Carsten wrote:You definitely need to play these files on a calibrated DCI projector. Don't count on color fidelity with software-only players.
- Carsten
Done! The subtitles come out just as green on the cinema screen (Barco DP2K-12C projector) as on my PC-screen. I've also had a friend verify my DCP's on a calibrated DaVinci Resolve workstation.
Everything I've said so far seem to hold true.
There really must be a bug in DCP-o-matic that makes the subtitles come out green. It only happens when burning in the subtitles, and when the master is another DCP. It doesn't happen when you go from DVD, Blu-ray or other RGB source.
Done! The subtitles come out just as green on the cinema screen (Barco DP2K-12C projector) as on my PC-screen. I've also had a friend verify my DCP's on a calibrated DaVinci Resolve workstation.
Thanks for all the work you have done to investigate this! Have you been using DoM 2.9.0 for these tests?
My latest tests yesterday were made with version 2.9.12.
I think I originally must have tried version 2.9.0, but moved on to test versions. My first example in this thread shows a subtitle before the improvement of outline rendering. It's not so obvious that it's green, since the outline "eats up" most of the letters, but you can still see it if you look for it. I didn't notice it at first, though.
I just made 3 trailers with burnt-in subtitles, and played them back both in FINAL DCP Player and on CHRISTIE/DOREMI combination.
One trailer was a very high contrast made from original Technicolor 1963 surviving print
Second trailer was too bright for my taste for that specific movie from 1974.
Third trailer was for a dark dense material from opera production, originating on HD video circa 2012.
On the software players the third trailer had a very pronounced greenish tint
but not the first and the second.
On a hardware projector/server the third trailer still has some slightly greenish tint to the subtitle,
But the two others were just fine.
With burned-in subtitles, you can also check with VLC. Open the MXF in VLC, make a snapshot with VLCs own snapshot function (set to PNG, preferable). Upload some examples to the forum.
I remember Carl applied some changes to burn-in subtitles color conversion when the cyan-bleeding occurred recently.
As a matter of fact, there is a lot of discussion going on about proper color rendering of subtitles, both TimedText and PNG. Some aspects are not properly standardized, that means, subtitle colors are rendered differently on different servers/projectors.
This doesn't seem to bother many people, as long as the subs are readable, few care wether it's in a darker or brighter yellow.
Of course, this should not be an issue for burn-in subs.
Try to create an RGB still with a full white (255,255,255) background for encoding, and burn in some text with 255,255,255, then watch for the text in the MXF/J2C created by DOM.
When I do that on my (OS X) machine and open the resulting snapshot in PS, I get the same pixel value for background and burned-in subtitle color.
I was never able to see MXF files created by DOM in VLC on my Mac. (MacPro 1.1 3GHz x 2 four core processors, 16 Gb RAM, AMD 67xx Video Card, Mac OS 10.10.3). And I don't know why. On the other hand PC version of VLC running in VM Fusion 8/Win7 Ultimate 64 bit on the same machine plays them fine.
Since my clientele are the cinematheques crowd, yellow subtitles are frowned upon. I am using grayish white (RGB 233.233.233).
Carsten wrote:Try to create an RGB still with a full white (255,255,255) background for encoding, and burn in some text with 255,255,255, then watch for the text in the MXF/J2C created by DOM.
When I do that on my (OS X) machine and open the resulting snapshot in PS, I get the same pixel value for background and burned-in subtitle color.
Sure, with an RGB source everything is fine. I never questioned that.
The problem only occurs when the source is a DCP. The situation is that I have a professionally encoded DCP without subtitles, and I want to create a new DCP with burnt-in subtitles.
All my tests were done under Windows 10. It's of course possible that running under a different OS may produce a different result. I don't own a Mac.
And I agree with Alex. I too care about the look of the subtitles.
Okay, that's an important fact to have confirmed now, because the burning-in to a pre-existent DCP involves different color transformation. I guess the best would be to uncompress the MXF into XYZ, transform the subtitle into XYZ/gamma 2.6, composite the two, then compress again, so only the subtitle get's a color transform.
Carl may comment on how it's actually done currently. Maybe there is something wrong now.
But, as a sideway, couldn't you just adjust the color (less green) to get what you want? After all, it's personal choice anyway. Yes, of course, white should be white, grey should be grey, but for now....
And yes, my Mac (even older than yours) is not able to play J2K MXFs properly with VLC. However, I can still snapshot color corrected stills from them.