Before we go into the various concepts behind these two screens – we have to understand Chroma keying first.
Chroma keying, also known as colour keying refers to a visual effects technique that layers two images or video streams together based on Chroma range. The technique is used to remove the background in a subject photo or video – especially in video games, newscasting, and motion picture industries.
Typically, chroma keying can be done with backgrounds of any colour as long as they are uniform and distinct. Green and blue are, however more popular due to their contrast with many human skin colours. Once the colour is removed – only a moving cardboard cut-out, known as an “alpha channel”, will be left.
After which, go ahead and add any background behind this alpha channel and you’re all set! The only thing to keep in mind is to ensure the subject isn’t wearing any duplicate colour of the background or otherwise you’re going to come face to face with some missing body parts.
While using film, blue screens are preferred as they have the smallest grain resulting in an image of better quality. Exposing the blue colour onto black and white film using a blue light manifests the blue colour as bright white.
With the help of an optical printer – and then… voila! Compositing begins.
Blue screens tend to have less colour spill compared to green screens. Blue doesn’t reflect much light and has a way lower luminance. This makes it easier to retain small details even after keying.
So, if you’re looking to animate your brand’s product in a recruitment video and ensure all the little details are captured – then, blue screen is your go-to choice.
Contrary to green screens – it’s much easier to key blonde-haired subjects. Moreover, since blue screens reflect less light onto the subject, they are efficient for dark composites.
To use blue screens – one needs a lot of lighting, which makes it not exactly budget-friendly.
Most clothing may be blue, which is quite a common object colour, and this causes problems in keying.
As for green screens – it has become much popular in recent years. This is because digital cameras are able to capture more green information than they would with red or blue colours.
The green is easier to key out during post-production, and green screens require less light in comparison to blue screens – making it both cheaper and user-friendly. The rarity of bright green in costumes also make compositing easier by eliminating problems in post-production.
Just look at how tons of acclaimed Hollywood films have done it – and how reality is without the powerful green screen.
Since most digital cameras capture more green information, the key around the subject is cleaner and has fewer noise objects. It makes scenes appear more authentic and unforced as the spill produced by the brightness of green screens makes it easier to key subjects when making a daytime scene.
Most of the present-day keying tools are pre-set to key out green speeding up the keying process and eliminating the need for error correction. Green screens are budget-friendly as they require less lighting in comparison to blue screens.
In some cases, the colour spill may be too intense and give away details and edges.
It is also not great for shooting dark and night scenes due to the high luminance of the green colour.
Live-action or animation – it’s pretty clear that you’ll need chroma keying; be it the blue screen or green screen if you want to incorporate unique elements which are not normally possible in real life. So, get in touch with a production company that focuses on both live-action and video animation services to get the best out of your video!