Subtitle text aliasing - open subtitles VF

[Ryan]

Hello,

I am seeing aliasing/jagged edges on subtitle text when creating a VF.

I'm using open subtitles and have tried the default font as well as additional fonts, regardless of the font, the text appears pixelated on the edges, as if the resolution is not high enough. The jagged edges are quite noticeable during projection. Adding a black outline helps obscure the problem slightly, but the issue is still present.

Please let me know if there is a solution to create cleaner looking subs in a VF.

Thanks,
Ryan

[carl]

Are these subs set to "burnt in"?

[Ryan]

Thanks for the reply.

No, they are not set to "burnt in"

I had previously done a test with subtitles burnt into the image, exported out of Premiere as ProRes 4444. The DCP created from that looked good during projection and the subtitles had no issues. However, as I need to create multiple subtitled versions of this film, I am hoping to create VFs without burning in the subs, but unfortunately I am running into this issue and the subs are looking as if they are quite a low resolution on screen.

[carl]

That's strange. If the subs aren't burnt in they will be rendered somewhere in the projection system. and I'm not sure there's much that can be done on the DCP creation side to change how that happens.

What system are you playing the DCPs back on when you see these problems?

[Ryan]

The problem is also visible in the preview window in DCP-o-matic, so I assumed there was something wrong with the font, but I can't seem to resolve the issue with other fonts. Does DCP-o-matic install with a font attached as it's default font?

I tested this on a Dolby IMS2000 with a Christie 4220.

[carl]

Could you send a screenshot of how it looks in DCP-o-matic?

DoM will use a font called Liberation Sans if you don't specify another.

[Ryan]

Okay thanks.

Screenshots attached here.

DOM_subs_issue.png (2.82 MiB) Viewed 1444 times

DOM_subs_issue2.png (320.82 KiB) Viewed 1444 times

[Carsten]

This is a projector issue. TimedText, or 'Open subtitles', as they are enabled in DCP-o-matic, are rendered by the projector cinema electronics. DCP-o-matic can't do anything about them looking jaggy. It will appear more obvious on a 2k vs. a 4k projector. It is quite common to see timed text with aliasing artifacts on 2K DLPs. You can try a different font for a test, but I don't think much will change. Setting the font size as large as acceptable also helps, as well as reducing contrast (no bright white), as far as background allows.

[Ryan]

Thanks for your response and suggestions.

Just to clarify, is the fact that the text looks jaggy in the DCP-o-matic preview window how it is meant to look?

I did test this on a 4K projector and the aliasing artifacts were quite apparent. I've projected and watched many other subtitled VFs and have never noticed the text look this rough, so I'm confused as to how this issue has been avoided by others creating subtitles this way.

[Carsten]

Are you sure this 4k projector has 4k processing enabled? It's not necessarily the case. If you find some Interop features with subtitles, you may extract their font or subtitle xml, reuse it in DCP-o-matic for a comparison (also compare with burn-in), But I guess you are out of luck.There is nothing to configure on projector subtitle engines. Of course, in theory, it could be a software problem. Again, try to dig up an interop feature with subtitles and try to compare. That Dolby IMS2000 has an option to either generate subtitles on the projector electronics, or on the server. If you have access to that level, try to switch between the two.

Just to clarify, is the fact that the text looks jaggy in the DCP-o-matic preview window how it is meant to look?

No. Your screenshot looks as if it is a 4:3/pillarboxed feature?

Can you upload a piece of text and font you use to the forum, I can try a test. In you screenshots, the font appears quite 'thin', that, of course exaggerates the problem.

- Carsten