Adobe Photoshop CS5 for Photographers - Martin Evening [104]
Custom camera profile calibrations
While the Adobe Standard profiles are much improved, they have still been achieved from testing a limited number of cameras. You can, however, create custom standard camera profiles for individual camera bodies. Creating a custom camera calibration profile does require a little extra effort to set up, but it is worth doing if you want to fine-tune the color calibration for each individual camera you shoot with. This used to be done by adjusting the Camera Calibration panel sliders, but is now mainly done through the use of camera profiles. However, the sliders do have their uses still, as I'll explain shortly.
In the early days of Camera Raw I used to shoot an X-Rite ColorChecker chart and visually compared the shot results with a synthetic ColorChecker chart, and adjusted the Camera Calibration panel sliders to achieve a best match. It was all very complex! Fortunately there is now an easier way to calibrate your camera equipment. You will still need to capture an X-Rite ColorChecker chart ( Figure 3.62 ). These can easily be ordered on-line and will probably cost you around $100. You then need to photograph the chart with your camera in raw mode. It is important that the chart is evenly lit and exposed correctly. The best way to do this is to use two studio lights in a copy light setup, or failing that, use a diffuse light source. Apart from that it does not matter what other camera settings are used, although I would recommend you shoot at a low ISO rating.
Camera profiles and white balance
In the step-by-step example shown here I recommend creating a camera profile using a standard strobe flash lighting setup. This lets you calibrate the camera sensor for the studio lights you shoot with normally. The camera profile measurements can vary slightly for pictures that are shot using different white balance lighting setups. It is for this reason the DNG Profile editor allows you to measure and generate camera profiles in the same way as the Camera Raw team do. For example, If you shoot the ColorChecker chart once with a lighting setup at a measured white balance of 6500 K and again at a white balance of 3400 K, you can measure these two charts using the DNG Profile Editor to create a more accurate custom camera profile.
DNG Profile Editor
In the quest to produce improved camera profiles, a special utility program called DNG Profile Editor was used to help reevaluate the camera profiles supplied with Camera Raw and produce the revised camera profiles. You can get hold of a copy of this program by going to the labs.adobe.com website and doing a search for ‘DNG Profiles’. At the time of writing it is currently in version beta 2 and available as a free download. There are a number of things you can do with this utility, but its main strength is that it allows you to create custom calibration profiles for individual cameras. You see, while the default camera profiles can be quite accurate, there may still be a slight difference in color response between your particular camera and the one Adobe used to test with. For this reason you may like to run through the following steps to create a custom calibration for your camera sensor.
1.
As I mentioned in Figure 3.62 , you'll first need to photograph an X-Rite GretagMacbeth ColorChecker chart. I suggest you shoot this against a plain dark backdrop and make sure it is evenly lit from both sides, and for the utmost accuracy, is illuminated with the same strobe lights that you normally work with. It is also