The REAL Reason Nobody is Using Red Screens.

If you know anything about VFX, you have probably encountered or heard of the use of both green and blue screens for keying or removing a background. This raises the question: Why don’t we use red screens? To answer that question I would have to tell you that while it is a rare occurrence, red screens are occasionally used for specific shots. This new piece of information would prompt us to re-phrase the question as: Why is the use of red screens so rare?

To answer this question we have to look at what most cases of background removal or chroma keying involve(chroma keying just means isolating a color and replacing it with a different background). A lot of shots involve people who have to be keyed. Human skin has shades of red which are more visible at some times than others, but are always there and a camera can see them. Imagine trying to digitally remove the background and ending up with part of the person removed with it. This would not be good at all.

Now think about some other reasons why a red screen could be problematic. Red is a relatively common color to wear, red ties, red shirts, red socks, even red lipstick. While it is quite easy to avoid wearing green during a shoot, red is a color that is harder to avoid. Now let’s think about fire and explosions. These definitely will have some shades of red or similar colors that could confuse the keying algorithm or even downright ruin your shot. If you have a fire or an explosion in the shot, this will almost definitely rule out the use of a red screen.

In these last few paragraphs I have been slowly narrowing down the situations where a red screen could be used. Now we are left with a very small area to operate in. Before you lose hope, remember that earlier I said that the use of red screens is very rare but not nonexistent. Perhaps now would be a good time to look at one or two of those rare cases where a red screen would be appropriate.

Example

Imagine, for whatever reason, your boss asks you to take a shot of a blue jay(that’s about as far as my knowledge of blue birds goes) and replace the background with a jungle scene.

a blue jay that would need a red screen

A Blue jay perched on a branch with leaves in the background.

Image by Mohan Nannapaneni from Pixabay

The director wants both the blue jay and the leaves to be in the final shot. Once you have finished marveling over the fact that this bird has been afforded the luxury of an entire VFX shot for no apparent reason, the first thing you might think of might be a green screen. Oh wait, that would mean all of the leaves would disappear. Well, how about a blue screen then? Well unfortunately, if you were to do that, the blue jay would probably become a ‘transparent-jay’ as soon as you tried to remove the blue background.

After trying both green and blue without finding satisfactory results, maybe it’s time to turn to a red screen. If you look at the image, you can’t really find any red that could be problematic. In this case, a red screen might just be the way to go.

A large number of the cases that need a red screen involve nature. Things like grass and trees will need either a blue or red screen if you want to remove the background. This is not often the case and therefore the use of red screens is quite rare.

Why are red screens so rare? Because there is not often a case in which a red screen would get the job done properly and effectively. If you ever need to add some grass elements to a shot, consider a red screen.

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