Upscaling from HD to 4K - 3 Steps
Most stills cameras already give us more resolution than we generally need and most images I produce end up being downscaled to a more user friendly resolution. The delivery is likely to be on a phone in many cases so a long edge resolution of 2000px is just fine. Upscaling is just not usually done, unless by mistake on a e.g. poorly designed website or maybe on an icon where the vector version just wasn’t available (a pet hate of mine).Upscaling in video is a little different. There are very specific frame sizes and standards which need to be stuck to for, among other reasons…
Acceptance for broadcast
Compatibility with video hosting sites
Encoder efficiency (multiples of 2, 4, 8, 16)
User viewability (black bars or, even worse, portrait videos)
As we begin to move through the transition from HD (pretty much standard on major channels in the UK in 2016) to 4K (still a long way off, particularly via terrestrial broadcasting) upscaling may be needed whether that be from SD to HD, 720p to 1080p or, as in this example, the extremes of going from 720p to 2160p UHD. A project may be filmed in 4K as that’s what a client needs but one essential piece of library footage may be in 1080p and require upscaling in the edit.
The Trade Off
So many things are about trade off. What we’re doing here is what any good engineer would do and try to go for the best balance of all components within a trade off. This method can be used in almost any NLE and doesn’t use costly third party plugins (we use FilmConvert in the video but you can also use film grain plates which are downloadable free of charge here).There’s really no good way to do this so it’s just about trying different methods to get acceptable results. It will never look great because even the best computer cannot make things up even with the complex scaling algorithms used. Remember the increase we’re talking about…
Original Resolution 720p = 921,600 pixels
Delivery Resolution 2160p = 8,294,400 pixels
‘Made Up’ Pixel Count = 7,372,800 pixels
In other words, 89% of what you are watching on the sample below has been completely made up with guess work based on e.g. color and brightness levels of adjacent pixels. That’s a lot of data! Fortunately, the human brain is pretty forgiving. If the content is good, you’ll still enjoy the film. We’re just being picky and technical here :-)[image_with_animation animation="Fade In" image_url="http://tdcat.com/wp-content/uploads/2016/03/HD_UHD.png" delay="500"] [/image_with_animation]
3 Step Process
I walk through the steps in the video but if you’re happy about how to do this Premiere Pro, here they are for you.
Upscale the footage to fill the frame in your NLE. In our case, this was a setting of 300%. I find that scaling using this method is just fine.
Apply Unsharp Mask to your footage but only with very gentle sharpening. You’re sharpening rubbish (almost like trying to sharpen out of focus footage) so just apply a tiny amount to give the impression of better quality. Level for 4K about 100, Radius 0.5 and Threshold 2-3. Whatever looks right.
Apply a subtle film grain over your footage to hide the imperfections with more natural imperfections. If something looks like a video, you kind of expect it to look perfect. It works better if you add that organic feel….what a crap word that is but I couldn’t think of anything better.
Third-Party Plugins
There are plugins out there that claim to do a better job of upscaling footage. In my experience, these are not worth the money and add little if any quality to the process. That said, you may prefer this approach so here are a couple for reference.