which, the sooner learned, the less frustration later on: there is no magic, perfect, correct setting that suits everyone, all the time. This is because of a second lesson that can be difficult to accept: machines don't 'see' color the way humans do, and, human vision is easily fooled. Despite the old adage, 'seeing' is not always believing.

Successful color management is achieved by using the tools we have, both electronic and visual, understanding their weaknesses and compensating with knowledge. The brain has to kick in where our tools -including our own eyesight- fall short. We'll explain some of these things as we walk through the calibration process.

The following information will give you a starting point, providing explanations behind some of the choices you'll need to make. This is not meant to be an exhaustive step-by-step, but an overview of sufficient depth to get you off on the right foot.

After calibration, there will be visual differences that go beyond calibration. We'll highlight some key factors that will help you to understand 'why you see, what you see' and how to properly compare printed output against the display. 

Note: Basic computer skills are required, which is beyond the scope of this article. If you require instruction beyond what is provided here, consult with a knowledgeable friend or schedule a 1on1 tutoring session.

Lets Calibrate!

First things First: Disable Adobe Gamma
If Adobe Photoshop is installed on your PC, there is a good chance that Adobe Gamma is running in the background: It needs to be prevented from loading when starting your computer. Locate Adobe Gamma Loader in the Start Menu and delete it. If unsure how to do this, click Here for instructions.

Install Calibration Software
Install the calibration software before plugging the device into a USB port. If multiple installation disks accompany the device, install the one with the latest/highest version number. Note that the CD will not automatically run... you need to locate the installation file on the CD and run it manually.

After installation and following a reboot of the computer, plug the device into a USB port. Your computer should recognize the EyeOne as a new Plug and Play device and install the appropriate drivers for it. If it doesn't, unplug the device, reboot the computer and try again. Start the software application (Gretag EyeOne) and follow the on-screen instructions.

Easy or Advanced setup
We recommend using Advanced Setup because it provides the ability to control certain preferences that are not available in Easy setup. Using Advanced setup requires a basic understanding of Luminance, Gamma, and Color Temperature, which are explained in this article.

Your display may not have some of the adjustment controls used during the Advanced Setup calibration process. Apple Cinema Displays, for instance, lack a contrast control. You may or may not have individual controls for adjusting Red, Green, Blue. In cases where the display lacks a particular control, simply proceed to the next step. 

There is nothing inherently wrong with using Easy setup. Easy setup will calibrate your display using the most common settings for Luminance, Gamma, and Color Temperature. These common settings may work for you. If they don't, Advanced setup gives you the tools you need to tailor the calibration to your specific needs.

If you choose Easy setup, the calibration process is largely automatic. Simply follow the on-screen prompts.

Advanced Setup Steps
Advanced setup walks you through the following nine steps. The program offers up detailed instructions for each step, so they are not covered in detail here. Luminance and White Balance, however, deserve a more thorough explanation in order to set them properly for your situation. These topics are covered at length in the paragraphs that follow.

1. Select monitor (display) type: LCD, CRT, Laptop

2. Settings: Enter preferred White Point, Gamma, Luminance.

3. Calibrate Device: Place on black surface to calibrate. Wait until it says it's finished.

4. Position device on display.

5. Calibrate Contrast: If you don't have a contrast control on your display, skip this step.

6. Calibrate R-G-b: If you don't have a color controls on your display, skip this step.

7. Luminance: Adjust brightness according to the on-screen instructions.

8. Measure: This takes several minutes as patches are displayed and read.

9. Save Profile: At the end of the process you'll be presented with information detailing the conditions of the display such as luminance, color temperature, and gamma. You'll be asked to save the profile and rename if desired. I generally include the Date, Color Temp, and Luminance in the profile name such as: 010108_5600K_60.5.icm. Do not change the file '.icm' extension.

Luminance
Luminance is set using the brightness control on your display. Most LCD displays are far too bright for photographic work. While the software recommends a LCD luminance setting around 140, we find this too bright. We calibrate our Cinema Displays to a luminance level between 60 and 80. There is more to consider about luminance, which we'll discuss later. 

If you're using a CRT display, extreme brightness is rarely an issue. Start with the recommended luminance level of 100 for a CRT display and recalibrate at a different level if needed.

White Balance
White balance is an area that will highlight one of the key differences between machine and human 'vision'. These differences need to be understood in order to perform a successful calibration and to properly interpret the final results.

When a white object -like a sheet of paper- is illuminated, its color is 'tinted' according to the color temperature of the light source. The color temperature of light from any source (the sun, a light bulb, a fluorescent tube) is measured on the Kelvin scale, expressed in degrees/Kelvin. The higher the Kelvin value, the 'cooler' (more blue) the light, the lower the value, the 'warmer' (more yellow/red).

We're all familiar with the different appearance of light from a typical household light bulb and a cool white fluorescent tube. Each has a different color temperature, impacting the appearance of objects they illuminate. White objects cannot be 'whiter' than the light illuminating them, so the warmer the light, the warmer white objects appear and visa versa.

Human vision automatically compensates for a wide range of illumination levels and color temperatures: within that range we interpret white as 'pure white' regardless of the brightness and color temperature (or tint) of the light source. This is a biological phenomenon that fools us into *not* seeing something that is actually there. In other words, we compensate for the tint, 'seeing' a white object as pure white under many different lighting situations.

If you have ever worn yellow or magenta sunglasses -particularly in snow where there's an abundance of pure white- you've experienced first hand the biological effect of color compensation. Remove yellow glasses and everything appears blue (the opposite of yellow). Take off a pair of magenta glasses and it's a green world - but....

...within a matter of seconds the tint disappears as we automatically adjust white balance in response to the removal of the artificial tint. Put the glasses back on and the same thing happens in reverse.... within a few seconds the snow becomes white, even though the light hitting your eyes is in fact yellow or magenta. 

Unlike us, cameras (digital or film) are not fooled. They see and record exactly what the lighting presents. If it's warm lighting, the picture leans toward red/yellow. If it's cool lighting, it leans blue/green. This is why digital cameras are enabled with white balance controls, so the tint of various light sources can be neutralized. This results in a photograph that more closely represents what a human observer would have seen when the picture was taken... as opposed to the tint the camera saw.

In setting white balance on a display, the accepted range of temperatures within the color industry ranges from 5000 Kelvin (5000K) to 6500K. 5000K is considered 'warm daylight', 6500K 'cool daylight', and 5600K 'neutral daylight'.

It's reasonable to ask why one wouldn't automatically use 5600K (neutral daylight) rather than a warmer or cooler setting. The answer is that it boils down to personal preference. Some prefer a warmer display while others prefer a cooler one. Remember, our eyes automatically compensate for tints. Given a few seconds to adjust, your eyes will neutralize the tint.

The general recommendation when calibrating a LCD display is to use its 'native' white balance (typically around 6500K). You'll have an opportunity to make that selection during calibration, so start there. If, after calibration, the display is too cool for your tastes, recalibrate at a lower setting. After much experimenting, my personal preference is 5600K. It is simply coincidental that my preference happens to be neutral daylight. Your preference may be different, and that's ok.

Gamma
Gamma refers to a correction made to the mid-tone section of contrast in order for images to be  displayed in accordance with human vision. If the full range of contrast, from solid black to solid white is represented by a straight line, human vision requires a slight 'bump' in the midtone area, or center of the line, in order for an image to appear correct to our eyes. In effect, this lightens the midtone area and places slightly more detail in the lighter areas of an image, and less in the dark areas... similar to the way we 'see' the real world. The gamma value for most users: 2.2.

Following Calibration
Following calibration, it's likely you'll want to compare the result against some printed output and rejoice at how close they match! But there's more to it than simply holding a print up to the display. We have to employ what we know about color temperature, and our own vision, in order to accurately analyze the results.

The color temperature and intensity of the lighting used to illuminate the print is not likely to be the same as the display. Calibration of the display is only part of the equation - one of three basic variables that need to be pinned down. Room lighting is another, with light intensity (brightness) more important than color temperature.

Professional color labs and commercial printers use specially designed viewing booths to illuminate and analyze the color of printed images. A viewing booth provides illumination at a specific intensity and color temperature. The intensity of the light is matched to that of the display (or visa versa). This provides a 'density' (or brightness) match between the display and the print.

Color temperature does not necessarily need to match the display, but should fall within the range  of 5000K to 6500K. On the surface it would seem to make sense for color temperature to match between the two, which works, but isn't necessary. Some people prefer a match while others set color temperature independently - one temp for the display, another for the booth. It is common for a display to be set slightly warmer than the booth. It boils down to personal preference and what works for you. Here's why....

The reason that matching color temperature isn't a necessity is simple when you think about the way our eyes work. They adjust to various color temperatures, automatically forcing white to be white within the context of the ambient lighting (remember the sun glasses). When comparing prints to a display, it's not done side-by-side as you might think. It's done at right angles so that the display and print are not viewed at the same time (see photo below). Facing the display, the print is positioned off the right or left shoulder. This allows each to be viewed within the context of their individual lighting environments.

Photo: Proper right-angle viewing setup between display and print.

As you switch back and forth between viewing the display and the print, you are allowing your eyes to adjust to the difference in color temperature between them. This is how we take advantage of our visual biology and why minor differences in color temperature are less important than variances in lighting intensity, to which we do not so readily adjust.

Once your display is calibrated and you are satisfied with the appearance in terms of color temperature and brightness, it's time to compare against a print using the right-angle method just discussed. The print needs to be one that has been produced with color calibrated equipment like we use at DigiGraphics; a comparison can't be made between a calibrated monitor and uncalibrated output... they are two different types of fruit.

The first thing to determine is how closely the display matches the print in terms of brightness. If the display is obviously brighter or darker than the print there are two possible causes and solutions. Either the room lighting is too dark, or the display is too bright. If the display is set to a luminance above 80 or so, you can recalibrate the display at a lower setting. If the display is already set to a luminance of 60 or below, you'll need to incorporate brighter lighting in the room. This is most easily done by utilizing a color-correct fluorescent fixture placed above the viewing area... a poor man's viewing booth of sorts.

Once brightness is fairly consistent between the display and print, it's time to take a look at color. To begin with, look to see if there is an obvious difference in color-cast. A cast is a pronounced shift in one direction or another. Since the color temperature of the display and room lighting is likely to be different, the most likely difference is a blue or yellow cast.

If the print is warmer than the display (more yellow), that indicates that the room lighting has a lower color temperature. Conversely, if the print is cooler (bluer), the room lighting as a higher temperature than the display. Either way, you have a choice to make:

You can recalibrate at a higher or lower white point, which will warm or cool the display in relation to the print, you can change the room lighting using bulbs that are higher or lower in color temperature, or you can leave it as is and do nothing.

Before you do anything it's important to employ what we know about color temperature and the way our eye adjust to color casts resulting from it. If you have placed the print and display in different fields of view, and allowed your eyes one or two seconds to adjust when switching between the two, it should be difficult to detect differences in color temperature between them.

If it's easy to detect differences and they are unacceptable to you, you'll need to recalibrate at a different color temperature or, change the color temperature of the room or booth lighting, or both. There is nothing wrong with spending the time necessary to calibrate the display and room lighting so that it suits your personal tastes. My recommendation however, is to spend a little time with your newly calibrated display, comparing several files and prints over the course of a week or more before deciding to take additional steps to control color temperature. With experience, your eyes and mind may gradually ignore difference caused by color temperature which at first seem unacceptable.

If, on the other hand, you feel you are seeing differences that are not caused by color temperature (or brightness) alone, the solutions will be more difficult to nail down. First, run another calibration to be certain that it is performed properly and all of the correct choices are made. Second, run a few test prints through the lab being certain that the files are prepared in accordance with our instructions for Print-Ready files. Lastly, try another display... not all displays are capable of rendering photographic quality, even when properly calibrated. There is a difference between the quality of low-end desktop displays and high end graphics displays. If, in the end, your display doesn't deliver the level of quality you need for your work, the investment in a high quality graphics display may be necessary. Typical cost ranges from about $600 to $2500 depending on the size and make/model of the display.

Some Manufacturers: LaCie, EIZO, Apple (Cinema Display)

Other Resources
Additional information about display calibration:
How To calibrate a display
Is your monitor trustworthy?
http://www.pnwcmug.com/images/Monitor_Calib_Slideshow_22707.pdf
http://www.drycreekphoto.com/
http://www.thedigitaldog.com

Calibration Setup Summary