Presets for Non-Ideal Surfaces?

[Ryan Gallagher]

What would you recommend for improving ALT presentation on non ideal surfaces like a theatrical cyc? A custom light file/preset? Go as far as shooting Rec.709 colors on the CYC and have alternate color files too? I can manage a light file by eye, but don't have a colorimeter to go deeper.

Background: In our small room our Christie CP2220 is always projecting "film" on a film type screen. But our ALT content shows in there can be on other surfaces, such as a traditional theatrical bleached or unbleached muslin cyclorama.

We had a band with a "music video screening" the other day, and they were unhappy with the brightness and contrast on the cyc compared to what they had graded with their editor. My counterpart managed to get them to a place of "good enough" with some software sliders to adjust brightness and contrast in our playout software.

AFAIK our ALT sources inherit the same DCI light files currently.

95% of shows are just happy their video comes up at all. But those 5% who look harder seem to suggest at minimum maybe we could be utilizing our lamp headroom better for the cyc with stage lights situation.

My initial (incorrect) post-mortem was they gave us a HDR Rec.2020 prores file that we were trying to play out in OBS which does not support that translation. But I checked the file today and nothing wrong with it, 4K Rec.709, albeit with some scenes intentionally shot very low contrast (fog engulfed river scene), and other fire lit scenes that demand some pretty good contrast/blacks, which may just not be possible on a cyc that is perhaps competing with band/stage lighting. It was not shot to excel in this situation, but the situation may have contributed as well.

[Marcel Birgelen]

You're mentioning a cyclorama, those are, most often, not perfectly straight, so already quite a challenge to get an evenly focussed picture projected onto. Also, you're mentioning stage lightning, which is probably not a static affair... Not something easily standardisable in some preset calibrations, I'm afraid.

Any woven kind of material like muslin will naturally reflect far less light than a modern, PVC based screen, perforated or not. Bleached, unbleached, those are already two different reference points, both will impact colors differently. It's also important to have some good blackout material behind those woven kind of screens, as they will not block any light reflecting from the back. Woven material like muslin has some uneven qualities to it. Depending on the viewing distance, it can make projected images look a bit like paintings on canvas.

[Ryan Gallagher]

You're mentioning a cyclorama, those are, most often, not perfectly straight, so already quite a challenge to get an evenly focused picture projected onto. Also, you're mentioning stage lightning, which is probably not a static affair... Not something easily standardizable in some preset calibrations, I'm afraid.

Any woven kind of material like muslin will naturally reflect far less light than a modern, PVC based screen, perforated or not. Bleached, unbleached, those are already two different reference points, both will impact colors differently. It's also important to have some good blackout material behind those woven kind of screens, as they will not block any light reflecting from the back. Woven material like muslin has some uneven qualities to it. Depending on the viewing distance, it can make projected images look a bit like paintings on canvas.

Thanks Marcel. I pretty much expected there to be no direct path, was just asking out loud cause perhaps others have integrated for rooms with similar use cases and had sage advice.

This space is a converted 90 year old movie theatre, no fly house, deep-ish stage but no wings, static catwalk systems overhead for lighting/rigging. The "Cyc" is not the wrap around traditional variety, but just an upstage bleached muslin fabric with a bottom pipe we refer to as a "cyc" still. It has a full stage black traveler in front of it that can frame it to different widths or reveal it "a vista". There is a full stage black panel backing it as well. When live shows ask for video elements but object to the roll-down 4:3 screen for practical or aesthetic reasons, that is pretty far downstage, this is the next go to without renting and rigging anything different. Intended for lighting effects, but doubles as backdrop video surface for us (no room to do a plastic RP screen with rear projection).

I think I'll try some lamp file brightness increases when I get a chance, to see if it makes much of a difference on some video test patterns (have 40% lamp headroom available). If it does help maybe one day I can borrow a meter to get a color file closer for the ALT/cyc projection modes. But I think brightness might get us a chunk of the way there towards a general improvement.