Digital Movie Remastering – Grain
I had a conversation today with someone who was asking me about film remastering. His first question was “if a movie was shot in digital format, then you don’t have to do anything but encode it right?” While several movies are being shot in digital format, there is a long held belief by many in the industry that film provides a much better look and feel for movies. We first learned this when working on the Interstellar project where we had to review our compressed digital delivery along side the original film output. Directors all take great care in their art, and rightfully so, as it’s their expression to the world of story they want to show and tell. Some directors will even go as far as choosing the type of film that they shoot on to get a particular look. This attention to detail is something that we spent a lot of time on when working on The Good The Bad and The Ugly project as we not only were trying to recreate the directors vision of the film, but also to match the choices made in lighting and apply coloring techniques to recreate the style of the print.
There are several considerations that have to be made when delivering a movie to the consumer on a TV over the internet. First and foremost, we have to look at what can be done to optimize the number of bits that are being streamed while trying to retain the original vision of the movie. A typical stream is going to deliver 6 to 8 gigabytes of data, which has been compressed down from the original 4 to 7 terabytes of raw digital footage. There is a significant amount of data to remove in order to make that work.
There are many areas of remastering techniques that are used on both analog and digital masters. One area that we are currently doing a lot of experimentation with and seeing some great results is film grain. Film grain provides a unique look to a film and helps the video being shown to get away from that plastic look that is especially prevalent in modern video that is shot on high end digital sensors at 60 fps. While that look is really great for showing off the color and brightness of the latest generation 4K HDR television sets, it can be off-putting for a movie experience. This is where grain can be your friend. By having grain, film has a more natural and fluid look. Capturing that grain is your enemy however, when trying to create a compressed digital file to be streamed. Grain is realized in pixels as what appears to be random patterns of different variations in the lighting of textures within a scene. This typically wreaks havoc when you are trying to compress a scene as compression does really well when you have long stretches of the same colored pixels in a row and does far worse when there are lots of subtle variations. There are a lot of grain filters that can be used during the post production process that can take the digital images and make them appear move film like. Where we are doing a bunch of work is to add that filter post expansion on the client side within the player as opposed to upstream pre-compression. This allows us to gain a better compression ratio but still apply the same “look and feel” of the graining filter that was desired.
With new techniques and tools literally coming out every week, and new projects coming on board we have the fun job of both redoing movies we have previously remastered and compressed and applying the new methods to improve them as well as taking some of the latest and greatest state of the art digital movies and applying new methods to them to show even greater improvement. This job is sort of like the guys that paint the Golden Gate Bridge, it’s never done. By the time they get to one end, it’s time to go back and restart.