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HCFR primary/second color calibration

post #1 of 9
Thread Starter 
Sorry for stupid question but which color patterns (75% or 100%) I should use with HCFR and EyeOne when I try calibrate primary/secondary colors?
post #2 of 9
Quote:
Originally Posted by Big Lebowski View Post

Sorry for stupid question but which color patterns (75% or 100%) I should use with HCFR and EyeOne when I try calibrate primary/secondary colors?

In an ideal world, i.e., a set with perfectly even behavior, it should make no difference. But in a less-than-perfect situation, one may be better than the other. The general advice is to use the 75% window patterns if you have them available. This avoids any unusual behavior that might appear when pushing the set to its extremes. As an intuitive argument, this matches better the typical level in scenes you will be watching, while still giving enough stimulus to be a reliable measure. You could use another criteria: at which level of the grayscale do you have lower deltaE values, 75% or 100%? Whichever grayscale level has the most even RGB balance could give you the best calibration of your secondary colors. Personally, I buy into the typical level of scenes reasoning, and use 75%.
post #3 of 9
Quote:
Originally Posted by Bill Mitchell View Post

In an ideal world, i.e., a set with perfectly even behavior, it should make no difference. But in a less-than-perfect situation, one may be better than the other. The general advice is to use the 75% window patterns if you have them available. This avoids any unusual behavior that might appear when pushing the set to its extremes. As an intuitive argument, this matches better the typical level in scenes you will be watching, while still giving enough stimulus to be a reliable measure. You could use another criteria: at which level of the grayscale do you have lower deltaE values, 75% or 100%? Whichever grayscale level has the most even RGB balance could give you the best calibration of your secondary colors. Personally, I buy into the typical level of scenes reasoning, and use 75%.

Now that you mention it, this seems to be an incredibly obvious and good idea. I often get my grayscale looking good at around 80%, but red, green or blue tend to be off at 100%. So when I'm tweaking the Color setting to get red Y to 21% of white Y I should use the 80% red and white windows (assuming 80% is the most accurate number on my grayscale)? And likewise when tweaking Tint?

Also, I assume that if I'm using AccuPel to come up with a custom red Y (not 21% because my CIE RGB is not standard), then I would use the exact same method? I would enter the grey, red, blue and green data for 80%?
post #4 of 9
Quote:
Originally Posted by HappyFunBoater View Post

Now that you mention it, this seems to be an incredibly obvious and good idea. I often get my grayscale looking good at around 80%, but red, green or blue tend to be off at 100%. So when I'm tweaking the Color setting to get red Y to 21% of white Y I should use the 80% red and white windows (assuming 80% is the most accurate number on my grayscale)? And likewise when tweaking Tint?

I've not seen any calibration disks that offer 80% stimulus colors; both the GetGray and AVSHD disks offer 75% stimulus color in windows, including white.

I've not used the technique for setting Color or Tint, since my Samsung has a CMS where I'm going to fine tune the Y of each color anyway. So the Color and Tint controls just set a starting point for the fine tuning, to put me in the ballpark. So for those I just use the 100% stimulus windows, and set the red for 21% of white, or the appropriate value if I'm targeting a gamma greater than 2.2.

Yes, I've observed the same thing, that the grayscale is more even in the 70%/75%/80% range, largely because we set the gains to achieve a balance there. So some of the unusual behavior I see in my set between 75% stimulus magenta and 100% comes from the red/blue balance changing at the top of the grayscale.

Quote:
Originally Posted by HappyFunBoater View Post

Also, I assume that if I'm using AccuPel to come up with a custom red Y (not 21% because my CIE RGB is not standard), then I would use the exact same method? I would enter the grey, red, blue and green data for 80%?

Yes, indeed, with Accupel you use the same technique. You measure the Y value of 100% saturated white in the 75% stimulus window, recompute the primary Y values and the secondary xyY coordinates from this, and then calibrate the other colors still using the 75% stimulus window. This is certainly calibrating for in an environment more typical of actual content. To the extent you get the RGB grayscale balance at 100% to be as good as at 80%, then you will see near perfect behavior of the 100% stimulus colors after having calibrated at 75%.
post #5 of 9
Quote:
Originally Posted by Bill Mitchell View Post

I've not seen any calibration disks that offer 80% stimulus colors; both the GetGray and AVSHD disks offer 75% stimulus color in windows, including white.

I've not used the technique for setting Color or Tint, since my Samsung has a CMS where I'm going to fine tune the Y of each color anyway. So the Color and Tint controls just set a starting point for the fine tuning, to put me in the ballpark. So for those I just use the 100% stimulus windows, and set the red for 21% of white, or the appropriate value if I'm targeting a gamma greater than 2.2.

Yes, I've observed the same thing, that the grayscale is more even in the 70%/75%/80% range, largely because we set the gains to achieve a balance there. So some of the unusual behavior I see in my set between 75% stimulus magenta and 100% comes from the red/blue balance changing at the top of the grayscale.



Yes, indeed, with Accupel you use the same technique. You measure the Y value of 100% saturated white in the 75% stimulus window, recompute the primary Y values and the secondary xyY coordinates from this, and then calibrate the other colors still using the 75% stimulus window. This is certainly calibrating for in an environment more typical of actual content. To the extent you get the RGB grayscale balance at 100% to be as good as at 80%, then you will see near perfect behavior of the 100% stimulus colors after having calibrated at 75%.

You're right. The ADV-HD disk has 0, 25, 50, 75 and 100%. I had previously only used 100% and had just assumed that it would have steps of 10% just like greyscale. Nonetheless, everything worked just fine. The greyscale at 75% was the closest to perfect, so I used that as the input to AccuPel to come up with new Y values for RGB, and new xyY values for CYM. I was suprised to see that the default Color and Tint just happened to be the right settings to dial-in the AccuPel values.

Thanks for your help.
post #6 of 9
Quote:
Originally Posted by HappyFunBoater View Post

You're right. The ADV-HD disk has 0, 25, 50, 75 and 100%. I had previously only used 100% and had just assumed that it would have steps of 10% just like greyscale. Nonetheless, everything worked just fine. The greyscale at 75% was the closest to perfect, so I used that as the input to AccuPel to come up with new Y values for RGB, and new xyY values for CYM. I was suprised to see that the default Color and Tint just happened to be the right settings to dial-in the AccuPel values.

Thanks for your help.

Be careful to avoid confusion. On the AVSHD disk (at least the AVCHD version I use), where you see 0%, 25%, 50%, 75%, 100%, those are saturation values, all at 100% luminance. In other words, they are intended to give you a line of points from white out to, say, red, including points 25%, 50%, 75% of the way. They will measure different xy values. These can be used in HCFR for its less used saturation-luminance and saturation-error graphs.

What I was talking about was 100% saturated red, measured at 75% luminance, just like a 75% point on the grayscale. As I recall, the AVSHD disk offers 75% colors, and 100% colors, in windows and full fields. For a particular color, comparing the two give the same xy coordinates, or roughly the same depending on grayscale and how the set works, but a different Y.

If you got the right results, I expect you were using the right patterns. I just worry, where you wrote 0%, 25%, 50%, 75%, 100%, you may have been looking at something else.
post #7 of 9
Quote:
Originally Posted by Bill Mitchell View Post

Be careful to avoid confusion. On the AVSHD disk (at least the AVCHD version I use), where you see 0%, 25%, 50%, 75%, 100%, those are saturation values, all at 100% luminance. In other words, they are intended to give you a line of points from white out to, say, red, including points 25%, 50%, 75% of the way. They will measure different xy values. These can be used in HCFR for its less used saturation-luminance and saturation-error graphs.

What I was talking about was 100% saturated red, measured at 75% luminance, just like a 75% point on the grayscale. As I recall, the AVSHD disk offers 75% colors, and 100% colors, in windows and full fields. For a particular color, comparing the two give the same xy coordinates, or roughly the same depending on grayscale and how the set works, but a different Y.

If you got the right results, I expect you were using the right patterns. I just worry, where you wrote 0%, 25%, 50%, 75%, 100%, you may have been looking at something else.

Ah. Thanks for the clarification. When you told me to use 75% color I knew that you meant luminance, just like on the grayscale. And I did use the 75% windows on the disk. (The xy values were as expected, so I know that I used the right patterns.)

But what I didn't realize was that the 0, 25,50, 75, 100 series of patterns were saturation, not luminance. Luckily I didn't use those patterns. I just threw those out to show that I knew what you were talking about. :-) And I did, but I completely failed in trying to prove it with those patterns. Thanks for setting me straight.

I'm always learning something on these forums. I love it.
post #8 of 9
I know this is an ancient thread, and probably an incredibly stupid question. But when I use the 75% color windows should I be basing things off of the Y value I get on a 75% white/gray pattern? Or the 100% white pattern?

I'll be doing my first 10 point gray scale, gamma, and primary color calibration with HCFR soon on my ST60.

I've only done 2 point gray scale calibrations before. I've never done primary color or gamma. Any tips not mentioned on the curtpalme guide would be appreciated.

I'm also wondering what gamma I should go for on this set. It seems like D-Nice was going for 2.5 with his settings, and I think I like the way the set looks better at 2.5 than 2.2. Can someone convince me why I might want to go for 2.2 or 2.4 instead?
post #9 of 9
Disregard what I said re: gamma... For some reason he says to set gamma to 2.4 or 2.6 in the Pro menu, but in his report it actually says 2.22 was his target.

I wonder why he says to set to 2.4 or 2.6 and that when I took readings my average gamma came out to like 2.5 with his settings, but his report says he was targeting 2.22?

Anyway, I'm still slightly confused re: the primary color calibration and if I should be basing my 21% of Y (for red) off of a 75% gray or 100% white pattern when using 75% color windows. I guess I should be able to tell by taking some readings and playing around though.

Edit: I missed this guide somehow: http://www.avsforum.com/t/852536/basic-guide-to-color-calibration-using-a-cms-updated-and-enhanced where it says "Display a red test pattern AT THE LEVEL OF STIMULUS AS THE WHITE TEST PATTERN, and then take another reading.", so nevermind.
Sorry for asking dumb questions. biggrin.gif

Edited by damag0r - 8/29/13 at 4:08pm
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