Film-Tech Forum ARCHIVE: IMS2000 (and IMS1000) with HDMI settings

This is topic IMS2000 (and IMS1000) with HDMI settings in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Steve Guttag (Member # 268) on 09-22-2016, 02:26 PM:

What have you all found when using a Doremi (Dolby) IMS2000 or IMS1000 with its HDMI port for obtaining the "best" picture?

That is, the IMS converts everything to XYZ color space so one would want their projector set to "DCDM XYZ" for that but I've noticed that the contrast is awful using everything at the "default" settings.

I looked at it with both a Blu-ray source and with a laptop (Apple). There were no "blacks" just greys.

The IMS has settings for color space (including auto...which since the source could be YCrCb or RGB would need to stay at auto) and one to play with the degamma...the choices are REC709 or DCI.

One can also modify the image on the ICP end of things to also alter gamma, input/output offsets as well as the transfer function.

It would be nice if they were ideal out of the box but that is, apparently, not the case. They also buried the IMS input controls with their "wonderful" web gui so I missed the degamma options on my first pass at it.

So what have you all found with it? Has anyone used test signals to really dial it in properly and are willing to share their results?

Posted by Marco Giustini (Member # 4544) on 09-22-2016, 02:58 PM:

it's the usual mess as every HDMI device is a world on its own. I recommend you use AVS-HD to check the black and white levels, I am not sure the IMS will adjust the levels so they matches with the projector's - the projector definitely does not.

I've found many times that none of the HDMI black level options- if available - give correct black levels and you have to play with the brightness/contrast controls.
Also found gamma sometimes completely off.

My advice - if you can - is to avoid the XYZ conversion. Leave the colour space as it is and let the projector handle that.

Posted by Steve Guttag (Member # 268) on 09-22-2016, 04:36 PM:

The IMS ALWAYS converts to XYZ. You can tell it what the source is or let it decide. The only other adjustment is degamma. The choices are REC709, DCI and "Custom" where you can play with the number.

I should point out that I've asked Doremi/Dolby and they acknowledge a problem with its contrast ratio and that its workaround, for now is to tell it to use YCrCb (So I hope most computers can deal with that).

Note, I did deal with it a bit on the projector side of things by adjusting the ICP directly on the input offset and coefficient on the CSC section.

Posted by Mark Gulbrandsen (Member # 72) on 09-22-2016, 05:12 PM:

No issues with HDMI on the SX-3000! Works perfectly. [Razz]

Posted by Steve Guttag (Member # 268) on 09-22-2016, 06:52 PM:

And amazingly enough, I didn't ask about it and your comment is of zero value, in this thread.

Posted by Alan Gouger (Member # 543) on 09-22-2016, 10:43 PM:

For black level if unity RGB ( full ) is not correct there was a RGB 10bit 16-940 ( limited ) in the ICP enigma control program.
With the IMS1000 I always used DVI when possible.

Posted by Dave Macaulay (Member # 813) on 09-23-2016, 05:06 AM:

Some projectors don't have DVI inputs.
You are screwed if you want "perfect" Rec709 images with the IMS I think. Doremi had a beta firmware version that made it better but i believe the changes were put in a released version. You could get decent contrast by changing the degamma setting but studio guys were never 100% happy.
We do what we can to convince production customers with a need for alternate inputs to find the cash and space for a projector with DVI inputs. A P model would be good... the cost is a nasty surprise though. The Alchemy does HDMI/DP better but an S projector with DVI would help.

Posted by Steve Guttag (Member # 268) on 09-23-2016, 07:23 AM:

Yes, the RGB 64-940 does help but it doesn't get it there...you have to do "more work" for it. Changing the gamma seems to overly saturate the colors before you get the contrast where you need it.

I think the short answer, for now, is it doesn't work properly. No doubt it is adequate for some but definitely not for others. I have it acceptable for now and Doremi/Dolby tell me that there is a fix in the works but I only believe that stuff when I actually see it. I've seen "fixes" take years or never to materialize.

Posted by Marco Giustini (Member # 4544) on 09-23-2016, 03:28 PM:

It's been a while since last time but I thought you could choose whether to convert or to leave the existing colour space.

Nice to know about that issue - would be nice to know from them officially. I do remember spending quite a lot of time trying to address HDMI colour issues with the IMS [Frown]

Posted by Mark Gulbrandsen (Member # 72) on 09-23-2016, 03:33 PM:

The real short answer is never install one of these pieces of crap and you won't have this issue. I know... there are certain instances where one is stuck with the thing.

Mark

Posted by Steve Guttag (Member # 268) on 09-23-2016, 05:38 PM:

Again, Mark; that is NOT an answer at all. I was attempting a discussion on the set up of a specific piece of equipment. I was not nor appreciate any solicitation of alternate equipment or even derogatory comments beyond first-hand knowledge of its problem and potential workarounds. This is an installed piece of equipment that I'm trying to get to perform as well as IT can. I don't have as much experience with it as I do other servers/IMBs so I was seeking some first-hand knowledge of it since others must have ventured before and there is no point in re-inventing the wheel.

Posted by Mark Gulbrandsen (Member # 72) on 09-23-2016, 09:11 PM:

I just take after you Steve.... [Razz]