Get the Green Screen Lowdown
Green Screens. What they are, how they work, and why they are so frequently used.
You may be familiar with the term green screen, but possibly aren’t sure what exactly it is, or in fact how they actually work. Hopefully by having a read of this blog you’ll soon be clued up and have all the know-how about what green screens are and how you can have a go at using one yourself.
Although most commonly referred to as green screen, the special effects tool is also sometimes known as a Chroma Key screen. The term chroma key refers to a visual effects technique that is put into place post-production, and allows for the layering of images and video. The process involves editing the green colour range in the editing software, changing it to appear as transparent so that other layers can be placed over the top.
By standing in front of a solid colour background, flexibility in editing then allows you to alter and play around with other footage so the final background can be anything of your choice. This change of backdrop could be anything, you may want it to feature some images or relevant graphics, text or just display an entirely new scene.
Making changes to the background so that the scene is more engaging adds depth to the video, and allows you to add further content to the scene, helping you get your message across effectively.
It is possible to set up and use a green screen quite easily, but more professional uses of green screen are common in television and film production, with one of green screens most well known uses being for the weather segment on news channels, allowing a presenter to stand in front of visuals of maps and weather forecasts.
Green screens are a good tool to use if you have a lack of space to film, or cannot film in the desired location. You are able to play around with an otherwise ordinary setting, allowing you to create a scene or setting that may otherwise be impossible to film.
Why green? Well, technically the green screen does not have to be green. The technology works by picking out the block colour and applying the chroma key technology. This means that other vivid colours could be used, providing they are lit in the same way. Green is the most frequently used as it is least common colour worn by people, and is less frequent in objects.
So, how can you get to grips with a green screen and have a go yourself?
While preparing a green screen, there should be a focus on making sure time is spent setting up correctly, so that the process is easier once the footage is on editing software. The most effective green screens are non-reflective, diffusing light and preventing hot spots. This will allow the software to more easily determine where the focus should be in relation to the screen behind.
Once the green screen is up it is time to start thinking about lighting. Wherever possible, you should try to prevent any shadows being cast against the green screen. Lighting should be positioned so that the screen is lit, rather than the subject in front of it. If possible, try to make the outline of the object as clear and well defined, otherwise there will appear to be a glow around the focus point which will be evident in post-processing.
After the lighting is set up, the focus point needs to be prepared. Ideally, the object can’t be too close to the green screen there will be more chance of it casting a shadow. The person or object in front of the green screen should also be lit separately, with lights at either side of them, and behind if possible, acting as a back light that doesn’t reflect on the green screen. This will ensure a sharp contrast with a well-defined outline. Being well lit will also help to accentuate features, making it easier to add effects on software.
If it is a person that is going to be in front of the green screen, always take note of what they are wearing. If a person is wearing glasses, there can sometimes be reflections that will show up in the recording which isn’t ideal, so be sure to place your lighting in the right areas. Also be sure that the person isn’t wearing any green that matches the screen, as the technology will pick up on this and project whatever image it may be on to that area.
When recording green screen footage, usually using auto focus will do the job and work effectively, picking up the subject as the focus and concentrating on that. It is recommended that you do adjust the white balance however, as this will set the correct colour for the recording.
So there you have it, you now have all the need to know information about green screens, hopefully you’ll now feel inspired enough to go and give it a try for yourself!