End Run

Photo by David Oakes / CC BY-SA 3.0

If you are doing your final post finishing in 2048×1152, you are actually hurting your picture, and you should stop at once. Here’s why.

Juggling your post finishing rasters has always been a mild pain. To wit:

  • HD masters are 1920x1080
  • DCI “Scope” is 2048×858
  • DCI “Flat” is 1998x1080
  • DCI “Full Container” is 2048x1080

Did you notice anything there?

Deliverables are 1080 lines or less. (Always.)

Yep: none of those containers have more than 1080 lines of resolution. As far as DCI, SMPTE, your SDI cables, and Digital Cinema projectors are all concerned, “2k” still means 1080 lines of resolution or less. This turns out to be pretty important.

If you are finishing in a 16×9 aspect ratio, and you’re finishing in “2k”, you’re actually going to deliver … 1920×1080. Which is HD.

Likewise, if you’re finishing in 1.85 and “2k”, your actual deliverable is 1998×1080. Again, 1080 lines. Not 1152.

But wait, it gets worse. Putting that extra 14% of spatial resolution into your DI can actually damage the picture that your audience sees. Why? Because your fancy, non-standard 1152 lines of resolution will have to be scaled down to 1080 lines of resolution. But that’s not a big deal, right? You just press the magic resize button, and there’s no penalty, right?

2048>1920 is not enough Oversampling

It’s become conventional wisdom that oversampling is a good thing. Shoot 4k or 5k, finish in 2k or HD. No problem. I happen to agree with that, and Charles Poynton made an eloquent, 5-hour long argument to that effect at a recent talk at the HPA retreat.

But in this case we’re oversampling not by 200% or 300%. We’re oversampling by a lousy 14%. To quote one guy on the topic:

“Resampling an image works well for large factors. A small factor like 2048/1920 is difficult to achieve as you basically need a very very large filter kernel to effectively remove just the frequencies you don’t want. In other words, the reject band (1920>2048) is very narrow as compared to the size of the image. That doesn’t give much room for any filtering to work in.”

In plain English: a small resize factor will only serve to soften your image. You’re stepping on your image. You’re making it worse.

You (or your client) may have thought that you were finishing in “better resolution” by “going 2k”. But since you have to down-res all deliverables—you know, the thing that your audience will actually see—that higher resolution is not only thrown away, but contributes to an inferior final picture.

[UPDATE: Graeme Nattress writes, “what will happen is necessarily softening, but aliasing because the downsampling filter, if inadequate, will let through aliasing artifacts.” Thanks Graeme.]

This is true for finishing in 1.78 (16×9) or 1.85. It’s not true for finishing in 2.39. If you’re finishing 2.39, stick with 2k, since you’re only at 858 lines of res anyway.

Canary In the Coal Mine

Scrolling credits turn out to be the canary in the coal mine here, because they can look really, really bad when you resize them by a small factor. They are very unforgiving. Our slate tries to point this out as politely as possible:

Endcrawl slate about resizing

(Endcrawl solves the problem by giving you unlimited renders in all aspect ratios, so you can kick out a native, shimmer-free version for each individual deliverable.)

(Of course, that doesn’t help if someone is still resizing your render after the fact.)

But janky-looking end credits actually just illuminate a deeper problem in your overall post workflow: it makes exactly zero sense to finish in 2048×1152.

A Better Workflow

If you shot in 2048×1152, there may not much you can do there. Sorry.

But if you acquired your picture at 2.4k or higher, and your DI is not native RAW, then you should be working from RGB frames that are in the actual raster of your Original Aspect Ratio (OAR). Meaning either 2048×858, 1998×1080, or good old 1920×1080. Again, nothing wrong with HD. It’s great.

For UHD/4k, just double all of those numbers.

But don’t finish in 2048×1152. It yields no benefit and can only serve to step on your final picture.

Unfortunately, this bad trend actually looks to be on uptick. It doesn’t help that ARRI recently introduced a 2048×1152 ProRes recording mode on their Alexa camera. Don’t blame ARRI though. There are legitimate reasons for shooting 2048×1152, but those legit reasons all have to do with cropping your final output. (E.g. it’s good kung fu to shoot ARRI ProRes 2048×1152 and crop for a 2048×858 finish.)

In summary:

  • There are no 2k display or delivery standards above 1080 lines of res.
  • The difference between HD and 2k is actually minimal and you shouldn’t care. HD looks great, even on large screens.
  • If you’re finishing in 1.78 or 1.85, you should not be working at 1152 lines of resolution. This is very bad kung fu.
  • Tell your post house, and if they are annoyed, just blame it all Pliny.

 

I build Endcrawl and work at HBO. Sometimes I'm wrong about things on the Internet. Feel free to point some of that out on Twitter, or down in the comments section.

  • I’m with pliny.

  • agreed!! That why I try to advocate fort clients to shoot at something in a multiple of 2048×1080. If you are finishing for 2.4 AR, then you can extract 2048×858 and to be able to make a decent 1.78 pan and scan, you can have the full height back without scaling. 1.89 should be the preferred capture aspect ratio

  • Marc Wielage

    Wow, both well-done and respectful to the great Hollywood craftspeople who worked on movies back in the day. I bet Natalie Kalmus should be in there as a “Technicolor Color Consultant.”

  • David Jahns

    My preferred workflow (for 2.39 projects) is to finish at 2048×1080 with letter boxing , then crop to either 2048×858 for DCP, or 1920×1080. Both deliverables are unfiltered and sharp, and no one ever misses those extra few pixels on the sides of the frame. Technically, it changes the aspect ratio to 2.23 for a the HD BluRay version, but I’ve never seen that to be a problem. It gives you 858 pixels tall, instead of 803 – and the fact that they are 1:1 pixels instead of resampled makes it worth losing the 64 pixels on each side…

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  • thanks for this
    In many case, clients ask me to convert 1920*1080 in 2048*858 (cropping) for DCPs. So what you recommend in this case ? stay on fullhd in 1998×1080 with letterbox ?

  • walter volpatto

    so, based on your reccomandation, if I have a scope picture shot with the Alexa above mentioned (2048×1152) I need to finish in 1920×1080 then scale again (and crop) to 2048×858 for the theatrical distribution (the master that will give you 90%of your revenue).

    you’re a genius!

    Walter volpatto.

    • Pliny

      What was your DP’s creative intent? There’s a big difference between 1.78 (16×9) and 2.39.

      Since the plan is for a 2.39 DCP, I’m guessing that’s what she framed for. In that case, 2048×1152 was a good choice on the Alexa–it gives you full horizontal width, and you can vertically crop to 858. The latter you can do mathematically if it’s center-cut; otherwise production hopefully provided a framing chart.

      On the other hand, if the film was framed for 16×9, I’d hope your DCP retains that aspect ratio. You can always just pillarbox a little. Author it 1998×1080 (1.85) but pillarbox to 1920×1080. I made a very pillarboxed DCP for “Meek’s Cutoff,” which was framed for 4×3.

      I’d advise strongly against a workflow scaling 2048 -> 1920 -> 2048. Those small conversions will step a lot on your image, unnecessarily.

      • walter volpatto

        Pliny, that “you’re a genius” is sarcastic…..

        i know hot to do it with the minimum amount of transformation possible (and exr workflow if necessary)…

        the last weekend me and my coworker exported 3.5 trillion pixels for all the versions theatrical of “independent day resurgence”….(yes, we did a rough count 🙂 )

        • Pliny

          Ah, that certainly makes sense. If you check the article again, it argues for a 1080p DI raster when finishing either 1.85 or HD. 2.39 is a bit of a different story.

          But sarcasm aside, you raise some interesting points.

          First, broadcast vs. theatrical deliverables. In your scenario you’d be cropping that Alexa frame to 2048×858. Which means your HD frame for broadcast would be cropped again ~1525×858, then blown back up to 1080. Not awesome. This illustrates how 2048×1152 is not an ideal acquisition raster for 2.39. Of course that’s already a done deal by the time it reaches you at Fotokem.

          Second, this illuminates the value of shooting 4k+ rasters for a 2k finish. For example, an early RED feature we finished was Fair Game. We output the 2k DSM for DCP authoring directly from camera RAW files. For HD deliverables we rendered 2581×1080 DPX first, then pan & scanned those. In each scenario, we only scaled the raster once, keeping Nyquist happy.

          Third, you mention “90% of your revenue”. I’d agree that for a wide release film you should optimize your workflow for the D-cinema deliverable. But I’ve seen plenty of indie directors (and DPs) focus relentlessly on 2k, P3 version while treating the 709 trim as an afterthought. In reality, most indie films will get between 99% and 100% of their eyeballs from VOD and EST. In those cases it makes sense to optimize for the HD/709 deliverable to begin with, or avoid P3 altogether.

          Finally, we’re seeing more TV shows mandating “1152p” finish for all shows — irrespective of the fact that 1920×1080 is the *only* deliverable. This is rank lunacy.

          Please hi to Tom and all the folks over there. Much respect for your employer — I think Fotokem is one of the top post houses on the planet.

  • Alex Beyer

    just consider how pictures are treated in general .. during shoot DPs tend to use old lenses which doesn’t match necessarily the sensor size in order to ‘destroy’ their pictures. During editing you start to reframe and resize and further on in post production pictures are denoised, re-grained, sharpend, grained and vignette shaped while screened by a 4K projector during grade ….yes of course you can also debate about small factor scaling, certainly something you should know. But you stepped on your pictures already …

    • Nate Opgenorth

      Some DP’s use old lenses and some don’t. The amount of content shot with Zeiss Master / Ultra Primes on an Alexa is skyrocketing, you can’t say that is not a sharp combo. But yes in post grain is added and what not but at the end of the day sharpness and resolution are just a piece of the whole formula of the cinematic experience.

  • Jonathan Furst

    Hey Pliny, I’ve got a master file of 2048×1152 of a film I cut. The film has been shot 2.39 which is contained within the 2.39. I created a DCP and it looked like absolute tosh. Have you got any advice; either resize the master and export in Avid or use DCP-O-Matic to do the conversion. Or both.

    • Pliny

      If the picture is 2048×858, just letterboxed in a 2048×1152 frame, then you should just crop, encode your DCP, and Bob’s your Uncle. (The DCP should be 2048×858 “scope”.) Not sure why it would look like tosh** in this case.


      ** I had to look that one up.

  • Raúl Fernández-Ballester

    Hi, the DI shot in 2048×1152 but director wants to deliver in 1:66. We need to deliver a ProRes or DCP to a Film Festival. In which resolution do you suggest I have to deliver? We are still in color grading process and I guess we’ll crop the image to 1:66 in DaVinci Resolve. Should we render in 1920×1080? Thank you!

  • Nate Opgenorth

    Wow this is very well written and much needed! I think shooting 2048×1152 might be good if you frame for having those 128pixels chopped off each side, it is good to have some wiggle room. So dropping a 2048×1152 image sequence into a 1920×1080 timeline and then just cropping it but knowing you have a bit of wiggle room. Theres been a few times where I’ve had a 1920×1080 image that is perfect but for some reason what I got was a portion of the image has some weird artifact, kind of reminds me of some of the overscan artifacts on analog displays but at the top of the image or bottom or on the sides. In a 1080 timeline I’d have to crop and zoom in, spend time trying to fix this issue, usually by adding a tiny letter box effect, or request a new render which way not be possible. With 2K I can avoid that.

    ANYWAYS I am a numbers guy when it comes to desired resolutions, I like clean numbers that divide nicely for reasons obvious if you read the article. I think 5760px vertical is a great number, you get a clean UHD down sample and a clean HD downsample and if you have to do a 4096px by whatever downsample it is sufficiently large that it doesn’t look bad despite being an odd 1.40625 factor.

    Admittedly I am not shooting high end movies but I am shooting RAW stills all the time. I do not always want, need, desire a 24megapixel image…so I downsize, but I always do it by a factor of 2, 3, 4 or 1.5 or even 1.25 and the down sample is not a meezly 128pixels of even triple that.

  • PunkDuck66

    My Blackmagic Cinema camera shoots RAW at 2400×1350. Is 25% a sufficent scale down to avoid issues? Or am I better to shoot at 1080P? I will be delivering an HD lettereboxed format for Blu ray/DVD etc. Thanks 🙂

    • Pliny

      That’s 2400px wide pre-demosaic. Figure that loses you about 80% of resolution along each axis. 2400 x 0.8 = 1920. Presto. It’s almost like they planned it that way.

  • Hans Lettany

    Well! This article will hopefully help me a lot in my meeting tomorrow! For almost 10 years I deliver titles to different (post) production companies in Belgium, the Netherlands and France… all went well till now. Recently I had to deliver opening credits and end scroll to a Paris post house. All the titles, even the still ones were not sharp and ofcourse jittery. Since I deliver my titles always the same way, and they alway look technically good, I really had no clue. But guess what… I had to deliver them 2048×1152…
    Thanks! Hope this article will work on them! Hans.

  • Wow. Someone that actually gets it! Well written, now if only the rest of the community would stop having numberlust for larger digits! 🙂

  • BTW. Endcrawl is awesome. I recommend all my clients to use it if they must have a roller!

    • Pliny

      Thanks, appreciate the kind words! 👊👊👊

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