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The Official ChromaPure thread - Page 117

post #3481 of 5348
I also just did my first Pre-Calibration on my Sony HW50 digital front projector! So proud of myself :grin:

I ve attachted a screenshot of the results. I m wondering what this all tells me and what the work there is that s need to be done. I m just talking only about the Grayscale yet, not the gamma and CMS, that s for later or else it is too much for me and I don t understand anymore smile.gif

Am I correct that the 'Y' shows the cd/m2 values per IRE and the CCT the Color Temp. per IRE? The rest (x, y, CIE94 and Output) I also would like to interpreting the correct way so maybe you guys can tell me what they tell me and how I have to read them?

Am I correct that when I try to aim the Red Green and Blue at 100% the Color Temp. automatically will go to approx. 6500K?

And last but sure not least, HOW do I get R, G and B for all the IREs as close to 100% as possible? I have a R, G, B Gain and R, G, B Bias setting on my projector which are all on their default 0 value now. I would like to know what the best way of working is.

Greetings Untitled.jpg 279k .jpg file
post #3482 of 5348
HI Sander, not too sound ill intended, buy have you read through the entire manual? It explains most this stuff quite good. Inclusing R G B bias and gain settings. I think it is hard to write an elaborate reply with the same level of detail as in the CP manual. For the grayscale the R G and B bars need to be at 100% respectively for every level of stimulus (!=IRE - athough IRE is used in the analog domain, it is better to use the R G B connotation or level of stimulus in %). That should indeed give you a CCT of 6500k. You are correcting x,y for white. Adding R, G or B coincidentally has an effect on Y. Adding G will have the most effect on lumunance. Adding B will have the least effect on lumincance. Getting the luminance spot on, can be done with gamma controls. Those will (if they work well) only affect Y.
post #3483 of 5348
Quote:
Originally Posted by sanderdvd View Post

I also just did my first Pre-Calibration on my Sony HW50 digital front projector! So proud of myself :grin:
I ve attachted a screenshot of the results. I m wondering what this all tells me and what the work there is that s need to be done. I m just talking only about the Grayscale yet, not the gamma and CMS, that s for later or else it is too much for me and I don t understand anymore smile.gif
Am I correct that the 'Y' shows the cd/m2 values per IRE and the CCT the Color Temp. per IRE? The rest (x, y, CIE94 and Output) I also would like to interpreting the correct way so maybe you guys can tell me what they tell me and how I have to read them?
Am I correct that when I try to aim the Red Green and Blue at 100% the Color Temp. automatically will go to approx. 6500K?
And last but sure not least, HOW do I get R, G and B for all the IREs as close to 100% as possible? I have a R, G, B Gain and R, G, B Bias setting on my projector which are all on their default 0 value now. I would like to know what the best way of working is.
Greetings Untitled.jpg 279k .jpg file

Are you using a Lumagen or DVDO for CMS/gamma adjustments?/Unless the 50 is different than the 1000, you're not going to be able to adjust much without an outboard processor.
post #3484 of 5348
Quote:
Originally Posted by sanderdvd View Post

Thxz for your replies guys.

New question (i m learning a lot already so the questions will become less overtime ):

How can take measurements on the same pc with both mpc and chromapure? I mean, I can t push the measure button in chromapure if my mpc shows the needed fullscreen test patterns....... Do i need a second pc eg.laptop just for chromapure?
EDIT: Can you tell me specific how I can do this exactly with Chromapure?

I think I might have a solution to this one smile.gif See if your videocard software has a setting like extended desktop where you make the tv first and monitor second then drag over the program display what patterns you need to and take your measurements.
post #3485 of 5348
You guys are doing a great job of answering questions. I look forward to the day when I can just step back and let users answer questions for other users.
post #3486 of 5348
Hi Tom,

Since we are doing such a good job-), could I tempt you to write an article on gamma on the CP website (with regards how it can change hue/saturation)? I'm kind of getting the feeling no one knows whether we should aim for 2.2, 2.3, 2.35 or 2.4. Moreover, whether this should be a 'power law' gamma or BT.1866 is quite confusing. I've started reading this thread http://www.avsforum.com/t/1409045/how-power-law-gamma-calibration-can-lead-to-crushed-blacks (slowly as it is hard to follow at times) and now I'm not sure anymore what to do.

Also, since gamma influences the Y of the white point, what effect does the "wrong" gamma have on color accuracy?
Edited by Jeroen1000 - 12/3/12 at 6:25am
post #3487 of 5348
Quote:
Originally Posted by Jeroen1000 View Post

HI Sander, not too sound ill intended, buy have you read through the entire manual? It explains most this stuff quite good. Inclusing R G B bias and gain settings. I think it is hard to write an elaborate reply with the same level of detail as in the CP manual. For the grayscale the R G and B bars need to be at 100% respectively for every level of stimulus (!=IRE - athough IRE is used in the analog domain, it is better to use the R G B connotation or level of stimulus in %). That should indeed give you a CCT of 6500k. You are correcting x,y for white. Adding R, G or B coincidentally has an effect on Y. Adding G will have the most effect on lumunance. Adding B will have the least effect on lumincance. Getting the luminance spot on, can be done with gamma controls. Those will (if they work well) only affect Y.
I ve just read the manual again and there is indeed an explanation of how to do a grayscale calibration with the Gain and Bias setting. My Grayscale is pretty nice now (I ll show some screenshots tonight) but the 10IRE value has a very big problem with too much red and to less blue. The oversatured red is clearly visible at the 10IRE pattern. Will this oversatured red maybe stabelize a bit when I begin with adjusting the Gamma and CMS?

And there s another strange thing: My Sony VPL-HW50ES digital front projector has an automatic iris that can be set to OFF, Auto - Limited and Auto - Full. The auto - Limited is for pitch black HT rooms. When I toggle between the 3 iris settings I get completely different Grayscale results, especially in the lower IREs. How is this possible? The iris is supposed to only affect contrast right?
post #3488 of 5348
Quote:
Originally Posted by hungro View Post

I think I might have a solution to this one smile.gif See if your videocard software has a setting like extended desktop where you make the tv first and monitor second then drag over the program display what patterns you need to and take your measurements.
nice solution! Thanks
post #3489 of 5348
Quote:
Originally Posted by sanderdvd View Post

I ve just read the manual again and there is indeed an explanation of how to do a grayscale calibration with the Gain and Bias setting. My Grayscale is pretty nice now (I ll show some screenshots tonight) but the 10IRE value has a very big problem with too much red and to less blue. The oversatured red is clearly visible at the 10IRE pattern. Will this oversatured red maybe stabelize a bit when I begin with adjusting the Gamma and CMS?
And there s another strange thing: My Sony VPL-HW50ES digital front projector has an automatic iris that can be set to OFF, Auto - Limited and Auto - Full. The auto - Limited is for pitch black HT rooms. When I toggle between the 3 iris settings I get completely different Grayscale results, especially in the lower IREs. How is this possible? The iris is supposed to only affect contrast right?

This is getting a bit more difficult. I think the meter is accurate down to 10 IRE (this depends on how black your PJ can go:)). So remeasure 10 IRE and adjust just using the controls? And then you should always recheck the other points too. You may have to compromise somewhere unless you have better greyscale/whitebalance controls at your disposal. When you talk about saturation, we are talking about the gamut. A CMS can fix this, yes. But this has a different goal then adjusting the greyscale.

I don't know a lot about the iris control things. Sorry:-)
post #3490 of 5348
Thanks for your reply. I can get 10IRE perfect (100%) if I want but then the rest of the IREs are not so good anymore......
post #3491 of 5348
Quote:
Originally Posted by sanderdvd View Post

Thanks for your reply. I can get 10IRE perfect (100%) if I want but then the rest of the IREs are not so good anymore......

hi Sander,

meassure 10 % could be a problem for your meter so do not trust this.

Better do a 30-80 2point measure and calibrate those.

0-20 (or maybe 30) could better be trusted by tweaking them (10 point RGB grayscale) during watch color shift in gray by eyes if your measures look perfect by numbers but the eyes see different.

greetz
post #3492 of 5348
Quote:
Originally Posted by sanderdvd View Post

I ve just read the manual again and there is indeed an explanation of how to do a grayscale calibration with the Gain and Bias setting. My Grayscale is pretty nice now (I ll show some screenshots tonight) but the 10IRE value has a very big problem with too much red and to less blue. The oversatured red is clearly visible at the 10IRE pattern. Will this oversatured red maybe stabelize a bit when I begin with adjusting the Gamma and CMS?
And there s another strange thing: My Sony VPL-HW50ES digital front projector has an automatic iris that can be set to OFF, Auto - Limited and Auto - Full. The auto - Limited is for pitch black HT rooms. When I toggle between the 3 iris settings I get completely different Grayscale results, especially in the lower IREs. How is this possible? The iris is supposed to only affect contrast right?

Your meter is not color accurate at that low of a stimulus ex 10% white, you can tweak your gamma for that level of stimulus and have the correct Y but i wouldn't worry and spend too much time getting RGB to 100%. It won't be accurate.
IRE doesn't exist in the digital world so please do not use this term , it is an analog term. I think the correct term is percentage of white.
post #3493 of 5348
Thanks for your replies guys. But how do I tackle the redish in 10% white then? Raising the Bias R will result in non-perfect 30% and up......

And what about my other question:
My Sony VPL-HW50ES digital front projector has an automatic iris that can be set to OFF, Auto - Limited and Auto - Full. The auto - Limited is for pitch black HT rooms. When I toggle between the 3 iris settings I get completely different Grayscale results, especially in the lower IREs. How is this possible? The iris is supposed to only affect contrast right?
post #3494 of 5348
I meant to suggest that you create a profile for the meter to be used facing the projector (use the reading off the screen as the 'reference' and the projector facing as 'field'). This way you'll get more light at the sensor so you'll be able to make more accurate low % readings. I used this method with my old i1LT so I could manually adjust the 5,10,20 % greyscale using my Lumagen. If you only have 2 points of greyscale adjustment, then it's a matter of chosing which % you want to get closest/lowest dE, or perhaps to make them all 'off' but by a similar amount rather than 30% spot on and 10% further out. It's all part of the calibration experience that even a Pro will have to compromise on if the display's controls are limited.

See if anyone else comments on the iris question. wink.gif
post #3495 of 5348
Quote:
Originally Posted by Jeroen1000 View Post

Hi Tom,
Since we are doing such a good job-), could I tempt you to write an article on gamma on the CP website (with regards how it can change hue/saturation)? I'm kind of getting the feeling no one knows whether we should aim for 2.2, 2.3, 2.35 or 2.4. Moreover, whether this should be a 'power law' gamma or BT.1866 is quite confusing. I've started reading this thread http://www.avsforum.com/t/1409045/how-power-law-gamma-calibration-can-lead-to-crushed-blacks (slowly as it is hard to follow at times) and now I'm not sure anymore what to do.
Also, since gamma influences the Y of the white point, what effect does the "wrong" gamma have on color accuracy?
There are two issues, one of which is shadow detail and the other is color. Of the two, shadow detail is the more important. I would not recommend running a power law gamma much above 2.22. You will get crushed blacks. The neat thing about BT.1886 is that it allows you to run higher gammas at the high end without crushing blacks on the low end.

The color issue is this: At 2.22 a 75% saturation Rec. 709 red is x0.5622, y0.3298, Y0.2126. Raise the gamma to 2.35 and you get x0.5720, y0.3298, Y0.2036, a CIE94 color difference of 1.2, which is on the border of visibility. It is not a big deal. Color will be slightly lower luminance and slightly more saturated at higher gamma.

The bottom line? I would recommend using either power law 2.22 or BT.1886. Try both and select whichever looks the best to you.
post #3496 of 5348
The Display 3 PRO is quite accurate and stable measuring 10% on a front projector (even if it were not, you could always use it in lens mode--the diffuser is quite good).

If you only have a 2-point RGB white balance control on a display, you may very well not be able to get 10% and other levels set properly at the same time. There is a solution. Get a Duo or Lumagen, which will give you a 10-point adjustment mode.
post #3497 of 5348
Thanks for your reply Tom.

What do you (and the others) think about this Grayscale?

I have some questions about it too:

- i have a pitchblack bat cave as htroom. Is it better to aim for a higher gamma then? Say 2.4 - 2.5?
- is it better to get a better 10ire at the cost of some other ire points?

Wha HW501.jpg 91k .jpg file
post #3498 of 5348
Quote:
Originally Posted by sanderdvd View Post

Thanks for your reply Tom.
What do you (and the others) think about this Grayscale?
I have some questions about it too:
- i have a pitchblack bat cave as htroom. Is it better to aim for a higher gamma then? Say 2.4 - 2.5?
- is it better to get a better 10ire at the cost of some other ire points?
Wha HW501.jpg 91k .jpg file

It looks fine. Shoot for gamma 2.2 - 2.3, and remember, nothing is perfect. The following graphs are from EBU - TECH 3325. Deviances from perfect are "allowed".




Edited by buzzard767 - 12/3/12 at 7:30pm
post #3499 of 5348
Quote:
Originally Posted by sanderdvd View Post

Thanks for your reply Tom.
What do you (and the others) think about this Grayscale?
I have some questions about it too:
- i have a pitchblack bat cave as htroom. Is it better to aim for a higher gamma then? Say 2.4 - 2.5?
- is it better to get a better 10ire at the cost of some other ire points?
Wha HW501.jpg 91k .jpg file
I wouldn't change a thing. The only way to fix the 10% reading is to add a processor that has 10-pt grayscale adjustments.
post #3500 of 5348
Small quick question. Tom, you measured that the i1 display pro III (I have the enhanced version, which shouldn't matter I assume) could read light down to 0.003 cd/m².Seeing my 2008 Panasonic 42PF11EK commercial plasma screen has a MLL probably around 0.04 cd/m², would you say that the probe will be accurate all the way down to 0% stimulus?
Edited by Jeroen1000 - 12/4/12 at 2:38am
post #3501 of 5348
No i1D3 (i1 Display Pro) can read to such low levels accurately.

The lowest level with any acceptable accuracy is 0.1 Nits.

That's as good as the physical optics in the probe will allow.

Steve
post #3502 of 5348
Have you tested this? (I think you meant can't judging from your reply). It appears Tom found it can. Although, I do not know whether his test included verification using a reference device.

Perhaps someone with a reference meter can make a comparison:)
post #3503 of 5348
Hello,

Here are my first calibration results for my Plasma Panasonic P42V20 :
I used an i1 Display 3 PRO and the AVSHD 709 DVD - Chromapure Windows patterns - via a PS3









Other useful Post-calibration charts :


CIE


Saturation luminance


Saturation dE


Amplitudes


Contrast (Set to 34 only)



My TV settings :

PRO 1
Contrast 34
Brightness +2
Colour 27
Sharpness 3

R-Gain 2
G-Gain 1
B-Gain 3
R-Cutoff -3
G-Cutoff -4
B-Cutoff 0

R-Hue 0
G-Hue -3
B-Hue 1
R-Saturation -1
G-Saturation -3
B-Saturation +5

Gamma 2.4


wink.gif
Edited by mlg33 - 12/4/12 at 12:31pm
post #3504 of 5348
I wouldn't take color readings below 0.1 cd/m2 very seriously, but luminance is another matter. Not sure what is considered acceptable, but here is a comparison between the Display 3 and the $7,000 Klein K10-A, the current champ at low-light readings.



This is from a Samsung LED flat panel. Below 0.1 cd/m2 the D3's luminance readings deviate from the Klein by an average of 0.004 cd/m2 and a maximum of 0.009 cd/m2. There are grounds on which to criticize the D3--which I am happy to discuss if anyone is interested--but low-light performance is not one of them. For the price, its low-light performance is stunningly good.
post #3505 of 5348
Hi Tom,

What do you think of my first plasma calibration above ? smile.gif

Thanks for your feedback.
post #3506 of 5348
Nice quick test. Looks like price/quality wise, this is nothing less of superb. Would the low light performance vary according to display type or isn't this a variable to consider?
post #3507 of 5348
Quote:
Originally Posted by Jeroen1000 View Post

Nice quick test. Looks like price/quality wise, this is nothing less of superb. Would the low light performance vary according to display type or isn't this a variable to consider?
Indeed - we have (ir have access to) K10-A, Pr-655, Jeti 1211, Hubble, i1D3, i1pro2, etc,.... and have compared all probes many times.

The display indeed make a significant difference. The biggest with filter based probes is the spectral response of the filters to the back-light.

Steve
post #3508 of 5348
hi Steve, are you saying the display type has an influence on the low light performance or are you talking about the gamut performance (measuring color?)
post #3509 of 5348
Yep, has an influence on low-light performance, as the 'grey-scale' measurement will deviate from what is expected. This impacts the colour reported, and the luma measurement.

Steve
post #3510 of 5348
Quote:
Originally Posted by Light Illusion View Post

Yep, has an influence on low-light performance, as the 'grey-scale' measurement will deviate from what is expected. This impacts the colour reported, and the luma measurement.
Steve

Doesn't this go back to the argument, even amongst experts, whether to calibrate with or without the Backlight being on?
Use to calibrate with it Off, but now Meter Menus appear to allow with it On.
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