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The Official ChromaPure thread - Page 132

post #3931 of 5345
Quote:
Originally Posted by TomHuffman View Post

The problem with the grayscale at the low end is that you are not getting nearly enough light out of this PJ. Your light output is about 1/3 of what it should be...

In the short run, turn the meter around, place the diffuser over the lens, and point at the PJ's lamp.

Thank you. Slightly surprised about output since it seems bright at 100%. Will do manual adj for the moment and order a new lamp this weekend.
post #3932 of 5345
Quote:
Originally Posted by visca blaugrana View Post

Would it be ok, on a projector with low light output, to profile a i1 display pro with the spectro pointing to.the screen and with the d3 facing the projector with the diffuser on?
It would depend on the screen. A color neutral screen, yes. An exotic screen, probably not.
post #3933 of 5345
Hi Tom
I have a query, after doing an advaced autocal with a lumagen XS I've noticed that the lumagen has not asked me to save my changes (like it used to when i did non-advaced cals on older lumagen firmware). Is this because chromapure now tells XS to save the changes now, or hase something gone wrong?

Thanks
Chris
post #3934 of 5345
It saves automatically.
post #3935 of 5345
Phew, I thought I was in the embarrassing position of thinking I could see improvements when non had been made.
post #3936 of 5345
Placebo calibration, cheapest kind wink.gif
post #3937 of 5345
Hi Tom and others,

Any tips on how to measure on/off contrast on a plasma?

Sure I can display a full black field (not a Window) and measure it (recollecting from memory, I believe I'm getting about 0.041 cd/m²). But for white, the peak output depends on the size of the white square. The smaller the white square (window), the better my contrast ratio. Showing a white field obviously yields the lowest number for the contrast ratio.
post #3938 of 5345
Quote:
Originally Posted by Jeroen1000 View Post

Hi Tom and others,

Any tips on how to measure on/off contrast on a plasma?

Sure I can display a full black field (not a Window) and measure it (recollecting from memory, I believe I'm getting about 0.041 cd/m²). But for white, the peak output depends on the size of the white square. The smaller the white square (window), the better my contrast ratio. Showing a white field obviously yields the lowest number for the contrast ratio.
What I do to measure contrast :
I measure my white peak with a SMALL APL 100% White pattern.
Then, I put a 100% Black Window Pattern and take measurement.

For example, I have 109 cd.m² against 0.012 cd.m²; which gives me a ration of ~9000:1.

I use the Window checkboard pattern to measure ANSI contrast. Which in my case is a bit lower of course.

Never take your white peak level with a full screen on a plasma TV. The ABL will be working and your contrast ratio will be altered.
Edited by mlg33 - 2/26/13 at 1:20am
post #3939 of 5345
Frankly, I'm just trying to support my idea that my display is slightly too dim.This is to say, that the content I'm watching is being displayed too dimly.
I've got an option (called contrast) on my plasma that compresses dynamic range in order to obtain higher peak white output (the true contrast control is called input level). I'm not sure what bad things will ensue from compressing the dynamic range though. I do know (from just looking at the screen) the effect is a brighter picture:-).

Anyway, using an APL-pattern makes sense if you know what kind of cd/m² you should be getting for a certain APL. So if the APL (which I assume means the pattern + the background) equals 50%, you should be getting 60 cd/m², right? But on the other hand, using a larger pattern (meaning here the area you will actually measure becomes bigger) with the same APL for the background will again have an effect on the peak white output numbers in cd/m². It's like chasing your own tail. So how do you balance between the size of the pattern and the video levels used for the background to achieve a certain APL?

I appreciate the fact that a screen will rarely be 100% white (Ice hockey and snow sports broadcasting may come close, however). So I could guess on and conclude that if you are getting sufficient cd/m² in the 20% to 70% APL area you are good, even if you do not get 120 cd/m² for 100% APL because of the ABL on a plasma screen (= the same as a completely white screen).
post #3940 of 5345
Quote:
Originally Posted by JimP View Post

Using Chromapure Deluxe and Accupel 5000 signal generator.

When running the Color Management module and you select 75% Rec.709, does the program change which patterns it selects in the Accupel or do you make the change in the Accupel's OSD under User/ color (selecting 075 for each RGB) and then chromapure selects the correct pattern(s)?
The application selects the correct colors automatically. No user intervention is needed.
post #3941 of 5345
Quote:
Originally Posted by JimP View Post

So if you go back and forth between 709 and 75% of 709, there isn't something else you manually change in the Accupel OSD?
No user intervention is needed.
post #3942 of 5345
I am currently in the process of learning the ins and outs of ChromaPure and am curious about something I have noticed during a calibration. Why doesn't CP always pick the lowest measurement number?

Last night and previously I was running an auto-calibration using default settings; i.e. dE 1.75. For grayscale as an example, I noticed the dE go from something like 4.15 up to 21.03, then head down to a low of 1.89 with the final number something like 2.98 for the final dE number. I will be watching the measurements scroll on the screen and wonder why didn't it stop on the lower number? I suppose there could be other considerations 'under the hood' that I am not aware of.

I must stress I am very happy with ChromaPure and the results I am getting with it. The above is not a complaint, just wondering.

Regards,

Steve
post #3943 of 5345
Quote:
Originally Posted by Thunderduck View Post

I am currently in the process of learning the ins and outs of ChromaPure and am curious about something I have noticed during a calibration. Why doesn't CP always pick the lowest measurement number?

Last night and previously I was running an auto-calibration using default settings; i.e. dE 1.75. For grayscale as an example, I noticed the dE go from something like 4.15 up to 21.03, then head down to a low of 1.89 with the final number something like 2.98 for the final dE number. I will be watching the measurements scroll on the screen and wonder why didn't it stop on the lower number? I suppose there could be other considerations 'under the hood' that I am not aware of.

I must stress I am very happy with ChromaPure and the results I am getting with it. The above is not a complaint, just wondering.

Regards,

Steve
It should pick the lowest number. If you can run this and copy/paste the text in the activity window and send it to CP support, I'll look into it.

Note: It won't "stop" on the lowest number if that number is above the selected target, as in your example. However, when it finishes trying to get a better number and fails, it should then apply the lowest dE achieved.
post #3944 of 5345
Thanks Tom, I will do that.

Just to reiterate, I am very happy with the results I am getting.

While I have you, if you recall we e-mailed recently about a totally different problem I was having with CP not giving me correct readings in any area and the color windows in the Duo not matching?. I am pretty sure it was my fault because oh how I installed the recent version update. Yesterday I deleted and then installed CP from scratch. Works fine now! So, was not CP. It was me.

Thanks for help.

Steve
post #3945 of 5345
Quote:
Originally Posted by JimP View Post


So regardless of selecting either 75% or 100% signal intensity in the options/signal generators/device settings, it doesn't impact using Rec.709 or 75%Rec.709 in the Color Management module?
I am going to spend some time on this, not just to answer your question but because this is an issue that comes up often and obviously requires clarification.

1. The 75% of Rec. 709 option in Color Management refers only to 75% saturation of Rec. 709. That means that the target point is 75% of the distance from the white point to the Rec. 709 gamut boundary--a much reduced gamut. The spec for a Rec. 709 red and a 75% saturated Rec. 709 red have different xy coordinates.

2. The 75% and 100% Intensity selectors in the Signal Generator setup refer only to % of intensity. This has nothing to do with the size of the gamut. It only refers to the level of luminance, which is not represented on the CIE Chart at all. A 75% intensity Rec. 709 red and a 100% intensity Rec. 709 red have exactly the same xy coordinates: x0.640, y0.330. They even have the same Y specification: 0.2126. This is true even though they are different levels of luminance because the reference white changes along with the color, thus the ratio between the color's luminance and the luminance of the reference white point stays the same. What changes is the absolute luminance, measured in cd/m2 or ft-L.

3. As a matter of best practice I always recommend using 75% intensity test patterns for color management. You may or may not choose to use the 75% of Rec. 709 target gamut in color management. It helps with some displays and not with others, and it really makes reporting more difficult. However, the two (intensity selection and target gamut selection) really have nothing to do with one another.
post #3946 of 5345
I have found a discrepancy in the Advanced Color Management module. Please tell me what I'm doing wrong as I'm pulling my hair on this one.
I've added screenshots to accompany the below information. My pattern generator is an iScan Duo with v2.32 firmware. My meter is an i1 display pro (so with extra tables).

When I do a baseline run, I get x = 0.646 en y = 0.332 for red.
dE = 1.6 here. This was measured with a pattern with 75% amplitude (=stimulus) and 100% saturation.

Next, I'm going to the Primary Color Amplitudes screen.

For the red 75 measurement (meaning 75% amplitude 100% saturation?) I'm getting x = 0.647 en y = 0.332 for red. Which is expected as the amplitude does not alter the x,y coordinates. The small change for x does not matter. It is proably a repeatability issue or the plasma screen has a faint variance.

Yet the the dE = 13.6.

So, why is this? This is the exact same measurement as the baseline measurement and the dE error is much worse here.


baseline.PNG 29k .PNG file
75 amplitude 100 sat.PNG 151k .PNG file
post #3947 of 5345
Since x and y are the same, the problem should be with the Y, the luminance of what you are measuring.
post #3948 of 5345
Nope, all good too I think (0.209 vs 0.21)
post #3949 of 5345
Quote:
Originally Posted by Jeroen1000 View Post

I have found a discrepancy in the Advanced Color Management module. Please tell me what I'm doing wrong as I'm pulling my hair on this one.
I've added screenshots to accompany the below information. My pattern generator is an iScan Duo with v2.32 firmware. My meter is an i1 display pro (so with extra tables).

When I do a baseline run, I get x = 0.646 en y = 0.332 for red.
dE = 1.6 here. This was measured with a pattern with 75% amplitude (=stimulus) and 100% saturation.

Next, I'm going to the Primary Color Amplitudes screen.

For the red 75 measurement (meaning 75% amplitude 100% saturation?) I'm getting x = 0.647 en y = 0.332 for red. Which is expected as the amplitude does not alter the x,y coordinates. The small change for x does not matter. It is proably a repeatability issue or the plasma screen has a faint variance.

Yet the the dE = 13.6.

So, why is this? This is the exact same measurement as the baseline measurement and the dE error is much worse here.


baseline.PNG 29k .PNG file
75 amplitude 100 sat.PNG 151k .PNG file

I see some weirdness in Advance Color as well. You just finish a 125 point calibration and everything is under dE of 2 and yet you get numbers that don't match when you run all measurements in Advance Color Management.. You go in post cal gamut and rerun and the numbers match up quite closely with 125 point calibration. This funny business in Advanced Calibration is not always the case and never anything like your dE 13.6 but general weirdness seems to happen fairl often.
post #3950 of 5345
Quote:
Originally Posted by Jeroen1000 View Post

I have found a discrepancy in the Advanced Color Management module. Please tell me what I'm doing wrong as I'm pulling my hair on this one.
I've added screenshots to accompany the below information. My pattern generator is an iScan Duo with v2.32 firmware. My meter is an i1 display pro (so with extra tables).

When I do a baseline run, I get x = 0.646 en y = 0.332 for red.
dE = 1.6 here. This was measured with a pattern with 75% amplitude (=stimulus) and 100% saturation.

Looks to me like you are feeding it a 100% saturated red and it wants a 75% saturated red. x,y needs to be at 75% of the distance from red to white.
post #3951 of 5345
I had thought of that and unless I made a mistake or the Iscan Duo Control Panel did something funny, I tried 75 stim 75 sat. (which made the dE even worse) and also 100 stim. 75 sat. and also 75. stim 50 sat.
I'm not sure what the 'Set pattern intensity' drop down menu in the second screenshot is referring too: saturation of stimulus?

I can't repeat before Tuesday but perhaps I should have rebooted all the gear and CP too. That's about the only thing I "forgot" to take into account as the source of this error.
post #3952 of 5345
Tom: A question. My understanding is that new 4k (UHTV) TVs will be required to use the Rec. 2020 color gamut which covers ~ 76% of the 1931 gamut versus the ~ 35% covered by today's Rec. 709 space. Will we need new calibration software and meters to calibrate these TVs? Thanks
post #3953 of 5345
I think any decent meter should be able to measure almost any color in the IEE chart and the available programs should be ablle to report that measurement. Of course new signal generators will be needed to generate the required test patterns at 4HD resolution.

I have no clue as to whether existing 4K displays have wide enough primaries for the new color space. I think it will be quite some time until we see 4HD sources with the new space. 4K with DCI color space can be had and I think all present 4K displays can support that wider space (than rec 709).
Edited by mark haflich - 3/3/13 at 3:11pm
post #3954 of 5345
Quote:
Originally Posted by Jeroen1000 View Post

I have found a discrepancy in the Advanced Color Management module. Please tell me what I'm doing wrong as I'm pulling my hair on this one.
I've added screenshots to accompany the below information. My pattern generator is an iScan Duo with v2.32 firmware. My meter is an i1 display pro (so with extra tables).

When I do a baseline run, I get x = 0.646 en y = 0.332 for red.
dE = 1.6 here. This was measured with a pattern with 75% amplitude (=stimulus) and 100% saturation.

Next, I'm going to the Primary Color Amplitudes screen.

For the red 75 measurement (meaning 75% amplitude 100% saturation?) I'm getting x = 0.647 en y = 0.332 for red. Which is expected as the amplitude does not alter the x,y coordinates. The small change for x does not matter. It is proably a repeatability issue or the plasma screen has a faint variance.

Yet the the dE = 13.6.

So, why is this? This is the exact same measurement as the baseline measurement and the dE error is much worse here.


baseline.PNG 29k .PNG file
75 amplitude 100 sat.PNG 151k .PNG file
When measuring amplitudes, you must use 100% stimulus test patterns, because that is the baseline from which the other targets are calculated.
post #3955 of 5345
Quote:
Originally Posted by dsinger View Post

Tom: A question. My understanding is that new 4k (UHTV) TVs will be required to use the Rec. 2020 color gamut which covers ~ 76% of the 1931 gamut versus the ~ 35% covered by today's Rec. 709 space. Will we need new calibration software and meters to calibrate these TVs? Thanks
You are way ahead of the curve here. Standards for 4K Blu-ray and broadcast have not been finalized. They MAY use the 2020 recommendation and they may not. If and when these standards become formally adopted, then ChromaPure will add the 2020 gamut to the list of available reference gamuts.
post #3956 of 5345
Quote:
Originally Posted by gtgray View Post

I see some weirdness in Advance Color as well. You just finish a 125 point calibration and everything is under dE of 2 and yet you get numbers that don't match when you run all measurements in Advance Color Management.. You go in post cal gamut and rerun and the numbers match up quite closely with 125 point calibration. This funny business in Advanced Calibration is not always the case and never anything like your dE 13.6 but general weirdness seems to happen fairl often.
Without more specific information I can't comment on this intelligently. However, in our next release (which will be out shortly) comprehensive Excel-based reporting will be built-in to the Advanced Auto-Cal process, so there will be no need to switch to the Advanced Color Management module to check this.
post #3957 of 5345
Quote:
Originally Posted by TomHuffman View Post

Without more specific information I can't comment on this intelligently. However, in our next release (which will be out shortly) comprehensive Excel-based reporting will be built-in to the Advanced Auto-Cal process, so there will be no need to switch to the Advanced Color Management module to check this.
hello Tom
I hope you can provide BT1886 support in the next release of Chromapure Standard.
post #3958 of 5345
Quote:
Originally Posted by turboman123 View Post

hello Tom
I hope you can provide BT1886 support in the next release of Chromapure Standard.
IIRC CP already supports BT1886 for auto cal but not manual cal.
post #3959 of 5345
Quote:
Originally Posted by TomHuffman View Post

When measuring amplitudes, you must use 100% stimulus test patterns, because that is the baseline from which the other targets are calculated.

Wait... Then you've lost me what the purpose of measuring "Primary Color amplitudes" is. For Red25, Red50 and Red75, aren't the numbers 25, 50 and 75 referring to the amplitude which is the same as the % stimulus of the pattern?

So when doing a Saturation sweep, I keep the stimulus (again this IS the same as amplitude yes?) at 75% for the entire sweep, and only vary the saturation between 25%, 50% and 75%. And hereby I thought, when doing a "Primary colors Amplitudes" sweep, I assumed I had to keep the saturation at 100% (or at 75% depending on what CP is expecting) and vary the stimulus between 25%, 50% and 75%. But you are saying I have to keep the % stimulus for the pattern at 100%. So here I also have to vary the saturation between 25, 50 and 100% and not the stimulus (amplitude?)

So...what is the goal of "Primary Color amplitudes" then as I'm clearly not understanding what I'm supposed to do:)
post #3960 of 5345
Quote:
Originally Posted by gtgray View Post

I see some weirdness in Advance Color as well. You just finish a 125 point calibration and everything is under dE of 2 and yet you get numbers that don't match when you run all measurements in Advance Color Management.. You go in post cal gamut and rerun and the numbers match up quite closely with 125 point calibration. This funny business in Advanced Calibration is not always the case and never anything like your dE 13.6 but general weirdness seems to happen fairl often.

I believe the ACM measures lightness and the post cal. gamut measures luminance. It has something to do with that if I recollect correctly. And lightness errors are always larger than luminance errors (I may have this all backwards). This question comes up every now and then. Perhaps Tom can address it in more detail and put it up as a FAQ as I'm also still a bit confused about it.
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