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Profiling of Digital Cameras with the Gretag-Macbeth Digital Color Checker SG
One of the most important tasks for all photographers is to get color right - with film cameras, one can use the well known Gretag Macbeth Color Checker and then use a profiling suite to get the color right but what to do with digital cameras? The standard settings of most better (more expensive) digital cameras are pretty good but what to do if color is an issue or if the illumination is very non-standard? The probably most precise way to get color right is to use the s.c. Digital Color Checker SG. This is a multi-color/multi-tone color checker which is optimized for use with digital cameras - many of the colors are especially selected to check digital cameras. This color checker is quite expensive but if you are concerned
about color, it is a wise investment which pays back immediately as you get
colors right. Here you can see a flatbed scan of this device:
Digital Color Checker SG
As you can see, there are besides the usual gray tones, black and white (5E-5J and 6E-6J)and the standard colors, which can be found also in the standard- and mini color checker (the matrix is 2E-2J to 4E - 4J), several more tones - more skin tones of several types (7D-7J to 8D-8J) and several rather special colors like 2B-8B, 2C-8C or the large amount of greens at 9B-9L to point a few out. In total there are 140 colors including colors which require an expanded gamut - all suitable to test your digital camera to its limits. To use this checker for profiling, the Gretag Macbeth Eye-One Software Suite is necessary - at least the smallest version which is capable of profiling as one needs to connect the color profiling device to the PC to enable the digital camera checker part of the software. My current version is 3.3 and this version is containing the digital camera profiling suite as well - so I refer to this version during the entire review. The first step is to take a photo with your digital camera of this test chart - the illumination needs to be rather even and the light should be one which you like to get a profile for - so it does not make much sense to take a photo in candlelight and then decide to apply this profile for shooting in broad daylight - I guess this is rather obvious, right Once that photograph is taken, it needs to be uploaded to a folder on the computer - this photograph will be used for profiling. Open the program, connect your profiling device, mine is the Eye-One Pro device, and click on the symbol of the digital camera.
As you can see, there are two options for profiling a digital camera - the "Easy" and the "Advanced" mode - first the easy way as it is quick, intuitive and very easy to do. After that choice was selected, the next screen tells what to do:
This picture of the ColorCheckerSG should be taken such that the illumination of the chart is more or less even and it should represent the lighting conditions which are supposed to be profiled - it does not make sense to take the picture of the chart in broad daylight if the light which will be used for taking the important pictures is totally different - like candlelight. After the picture was taken, it needs to be uploaded from the camera (or from the file folder, if it was stored already on the computer) to the program
The picture needs now to be cropped - the magnifying glass below the picture of the color chart helps the alignment process - the crop frame corners should be placed over the corner marks outside the color chart area - they are made visible in the magnifying glass
Once this was done, the next screen shows the stored chart and the imported one - they should be (except for the colors) identical - which means that the program will be able to compute the profile correctly
The next step is then already the automatic calculation of the camera profile and after this was done, the last step will be to store the computed profile on the computer
That was all, the customized profile for the digital camera was done and stored. It can be used now in programs like Photoshop by assigning that profile to the pictures taken with the camera.
The "Advanced" mode is a bit more detailed but delivers even more precise profiles as there are some intermediate steps to refine the profile which are added to the entire process. After starting again with taking a picture of the color chart, after importing it and aligning the crop frame in the very same way to the four corners, the initial profile is computed as well. Then, in the Advanced mode, the next steps differ from the Easy mode as the following screen shows - it tells already what might be wrong with the uploaded picture of the chart - this does not mean that the profile cannot be calculated but it makes it clear that there is room for error or that the computed profile might not be absolutely perfect
As one can read here, the program complained that I have taken the picture of the color chart with not perfectly even illumination - OK, that is nothing uncommon and I just continued without re-taking the picture
The next step is to select the illumination which was used to take that picture - my illumination was close the standard illumination D65. I could also say, that D65 is the closest match in my case, but as one can read, there are more options for the illumination available
In the next step, a reference picture needs to uploaded - this is supposed to be a picture which will be used with the profile which will be computed. The preliminary profile is now automatically applied to this uploaded picture and like that, one can see if the profile is a good match or not. More fine adjustments of the profile will follow in the next steps
The next step allows to fine-tune the profile regarding contrast and brightness. The step size can be larger or smaller, depending on the number of selected mini-thumbnails per display (9 or 25) - lower left corned of the screen
The next steps allows the adjustment of the saturation - for highly saturated colors and for the pastel tones of the image - again either rather coarse or rather fine in step size
The final fine tuning screen enables the user to adjust the highlight-shadows relation, one can assign more details to either one or make either one darker. Same option regarding step size, small or large, as before. This fine tuning is not an absolute must, but if one wants a profile which is really customized and optimized for a certain setting, then it is a very attractive feature to have it.
As expected, the final step is to save the profile - here in this mode, the screen shows the fine tuning adjustments made to the raw initial profile. The entire profiling can be done in less than 5 minutes and is very easy to perform - digital cameras profiling as easy as possible with the ColorCheckerSG SG and the Gretag Macbeth software. Out of my experience, I can highly recommend to everyone who wants to have accurate color from digital cameras to get this chart and program and do the profiling, it is worth every single Dollar. After I have put this review online, several readers asked me what to do now with this profile, how to implement it into any workflow. Let me show one possibility by using the program Photoshop CS2: After having uploaded the digital image into Photoshop (in my case, I used a shot taken with a Kodak DCS 460 camera), click on the "Edit" menu and go to "Assign Profile"
The next step is to click on it and a window opens and one can select the right profile from a long list - these profiles have been imported by the Gretag Macbeth Eye-One software and need to be in the correct (Windows) folder (if you are using Windows of course) to be found by Photoshop
When the right camera profile is selected,
this profile is now assigned to this shot and like that, the previously computed
digital camera profile is in use as long as it is not overruled by the user
(selecting another profile..).
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