The Official ChromaPure thread - Page 127

Can the i1Display Pro be damaged by excess light? You could start further out from the projector, take a reading, move closer, take a reading, etc. Once you get near the upper limit of the i1Display Pro capability the readings should level off so then you could back off knowing your within the operating range of the meter.

I think another way of doing this is to use a lux meter to measure CR and then use that value to compute the black level (Use the i1Pro to measure WL off the screen then infer BL using the CR found with the Lux meter).

I also understand that one should check BOTH overrides. I'm not sure why there are two independent check boxes for WL and BL but Tom did tell me to check both and input both values - in cd/m2.

EVERYONE who has a JVC projector or any similar high contrast display MUST use the override feature if you want the BT.1886 gamma curve. Otherwise, the system will not be able to accurately measure the black level.

From the Help topic on auto-calibration" "If you have a JVC projector whose black level you cannot read, then simply measure the contrast ratio by pointing the probe at the lens (using a diffuser). Once you have the ratio between black and white, just take a reading from the screen for 100% white, then you can calculate the black level from this."

Be sure to input white and black values in cd/m2.

It will read up to 1000 cd/m2. You cannot simply calibrate without the override feature by pointing the meter at the lens. You need accurate luminance values off the screen.

Thanks Tom,

Somewhere in the jumble of my post was the intention to do what the 'help topic' suggests regarding measuring the contrast ratio (I knew I'd seen it somewhere). I won't waste my time trying to do BT 1886 with the meter facing the lens.

In fact I'm so busy just enjoying the existing 2.22 result on my X35 that I haven't really taken any time out to do any more calibration.

I just got home and my Display 3 Pro was at the door. And the email with the license and calibration corrections was waiting for me as well.

Thanks Tom.

I guess I'll try it tomorrow with my DUO. Since it's been sitting outside most of the day I'm guessing I need to wait for it's temperature to stabilize to room temp first anyway.

Maybe I'll try it out tonight if I can find my tripod.

That's all it needs is a tripod isn't it?

Also is there a case that is sold specifically for the Display 3 Pro? Or is there another type of case that someone has used to store it in?

I just started messing around with Chromapure. It's doing it's first auto calibration right now. I just want to verify about the Pro corrections. These are implemented when I select the display. For me it's an RP DLP.

But in Chromapure, am I supposed to see the corrections? Or are the corrections just done behind the scenes. When I look at the section for the corrections they are all listed as zero. Is this correct?


The only issue I ran into when setting up was the font size. I had to change the font size to small to be able to see the entire window in Chromapure. I could not see it all with medium font settings and there was no slider bar on the auto calibration page like there is on other pages to go down further on the page.

Yes, if you've got the PRO version of the Display3 from Chromapure the corrections are stored within your License file, and get incorporated into the measurements when you make the appropriate selection when initialising the meter. The Corrections tab is for those of us that use two meters, a Reference and a Field meter - with the Ref providing corrections for the Field.
Regards, Mike.

thanks. I just wanted to make sure.


I also see that Chromapure runs fine on my 1.2Ghz(Intel) dual core Netbook. I thought I might have some issues since the requirements list a minimum 1.5Ghz processor.

Please see the e-mail you received that provided the license and download link.

"The PRO corrections are stored in the license file and documented in the attached report. No action is required to enable them."

Thanks. I had read the email and figured they were enabled. When I saw the corrections option I just wasn't sure if the program would show the corrections from the license.

I'm still not sure what are correct patterns in Color Management module and Color Decoding module. I'm using AVSHD calibration disc - Chromapure Fields directory..

When I should use 75%Color, 100%Color and Saturation patterns ?
In Color Management module there is combobox "Select Reference Gamut". What are correct patterns for Rec.709 and 75% Rec.709 options ?
In Color Decoding module should I use 75%Color or 100%Color patterns ?

Thank you for answering noob question.

Use 75% Color for Color Management, Color Gamut, and Color Decoding.
Use the Saturation patterns only for Advanced Color Management or for the 75% of Rec. 709 Gamut option in Color Management.
There are no special patterns for Reference Gamut (other than 75% of Rec. 709). This is just the target you want to calibrate to.

Thank You Tom,

so for 75% of Rec.709 option in Color Management i use 75% saturation patterns. Measuring starts with measuring White. Should I measure 100% white or 75% White?.

At whatever level of stimulus the 75% saturation patterns are at. I think the AVSHD saturation patterns are at 100% stimulus.

Saturation = distance from the white point
Stimulus = luminance

This is probably presumptuous but I thought I would throw it out there. i have just started calibrating my TV with ChromaPure and I haven't attempted anything like this before. I think I have the brightness and contrast appropriately set up and I have measured greyscale and color gamut. I can tell that things aren't ideal, maybe not a bad starting point but still wroth some adjustment. I am wondering if anyone out there might be interested in taking a look at my quick reports and offering some advice or discussing where to start with the next round of adjustment?

Not presumptuous at all. Just post Quick Reports for Grayscale/Gamma and Color Gamut.

Ok, I am new using this editor for posting here so I will give it a shot. Let me know if there are any issues with the posts...

This should be the Color Gamut (I think that is the right name) PRE-CAL COLOR GAMUT1.jpg 74k .jpg file

This should be the GrayScale PRE-CAL GRAYSCALE1.jpg 91k .jpg file

I think I have set Black and White according to page 41 of the ChromaPure manual. I am using the AVSHD files available from here. One question on setting white (contrast). In order to check the "Light Output Target" I displayed a 100% white screen went into the Raw Data module and selected continuous measurement. I adjusted my contrast until the Y value was very close to 120 (I was assuming this measurement was the 120 cd/m2 that I was targetting). Is that right? I also then went to a checkerboard pattern of black and white and put the meter on a white square just to check to see if white was still as bright, it wasn't the exact same number but it was very close.

I checked that with this contrast setting the "just below white" bars were visible. Seemed fine.

The third check was that the color of white is neutral. This is where I have stalled and could use some help. I am assuming that getting in and adjusting White Balance (which I can do on my TV) as per page 44 will probably also mess with the color gamut? But that is just a newbie assumption. Any guidance would be appreciated.

The real question I have is about Step 6 on page 44 (ADjust your display's white balance controls". As I understand it different panels use different names for this "feature". I think I have two options (not sure if they are additive or mutually exclusive). I can modify Gain/Offset or use 10p White Balance. First, which one should I use? Second, HOW do I use them? I can see from my GrayScale at 80% that Red needs to come up and Blue needs to drop but I don't know what adjustments to make to do that and I don't really want to flail around blind!

Thanks!
H
Edited by henryoh - 1/11/13 at 7:52am

Your greyscale need adjusting so that the blue level is lower and the red level is brought up. Depending on how many points you have for adjustment this might be a matter of finding the best compromise (somethings Pros tend to be better at than us mere mortals ). You may find that you then need to lower your main contrast if you then suffer from clipping in the red channel as it looks like you need to increase red gain by a fair bit.

Once your greyscale is down to 6500K then you may find it effects your colour gamut too, but you could try measuring at 75% rather than the 100% as many displays aren't very linear: Better to get 75% spot on and let 100% be a little further off if you have to compromise as there is little 100% in real content, but 75% is much closer to typical content levels.

Hopefully Tom will add to this, but just to give you a start.

Thanks.

Doing a little more reading and thinking leads me to a theory that I want to test with the experts.

As I understand it adjusting Offset changes the contribution of each color at the "dark" end of the grayscale (is that 10% - 50%)? Adjusting Gain changes the contribution of each color at the "white" end of the grayscale (is that 50-100%?)

Then adjusting a 10p white balance I have interval 1 through 10 inclusive, which I THINK would line up with 10% through 100% grayscale respectively.

Looking at my grayscale quick report I think red needs to bump up, across the whole grayscale, blue needs to come down and green is about right.

Would it make sense to use Offset and Gain to move up red and move down blue on a wholesale basis? Then I could measure grayscale again and see if I need to use 10p to fine tune a given point? It seems likely that 10% gray will need a little extra tweaking because it is further out than other points...

I always describe these two (Cut or Offset and Gain or Drive) controls to customers as a slope-intercept system (going back to High School geometry) with Offset being the intercept and Gain being the slope. They are highly interactive, so there is a fair amount of back and forth. Typically (not always) Gain is adjusted first at 80% and then Offset is adjusted at 30%.

Generally, with a 10 (or 20) point adjustment system you want to first get the Offset & Gain controls for the best overall balance, and then tweak with the 10 point adjustments. CAUTION: The 10 point adjustments usually do not line up correctly - so the 50% adjustment may actually be adjusting 38%! Some experimentation is required to find the right adjustment for a given percent white. Also, avoid extreme adjustments here, as you can introduce unintended effects at points not covered by your pattern generator. Things can vary from manufacturer to manufacturer, so it is helpful if you identify the display when seeking specific advice.

If I interpret that correctly, then I would pull up an 80% gray screen. I would adjust Gain to try to level out RBG. Meaning for my grayscale that needs red up and blue down, I would increase R-Gain from where it is now and I would decrease the B-Gain numbers from where they are now. I could do this with a continuous read in Raw Data and try to get all three primary colors to 100%. Then I would pull up a 30% gray (according to your note) or perhaps 20% gray (according to the ChromaPure manual) and this time adjust Offset.

Then I can measure across the grayscale and plan from there....

Sounds like a plan. I didn't realise you had a 10 point adjustment, so using the 2 points first to see where it gets you is a good start. You could be lucky and get it pretty close without spending a lifetime on it. I'd only progress to the 10 point if you have problems with a particular point with a large error, but take note of the comments above regarding small changes (large changes can cause banding and other issues, so best to leave some error and not introduce a side effect).

Watch the videos, try it on your system, and then ask questions if you can't figure it out. They aren't all exactly up to date but you'll get the idea.

white point (grayscale 2 point) - http://chromapure.com/movies/WhiteBalance/WhiteBalance.html

My apologies if my newbie questions are too basic or if I am wasting bandwidth here. If I am out of line please let me know directly and I will certainly try to further this more on my own.

I have used Gain and Offset to make a two point grayscale adjustment. Here is the new Greyscale quick report Jan 11 Grayscale1.jpg 91k .jpg file

I THINK things are generally looking much better, except at the 10%(and maybe the 100%?) point. I am thinking this means going into 10p White Balance and adjusting Interval 1. Does that make sense?

If I can get the 10% point looking better would this level of error be reasonable or should I be striving for even lower dE's?

There's no need to worry about any dE below 2.0. 100% is fine. Use the 10-point control to get 10% a little better and call it a day with the grayscale. I would try to get the gamma a little higher, somewhere in the 2.2-2.4 range. Adjustments to gamma will affect grayscale, so this will have to be readjusted.

Tom, thanks.

Reading up on how to move gamma around seems to be changing brightness or contrast on most panels. I would assume to increase gamma I need to increase either/both of those. The question I have is if I do that I will end up with peak white (might be using that term wrong) over the suggested 120 cd/m2 (I think those are the units). Am I missing something? Is this just one of those compromises that needs to be made? If so, which is more important bumping up gamma or maintaining Peak White at 120?

What display are you working on?

Samsung ES8000.

Another ES8000 specific question is that I plan on turning on the Eco Sensor function that drops Backlight in response to ambient lighting....I figure I will keep Backlight set relatively high (it can go up to 20) with the Eco Sensor allowing it to go as low as 5 or so, this is based on where the Backlight can be set to minimize flash lighting for day and night conditions. I know from a purists standpoint it would be best to just have Night and Day settings, but for my panel I would have to go into the service manual to enable them, and I am too much of a chicken to do that....Given all that I am trying to figure out the best static (Eco Sensor off) Backlight setting at which to calibrate the set....I guess I could just try it at different ambient lighting condistions and figure it out....Any advice out there would be appreciated!

Don't turn on the Eco sensor would be my first advice. My second piece of advice is to not raise the backlight control. In fact, it should be as low as possible consistent with adequate light output. Otherwise, you'll ruin the black level.

You can adjust gamma on this display by, first, just selecting the gamma preset that is the most accurate. That may be enough. If it isn't you can make spot corrections using the 10pt grayscale control. Adjust Green up or down to change gamma at the desired points and then readjust red and blue to maintain white balance.

Is your advice on the Eco Sensor for viewing purposes or for calibration purposes or both?

If for viewing purposes would you still advocate that even in a room highly variable lighting conditions? I havent calibrated my set yet so perhaps it will make a big difference by having it set up better, but so far I have found that having the Eco Sensor on gives me pretty good results in the middle of the day and at night...
Edited by henryoh - 1/12/13 at 3:40pm