What is video post production?

So your film is planned, you’ve designed characters in your 3D Animation program of choice, and you’ve spent many days running around your hometown in a taxi with a film crew capturing people doing various things in different places. That whole process is the video production, so what comes next naturally is the post production, which is often referred to as the third stage of production, the final stages. So how does one proceed with the film production process when everything is created, captured and recorded?

What is compositing?

Compositing is the process or technique of combining visual elements from separate sources into single images, often to create the illusion that all those elements are parts of the same scene. This can involve a green screen and imposing those green-screened images (more often than not, people) on top of one another to complete or blend them together. And make a scene that the viewer would assume would have all been captured at the same time. Obviously just putting one image on top of another, even if perfectly rotoscoped or chromakeyed would result in a myriad of imperfections. Some basic things to take into consideration – at what time of day is the scene meant to be taking place ? What about the weather? Where is the light coming from? One look at a tree from Nuke – even a simple one – would show the enormous range of possibilities available and the range of considerations to take into account.

A node tree in Nuke
A Node Tree used in the program, Nuke.

What is rendering?

Rendering (otherwise known as image synthesis) is the process of generating a (photorealistic or non-photorealistic) image from a model using a computer program and as big an array of computer processors as you can afford. Essentially rendering is what takes a list of computer commands and turns it into something actually playable and recognisable, baking the commands in that process. Except at the margins, a render cannot be changed if you don’t like it. You throw it away and alter it at source. And render it again.

Colour correction & grading in post production

Clearly, as even a short film can be created over a period of months, in many different environments, quite apart from adding CGI, 3D Animation or VFX to it, it is almost impossible to get a coherent look to the output. As per grading this can be done across all shots, as well as specific elements within a shot. A red dress filmed on one day may well turn out to be a slightly different red under different lighting conditions! Thus the first step of a colourist is to “correct” the shots so that some of that expected visual coherence is there. The 2nd major role of a professional colourist is to use “colour” to create a mood that reflects the story or the director’s intention – ie how he/she want the audience to feel. Some of this is very subtle and very subliminal. Sometimes, not so subtle! But the style of the film (or whatever else it is, like a television ad) is more often reflected in the colour grade than a lot of people realise. An ad for breakfast cereal never looks like it has the same grading elements as a horror film! Whilst a great DoP and Lighting Director can create wonders, the final, and often, crucial finishing touch is created in post- production (and many times under the DoP’s or Director’s instructions).

Sound design as part of post production

Sound “Design” is quite different from Sound “Effects” (SFX). The latter refers to a specific audio input for a specific visual action. A sound designer works on all of them + the soundtrack throughout the film. For example, if somebody is walking along the street, a sound designer would not be the person to create that sound, but work out how far away the character is, what kind of shoes, what kind of ambience is in that scene, whether it is integrated into the soundtrack, and even whether the sound of the shoes needs to be heard by the audience at all. A sound designer will often create the sound fx, but he/she takes a much more holistic approach to the overall needs of the production. It is another hidden job, but a crucial one if the visual action is to be believed by the audience. It would be very hard to over-estimate the importance of good sound design in a film.