To the average person, the ColorChecker chat looks like nothing more then a cheap piece of plastic with a bunch of random colored squares on it. To a photographer however, the ColorChecker is often times one of the most invaluable pieces of equipment in their arsenal. With more uses then one of those two inch thick Swiss Army knives, once you unlock the powers of the squares, you will never go without one. Purchased for about $60 from Amazon (link to product page), it is quite possibly the best deal in town.

What is it? - The ColorChecker chart, formerly produced by GretagMacbeth, now produced by X-Rite, is a plastic based board, measuring roughly 8.5×11, with 24 differently colored squares on it, all equally sized and spaced. The colors are not printed, but instead applied to a special polymer, formulated to minimize color shift over time. Each chart comes with a small panphlet, identifying the exact color of each square in both RGB values, as well as LAB. Each color is made to represent a real life value, including skin tone, sky, grass, water, etc. The purpose of this chart is to be a reference for these colors, as well as all colors, to assist in the calibration of cameras, scanners, as well as help check the calibration of monitors and printers.

The Most Photographed Object - It is often said that the ColorChecker chart is the number one most photographed object of all time. Many photographers, for both in studio and location shooting, will place the ColorChecker chart in front of their subject and capture an image with it, before continuing on with the shoot. The reason for this is simple; if you are able to capture an image of this chart, and you know what values each color is supposed to be, then you are able to alter the image until those colors displayed on the chart in the image match what they are supposed to be. This not only adjusts the white balance, but any shifts that may exist in the rest of the gamut.

There are a few ways to perform this calibration. The hard way involves manually comparing the values of the samples in the picture with either the physical chart or the known values of the colors in the chat. The much faster accurate, and easier way would be to have a program do it for you. One such program is ACR Calibrator L. A free download (http://www.21stCenturyShoebox.com/tools/ACRcalibrator.html) as a plugin for Photoshop, it simply requires you to select the chart, and the program will do the rest, creating an ICC profile for you to use. ACR Calibrator L adds several functions onto the already accurate ACR Calibrator, namely the support for use of all 24 patches, vs the use of just three. As the name implies (ACR for Adobe Camera Raw) it is best to use RAW files with this application.

Just like white balance, a calibration performed for a picture, will only be valid for pictures with identical lighting conditions. Changes in lighting conditions will require a new calibration shot and profile. It is a good idea to get in the practice of throwing a shot of the chart in the mix every time conditions change.

Fire up the scanner - Just as with photographs, it is possible to use this chart for the calibration of scanners as well. The process is a little more difficult, as some scanners do not have the ability to capture and output the gamut necessary to reproduce the colors of the ColorChecker chart. It is recommended that you scan at the highest bit depth (16-bit is preferred) as well as export to a TIFF or other lossless file if possible. A scanner requires far less profiles then does a camera, as there are typically no variations in lighting conditions to take into account, so this is something that will most likely only be done once.

What else can it do? - One of the most useful things the ColorChecker chart can do aside from performing the calibration is checking the calibration of other devices. You can easily use the chart, by just holing up and comparing, the colors on the chart vs the colors either displayed by your monitor or outputted by a printer. It is a good practice to do this often, as all output devices can shift out of calibration over time and cause serious problems. It also serves as a good tool to determine if your calibration device is creating an accurate profile.