Calibration Corrections for the 5D Mark lll
In my recent article comparing the color response of the Canon 5D Mark ll to the 5D Mark lll, I showed the calibration adjustments from Datacolor’s SpyderCheckr for both cameras. Today I am focussing on the Mark lll, and what calibration does to improve its color response, so I will limit myself to the Mark lll correction chart only.
While there are several colors where the combination of hue and saturation adjustments are fairly significant, I will limit my examples to the primary color channels with the largest Hue shift (Green, with Hue -16, and Saturation -4) and the largest Saturation Shift (Red, with Hue +6, and Saturation -15). The first question is: are these adjustments visible in real world images? And the second is: do they actually improve the results in images where they are visible? I selected images from my first test shoot with the 5D Mark lll that showed these adjustments clearly, and which can be used to judge the value of these calibration adjustments.
Limitations of Web Color
The images you will see below were color accurate on a calibrated display. On an uncalibrated screen, or with a non-color managed browser, the results may not be as accurate. However they should still show the degree of difference, even if the colors are not exactly as they would be under color management. So try to visualize what the text describes for color and saturation, and use the images to compare the degree of change, if the actual changes described are not reflected on your screen.
First the Reds
To judge the effect of red adjustments, I selected am image with saturated red flowers, and cropped a section at 100 percent. The red flower petal in the center of the image moves forward from the point of focus, and becomes less focussed in the lower regions. The reds are extremely saturated, and the trained eye sees a color that will be problematic to print as well as having the bleary quality that over saturated colors often exhibit.
Next we’ll examine a similar closeup from the same image after the SpyderCheckr calibration has been applied to the image. Here the colors look more believable, and show a good deal more color detail, that was lost the the bleariness of the uncalibrated version. The Hue Shift, while far smaller then at the Saturation reduction, also improves the realism of the image, accurately reflecting the transition from magentas to a more orangey red in this type of flower. Its often surprising to see that color correction does not just improve the colors; it improves the color detail, which results in a more detailed image; something we tend to associate with focus and lens quality, when it can actually be an artifact of incorrect color.
Now the Greens
Next we’ll move on to the greens, which are a subtler situation, since it is the Hue, not the Saturation, that has the largest adjustment. Here the issue is less one of lost detail, than one of lost color richness. Leaf greens must contain an appropriate yellow component to read correctly to the eye; an emerald green leaf looks as false as the Emerald City, painted onto the Wizard of Oz backdrop.
Now we’ll compare this with the calibrated green, which has a 16 point Hue shift towards Yellow, and a 4 point Saturation reduction. Here the greens read as much more realistic, with the necessary yellow component, and the slight reduction in saturation to produce photo-realistic foliage. This will be a much more printable green, and much more satisfying in print, as well as the improvement shown on screen.
And the Rest
Other calibration corrections for the 5D Mark lll follow a similar pattern, but the effect is reduced for those channels requiring less adjustment. Overall, native color on the 5D Mark lll is very good, but calibrated results are truly excellent.
The color corrections shown above are aimed at accurate color portrayal. They are from the Colorimetric option in SpyderCheckr. Personal preference may lean towards emerald green leaves and over saturated flowers; thats fine as artistic intent, but it should occur by intentional adjustment, not by incorrect original coloration.
A Note to Nikon Shooters
Vincent Versace recently requested that I do a color comparison of the latest Canon and Nikon models. As a Nikon shooter, he as always felt that the Canon results were more saturated; perhaps too saturated. The calibration corrections above do tend to lean towards desaturation of the RAW file’s color; in fact there is not a single channel where calibration increases the saturation. I plan to analyze the color of the new Nikon D4 against its predecessor, the D3, and similarly the D800 against the D700. Once I have completed those results, I will be in a position to compare the 5D’s color saturation, and other color characteristics, to those of the D4 and D800. Perhaps the results will reinforce Vincent’s personal impressions. It will be interesting to find out.
A Note on Camera Color
What cabbage leave does camera color come out from under? It has two parents: the camera manufacturer, who is responsible for the hardware, and for the firmware that produces the proprietary file, and the RAW converter developer, who uses their own form of camera profiles to convert that proprietary camera format to a RAW file on screen. At one time, both these were the same parent; and we felt obliged to use the manufacturer’s RAW converter when testing the camera. But today the majority of RAW files, at least those from DSLR and subDSLR cameras, are processed in third party software. And by far the most common of those third party products is the Adobe engine used in Lightroom, ACR, and therefore Photoshop. So when I talk about camera color, I’m speaking of the camera color we are going to get in the real world, where we process our images in Lightroom or ACR. Using another third party RAW converter, or a camera manufacturer’s conversion utility, may produce different results. But given the success I have been having with the Adobe engine and a SpyderCheckr HSL correction set, I am quite comfortable with the color from this workflow, and don’t see any significant reason to be looking at less common or more complex workflows in order to achieve the results I need; especially with Lightroom 4’s much improved capabilities.