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calibrating Eizo cg241w

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Ian Roberton
calibrating Eizo cg241w
on Jan 21, 2011 at 6:59:52 pm

Hi Everyone,

I am trying to set up a Smoke suite and I have a question about calibrating my 'broadcast' monitor. First off, I do not have a proper broadcast monitor -- nor will I ever have one. However, I do have a EIZO CG241W. I am trying to calibrate this so it can come as close to REC709 as possible.

1.) Does the EIZO remain calibrated only with a straight DVI connection between it and the computer.

2.) Are you supposed to follow the same routine when using SMPTE Bars on a LCD monitor in order to calibrate it?

I have attempted to do this using EIZO color navigator software and following along with Autodesk's Lustre Set-up Instructions for EIZO monitors to emulate HD.

Here was my workflow:

- Calibrate EIZO with the puck and with a direct DVI connection between the monitor and suite.

- After calibration, take the HD-SDI signal from the Kona3 pass it through a Blackmagic HDLINK converter to convert it to DVI.

- Go from HDLINK DVI Out to EIZO so I can monitor the Kona 3 output.

- So I do this and then throw some SMPTE bars on to the EIZO and the pluge is way off. I then enable the blue only channel on the HDLINK and my colour bars are off.

Ultimately, how am to calibrate the EIZO monitor so I can use it to colour grade?


(Mac 10.6.4. Kona3. 16 gig ram.)


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Hans von Sonntag
Re: calibrating Eizo cg241w
on Jan 25, 2011 at 10:08:30 am

This is an interesting topic I've been dealing with quite a long time. This is what my findings are:

1. The headline to all of this is: All displays the audience is using are different from each other, none is calibrated. So even if your display were THE ultimate Rec709 display (e.g. Cinetal) people would see your content with different gammas and matrices.

2. Nonetheless, it's valuable to know that your display in not "way off". And, of course, for collaboration with others it makes sense to review the pictures with the same colours and contrast.

3. In the beginning it's good to know what Rec709 actually is. The technical specification of Rec709 can be read here: http://en.wikipedia.org/wiki/Rec._709

This is the part that interests us:

"Rec. 709 is written as if it specifies the capture and transfer characteristics of HDTV encoding - that is, as if it were scene-referred. However, in practice it is output (display) referred with the convention of a 2.4-power function display [2.35 power function in EBU recommendations]. (Rec. 709 and sRGB share the same primary chromaticities and white point chromaticity; however, sRGB is explicitly output (display) referred with an average gamma of 2.2.) [5]"

4. From this excerpt you can see that Rec709 is basically sRGB with a gamma of 2.4/2.35. Your Eizo display should have an sRGB default you can reset to. By doing so with a gamma of 2.35 set in your graphics driver you are pretty close to Rec709 IF your hardware works correctly. Assuming that you don't use consumer grade stuff in your box I guess you can rely pretty well on these settings.

5. You can use Eizo's calibration tools hat comes with the monitor (I'm talking about the calibration mouse and the Eizo software) to fine tune the Rec 709 setting. Personally I never got satisfying results. On the contrary, I must say.

This are the findings I have with our Eizos:

- An older Eizo CG 240 from 2005 has a slight green cast in the shadows that cannot be compensated meaningfully with the calibration tools. The best result is to set it to default sRGB, gamma 2.35 and live with the slight green cast.

- A 1 year old Eizo CG 242 has a much better picture (no wonder) and no cast in the shadows. Calibrating it to Rec709 with the Eizo tools makes it less vibrant, almost dull while the colours are un-touched. This may be correct by engineering criteria but is not desirable for working with video.

7. In doubt rent a Cinetal for reference and compare it with your displays. If your display is way off even in default sRGB and gamma 2.35, e.g magenta cast in the whites, green mids, funky blacks, etc... your display is lost, IMHO. For us the internal sRGB and gamma 2.35 were the closest match. For my taste the Cinetal is a great monitor but still a bit on the dull side due to the LCD technology.

6. The best thing is to add a good consumer display, such as a Panasonic plasma, to your mix. Such a display may be slightly off in the colours but has the punch you miss with your LCDs. It gives you a good reference in this regard. Many high-end grading suites use Panasonic plasmas.

8. Finally, the viewing environment is very important. White walls, tungsten lighting, etc... are counter productive. Your graded footage may look warmer afterwards than anticipated. Paint your walls dark grey, add a white screen behind your display and light it with a daylight source to match the whites of your display.


Hans


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Ian Roberton
Re: calibrating Eizo cg241w
on Jan 28, 2011 at 3:09:50 am

Thanks for the great answer!

It definitely gives me a lot to work on...


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Steven Dent
Re: calibrating Eizo cg241w
on Feb 20, 2012 at 9:04:27 am

"From this excerpt you can see that Rec709 is basically sRGB with a gamma of 2.4/2.35. Your Eizo display should have an sRGB default you can reset to."

Thanks, that's an awesome piece of info which I never knew.



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