When to use an LUT Calibration
I was interested in testing how much added advantage one receives by running a 729-point color calibration on the Lumagen vs. the 125-point. It's an important question. The 125-point is more widely available and it takes only a few minutes to run--8 minutes using a D3 and 5 minutes using a K-10. By way of comparison it takes 44 minutes/28 minutes to run a full 729-point calibration. I ended up testing something else entirely.
I decided to run the test my my 9th generation Pioneer Kuro PDP 5020FD plasma because I knew from past tests that it had problems with color accuracy inside the color space. First I took some baseline readings.Standard Mode
As you can see, this is terrible performance. The only reason I tested it is that this is the default mode the display is in when delivered. You should almost always change the default Picture mode when you first get a new display.Movie Mode
Clearly, this is much better. It still needs calibration, but the simple act of changing the Picture mode made a huge improvement.Movie Mode, Standard Calibration
This is what really surprised me. Obviously, the grayscale is now excellent. However, although the color performance at the gamut boundary is now nearly perfect, the overall color performance is actually WORSE than it was before it was calibrated. How is this possible?
Clearly, what has happened is that correcting the color points on the gamut boundary had the effect of also wreaking havoc on the color inside the gamut.
This obviously called for a LUT calibration. I ran a two-pass 125-point correction using the Lumagen 2021. With the Klein K-10 this only took about 10 minutes. The results were excellent.
The improvements made by the 125-point LUT calibration were huge. Later this evening I will run a 729-point LUT calibration and see if the added time is justified by improved results. However, there is not a lot of residual error left, but I'll reserve judgment until I see the results.
There are few lessons to be learned from this.
1. The single most important step you can take to improve your image quality is select the correct Picture mode. If you don't do that, then nothing else much matters.
2. A standard 6-point CMS correction may not be doing any good. You simply cannot tell if a standard CMS color correction has had the intended result unless you look inside the color space as well as looking at the gamut boundary.
3. Whether a 6-point CMS correction is sufficient or not depends entirely on the display. On this Pioneer, it created more error than it removed. However, on other displays, it may very well be all you need. It just depends on how the color performance of the display has been engineered. For example, a Panasonic VT50 I worked on last summer
showed excellent results with just a standard calibration. The fact that this was a 2013 display and the Pioneer is a 2009 display may mean that manufacturers are just getting better at this.
The bottom line is that you should always check your color with the Advanced Color Management module and/or the ColorChecker module after a standard calibration. Depending on your display, you may be better off simply leaving the display's color in its default state. Although a grayscale/gamma correction is always a good idea, a CMS correction may not be. If you have a Lumagen you may need to run a 125/729-point LUT calibration.
BTW, I can't recommend the Lumagen 20xx processors enough. I don't know if it is the Darbee processing or simply due to some other enhancement to the processing engine, the 20xx improves image quality beyond what you would except from the sophisticated color correction. The image has a clarity and pop to it that I immediately noticed.Follow-up PostEdited by TomHuffman - 2/27/14 at 9:12pm