4K video editing

low_iso wrote:

Lets clear up some mythology flying around here.

1. All NLEs will scale your video for you to whatever specs you choose for your project

2. Scaling video does not improve it. Ever. There's no magic here. Up-scaling 1080p to UHD (NOT 4K!), which is 3840x2160 is an even multiple. That means within a line every 1080p pixel is faithfully reproduced, and the missing pixel inbetween is created by assigning an interpolated value, and the ineropolation is simply linear. What you get is a 3840x2160 blow up image of a 1080p image, but it isn't improved, it's just a blow-up. There's no magically creating detail that didn't exist in the original. It's still just a 1080p image, and it will look like a 1080p image, though content of the image may not show that it's really a bit softer than the 4K footage. Or it might. The exceptions might be 3rd party apps and plugins like Topaz Video Enhance, because it does SO much more than the upscaling found in NLEs. It applies several content-aware AI based processes. It also takes an eternity, and results vary a lot from flat out amazing to unusable.

3. Scaling video can degrade it. If you attempt a scaling that isn't an even multiple, like 1080p to actual 4K (4096 x 2160) you'll end up degrading the 1080p image because it won't scale evently. Much more interpolation must take place, there are no even pixel relationships at all, if you want to fill the 4K frame. Mostly when that's done it ends up just as a 2x scale and not filling the (real) 4K frame. Full up-scaling to real 4K should be avoided.

Actually,  in todays world of NLE editing apps, there IS "Magic". that magically fills in the missing pixels while retaining sharpness.

Not all NLE's do it, or do it the same.

Davinci Resolve (which is one of the most popular NLE's on this forum) has super scale, Adobe Premiere (via After Effects) has Detail Preserving Upscale. (not to mention AE natively offers different options on scaling  - BiLinear or BiCubic, the later is better for non-graphic elements)

Also keep in mind that 1080i footage needs to be de-interlaced prior to up-scaling,  in which case there is the "Preserve Edges" option in After Effects (maybe Premiere?). that also makes footage look better than just scaling it up using nearest-pixel.

and yes. all this technology does indeed improve the appearance of upscaled 1080 video, even that which has been upscaled to "true" 4k. (which honestly,  is irrelevant to the OP's question, as very few work in true-4k).

But just like with photographs that have been scaled up 200% in Photoshop, video scaled up 200% will look better.