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post #1 of 23 Old 10-07-2013, 05:55 AM - Thread Starter
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I have a situation about which I am totally confused. About a year ago I calibrated my home TV using an X-Rite i1Display Pro and a notebook computer running ColorHCFR. The notebook computer I was using did not have a HDMI port so I used the AVSHD 709 disk and my Sony PS3 as a calibration video source.

About two weeks ago I decided to check and update the calibration of the TV. My current notebook computer has a HDMI port. I am also running ColorHCFR on it. I started out using the same AVSHD 709 disk that I had been using. Then just for grins, I decided to try and using the built-in images in ColorHCFR. Much to my surprise while the red and green levels were normal, the blue level was way high across the board by 50 to 100% high. The computer is a Dell M6700 and is still under warranty. So I started a dialog with Dell tech support about this issue. The high blue levels also showed up on the internal screen and also on the VGA port using a separate monitor. Dell decided that the video card was bad and Friday they changed it out.

Unfortunately that did not solve the problem. I then had an idea. . I have at home a Samsung MultiSync monitor which has a HDMI port. Using a third computer as a tester, I performed measurements using that monitor with the M6700, my home computer and also my blue ray player. I also tested the tester computer (Dell M6300). My home computer tested normal, the M6700 and the Blu-Ray player both showed high blue levels. The tester computer showed normal. I am now totally confused.

At this point I do not know if I have a problem with my i1Display Pro colorimeter, or have issues with the M6700 and my PS3. Can someone way in on this and make some suggestions?

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post #2 of 23 Old 10-07-2013, 04:31 PM
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I'm also quite confused at your description.

Perhaps if you could break down, in a list, which combinations of vid inputs and displays yielded normal or too blue.

i.e.

Laptop A -> TV : blue
Laptop B -> TV: blue
Laptop A screen: normal
PS3 bluray -> TV: blur

etc.
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post #3 of 23 Old 10-07-2013, 04:58 PM
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Welcome to the world of imprecision in computer video. It's a mess and you will NEVER fix it with any amount of work or experimenting... but if you did fix it by some miracle, the first time there's an update for your video board, you'll very likely get bad results again.

Your PS3 is accurate... highly accurate actually. Your computer is not and I would NEVER recommend using a computer as a test pattern source with ONE exception...

Dr. Ray Soniera sells software called DisplayMate that runs on Windows. He stores his test patterns as equations (not as image files). When the computer "solves the equation" to display a particular test pattern, Display Mate sends the result directly to the video buffer, completely bypassing Windows image/video processing AND bypassing the video board completely. That is the ONLY reliable way to get a computer to send the right thing to your monitor. The idea of an HTPC is a pleasant idea, but the reality is something entirely different than you might think.

There is a thread on AVS somewhere that reports disc players and game consoles that produce accurate HD images... the PS3 was about the first accurate Blu-ray player on anybody's list. And it remains accurate up through current versions. Oppo disc players are also accurate, and a couple of years ago, there was one Panasonic model on the list. I haven't seen that list in quite a while. But computers just aren't going to give you accurate images without something like DisplayMate's imaging solution that bypasses everything bad about computer video.

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post #4 of 23 Old 10-07-2013, 05:14 PM
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Originally Posted by Doug Blackburn View Post


Dr. Ray Soniera sells software called DisplayMate that runs on Windows. He stores his test patterns as equations (not as image files). When the computer "solves the equation" to display a particular test pattern, Display Mate sends the result directly to the video buffer, completely bypassing Windows image/video processing AND bypassing the video board completely. That is the ONLY reliable way to get a computer to send the right thing to your monitor. The idea of an HTPC is a pleasant idea, but the reality is something entirely different than you might think.

Can you give a colorimetrically relevant example of where a modern video card would be a weak link in generating a signal?
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post #5 of 23 Old 10-07-2013, 08:15 PM
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Originally Posted by spacediver View Post

Can you give a colorimetrically relevant example of where a modern video card would be a weak link in generating a signal?

The list of "enhancements" nvidia and AMD have come up with are extensive.

Nvidia has something called digital video vibrance.
AMD defaults to have flesh enhancement enabled.

There are also the range issues between RGB and YCC. In the past they haven't even always done the YCC conversion correctly, causing chromaticity shifts (All though that bug has been fixed). Also just about any application could have modified the computers gamma ramps and/or if you'd gone through the calibration wizard on the machine.

It's not that a computer can't be configured to be accurate, it's just that you can't trust it to be accurate. It takes a good amount of knowledge and an attention to details to ensure that you are getting the correct output.
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post #6 of 23 Old 10-07-2013, 08:46 PM
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From what I understand, it's not as complicated as it sounds. Keep everything at default (see image below), make sure you haven't loaded up a color profile on boot, and make sure that whatever software you're using to display patterns is using the native color space (something that isn't ICC aware should do this, if I'm not mistaken).

But agreed, many non savvy users will not think about these issues.




more importantly, if you really are going to use your windows system as a source for enjoying calibrated content, wouldn't it make sense to make calibration measurements in the same environment that the content is being generated? Assume for argument's sake that there is unavoidable image processing going on that taints the native color space, adds invisible gamma luts etc. And assume that displaymate bypasses this. And suppose you calibrate the display, using its OSD, based on patterns generated by displaymate.

Now when you watch some content back in the "tainted" environment, the content will not be properly shown, as it is based on a set of adjustments to a different reference.
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post #7 of 23 Old 10-07-2013, 09:44 PM
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Thanks, Doug - informative as always.

That leads me to a related question. What about test images generated via a media player? I used test images stored on my computer and fed to various streamers as a network share to do some calibration with a meter. Are they as bad as computers or is the lack of a video card and associated processing a game saver?
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post #8 of 23 Old 10-08-2013, 12:16 AM
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Originally Posted by Matt L View Post

Thanks, Doug - informative as always.

That leads me to a related question. What about test images generated via a media player? I used test images stored on my computer and fed to various streamers as a network share to do some calibration with a meter. Are they as bad as computers or is the lack of a video card and associated processing a game saver?

Media players can have the same kinds of video issues as computers can. And their firmware updates many times either don't correct existing issues or introduce new ones...

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post #9 of 23 Old 10-08-2013, 08:56 AM
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Greetings

Just ask anyone that uses that Western Digital Media player as a signal generator. When they buy it under the DPG name, they are usually told to never update the firmware. Because once it gets done, the so called "reference" level performance is lost forever. FW cannot be rolled back.

If they really want to use a $700 signal generator as a media player, they should just go buy the stock WDTV for $100 and use that.

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post #10 of 23 Old 10-08-2013, 09:09 AM
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The iScan Duo can be used at pattern generator (even % RGB Triplet) and can be found around $650-$800..

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post #11 of 23 Old 10-08-2013, 12:20 PM - Thread Starter
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I have discovered what some of my issues were. On the M6700 notebook I am running VMware Workstation with most of the software installed on various virtual machines. This includes ColorHCFR. I have discovered that when VMware Workstation starts a virtual machine it hoses the color balance not only for the virtual machine screen but also for the host operating system. This distortion persists even when all virtual machine have been shut down. The only way I have found to reset it is to reboot the computer.

So now that I have discovered the root cause of the high blue levels, I really need to go back and retest every thing once more.

As far as calibrating a computer, I have been successful in calibrating the M6700 (without virtual machines). One big issue with Windows and video calibration is that the color management system is not applied across all programs. The color management is only used by programs that that are "color aware". So for example you have a color profile loaded. That profile is not used to display the desktop. It will be used by some web browsers, and I believe that it will also be used by the windows media center. However windows media player will not used the profile.

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post #12 of 23 Old 10-08-2013, 01:39 PM
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I just decided to purchase software and a meter. I have been debating on doing this for about a year now. I have been reading everything I can get my hands on before I do a thing.
There seems No absolute correct way to go about this. Everytime I think I have a handle on it and ready to go into battle someone chimes in and says that 's not right. There are even discrepencies between calibrator's.. I am having a real hard time getting a good grasp on this because of the constant changes of right and wrong on a weekly Basis. Is there any place a beginner could get some good absolute Basic information and set rules and steps to start at.
I have just never seen this much doubt and second guessing in any Audio/Video side of any buisness.
Now rember that I didn't decide to do this just overnight. I have been reading and studying on these forums for a while.
I can't even sort out right from wrong at the moment. I was going to watch Michael's Video's but you have to have a YouTube Account. I have not checked with him to see if there is any other Avenue of using his video's without YouTube.
Somewhere there has to be some Rock Solid Info on CMS, Gamut, Low Drive Color adjustment, and so on.

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post #13 of 23 Old 10-08-2013, 01:53 PM
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Quote:
Originally Posted by Michael TLV View Post

Greetings

Just ask anyone that uses that Western Digital Media player as a signal generator. When they buy it under the DPG name, they are usually told to never update the firmware. Because once it gets done, the so called "reference" level performance is lost forever. FW cannot be rolled back.

If they really want to use a $700 signal generator as a media player, they should just go buy the stock WDTV for $100 and use that.

Regards

I'm one of those people, Michael. Since I got a Lumagen processor, life is MUCH easier!

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post #14 of 23 Old 10-08-2013, 02:18 PM
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Originally Posted by Glenee View Post

I just decided to purchase software and a meter. I have been debating on doing this for about a year now. I have been reading everything I can get my hands on before I do a thing.
There seems No absolute correct way to go about this. Everytime I think I have a handle on it and ready to go into battle someone chimes in and says that 's not right. There are even descrepencies between calibrator's.. I am having a real hard time getting a good grasp on this because of the constant changes of right and wrong on a weekly Basis. Is there any place a beginner couold get some good absolute Basic information and set rules and steps to start at.
I have just never seen this much doubt and second guessing in any Audio/Video side of any buisness.
Now rember that I didn't decide to do this just overnight. I have been reading and studying on these forums for a while.
I can't even sort out right from wrong at the moment.

You have to take the conflicting statements in context. Many times these are due to the behavior of the displays that are being calibrated. General goals of calibration are the same from display to display. It's how you get to the goals that is different.

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post #15 of 23 Old 10-08-2013, 02:30 PM
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Quote:
Originally Posted by Glenee View Post

I just decided to purchase software and a meter. I have been debating on doing this for about a year now. I have been reading everything I can get my hands on before I do a thing.
There seems No absolute correct way to go about this. Everytime I think I have a handle on it and ready to go into battle someone chimes in and says that 's not right. There are even descrepencies between calibrator's.. I am having a real hard time getting a good grasp on this because of the constant changes of right and wrong on a weekly Basis. Is there any place a beginner couold get some good absolute Basic information and set rules and steps to start at.
I have just never seen this much doubt and second guessing in any Audio/Video side of any buisness.
Now rember that I didn't decide to do this just overnight. I have been reading and studying on these forums for a while.
I can't even sort out right from wrong at the moment.

Greetings

I would think a good place to start would be to see how the material is being taught at the professional level, then build on that.

After all, it was never supposed to be good practice/ideal to learn to drive a car with your parents or friends first before taking a driving course.

Of course it then depends on how serious you are and how you value your time. Professional level training is available anywhere from $1600 and travel costs to something as cheap as $100-$150 ... and paying more does not mean it is better.

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post #16 of 23 Old 10-08-2013, 02:36 PM
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Greetings

This hobby is funny sometimes because it can get like anyone who owns a TV is an expert at setting it up. I come from a traffic engineering background and I got that for years. People think they can drive a car so that makes them a traffic engineer too. Uh ... no. I'd get them yelling at me day in and day out wanting signs here ... traffic signals there ... and when you came back to them with the objective analysis ... contrary to what they wanted ... they often said F-you and hung up. frown.gif

Explains why I am not a traffic engineer anymore. smile.gif

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post #17 of 23 Old 10-08-2013, 03:28 PM
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What I am having trouble finding are the good Solid Foundation Building Blocks. The absolutes, the rules you know to be true and never depart from. These don't seem to exist in this Video World of Calibration, or at least I am having one hell of a time finding them.
The case may be that No One knows them Yet.
There is a Old Saying that say's : If you think you know something as well as you think you do,try teaching it to someone who doesn't understand the first thing about it. Until you can do this there a lot of holes and voids in your expertise.
I am not ragging on anyone, I'm just saying I haven't found this yet in one Hell of a lot of research.
Michael I watched a couple of your Video's and thought they were well presented and explained, as a matter of fact, the best I have seen so far.
Just my Thought's
Best Regards to All,
Glen

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post #18 of 23 Old 10-08-2013, 03:37 PM
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All the hard and fast rules are abstract and unrelated to the display you are actually calibrating.

Because the processing chain inside the display is what creates the rules for what you should do for any given display, any given display could require a different set of procedures.


The basics are pretty consistent, exactly how you go about it may be different.
Brightness and contrast first.
Then do cuts and gains
Double check bightness and contrast.
Do multipoint grayscale if available.
Do CMS.
recheck everything.
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post #19 of 23 Old 10-08-2013, 04:21 PM
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Joe Kane is a much better source of specifics about what PC video systems do to video to make it inaccurate. He worked with a manufacturer for a LONG time to make one of their premier boards accurate. Everybody felt like they had accomplished a near-miracle and congratulated themselves for finally getting rid of everything the board (and firmware) were doing that made the video change.

Flash forward several months and the first firmware update released for the board ruined the video accuracy in SPITE of the manufacturer trying to maintain accuracy.

You are WAY naïve if you think all you have to do to get accurate video from a computer video system is leave things at default and not enable features. That's nothing but wishful thinking with no basis in reality. Joel touched on some of the issues. Joe Kane will tell the story of his experience in a private conversation, but I don't think he has written about it.

Dr. Ray Soniera would not have bothered using equations for his test patterns if there was ANY easier way to display accurate test images from computers.

You also have to deal with things the Operating System might do that are outside anything the video board itself has done. I've seen HTPCs updated from Windows XP to Windows 7 and the video changes. And it has nothing to do with any settings you can "touch" with any O/S settings.

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post #20 of 23 Old 10-08-2013, 04:59 PM
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Interesting. I'm not throwing out these claims as absurd, but it would be nice to have some specific details about what sort of problems we are talking about.

For example, I've measured my primaries using an i1 pro, rendered through HCFR on windows XP, and the chromaticity matches remarkably well with other professional researchers' measurements on the same monitor.

From one of the studies I'm referring to:

"Stimuli were generated on a color video system consisting of a Macintosh Power PC 7500 controlling a calibrated Sony GDM-FW900 Trinitron Color Graphic Display."

Another study, run by the National Information Display Laboratory, measured chromaticity of the primaries that also matched my data (although for red, they tabulated it as x = 0.602 and y = 0.344: I'm assuming the 0.602 is a typo and should read 0.62, as all the other values they listed in that table match almost perfectly with my measurements and the measurements of the researchers in the first paper I mentioned.) From this second paper:

"All measurements will be made with the display commanded through a laboratory grade programmable test pattern generator. The system will be operated in at least a 24 bit mode (as opposed to a lesser or pseudo-color mode) for color and at least 8 bits for monochrome."

So we have three different sets of data, at least one of which can be considered reference, and whose primaries match up almost perfectly.

From this, I can be fairly confident that at least on my system (XP, nvidia geforce GTX 660, default settings), there is no gamut correction being applied.

So I'd be very curious to find out what other sorts of alterations are potentially introduced into the pipeline, whether through noisy processing mechanisms, or deliberate (but invisible) alterations to the LUTs, and whether these issues exist for modern video cards.
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post #21 of 23 Old 10-08-2013, 07:19 PM
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Originally Posted by spacediver View Post

Another study, run by the National Information Display Laboratory, measured chromaticity of the primaries that also matched my data (although for red, they tabulated it as x = 0.602 and y = 0.344: I'm assuming the 0.602 is a typo and should read 0.62, as all the other values they listed in that table match almost perfectly with my measurements and the measurements of the researchers in the first paper I mentioned.) From this second paper:

"All measurements will be made with the display commanded through a laboratory grade programmable test pattern generator. The system will be operated in at least a 24 bit mode (as opposed to a lesser or pseudo-color mode) for color and at least 8 bits for monochrome."

So we have three different sets of data, at least one of which can be considered reference, and whose primaries match up almost perfectly.

From this, I can be fairly confident that at least on my system (XP, nvidia geforce GTX 660, default settings), there is no gamut correction being applied.

So I'd be very curious to find out what other sorts of alterations are potentially introduced into the pipeline, whether through noisy processing mechanisms, or deliberate (but invisible) alterations to the LUTs, and whether these issues exist for modern video cards.

Actually, if you read down the NIDL .PDF, to page 49, they measured x,y coordinates of the primaries a number of times over a 2-month period. At no point did the x value for Red exceed .6110. So it probably isn't safe to assume they printed a typo for .62...

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post #22 of 23 Old 10-08-2013, 07:54 PM
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yep, I noticed that. The thing is, those measurements were taken with the color temperature at 9300K (based on the description of the reset function). I found that confusing, since the last table of the paper (bottom of page 50), the color coordinates for 9300K don't match the table on page 49.

I do wonder what the values on table II.22.1 (top of page 47) are based off of.

For reference, here is the table from page 47, and below it is the data from the other paper. At the bottom is data from my own measurements. This is what led me to believe it was a typo, but I could well be wrong.

NIDL:



Teller et al. (2004)




my data:

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post #23 of 23 Old 10-08-2013, 08:20 PM
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actually, I just noticed that the u' v' coordinates are given in that first table. I just calculated the transformation to x y, and it turns out that the two coordinate pairs match each other. It's possible they made a data entry error in the coordinates before they calculated the different color space coordinates, but it's also possible that no error was made at all.


edit: I also just noticed that the top table has a listed color temperature of 9652K.
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