Small room for color grading and sound mixing

[Tony Bandiera Jr]

Steve is spot on with his post (#14) on the issues with using laser for color grading. While I agree in principle with using a laser projector to judge the results to see how it would match in cinemas, the points he made about different eyes seeing the spectra differently (See Harold's excellent post explaining why) means that the end product could potentially be a huge mess when released to the masses.

My own vision seems to be red deficient, as I always have to have the tint skewed to the red side on all my tv's and monitors. The few laser projected movies I have seen in the past therefore always seem a bit on the green side to me, and were not consistent from one location to another. Is that due to the grading? Variables in which type of laser projector? (I did not bother to ask which type was used at any of the locations, and the popcorn kids wouldn't know anyways.)

Xenon has a full and relatively balanced light spectrum, which is precisely why it is used and preferred over laser for grading.

Bottom line for Tomislav: Find a good xenon projector, used, buy two or more so you have spares (which would most likely still end up cheaper than one NEW laser machine), there are plenty of new xenon lamps still available, stock a few of those (they tend to have a very long shelf life, if not dropped or improperly stored), and call it a day. You will be able to KNOW with confidence that the color rendering will be BALANCED and CONSISTENT, which is your end goal. You will also have less "callbacks" or "do-overs" (or whatever it would be called in post world) and that means less losses and unhappy clients.

AFTER you build the business, invest in a laser projector for side-by-side comparisons for your clients. But remember: since individual people's color spectra differ, what looks great on xenon to a client may not look so good on laser. (The upside is if you have a KNOWLEDGEABLE client, they can suggest some tweaks of specific colors to get the laser looking more like they want. But they may ruin it for the masses in doing so.)

[Marcel Birgelen]

In my opinion, there is a notable improvement when one gets to 2300:1 and stark improvement at 3000:1 (typical HC lenses on laser projectors). The overall picture looks notably better. While the 5000:1 does look better, it just doesn't seem to have the dramatic impact that you'd expect...perhaps because of how films are mastered? If they were to actually presume theatres had 5000:1 contrast ratios, black detail would be lost...even for theatres that set up their equipment properly. Anything below 2000:1 (xenon 4K, all lamp based .69" S2K and NEC .69" LP) look notably worse in the contrast department (one need not have an eagle eye to notice that there are no blacks...just greys

Our machine is a non-post machine. Back when we did invest in it, it was a budget decision. In the end, it didn't hurt. Eventually, people want to see the stuff the way it will look in your average, well-maintained theater. If people start doing post with 5000:1 as reference, then you'll end up with a movie like the last Batman, which mostly looked like grey upon black with vague shades of blue in the theater I've seen it back then.

Still, despite it being a 4K xenon machine, the contrast we can achieve is pretty great and easily beats most setups out there. The machine is highly overpowered for the size of the room, even with the HC lens on it, which "eats" a lot of light and a 0.95 gain screen. With some careful calibration and no external trickery, we'll get to 2300:1 without a problem. Over the years, we have achieved beyond 3000:1 by employing "some trickery" like using an ND filter and cranking up the light. I like watching movies that way myself, but it's not how the setup is usually being used.

As for Barco's post laser solution... I'm sure they'll sell a bunch of them to post houses, but colorists still will cry wolf. With those guys it's like me with the convergence on a big old CRT projector: it's never calibrated good enough. And now, you simply never can have two in the same room with those machines... But, maybe it's generally a bad idea to have two colorists in the same room...

Eventually, we'll need to move on with where the industry is moving, I simply hope that by then the industry figures out how to create new light sources that are as efficient as laser but produce a broad spectrum of light. Laser certainly has its applications, but I'm not really convinced that digital projection is the best application for it. Meanwhile, the technology for direct view screens is steadily progressing. Giant LED screens are turning up everywhere and their resolution is also steadily increasing. Looking at something like the Las Vegas Sphere which recently opened, it's clear to me that direct view screens will be the future of cinema, no projection setup in the world can beat the dynamic range of such a setup...

[Marin Zorica]

It is always compromise, there is no best solution! Xenon projector is go for this, but since it is small facility, and on other end, as industry are progressing towards laser, best would be to use both so you have side comparasion what it would be in average theatre. I think buying used 12C or Christie 2210 today should be not a big investment, except finding one which is decent, as those are now 10yr old machines.... Even if money is not bih thing and if they source decent xenon unit, and laser in same time, maybe fit them one a ove other in auch small room could relly be trick to have a something xenon to be reference and laser to be real life conditiin. So during post everybody can check and compare end result. This setup would probably be standard in some post house plus in barco case with both xenon and laser using post licence. On other hand, first is the budget, then i think it is problem for them just to buy few xenon units and use them as spare, plus where to source them.....
I know for some cinemas doing same when they went i to bussines and they go with used series 1 few years ago. For 4 rooms they bought 6 projector, in next two years i did change both of them and in next year we did find them two more. Same thing was with dolphin cards in doremi and some christie board.
They are running fine for now, but don't know where to source parts plus if they need them fast in case of failure.....
I know with series 2 are different story as they are more realiable and there were much, much more series 2 machines around here which could be potential buy as used.

[Steve Guttag]

I agree on above about laser disadvantages, but in near future we will be off xenon unit's and leave to laser. Not my personal like too, but, that is market, and cinema owners like when they cut maintance and electricity cost to half.... As you stated for Post version of SP's, still investing in SP is good way to go and later invest in post licence.

Marin, that is justification for using lasers in cinemas...it is no justification for using them in color grading and in post houses beyond having a laser projector to see how things will look in cinemas (the equivalent of NS10s in an audio mastering suite beyond the good monitors.

You can't judge the color of the image when what you see and what someone else sees are different. It is one thing when the switch from Carbon Arc to Xenon caused a color shift from about 5400K to over 6000K (and even then, they tried to use reflectors to shift it back down)...at least when a color temp is set, everyone grading the image is seeing the same thing and it can be representative of what people will see in the cinemas...including if their color temp is off standard...it will be uniformly so on every movie they run. With laser in the color grading stage, you lose that uniformity.

To put it another way. If half the audience wears red tinted glasses when they watch the movie and the other half wears green tinted glasses...do you want the person grading color to be wearing any tint or one of the two tints? And if so, what happens to the experience for those that are wearing the other tint?

[Marin Zorica]

I understood you're point and it is right way. But, in near future when xenon will be obsolete (allready are) and as i know here in EU they want to remove using xenon lamp, what we will offer to grading rooms? As for studios, as you mentioned NS10, the point is you have 2-3 sets of monitors for mastering to get mi decentan on all. So, in my opinion, both xenon and laser would be great.

[Tomislav Stojanovic]

The thing is - once we go Xenon, it would be huge investment later on to upgrade to laser. And laser *should* be able to mimic Xenon when we figure out alternative color coordinates. I am trying to get some first hand experiences on that. Problem with metamerism failure is in color matching functions that are currently used for calibration, not necessarily in display tech. And other problem is that all people see colors differently.

Monitors with metamerism problems are common in postproduction world. RGB OLED screens had problems, same with dual layer LCD panels. So it is nothing new in postproduction world to be using wide gamut / spiky SPD monitors. I am talking about mastering monitors, one of the most popular ones are BVM-X300 and BVM-HX310.
More on HX310 vs X300 here: https://pro.sony/s3/2021/01/22153635...0_201222_E.pdf

And here is the graph (from that link) representing how different observers see white on that particular monitor:
Screen Shot 2023-12-19 at 14.21.33.jpg
... and it is perfectly good (maybe best monitor) you can use for color grading today. Still, people will see it differently. The question is - are these margins between observers important for decisions that you are making while color grading?

For example, right in front of me is Eizo CG3145. It is same panel as before mentioned HX310. It is supposed to have huge issues with metamerism. When calibrated it does not look the same as regular calibrated LCD monitor. After carefull perceptual match, it looks the same. I never had a situation with someone in a room saying - "it looks green" while at the same time it looked red to me.

I am sure these effects are more pronounced with laser, but the question is how much and would it be possible to mitigate these effects.

Barco created similar whitepaper like the one from Sony I linked earlier. It is at the end of this page:
https://www.cinionic.com/white-paper...ostproduction/

[Tony Bandiera Jr]

Are Steve, Harold and I the only ones in this discussion who are actually listening? Seriously, y'all keep carrying on about how laser should be able to mimic Xenon when we figure out the color settings, etc. Laser will NOT, in the foreseeable future, EVER be able to give the true, BALANCED spectrum of light that a Xenon arc does. Further, even if in the unlikely event they ever get lasers to have that balance, the FACT that it is such a tightly collimated source (unlike natural light, Xenon, etc which is uncollimated...do you own homework on that subject since you won't listen to reason) will continue to have other artifacts that make it, in terms of visual accuracy, an inferior light source.

So Tomislav, go ahead and waste money on doing just laser, but when, not if, your clients start getting upset about the output don't come back here asking how to fix it. You have, by my estimate, over 100 YEARS of combined experience trying to help you make a sound BUSINESS decision, but you apparently choose to ignore it. I wish you all the best in your venture. **mic drop**

[Steve Guttag]

When I first learn of the metameric problem was exiting a screening and mentioned..."yeah...this laser stuff always looks redish to me" The person I was talking with said..."no they always look greenish to me." The very scenario you never had the situation with has already happened to me, personally.

Marin. Christie still produces NEW Xenon projectors. All of the xenon lamp manufacturers (we most, if not all) that have been manufacturing xenon lamps in the past decade still are. Will that change as demand goes down? Sure. I have no doubt that it will become more of a specialty lamp, as time moves on. However, you cannot predict when obtaining xenon lamps/parts for xenon projectors will become scarce. While the EU may indeed impose its arbitrary restrictions on substances it objects to but that does not stop the rest of the world. If one cannot operate a xenon projector (so I guess film better find a new light source too), then those areas simply will not be suitable for such work. The realities are...we are a tiny, tiny industry and the post work is but a fraction of that. Whatever claims about environmental impact of the use of materials in the electrodes (is isn't the Xenon gas...its the metals and the stuff they are coated with) is practically immeasurable due to near zero quantity. There could even be inventive ways of allowing for "returning" of spent lamps for recycling (I've always wondered why the tungsten isn't reclaimed better).

[Randy Stankey]

(I've always wondered why the tungsten isn't reclaimed better.)

I always broke my old xenon lamps, collected all the metal and, when I had enough, took it to the scrapyard.
I separated out the electrodes from the rest. I told the scrap guy that the end caps and stuff were stainless steel. The electrodes, I simply called them "electrodes."

Many scrapyards take spent TIG welding electrodes as a separate item, paying a separate price. Xenon electrodes are tungsten, doped with thorium. From what I've learned, they are the same or very similar to TIG electrodes. The first time I took in a bucketful of electrodes, the scrap guy zapped them with his X-ray gun and said, "Yup!" then wrote me a ticket for TIG. On subsequent visits, I just said "electrodes" and they took them without question.

It's been a while since I last recycled a batch of old xenon lamp parts but, the last time, I remember taking home a little over $100 for a five gallon bucket full of mixed metal, steel and tungsten. None of my bosses ever clamored to get the money back but, still, I kept the proceeds in a slush fund used to buy odds and ends for use in the booth. That's probably why the boss never complained about the money because it meant that they'd have fewer petty cash receipts and purchase order requisitions to deal with later on.

I'm with you, Steve! We really need to get on the horse and start recycling more! Not only is it better for the environment, there's money in it for those willing to put forth a little effort!

[Tomislav Stojanovic]

Are Steve, Harold and I the only ones in this discussion who are actually listening? Seriously, y'all keep carrying on about how laser should be able to mimic Xenon when we figure out the color settings, etc. Laser will NOT, in the foreseeable future, EVER be able to give the true, BALANCED spectrum of light that a Xenon arc does. Further, even if in the unlikely event they ever get lasers to have that balance, the FACT that it is such a tightly collimated source (unlike natural light, Xenon, etc which is uncollimated...do you own homework on that subject since you won't listen to reason) will continue to have other artifacts that make it, in terms of visual accuracy, an inferior light source.

So Tomislav, go ahead and waste money on doing just laser, but when, not if, your clients start getting upset about the output don't come back here asking how to fix it. You have, by my estimate, over 100 YEARS of combined experience trying to help you make a sound BUSINESS decision, but you apparently choose to ignore it. I wish you all the best in your venture. **mic drop**

Dear Tony, my intention was not to upset or offend you. My post was merely a parallel about metamerism problems that were present in postproduction industry longer than laser is present in cinemas. These are very similar discussions we had about monitors years ago. I am not saying that manufaturers will be able to fix this problem. I am just trying to asses what is best for my use case and to understand it better from many different perspectives.

I really think I am not ignoring anyones experience. On the contrary - writing here was very deliberate and because I saw this as a place with many experienced people.

To be able to make business decision, I have to take into account many different things. We live in very different markets... For example, I think everyone on this forum would find it crazy, but most films in my market are distributed as unencrypted DCPs. But it is just reality of different markets. Most of my clients are fine with grading on a monitor for theatrical. Nothing wrong with that. I am just exploring ways to do it better... And like I said in my first post - I understand there will have to be some compromises that are unavoidable. Maybe laser is just too big of a compromise, that is a possibility.

[Marcel Birgelen]

We've come to the conclusion that you can't do color grading on laser machines quite a while ago. If it will be possible in the forseable future, I highly doubt it. The software solution Barco offers, doesn't fix the underlying metameric problem, with more than just one person in the room. The whole idea of a screening room is to be able to work on a project with multiple people.

We're still contemplating what to do though. We have two realistic avenues forward: One is replacing our Barco with a Christie xenon machine. I doubt that xenon will be completely banned from the EU in the foreseable future, also: Christie Digital is owned by Ushio, which is still one of the biggest xenon lamp producers in the world. Xenon is used in many professional lightning solutions, it's present in many millions of cars. Sure, there may be more strict regulations, car manufacturers are moving towards LED and even laser and new xenon projectors will be harder to get. There is still an existing fleet of many thousands of projectors out there that won't be replaced overnight.

The second solution we're contemplating is to buy a laser projector, probably a Barco S4-series and add it to the setup instead of replacing the xenon machine. We could use the xenon machine solely for color grading and that way, we'll probably be getting quite a few years out of it. It will be somewhat of a tight fit, but we could make it work. It will be an expensive solution though, since we need to maintain two machines and somehow work out the audio routing between them.

Still, no matter what magical software Barco dreams up, you simply CANNOT correctly color-grade with more than one person on a laser machine. Yes, even color grading on a correctly calibrated monitor is better than color grading on a laser projector.

[Marin Zorica]

We all understood laser thing, and every single of us did laser projector, for example exchange xenon for laser projector, so it can compare direct. But if we would use two projectors for the works, xenon and laser together, or monitor and laser. Why is such "bad" to have laser unit in screening room to have test of content, when at end 80% will be laser units in cinemas.

[John Eickhof]

remember...color rendition is relevant, so sound is relevant...it's up to the eyes and ears of the beholder ! no two people are alike...the sun is a constant, as was carbon arc to an extent, and so is xenon as well as a prism, but laser is not a constant when blended into a color spectrum...I think you should stick with what is proven and let the poor beat up horse die! That's my one cent opinion on a five cent question...

[Stefan Scholz]

Lasers are "spot on" when adjusted and measured, never seen such close measurements to theoretical points. But, that's leaving enough room for personal perception.
A spot on white point does not warrant, it's white for everyone. One sees purple, others greenish or cyan tint. For some, reddish. Laser is very narrow wavelength, constant and nearly perfectly stable on that. The human vision isn't.
I have seen a color grading process, where the grader and the crew were totally disappointed about what they saw, in a festival calibrated lamp projector, so it was porepared to be on spec regarding color and brightness. They were discussing, that it had to be redone.
Then we took them to a new Laser auditorium with UHC lens, and a brightness that resembles the 70 mm specs from the late 50s, so at least double brightness.
Suddenly the grader was happy, that's how he wanted the film to look. And also his crew, said perfect.
Which showed one to me. He was doing his work on his calibrated to 150 nits (O)LED flat screen, not on a projection device calibrated to roughly 15 fl/ 50 nits. At that brightness were are in the border to night vision, with limited color reception for many humans. A bad choice in the time of film based movies, where flicker reception, maximum achievable brightness with limited to 13000 lumen lamp power without film in the gate were reality. 70 mm enabled you to aim for way higher lumens, hence the extra brightness could be delivered "on screen" to go over the max point for flicker sensitivity into a lower sensitivity region above 30 fl. And therefore better color vision.
Vision is subjective, and not static. Grading on lamp based units is eventually easier for a larger target audience, than on monitors or Lasers.

[Dave Macaulay]

Was it a big issue when smooth spectrum carbon arc lamps were replaced by spiky spectrum xenon lamps? Did colour timing rooms stick with arc light until forced to adopt xenon?
I remember trying to match colour on two timing room xenon projectors (for changeover operation).
Our matching involved getting about a dozen Super Lume-X mirrors and finding the two with the closest colour temperatures. Once that was done, measurements were taken and expensive custom filters were put in the light path to be "perfect".
I respect that colour timing is important.
But timed prints were going to cinemas with whatever colour temperature they had, and from trying to match two mirrors I can say that (at least with Strong) xenon mirrors were not consistent. I never came across a spectrometer with xenon except at that timing room job. Until we went digital.
You got what you got when you went to see a movie, the mirrors, port glass, screens were an unknown... I don't recall any complaints about image colour. (And cinemas had allowed smoking so many screens were stained)
Now we set up digital projection to the DCI colour specs. Presumably just because it's possible.
I check colour at drive-ins but because of the screen paint etc they are usually pretty far off spec with uncorrected white. I leave them uncorrected because that much correcting steals so much light, and for a drive-in... well, a brighter image a bit off colour is preferable to a 314/351 dim image. And again I have not heard of one complaint about poor colour at any of these drive-ins.
After calibrating colour on a xenon digital system, the screen colour looks a slight brown to me. I'm used to that and can tell at a glance if one isn't close to spec. With lasers, whether RGB or phosphor, it does not look "right" although reading 314/351 exactly. I see it as a bit pink maybe, but someone else used to xenon DCI white may see it as a bit blue or orange. I don't know what's up with that. But an actual movie (the DCP presumably timed by golden eye experts) looks just fine.
So I don't have much to say about grading room projection. If the experts have trouble with laser projectors, use xenon. Eventually they will presumably be obsoleted... but by then cinemas may have direct view screens and another can of worms will be cracked open.