Originally Posted by C_Terpstar
You have to admit I'm making SOME sense. I apologize if my terminology is not spot on but I do "get" what I'm trying to accomplish. I'm a DIY'er and do not want to give the impression that I'm a pro, so please have patience.
I read over Tom Huffman's Basic Guide to Color Calibration (http://www.avsforum.com/avs-vb/showthread.php?t=852536
) just to get on the right page. Correct me if I'm wrong that the following terms are synonymous: Color decoding, Color brightness, Color luminance, Chroma
. The exception is that color decoding also refers to the hue of the secondaries. Saturation
fall under Color Gamut
and are plotted on the CIE chart, correct? I just want to make sure I understand these properties and feel free to correct me at any point as I'm here to learn.
I agree you don't set tint by measuring luminance but from what I've read from Tom the color control effects color brightness. From the guide:
And brightness is...
So from that I gather, you DO set the color control by measuring luminance. Again, if I'm wrong I don't mind being corrected.
An example would be? I'm just trying to follow the only "textbooks" I have so if they fail to mention something important, don't blame me.
Doug, Thanks for your extensive post. I'll look into the Accupel calculator. I've also appreciated your patience in answering my PMs regularly and honestly. You've been a great resource.
That's what I thought as well but THX mode takes the brightness out of this display. I've read the same in other reviews. It actually came set at 100 contrast in THX mode. It's still very acceptable brightness but 35fL or the option of 40 would be nice to have. The grayscale seems to track well at this setting but I don't know about above-white color shift. There's not much you can do since lowering contrast just makes it too dark.
Haven't measured with 75% color windows yet but I'll let you know what I find. Thanks.
I've calibrated a number of 800u models in THX mode... I never had to set contrast that high (100) to get 30 fL. They would typically get to 40 fL or a little more when set to 100. BUT... every time I've seen an 800u in THX mode it just plain looks DULL. Doesn't matter if it IS putting out 40 fL, it STILL looks DULL. I typically measure lower gammas at low luminance steps and higher gammas at higher luminance steps (as you mentioned you did, if I remember right). I believe THAT causes the DULL look the images have. The low gamma at low luminance makes shadows too light and the high gamma at high luminance steps makes 80% and 90% darker than they should be. Those 2 things combined WILL give images a dull, flat look.
You are having problems with terminology... not all of those things you mentioned are the same thing. Chroma is just a way of indicating you are talking about COLOR instead of the luminance portion of the image (the B&W image or grayscale). A "chroma error" is just a color error of any kind. Color Decoder is a very specific "thing"... it converts color data to different formats. When you send YCbCr data to a (current) video display, the data is processed in that format, but just before the data is displayed, it is converted to RGB - the Color Decoder or Color Decoding Matrix does that conversion. If you send RGB to almost all current video displays, the RGB goes to a color decoder matrix FIRST where it is converted to YCbCr, is processed, then put through a DIFFERENT color decoding matrix to convert the YCbCr back to RGB for display. The decoder matrix is no better than whoever enters the numbers/formulas for each "cell" in the matrix. You'd think by now that everybody would simply use accurate values in the decoding matrix - the values/formulas that give accurate results are certainly well-known by now. But manufacturers often force their engineers to make the matrix intentionally inaccurate to get what they think is a beneficial side-effect that will sell more video displays. This is where red-push came from years ago... TVs were so blue that fleshtones looked vampirish. Some big brain got the idea that you could add some red back in as YPbPr (it was mostly an analog thing when the red-push was so prominent, though you might still see some in a digital display) was converted to RGB in the matrix. A GOOD decoding matrix won't change anything.
You have to watch terminology a bit also... for example... uvL color space is hue, saturation, and Luminance. This is one of the more perceptually accurate color spaces. Some CMS controls work this way (i.e. 1 slider for hue, 1 slider for saturation, 1 slider for luminance). So clearly, saturation and luminance are not the same thing.
uvL space can be thought of as a cylinder that's tapered on the ends. One end is black, the other end is white... that's the luminance axis. The saturation axis is the radius of the cylinder... one end is 100% saturation, the other end is 0% saturation. Hue travels around the cylinder (circular). Hue tells you what the color is, saturation tells you how intense the color is, luminance tells you how bright the color is.
In xyY space xy defines a color and how saturated it is at the same time (the color is more saturated when the xy coordinates move the color closer to the limits/edges of the CIE color space). Y determines how bright or dark the color is.
It can be tricky to perform the mental gymnastics needed to convert the actions of CMS controls into moves in xyY space that get you where you want to be... that's why I recommended the AccuPel calculator if your software doesn't provide this information. CMS controls are still evolving, though Lumagen and Samsung are both at the same place now... take "green" for example... one slider moves green closer to blue, the second slider moves green closer to red, and the third slider controls how bright the color is. For me, using xyY is easier to keep straight because you can think of what you are doing in 2 dimensions (using the 2 color sliders to get you where you want to be) then simply setting luminance to be accurate. You're doing a 3-D adjustment, but your brain isn't overwhelmed with 3-D space while you are doing it.