Ask Mike Most Anything

[Marc Wielage]

The files that are usually needed are Avid MXF files (usually 1920x1080, DNxHD36), as the vast majority of TV shows are cut on Avid.

All the ones I've done lately have been either full-res DPX files or Avid DNxHD220x, which is great for 10-bit deliveries for TV. I've done some indie projects for DVD and Blu-ray release at the same res, and those have worked out fine.

Those who are interested in learning about the different Avid codecs can read this white paper:

http://www.avid.com/static/resources...ents/dnxhd.pdf

To me, DNxHD220x is essentially identical to Apple ProRes 444 HQ. All the major networks I know of have blessed these formats for post, but it's a good idea to check first to make sure the workflow agrees with what the network or channel wants.

If push came to shove, I would always prefer color-timing from a 2K 444 DPX file, and once the color-correction decisions are finalized, load in the 4K uncompressed files for the final render out. I don't see a need to monitor 4K 100% of the time, because of the huge performance hit you get on most color-correction systems. No doubt this will change over time, and eventually you'll be able to handle dual streams of 4K 3D with 20 layers without a hiccup. But not today.

Incidentally, this is much worse within the industry than it is in the consumer world. You've got colorists working on proper calibrated monitoring in proper environments, but you've got DP's and directors looking at dailies on everything from laptop computers in bright sunlight, to iPads, to video village monitors, to tiny CRT's in the camera truck, to home TV's that are set up to who-knows-what. And you've got studio execs looking at digital dailies that have been compressed beyond recognition and are playing in postage stamp sized windows on a computer screen and blown up to full screen size. The whole thing would be funny if it wasn't so ridiculous.

This is very sad, and very true. I continue to be flummoxed by directors and producers who are trying to make creative decisions about lighting and color based on what they see on iPhones and iPads, or even Apple computer displays. An editor/friend of mine (who should know better) was recently trying to tweak a picture in Final Cut Pro, and I asked him, "have you set the display gamma correctly?" He had that deer-in-the-headlights look. Not good.

[Marc Wielage]

After 6 years and about 40 full features and don't know how many shorts, using for chemical processes and projection Kodak Cinelabs Greece, we have achived a level of accuracy that is +/- 1 printer light... and that's a common ground for all my clients... If you allocate the 2 printer lights range in the density equivalent you can easily see from where the 3% number is coming...

Wow, that's remarkable. I mean no disrespect, but I've never seen a photochemical film lab that can guarantee prints at +/- 3 printer points, especially in a mass run. But that's here in America. Maybe things are better where you are.

Deluxe and Fotokem here in LA are very, very vague when you try to pin them down on how many points off a theatrical print can be before they consider it to be unacceptable. (Technicolor is no longer in the print business in North America.)

[David Mullen ASC]

I remember years ago finishing a movie photochemically at one of those labs, and the second answer print came back with an overall bias towards the pink and was also too bright -- the lab tried to say that this was within their normal tolerances! I tried to watch the print but after the first reel, I got tired of saying that every shot was too pink and too bright and I couldn't see the actual variations underneath anymore. They finally agreed to reprint it more accurately so I could give them accurate notes for the third answer print. But I was appalled that they considered this pink print to be acceptable.

[Evangelos Achillopoulos]

Wow, that's remarkable. I mean no disrespect, but I've never seen a photochemical film lab that can guarantee prints at +/- 3 printer points, especially in a mass run. But that's here in America. Maybe things are better where you are.

Deluxe and Fotokem here in LA are very, very vague when you try to pin them down on how many points off a theatrical print can be before they consider it to be unacceptable. (Technicolor is no longer in the print business in North America.)

Yehh +/- 3 is big time off... it makes a movie the "red movie" or the "green movie"... I explain it in a just before post, why in mass production they can't do it... apart from obvious production reasons...

The typical use of butterfly projections is to make that ONE or TWO copies super accurate no matter what is the mambo jumbo needed by the photochemical colorists... like PH tweak, temperatures and many many tricks, to make these two super copies and have a happy DoP and Director... the only diference is that magic is NOT on neg... so when the mass production starts all is like +6 printer lights miss match... different contrast etc...

To give an example... not even one ImageCare lab is on the list for US in Kodak web site... check your self...

http://motion.kodak.com/motion/Suppo...am/members.htm

Our lab in Greece is a Kodak Cinelab... and its the first that got the ImageCare in Europe... My film recorders are very well aligned with EVERY film emulsion EVERY time... and the color management I do is very strict...

All our corrections never going further than these 2 printer lights... and the result is accurate with NO extra tricks... some times even the first answer print goes to festivals... Like "Restoration" that went to Sundance 2011 and won the World cinema dramatic screenwriting award... Variety wrote "Marked by disquietingly beautiful imagery" it was neg development -> answer print -> festival...!!! http://www.motionfx.gr/client-work.html

How the hell you can live with 4 or 6 printer lights difference? is like night and day...

[M Most]

All the ones I've done lately have been either full-res DPX files or Avid DNxHD220x, which is great for 10-bit deliveries for TV. I've done some indie projects for DVD and Blu-ray release at the same res, and those have worked out fine.

My answer was based on transcoding for editorial, not finishing. I thought that's what David was asking, because I perhaps falsely assumed that for finishing, a conform would be done from the original media, which it often - but not always- is.

If push came to shove, I would always prefer color-timing from a 2K 444 DPX file, and once the color-correction decisions are finalized, load in the 4K uncompressed files for the final render out. I don't see a need to monitor 4K 100% of the time, because of the huge performance hit you get on most color-correction systems. No doubt this will change over time, and eventually you'll be able to handle dual streams of 4K 3D with 20 layers without a hiccup. But not today.

My answer was also based on television, not features, because that's what David was asking about. In television this season, the most common source format is ProRes 4444 because the Alexa is a rather dominant camera this year. I do realize this is RedUser, but even in the case of a Red originated show, you wouldn't be doing anything in 4K other than perhaps archival re-renders after the show is done and delivered - something we've done for a number of Warner Brothers shows.

[Florian Stadler]

Hi Mike,

I have a question regarding Log to Lin conversion in general/philosophically - RedlogFilm & AlexaLog:

I tend to grade straight from the log file and work mainly with Lift/Gain/Gamma controls in Davinci Resolve to first get the image in the ball park and then move on to a creative grade grade from there. I find that I get a good feel for the footage that way and am basically creating my own customized LUT that way compressing the highlights/shadows as dictated by the footage. Almost like in an old-school telecine session where you'd get back to looking at the "negative" when you wander too far away from the base grade and adjust the lights on the machine...

Am I missing something here? Am I missing something important in the Log to Lin conversion that would better be left to a LUT? If so what specifically would I be missing?

Thanks for this great thread...

[M Most]

Hi Mike,

I have a question regarding Log to Lin conversion in general/philosophically - RedlogFilm & AlexaLog:

I tend to grade straight from the log file and work mainly with Lift/Gain/Gamma controls in Davinci Resolve to first get the image in the ball park and then move on to a creative grade grade from there. I find that I get a good feel for the footage that way and am basically creating my own customized LUT that way compressing the highlights/shadows as dictated by the footage. Almost like in an old-school telecine session where you'd get back to looking at the "negative" when you wander too far away from the base grade and adjust the lights on the machine...

Am I missing something here? Am I missing something important in the Log to Lin conversion that would better be left to a LUT? If so what specifically would I be missing?

Thanks for this great thread...

Yes, you are missing a number of things.

First, understand that a log image is not an image, at least not in the sense of something that should be looked at and/or graded using traditional video style tools. It is, rather, a container, a way of fitting more information into a smaller space and using the available values in a more effective way for visual images. Think of it exactly the same way as you think of a film scan, because that's what these formats are. You would not likely look at a Cineon film scan and judge the image, and you would not likely try to grade it by using lift, gain, and gamma. In almost all cases, you would use a grading system that hopefully has log scaled controls (i.e., printer lights, or exposure/contrast controls) and observe the result through a LUT that is tuned to your delivery path and monitoring format. That is standard DI practice. The fact that your images are coming from a digital camera doesn't change the fact that they are essentially Cineon coded images. To get the most out of them - and by that, I mean to re-establish a proper greyscale and get the saturation correct - you should be using a grading path that consists of a base grade, followed by a Cineon Log (or LogC, basically the same thing) to Video LUT, followed by whatever color trims you want to do on the result. By going this route, you accomplish 3 things. First, you get to work with all of the information in the original image, because you're using that as your grading source. Second, you create a proper greyscale by using the LUT, and since you're doing a base grade prior to that, if the LUT is a bit "strong", you can change what's going into it to get back as much of the exposure extremes as you want, while still maintaining proper contrast. Third, you can do whatever final trims you want - usually some minor balance tweaks, and whatever secondary corrections you want to apply - in the video realm, after the basic image has been made correct. This gives you the richest and most detailed image possible.

As you noted, you can go without the LUT. Stefan Sonnenfeld often does. But - and this is not any kind of knock on whatever grading abilities you might have - you're not Stefan. Quite frankly, neither am I. And neither are most colorists. When you go without the LUT, you're usually forced to crush blacks in order to get proper overall contrast, losing detail and control in the process. You're essentially working the color corrector much harder than it should be worked. If you're crushing gammas as well, that sometimes leads to even worse results even if it feels right at the time. And even if you do it "right," you're not accounting for the fact that the log encoding puts the upper midrange values higher than they should be for a proper greyscale, so hot flesh tones tend to look very flat unless you crush those blacks even further. If you haven't tried using a processing path like the one I've described, you really should because it will get you much richer images, and much better results, much easier.

Now, although I've only mentioned a LUT, it should be noted that a curve grade can and does accomplish essentially the same thing, so if you want to design an S-shaped custom curve, that would do the same thing a proper Log to Video LUT does. There's also the issue of a color matrix, necessary to re-establish proper saturation and accurate color reproduction from any Bayer sensor camera. Red makes that easy by giving you Redcolor and Redcolor2. If you're coming off Alexa footage, you need to create a LUT that incorporates the matrix, for video, that would be their Rec709 matrix. I know that you're not the only one using the approach you're using, but I have to say it's not optimal, and until you try a more optimal path, you won't really know what you're missing. And although the direct approach can yield very dramatic results in the right hands, it's pretty difficult to get classicly beautiful images that way, especially if you value a proper, full greyscale and minimal black and white clipping. Unless you're Stefan, of course.

Try it, I think you'll like it.

[Marc Wielage]

I tend to grade straight from the log file and work mainly with Lift/Gain/Gamma controls in Davinci Resolve to first get the image in the ball park and then move on to a creative grade grade from there. I find that I get a good feel for the footage that way and am basically creating my own customized LUT that way compressing the highlights/shadows as dictated by the footage. Almost like in an old-school telecine session where you'd get back to looking at the "negative" when you wander too far away from the base grade and adjust the lights on the machine...

Our engineers at Technicolor (well, at least some of them) used to say: "the DaVinci (the old 2K) is essentially a variable LUT... if you can set up a basic look, and then do a final as another layer on top of that, it can work." I think this is where Stefan's philosophy comes in, and if you have his experience and reputation, you might be able to get that to work for you.

Today's more sophisticated LUTs will get you closer, and faster, especially if you're trying to finish in Rec709 color space. Me personally, I'd rather not waste a node or a layer just trying to simulate a LUT; I'd rather have a more accurate starting point, assuming the material is shot correctly.

Just starting off with the right Log -> Lin LUT can be very helpful. But so much depends on the nature of the original material, I'm not sure there's a one-size-fits-all solution. It's whatever works, based on the colorist's experience, how the footage was shot, and where the cinematographer wants to go with it. I've had LUTs so good, all we needed to do was minor tweaks here and there; I've had other cases where tweaking every other shot was an ordeal, like a self-root canal.

I've never had any luck with using custom curves to simulate a LUT... but then I'm not Mike Most or Steven Sonnenfeld.

[M Most]

Just starting off with the right Log -> Lin LUT can be very helpful. But so much depends on the nature of the original material, I'm not sure there's a one-size-fits-all solution. It's whatever works, based on the colorist's experience, how the footage was shot, and where the cinematographer wants to go with it. I've had LUTs so good, all we needed to do was minor tweaks here and there; I've had other cases where tweaking every other shot was an ordeal, like a self-root canal.

Root canal aside, I've sometimes experienced the same thing. But there was one very common thread to that experience - those LUTs almost invariably came from either a DIT or a dailies colorist. Those aren't the LUTs I'm talking about. In fact - and this is probably going to get me flamed by a lot of DITs here - I don't think those kind of LUTs should be used by colorists at all, other than purely for viewing purposes. A properly designed Cineon Log to Video LUT is not a variable proposition and it's not something that should be "tuned" to a specific shot. It's a mathematically derived conversion table that takes an image in a known Log format and converts it to properly display in Video space. That's it. It's not a color correction per se, and it's not a creative tool. It's no different than a video downconverter in that it takes a known source in, and spits a known result out. Now, the power of a properly designed LUT in a color pipeline is that the creative work is done by the colorist on the material as it was shot, not based on some unscientific result that was created without a proper pipeline in the first place. It gets you proper values based on what the camera captured, allowing you maximum flexibility but also giving you the most sensible starting point. There's no magic to a LUT, it's simply a mathematical conversion table designed to take one format and convert it to another. If you use a properly designed LUT on unencumbered camera original images, you'll get a good result. There is no ambiguity to this - it's based on the parameters of the color spaces and gamma curves that are used. Using DIT created LUTs invalidates that. If you're converting Red footage to RedLogFilm, and want to see a representative result of the photography in Video space, the easiest and perhaps best way to do that is to use a simple 1D LUT designed for the purpose (you can make one using, ironically, Arri's online LUT builder, by specifying LogC in, Video out, Extended range on both in and out, and no matrix). If you're shooting an Alexa, you can do the same thing, either with or without a matrix. In both cases you will get a result that's proper for the photography - no exceptions. If you substitute a LUT that incorporates some sort of creative intent - well, then you're on your own.

[Michael Olsen]

The following question comes from another thread, but I would love to hear the answer come from an imaging professional such as yourself, Mr. Most. It does, in some ways, pertain to recent posts regarding Log formats.

...I am wondering the advantages of [REDCODE] over Sony S-log. what people's opinions are over the matter, etc etc as I have shot Red before and I want to shoot Epic asap to see what I can learn about the RedCode capture codec vs s log.

As always, thank you and all the others for your time - this is a very enlightening thread.