Wanted: a workflow to alter video for projection in a cinema

[Guy Burns]

Background

I'm converting my three-screen audio-visuals to Blu-ray format, with the aim of presenting them at the local cinema. Basically they're slide shows from the 80s and 90s, with a few added clips from my GH3, and new stereo soundtracks. It's just a hobby, but I want to do the absolute best job I can.

All content enters Premiere as sRGB, exits as H.264 Blu-ray (m4v format), and passes through Encore (without transcoding) to a Blu-ray disk. I then check it out on a BenQ W7000 projector in my home theatre  – my test bed.

At the Cinema

What I am concerned about is how the presentations will look in the cinema. I've had a short tour of the projection room. They run four Barco projectors…

https://www.barco.co...5ft.aspx#!specs

… and the projectionist assured me that I can feed in my Blu-ray content via the HDMI input on the Barco.

Different Gammas

My entire workflow is in sRGB, from scanner (or GH3), to my iMac's monitor, through to my BenQ W7000 projector. However, Cinema projectors, I read somewhere, have a gamma of 2.6, and I assume they use the colour space I've seen in my list of Photoshop profiles: DCI P3 RGB (Gamma 2.6) 5900K. When, as a test, I applied that profile to a scanned image, there was a significant darkening.

I want to retain my sRGB workflow as it works well with Premiere, but I suspect I'll have to alter the rendered video so that what I see in the cinema matches what I see in my home theatre. And I'm not sure of the best way to do that, but I suspect I'll have to use After Effects.

Ques 1

If I play my Blu-ray disk – as it stands now – through the Barco projector at the cinema, is the image really going to look darker than at home?

Ques 2

My first thought on how to alter the video was to use an effect in Premiere. I came across Cineon Converter, and when I selected the options log-log, and set the gamma to 2.6/2.2 = 1.18, it seemed to work well. I altered the monitor gamma to 2.6 during the test (which darkens Premiere's image), and when I applied Cineon Converter the image seemed to return to it's original look.

Is using Cineon Converter an effective way to alter sRGB to DCI P3?

Ques 3

Another idea I've had:

1. In Premiere, create a Master sequence of the entire video and replace that with an After Effects composition.
2. In After Effects, convert the composition to the DCI P3 colour space. (I don't know how to do that, but I'll work it out).
3. Back in Premiere, export the Master sequence as I normally would and build to Blu-ray in Encore.

Would the above steps work? Is that the best way to have the cinema and home-theatre images look the same?

[Kevin-Monahan]

Hi Guy Burns,

Are you still facing this problem? If not, let us know how you solved it. If so, please let us know so we can assist you further.

Thanks,

Kevin

[Guy Burns]

Thanks, Kevin, for the reminder about this thread. Since there were no responses here, I took this question to the film-tech forum…

Film-Tech Forum: A hobbyist asks: how best to prepare material for a Barco DP2K-20C

… and had kind of forgotten about this one.

The short answer is… colour space should not be a problem because:

• if the source is Blu-ray via a HDMI cable,  the cinema projector will automatically do the conversion to the correct colour space for projection;
• or if I use software like DCP-o-matic to convert my Blu-ray to DCP format, the software converts the colours.

So, either way, this gamma thing shouldn't be a concern.