Film-Tech Cinema Systems
Film-Tech Forum


Post New Topic  Post A Reply
my profile | my password | register | search | faq & rules | forum home
  next oldest topic   next newest topic
» Film-Tech Forum   » Operations   » Digital Cinema Forum   » Excessive noise/jitter Barco DP2K-12C (Page 1)

 
This topic comprises 2 pages: 1  2 
 
Author Topic: Excessive noise/jitter Barco DP2K-12C
Joachim Heden
Film Handler

Posts: 7
From: Malmö, Skåne, Sweden
Registered: Nov 2016


 - posted 06-14-2017 03:08 AM      Profile for Joachim Heden   Author's Homepage     Send New Private Message       Edit/Delete Post 
Dear all,

We have made a warranty claim on a Barco DP2K-12C due to excessive noise/jitter in the dark areas of the image.

We are getting some pushback on this from the Swedish importer / service company Videvox - basically they are saying the projector is within spec.

We have now benchmarked the projector against another DP2K-12C and the result can be seen in this video:

https://vimeo.com/221418661/12a2c514e6

The light engine and the ICMP have both been replaced - no change in the noise/jitter.

Has anyone seen this before? Any other thoughts on this?

Kind regards,

Joachim

Way Creative Films
Sweden

 |  IP: Logged

Carsten Kurz
Film God

Posts: 3786
From: Cologne, NRW, Germany
Registered: Aug 2009


 - posted 06-14-2017 05:09 AM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
Very basic idea - did you try a full clone from a 'good sample' to this projector?

Because, after the ICMP and Lightengine have been swapped - signalwise, this is a new projector. No idea wether powersupplies or EMI could also have this effect.

I guess I would bypass the service company and contact Barco directly about this.

- Carsten

 |  IP: Logged

Dave Macaulay
Film God

Posts: 2138
From: Toronto, Canada
Registered: Apr 2001


 - posted 06-14-2017 06:55 AM      Profile for Dave Macaulay   Email Dave Macaulay   Send New Private Message       Edit/Delete Post 
It's not entirely a new projector signalwise - the signals all go through the original backplane. I have replaced a couple of backplanes to fix image issues, but never have seen this noise problem.
The backplane is not super difficult to replace. Just make sure you move the "sim card" over!

 |  IP: Logged

Magnus Eriksson
Expert Film Handler

Posts: 120
From: Stockholm, Hägersten, Sweden
Registered: Jan 2011


 - posted 06-14-2017 08:45 AM      Profile for Magnus Eriksson   Email Magnus Eriksson   Send New Private Message       Edit/Delete Post 
I swapped that ICMP and light engine. And I swapped the back plane without success. And I work at another service company nowadays.
Hi Joachim [Smile]
Strange is that this noise also can be seen in other projector models. I have observed it on:
Barco: DP2K-12C, 15C, 23B and DP4K-19B & 32B
Christie: CP2210 & CP4220
NEC NC1200C
HDSDI/Enigma, IMB, IMS or ICMP in the projector makes no difference.
Choose test pattern "RGB-12bit-Shallow Horizontal Ramp" or "RGB-12bit-Full Horizontal Ramp" (Barco) and look from close distance on the left side of the screen (where gray goes to black).
Since it´s visible on all three brands I guess it´s a TI/DLP thing?
/M.E.

 |  IP: Logged

Joachim Heden
Film Handler

Posts: 7
From: Malmö, Skåne, Sweden
Registered: Nov 2016


 - posted 06-14-2017 09:12 AM      Profile for Joachim Heden   Author's Homepage     Send New Private Message       Edit/Delete Post 
Sorry, forgot to mention, the backplane has been replaced also - no difference.

Joachim

EDIT:

Hi Magnus,

Yes if you look closely, there is a hint if this noise/jitter in other projectors, but I think it should be obvious that our projector exhibits this FAR more than anything else - video link above.

If we put up a 4% white (very dark gray) on the whole screen, it's like standing in a blizzard.

Clearly, what our projector exhibits can not be considered normal...?

Joachim

 |  IP: Logged

Magnus Eriksson
Expert Film Handler

Posts: 120
From: Stockholm, Hägersten, Sweden
Registered: Jan 2011


 - posted 06-14-2017 10:06 AM      Profile for Magnus Eriksson   Email Magnus Eriksson   Send New Private Message       Edit/Delete Post 
Is the light (measured on screen) about the same on both sites? Same PCF used??
What happens if you use the same mcgd file on both? Or use nominal?
/M.E.

 |  IP: Logged

Mark Gulbrandsen
Resident Trollmaster

Posts: 16228
From: Bountiful, Utah
Registered: Jun 99


 - posted 06-14-2017 12:12 PM      Profile for Mark Gulbrandsen   Email Mark Gulbrandsen   Send New Private Message       Edit/Delete Post 
WOW! I have never observed that sort of noise in any S-2 NEC projector and I have quite a few NC-1200 under my wings, but mostly NC-2000's. It really is unacceptable IMHO.

Mark

 |  IP: Logged

Joachim Heden
Film Handler

Posts: 7
From: Malmö, Skåne, Sweden
Registered: Nov 2016


 - posted 06-14-2017 12:56 PM      Profile for Joachim Heden   Author's Homepage     Send New Private Message       Edit/Delete Post 
Magnus,
Yes measured light is about the same in both cases 14fl -- Also, the camera settings (aperture, iso, shutter angle, framerate) are all identical between the two captured sequences in the split screen video (and no image manipulation has been applied to match the images).
Joachim

EDIT:

Oh, and I should add -- the perceptual difference in real life is GREATER than what is evident from the split screen video.

J

 |  IP: Logged

Marco Giustini
Film God

Posts: 2545
From: Reading, UK
Registered: Nov 2007


 - posted 06-14-2017 01:58 PM      Profile for Marco Giustini   Email Marco Giustini   Send New Private Message       Edit/Delete Post 
this is very interesting. I have seen that noise before but not so severe to be honest.
As it's been said, new ICP, engine and backplane should have cleared it. The engine also includes new signal wires.

What about mains, interference from LPS or other devices on the machine? It'd be interesting to know what happens when you get the new projector, please keep us posted.

 |  IP: Logged

Joachim Heden
Film Handler

Posts: 7
From: Malmö, Skåne, Sweden
Registered: Nov 2016


 - posted 06-14-2017 02:04 PM      Profile for Joachim Heden   Author's Homepage     Send New Private Message       Edit/Delete Post 
Magnus, and anyone else following this thread,

Although the measured light on the screen is the same (give or take) your question got me thinking...

The only thing that is "unusual" about our setup is that the screen is very small, only 4,20m wide (this projector is being used in a post production environment) so we are running it with an 800w lamp dimmed all the way down...

This is all layman's armchair reasoning, but perhaps the projector doesn't "like" to be run at this low of a light output level... if the noise/jitter is somehow constant/nominal independent of the light output a higher light output would "drown it out"?

Does this seem at all plausible?

I guess we could try tomorrow to pop a 1200w lamp in and crank it all the way up, bring the screen levels down by throwing an ND filter in front of the lens and see what that does.

Does this seem like it would be worth a try?

J

 |  IP: Logged

Carsten Kurz
Film God

Posts: 3786
From: Cologne, NRW, Germany
Registered: Aug 2009


 - posted 06-14-2017 07:24 PM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
Well, normally: DLP noise is only strong in dark areas. From that follows, it is usually masked by it's low luminance for our eyes. If you raise the light level on the DLP, the noise luminance will rise as well, making the issue even more visible.

Again, try to do a full backup of this system, full clone from a 'good' system, and apply full clone to the problematic system, just to rule out weird configuration residuals.

But - 'real hardware' can be complex. It could be possible the lamp ballast is doing 'weird' things when running low, causing that noise, and that could vanish when you pull the current up, which would be no contradiction, but simply to opposing effects.

Do you have a luminance meter? Measure peak white when testing different setting.

From the video, it also occurs to me that while the noise level is higher, the noise frequency ('resolution')is lower on the bad projector (around a factor of two, I'd say). Are you sure the grey areas are within the same pixel area and have similar resolution?
Also, the 'good' projector is working on a perforated screen, while the 'bad' one on an unperforated. The perforation also masks the effect somewhat. That said, without being able to weigh in on luminance, camera settings, etc. the noise level on your system does appear excessively high indeed.

What types of lenses do both machines use?

- Carsten

 |  IP: Logged

Joachim Heden
Film Handler

Posts: 7
From: Malmö, Skåne, Sweden
Registered: Nov 2016


 - posted 06-15-2017 01:03 AM      Profile for Joachim Heden   Author's Homepage     Send New Private Message       Edit/Delete Post 
Dear Carsten,

In the video, both projectors display the same custom test pattern so yes, even though our screen is much smaller, the relative size of the samples are the same (same pixel density). I'm attaching an illustration of the test pattern indicating what the camera is shooting in both samples (please note that I've bumped up the contrast of the test pattern in this illustration for the purpose of clarity here)

So it is indeed strange, that on our projector, the "noise" seem to be "bigger". We will do a quick test this morning increasing the light output to see if this has any effect when the lamp/ballast is running at full capacity.

Kind regards,

 -

 |  IP: Logged

Joachim Heden
Film Handler

Posts: 7
From: Malmö, Skåne, Sweden
Registered: Nov 2016


 - posted 06-15-2017 05:22 AM      Profile for Joachim Heden   Author's Homepage     Send New Private Message       Edit/Delete Post 
UPDATE:

Increasing the light output so that the lamp/ballast is operating att full power does not make any difference.

We will start looking into all the other suggestions in the thread as they apply, but it seems we might have a lemon on our hands, and the warranty claim should proceed.

Kind regards,

Joachim

 |  IP: Logged

Carsten Kurz
Film God

Posts: 3786
From: Cologne, NRW, Germany
Registered: Aug 2009


 - posted 06-15-2017 06:12 AM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
Hmm. Could you create a test pattern with low greys, and some lines/ single pixel patterns in it? Or place the camera on a tripod and take two pictures of exactly the same area, one with the grey patterns, one with some lines (e.g. Barco Focus pattern)?

I'm not an expert on DLPs, but in general, DLP dark noise is not actually noise, but intentional dithering. This, however, should always take place on the pixel level. It shouldn't combine pixel clusters. So, by overlaying/comparing clearly visible single pixel structures, you should be able to find out wether this is actually single pixel noise/dithering.

The way DLP works, I would think that things like thermal noise etc. should not be able to excite the micro mirrors enough to become visible. They need a hard kick to move.
As such, I would think any noise must be introduced by some intention e.g. from the formatter boards, like the mentioned dithering. But again, I am not an expert, and DLP/formatter power supply or noise on control lines could possibly also cause this.

You can also zoom wide to maximum to enlarge everything as much as possible.

- Carsten

 |  IP: Logged

Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12213
From: Annapolis, MD
Registered: Dec 1999


 - posted 06-15-2017 07:17 AM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
How similar are the software versions in the various test projectors? Newer isn't always better either.

 |  IP: Logged



All times are Central (GMT -6:00)
This topic comprises 2 pages: 1  2 
 
Post New Topic  Post A Reply Close Topic    Move Topic    Delete Topic    next oldest topic   next newest topic
 - Printer-friendly view of this topic
Hop To:



Powered by Infopop Corporation
UBB.classicTM 6.3.1.2

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.

© 1999-2018 Film-Tech Cinema Systems, LLC. All rights reserved.