Film-Tech Forum ARCHIVE: Real-D ghosting

This is topic Real-D ghosting in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Thomas Pitt (Member # 4322) on 12-25-2010, 06:43 PM:

The last few times I have been to the Bradford Cineworld to see a 3D movie, there was ghosting between the left and right eyes - particularly on high contrast scenes such as white text on a black background. Wasn't quite enough to spoil the 3D effect, but it was noticeable during the film.

This ghosting effect happens both in their Delux screen and in the other auditorium they have upgraded for Real-D. I've never seen ghosting this bad in other Real-D installations, and it's odd that the ghosting occurs on both screens in the same way.

Anyone have any ideas what would cause noticeable 'ghosting' on Real-D movies, and what would cause the same effect to be duplicated across two screens?
Screen not 100% reflective? Defective glasses? Projector lag?

Posted by David Zylstra (Member # 4230) on 12-25-2010, 08:46 PM:

On our series 1 machines there was some tweaks the service company and RealD came up with to reduce ghosting - there was a marked difference before and after, the ghosting was originally more pronounced on one eye (if my memory is correct - it has been 2 years since they tweaked it).

It is also possible they are showing a non-ghost busted copy and/or do not have ghost busting turned on in their servers.

Posted by Robert D Hall (Member # 5674) on 12-25-2010, 09:32 PM:

I would bet that there sever has not been setup for ghost busting or is not turnd on like david said. When we first started getting non-ghost busted prints our Dolby sever had to be setup the do the ghost busting.

Posted by Carsten Kurz (Member # 5396) on 12-30-2010, 06:31 AM:

With polarizing 3D systems, it's always a combination of issues - polarization efficiency of Z-Screen, screenquality , glases, seating, and Z-Screen settings.

On a typical Real-D installation, glases and screen are fixed issues (unless you have a very bad screen and opt to replace it). The Z-Screen switches light polarity dynamically - and you can adjust the timing for this device to optimize ghosting.

Another issue is that until the End of 2009, special Real-D releases were available which had special 'Ghost-Busting' mastering applied. Now all servers have an option for internal realtime GhostBusting, available through a firmware update, so DCPs in general have no ghostbusting applied in the mastering. The operators should check wether the server firmware is up-to-date and wether the RealD-EQ has been activated to do real-time ghostbusting.

You can not solve all ghosting issues with these measures, but it seems you can get RealD to an acceptable level - unless you have a really bad silver screen.

- Carsten