A CMS has two major goals: achieving the correct colors and the proper amount of each color. In layman's terms, you want the three primaries and three secondaries to match the SMPTE standards on the CIE triangle. This standard is also referred to as Rec 709 which is the HD color space. Most TVs with a CMS allow you move the color points to make this happen. What Samsung allows which is a real plus on a consumer TV, is adjustment of the luminance of each primary. There is a standard for that as well but most CMS equipped TVs won't allow adjustment of the color luminance independently. Below is a CIE chart from a 650-series LCD.
It's not absolutely perfect but I've never been closer on any other TV. What the CIE chart doesn't show is the luminance of each color. That is the third axis that I can now address thanks to Samsung. By using a luminance calculator, I can input the actual measurements of each color at 75IRE and find out what the luminance should be. My initial measurements on this TV showed the luminance levels to be about 20% too high for green and blue while red was almost perfect. You can see what needs to be done: the balance must be restored! By using the Custom mode in the Color Space menu, I can adjust each color individually. Once I dropped the luminance of green and blue, I had each color within .5fl of the correct number.The net effect is a more realistic color representation. The "looking through a window" effect is heightened and the sense of depth and dimension in the image is greater. You see, low black levels aren't the only thing needed for a great image! Samsung has added a feature that makes their TVs truly capable of unprecedented image accuracy. Thanks to the ISF, the community of independent calibrators and probably influential internet forums like AVS, manufacturers are finally delivering displays that offer accurate image modes in addition to their retina-searing showroom ones. These latest Samsung panels can provide an image to rival any professional monitor. I have revisited the current-generation Samsung TVs I've calibrated to adjust the CMS and I now employ this technique on all Samsung flat panel calibrations.
Thanks for reading and enjoy the view!
Hi. Could you explain the differences between the color space settings Auto and Native?
ReplyDeleteThe Native color space is actually a slightly expanded (inaccurate) gamut. Auto will give the closest result to Rec 709 (HDTV). Even better is if you can calibrate the Custom color space. The color points are pretty good but the CMS allows you to dial in the luminances to near-perfection.
ReplyDeleteIt's interesting this. I've recently started to calibrate the screens around our house. All of them are 2006/2007 models of Samsung televisions. The main set in the living room is the LE46M87BDX which I bought on release. It's a future proof T.V. and has a lot of bits and bobs, I haven recently achieved near-perfect grey scale with it, and all deltaE readings are 3 and below from 10-100%. The only thing missing from it is an advanced CMS system like the one you have mentioned.
ReplyDeleteMy friend owns the LE40A565 which does have this new colour space setting and allows adjustment of all primary and secondary colours (I set up his T.V. and it was amazing). Alas I am left with nothing, poor yellows and inaccurate colours.
I have only started calibrating using a Spyder 3 and from reading posts online, is there nothing I can do for my T.V.? Auto is far too bland, and Wide is off the chart with aqua and green.
A Spyder 3 is a poor instrument for measuring color. It's really designed for grayscale calibration only. Don't be too concerned with the readings you're getting. They aren't all that close to reality. The Auto color space setting is the closest to Rec 709. If it seems bland to you, try clicking the color control up a notch or two.
ReplyDeleteWhat are the correct luminance values for the primaries under rec 709? Also, did you use movie or standard mode? Lastly, did you have dynamic contrast off or on low setting?
ReplyDeleteIf white luminance (Y) is 1 at 100% the values for the other colors are: Red .2126, Green .7152, Blue .0722, Yellow .9278, Cyan .7874, and Magenta .2848. To get actual values, multiply the measurements for each color by the appropriate factor.
ReplyDeleteI always calibrate the Movie mode on Samsung displays. This mode turns off all enhancements and dynamic features. Dynamic contrast should always be off as it has an adverse effect on gamma.
So I bought a Samsung PN58C550 that has color space (Auto/Native) and HDMI Black Level (Normal/Low). I have an Oppo BDP-93 Blu-ray player. Should I leave the Oppo and the TV on Auto color space? What about the black level setting, does Normal represent (16-235)?
ReplyDeleteYes, the Auto settings are the best for both your TV and player. Calibrating the Custom color space on your Samsung will require instruments to derive any benefit. The Auto setting is actually very accurate especially on the newer models such as yours.
ReplyDeleteThe Normal black level setting is the correct one and will pass below black and above white.
How do I test the gamma?
ReplyDeleteTo measure the gamma you would need at least a luminance meter but preferably a colorimeter or spectroradiometer. Measure the luminance of window patterns from at least 20 to 100 percent. Calibration software such as Calman will tell you the average gamma and the gamma level at each stimulus point.
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