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Is it best to calibrate at 75%

post #1 of 33
Thread Starter 
For the guys with a lot of calibration experience, do you get your best results calibrating at 75% or 100%?
Would it best to calibrate a 65VT30 at 75% with v2.1 firmware?
Thanks!
post #2 of 33
Quote:
Originally Posted by EmilG View Post

... best results calibrating at 75% or 100%?
Would it best to calibrate a 65VT30 at 75%

I am no expert, but if it is a plasma TV, I think the lower color level (75%) may be the best choice for calibration independent of firmware. I believe it would be closer to more of the program material veiwed and therefore give more accurate color results. It also minimizes the effect of any average light level effects that plasma TVs have. I believe the term is ABL (Auto Brightness Limiter or Brightness Fluctuation).

I hope the experts agree with these statments?
post #3 of 33
Quote:
Originally Posted by EmilG View Post

For the guys with a lot of calibration experience, do you get your best results calibrating at 75% or 100%?
Thanks!

I would think if you calibrated at 75%, then it's important to check that colors aren't clipping at 100%.

bruce
post #4 of 33
There needs to be a bit of clarification I think.
I have seen people talk about calibrating at 75% saturation vs 100% Saturation, which is different from 75% stimulus at 100% Saturation and 100% Stimulus at 100% Saturation.
Spectracal CalMan expects 75% Stimulus at 100% saturation and according to post in their forum by their people that is the best way to do it..
Hope that helps..
post #5 of 33
Quote:


I believe it would be closer to more of the program material veiwed and therefore give more accurate color results.

Makes sense. I also think that if the 100% patterns on any color tend to push the Y capabilities of that color to the limit, so that it's difficult to determine where the adjustment should be, perhaps it would be easier to dial in the Y with a 75% pattern, then check with a 100% pattern to be sure the color doesn't clip.

bruce
post #6 of 33
Thread Starter 
Quote:
Originally Posted by airscapes View Post

There needs to be a bit of clarification I think.
I have seen people talk about calibrating at 75% saturation vs 100% Saturation, which is different from 75% stimulus at 100% Saturation and 100% Stimulus at 100% Saturation.
Spectracal CalMan expects 75% Stimulus at 100% saturation and according to post in their forum by their people that is the best way to do it..
Hope that helps..

Boy I'm a definite noob here but having a 75% strength signal map to a 100% saturated output just seems inaccurate. What will you see if you get a 100% strength signal? Seems to me the color would be very inaccurate.

I was thinking having a 75% strength signal map to a 75% saturation point on the gamut.
If the 100% point is now a bit off it's less noticable than having a 75% point off.
post #7 of 33
Quote:
Originally Posted by EmilG View Post

Boy I'm a definite noob here but having a 75% strength signal map to a 100% saturated output just seems inaccurate. What will you see if you get a 100% strength signal? Seems to me the color would be very inaccurate.

I was thinking having a 75% strength signal map to a 75% saturation point on the gamut.
If the 100% point is now a bit off it's less noticable than having a 75% point off.

calibrating to 75%stimulus does make sense as long you use 75% stimulus of white as your reference,

depending on what software you use would i suggest you calibrate to 100%stimiulus & 100% saturation.

then measure with 25% increments both the amplitude and saturation, if deltaE for all measurements is below 3 then job done if not its worth having a look to calibrate to either 75% saturation or stimulus (depending on where you are having your problem.
post #8 of 33
Quote:
Originally Posted by EmilG View Post

Boy I'm a definite noob here but having a 75% strength signal map to a 100% saturated output just seems inaccurate. What will you see if you get a 100% strength signal? Seems to me the color would be very inaccurate.

I was thinking having a 75% strength signal map to a 75% saturation point on the gamut.
If the 100% point is now a bit off it's less noticable than having a 75% point off.

Saturation is a measure away from white, sort of like a radius of a cylinder.
Luminance or stimulus is a measure of intensity, sort of like the height of the cylinder

Yes hue would be the angle on the cylinder. Maybe these graphs will help.

75% Luminance:


100% Luminannce:


Especially for the lab version I'd recommend opening each up in a separate tab and then you can flip back and forth to see the differences.
LL
LL
post #9 of 33
Thread Starter 
I did calibrate to 100% then backed down the color three notches, I have a VT30 with v2.1, I'm extremely happy with the result!

For calibrating at 75% I came up with a gamut chart with 75% values as a reference (I edited the values to do this in HCFR). I could then place my points but I haven't done it yet because of my satisfaction at 100%.

Thanks guys!
post #10 of 33
I have an LCD TV that is unable to give me full saturation of blue so 100% saturation patterns would seem to be not best for me.
If I use 75% saturation (at 100% stimulus) patterns I am able to get almost exact technical results for all colors.

It would be easy to assume I should use the 75% saturation patterns but unless I measure the effect of each calibration on the range of saturation values (say 25%, 50%, 75% and 100%) I cannot assume the result.

So that is what is needed then calculate the average dE at the 4 saturation percentage points when calibrations done using 75% and 100% saturation patterns.

The one that gives the lowest dE over the range is the one I should choose.
Probably 75% but not certainly.
post #11 of 33
I calibrated using the 75% saturation today.

Afterwords I measured at 75% stimulus just to collect the data.

I'm trilled with how it turned out.

I think I could even do better but I love the current PQ.

-Brian
post #12 of 33
FWIW, the Iscan Duo's internal pattern generator uses 100% saturation 75% amplitude patterns. This is the same pattern ChromaPure uses for its AutoCal procedure. This leads me to believe a 100% saturation 75% amplitude is the way to go - at least as a starting point.
post #13 of 33
The only reason to calibrate using 75% Saturation patterns is if your display has a faulty CMS.

What you should do is calibrate using 100% Saturation patterns. Then, do a full run of Saturations and Primaries at 25%, 50%, 75% and 100% Saturation, and check to see where they lie on the gamut. If you find that the points at 75% and below do not line up properly, odds are that your display's CMS has problems. You should then do a new calibration using 75% Saturations instead. 100% Saturations may be off, but it is much more important to have 75% and below be accurate (even if 100% is off) than it is to have 100% be accurate and have 75% and below be off.

Epson projectors have notorious CMS problems. If you use the Epson CMS, you have to use 75% Saturations when calibrating. Otherwise, you'll end up with 75% and below undersaturated.
post #14 of 33
Quote:
Originally Posted by "Kilgore View Post

Epson projectors have notorious CMS problems. If you use the Epson CMS, you have to use 75% Saturations when calibrating. Otherwise, you'll end up with 75% and below undersaturated.

Same for Panasonic AE4000 here. Calibrate using 75% saturation method gives a very good result.
post #15 of 33
Very easy to generalise but as Tom H. says, it depends.

My Display refuses to give me 100% saturated 'blue' but was not necessarily better to calibrate using 75% saturation patterns.

The only certain way is to calibrate using patterns at 75 and 100% saturation then compare the results from each calibration at say 25, 50, 75 and 100%.

I used Tom's 'Advanced Color Management' Tool (in Chromapure).

Results enclosed.
LL
LL
post #16 of 33
Thread Starter 
Thanks guys for all the input!

I'm very happy with my latest calibration at 100% but in the quest for perfection I will be trying 75% probably some time next week.

On my VT30 the color needing the most adjustment is magenta. With no adjustment it's just off slightly but to get it in line requires a major adjustment. Because of this I'm thinking it may be best to adjust at 75% since I suspect the heavy adjustment is affecting 75% more than 100%.

BTW, does anyone know of a direct way to get the 75% points to show up on the HCFR gamut chart? I manually edited my 100% results to scale them down to 75% and then plan on using that as a reference picture.
post #17 of 33
Quote:
Originally Posted by EmilG View Post

BTW, does anyone know of a direct way to get the 75% points to show up on the HCFR gamut chart? I manually edited my 100% results to scale them down to 75% and then plan on using that as a reference picture.

I'm confused. The HCFR gamut CIE chart x/y readings won't change as a result of using 75% color patterns for your measurements. The only change would be the Y luminance value, which is not plotted on the CIE chart. The Y value, is read off the Measurement tab of HCFR.

For example, the Red readings when using a 75% Red color pattern would be x=0.640, y=0.330 and Y= 21.26% of the 75% White pattern reading.

At least, that's how I see it.

bruce
post #18 of 33
Thread Starter 
Quote:
Originally Posted by bruce View Post

I'm confused. The HCFR gamut CIE chart x/y readings won't change as a result of using 75% color patterns for your measurements. The only change would be the Y luminance value, which is not plotted on the CIE chart. The Y value, is read off the Measurement tab of HCFR.

For example, the Red readings when using a 75% Red color pattern would be x=0.640, y=0.330 and Y= 21.26% of the 75% White pattern reading.

At least, that's how I see it.

bruce

Well I'm sure I'm more confused than you are .

I thought 75% meant 75% saturation with 75% saturation patterns.
This means that some grey would be in the pattern so on the gamut chart it would be at a 75% point from D65 toward the pure color(R,G or B).
I'm assuming these are all at 100% luminance.
post #19 of 33
Not sure about the actual calculations for say red.

Perhaps this old excel calculater I originally got from this forum will help (thanks to the original publisher).

 

Gamut, Saturation, Brightness, dE Chart.zip 376.2724609375k . file
post #20 of 33
Quote:
Originally Posted by EmilG View Post

Well I'm sure I'm more confused than you are .

I thought 75% meant 75% saturation with 75% saturation patterns.
This means that some grey would be in the pattern so on the gamut chart it would be at a 75% point from D65 toward the pure color(R,G or B).
I'm assuming these are all at 100% luminance.

I may be wrong, but, in the Tom Huffman calibration post here, he says this:

Test Patterns
I provided a download link at the end of this post for a file from which you can create a calibration DVD with all of the necessary test patterns discussed here. There are two important rules to keep in mind.
1. When you use color and white test patterns, ensure that they are the same level of stimulus. For example, use 75% white test patterns with 75% color patterns and 100% white test patterns with 100% color test patterns. The same rule applies to windows and full fields. Use one or the other. Don't mix and match.


bruce
post #21 of 33
Thread Starter 
Quote:
Originally Posted by bruce View Post

I may be wrong, but, in the Tom Huffman calibration post here, he says this:

Test Patterns
I provided a download link at the end of this post for a file from which you can create a calibration DVD with all of the necessary test patterns discussed here. There are two important rules to keep in mind.
1. When you use color and white test patterns, ensure that they are the same level of stimulus. For example, use 75% white test patterns with 75% color patterns and 100% white test patterns with 100% color test patterns. The same rule applies to windows and full fields. Use one or the other. Don't mix and match.


bruce

I looked at the contents of the AVS disk and they have 75% saturation patterns and 75% color patterns which I'm assuming is luminance, that's the confusion.
I'm referring to using the 75% saturation patterns which I think are at 100% luminance.
post #22 of 33
Quote:
Originally Posted by EmilG View Post

I thought 75% meant 75% saturation with 75% saturation patterns.
This means that some grey would be in the pattern so on the gamut chart it would be at a 75% point from D65 toward the pure color(R,G or B).

I don't think really think so. When you do a grayscale test and you use 10%, 20%, ...... 80%, 90%, 100% patterns, and you plot each of these gray window patterns, they all lay at D6500. Why would a 75% gray window tend toward any pure color. They are all setup to be at D6500

Quote:


I looked at the contents of the AVS disk and they have 75% saturation patterns and 75% color patterns which I'm assuming is luminance, that's the confusion.
I'm referring to using the 75% saturation patterns which I think are at 100% luminance.

I use both the Get Gray calibration disk and the AVS HD709 calibration disk and they both have a set of 75% color patterns (that include a 75% gray window) and a set of 100% color patterns that include a 100% gray window.

bruce
post #23 of 33
Quote:
Originally Posted by bruce View Post

I don't think really think so. When you do a grayscale test and you use 10%, 20%, ...... 80%, 90%, 100% patterns, and you plot each of these gray window patterns, they all lay at D6500. Why would a 75% gray window tend toward any pure color. They are all setup to be at D6500

Other way around. Talking about mixing some white into a primary color to desaturate the primary, you'd do it with all of them to measure inside the triangle instead of at the edge.
post #24 of 33
Quote:


Talking about mixing some white into a primary color to desaturate the primary, you'd do it with all of them to measure inside the triangle instead of at the edge.

I don't really understand what you're saying.

I've calibrated CMS with 75% color patterns using the 75% gray window and then checked those adjustments using 100% color patterns using the 100% gray window and they all pretty much match.

Is this not the correct way to do it?

bruce
post #25 of 33
You need to use 75% color patterns at 100% Stimulus.

The AVSHD disk has a set of Saturation patterns in each of the HCFR, Calman, and ChromaPure pattern sections called "Saturation". They contain 25%, 50%, 75%, and 100% patterns, all at 100% Stimulus. These are the color patterns you want to use. If you do readings of the primaries and secondaries of all these patterns, they will all show up on the color gamut chart.
post #26 of 33
Quote:
Originally Posted by Kilgore View Post

You need to use 75% color patterns at 100% Stimulus.

The AVSHD disk has a set of Saturation patterns in each of the HCFR, Calman, and ChromaPure pattern sections called "Saturation". They contain 25%, 50%, 75%, and 100% patterns, all at 100% Stimulus. These are the color patterns you want to use. If you do readings of the primaries and secondaries of all these patterns, they will all show up on the color gamut chart.

OK, I do see the Saturation directory, but I'm confused as to the difference between those and the patterns in the 75% and 100% color directories (contents of those directories shown below).

To me, those two directories contain the 75% and 100% saturation patterns along with the appropriate 75% or 100% gray pattern to be used in each case.

Or am I way off.

bruce
LL
LL
post #27 of 33
Quote:
Originally Posted by bruce View Post

OK, I do see the Saturation directory, but I'm confused as to the difference between those and the patterns in the 75% and 100% color directories (contents of those directories shown below).

To me, those two directories contain the 75% and 100% saturation patterns along with the appropriate 75% or 100% gray pattern to be used in each case.

Or am I way off.

bruce

Forgive me if I get too basic, and explain something you already understand. When you measure color, there are three dimensions: x, y and Y. The measurements of x and y determine the hue/saturation of the color. These are fixed values for each color. For example, pure green (in terms of Rec. 709) always measures:

* x = .300
* y = .600


Y, on the other hand, measures luminance only. Luminance is a measurement of how bright the color is. This measurement is relative to a 100% white pattern (or 75%, if that's the brightness of the color pattern).

When people refer to 75% saturation, it means the color is 75% pure with 25% white thrown in. When people refer to 75% stimulus, it means the color is at 75% brightness.

When I calibrate my television, I calibrate at 100% saturation, but 75% luminance. I do this because my video processor automatically generates this pattern for me, and because I feel it better simulates real world applications.

I hope that helps.
post #28 of 33
Quote:
Originally Posted by bruce View Post


OK, I do see the Saturation directory, but I'm confused as to the difference between those and the patterns in the 75% and 100% color directories (contents of those directories shown below).

To me, those two directories contain the 75% and 100% saturation patterns along with the appropriate 75% or 100% gray pattern to be used in each case.

Or am I way off.

bruce

In the AVSHD709 disc,

75% Color patterns: 75% luminous, 100% saturated colors + 75% gray

100% Color patterns: 100% luminous, 100% saturated colors + 100% white

Saturation patterns: 100% luminous, 0/25/50/75/100% saturated colors
post #29 of 33
Quote:
Originally Posted by bruce View Post

OK, I do see the Saturation directory, but I'm confused as to the difference between those and the patterns in the 75% and 100% color directories (contents of those directories shown below).

To me, those two directories contain the 75% and 100% saturation patterns along with the appropriate 75% or 100% gray pattern to be used in each case.

Or am I way off.

bruce

They are different.

The ones in the 75% Color directory are 100% Saturation, 75% Stimulus.

The ones in the 100% Color directory are 100% Saturation, 100% Stimulus.

The ones in the Saturation directory are all 100% Stimulus, but are 100%, 75%, 50%, and 25% Saturation.

If you calibrate using the 75% or 100% Color patterns, you will get the same results either way, as long as you use only 75% or only 100% patterns since they all have the same Saturation levels. They will show up on the same 100% points on the color gamut chart because the color gamut chart shows Saturation and Hue levels, and all these patterns are 100% Saturation.

However, the Saturation patterns will show up at different points on the color gamut chart.



Here is an example of a color gamut where a display has been calibrated to 100% Color patterns but where the resultant lower Saturations are off. This shows an instance where calibrating using 75% Saturation patterns would be preferable.




Here is the link where these images came from. Although the thread there describes issues with Epson Projectors, the information there can be applied to any display. Many thanks to stereomandan for this detailed explanation.

http://www.avsforum.com/avs-vb/showt...7#post16166537
LL
LL
post #30 of 33
Kilgore and others, thanks for the excellent explanations. Much appreciated. I do believe I finally get it.

bruce
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