How do they remaster old grainy footage of films/videos and make it 4k without any pixelation?


They are technically just stretching the video right? Where do the additional information for the new pixels come from? Does it cost a lot? What’s the simplest way to restore similar home videos to 4k crisp quality, can it even be done by a regular guy on a home computer?

In: 3

A remaster isn’t stretching the video. They re-scan the original film or video at higher resolution. Film has *very* high resolution, a ton is lost during the reduction to pixels. You can also use image processing to “fill in” (fancy word for “guess”) the missing information when going up resolution from something that was previously limited resolution, like old video.

It doesn’t look pixelated because you’re not just making the original pixels bigger, you’re rebuilding the image with new smaller pixels.

You can’t restore video the same way you restore film because video has a physical resolution that is already very low like 480p.

Film has a theoretical resolution of at least 4k. Film is restored by essentially scanning each frame into a computer at a high resolution.

35mm film has a resolution of a digital image size of about 5,600 × 3,620 pixels. About 5.6k. Many older videos were 720k or lower.

If you go back to the original film you can get better resolution.

They’re not really stretching it. It’s called upscaling where they use programs and AIs to create a new approximation of what the new resolution will be. It’s kind of like painting in the gaps. You can do upscaling yourself at home depending on how good your computer is and how much RAM you have you can use things like Topaz AI

Film actually has a very high resolution, especially large film stock (i.e. film where each frame physically takes up a large area). You can get a lot of pixels out of good-quality film before you hit diminishing returns (eventually the pixels get smaller than the film grain and then going any higher is pointless).

So when film footage is re-released in a high digital resolution, that doesn’t mean this new release looks *better* than the original (at least in terms of the level of detail – they might of course recolor it or whatnot). It just means it looks better than previous releases. Like, maybe in 1997 they did a VHS release. VHS is roughly equivalent to 240ap (vertical resolution). Then in 2004, they did a DVD release, which was 480p. Then in 2010, then did a Blu-ray which was 1080p. And in 2020 they did a release for streaming in 4k. If the original film master was 35 mm, then 4k still isn’t at the limit of the digital resolution you can squeeze out of that, but it’s getting there. So each of these digital releases is just getting better and better at showing the footage in its original film quality.

Home movies were rare in the pre-video era. That is, not many people had cameras at home for shooting on film. If they did, these tended to be cameras that shot on small, lower-quality film stock (like 8 mm), as opposed to the larger film stock (often 35 mm) common in big film productions. Besides which the camera system itself would also have been lower quality. So a home movie film would have had lower quality to begin with and can’t be remastered to a high digital resolution. That is, you could do it, but it would never look better than the original film resolution, which for 8 mm is equivalent to about 720p (vertical resolution).

The real home movie era began with the advent of home video cameras which shot on video tape. Video tape (at least back then) is still sort of analog but it uses scan lines, so it has a fixed vertical resolution. The most common format used 480 scan lines so the best digital resolution you can get out of that is 480p.

So in short: professional 35 mm film stock is equivalent to better than 4k digital resolution. Home movies would typically have been shot at the equivalent of either 720p or 480p, depending on the medium. There is no way to “restore” something to a higher resolution, short of using image processing techniques that will dream up detail that wasn’t there in the original footage (but whether you can still call that “restoration” is debatable). These exist but aren’t readily available to, or easy to use for home users.