ADMEC Multimedia > Post Production > Why is Blue Color in Chroma?

Choosing blue color in chroma makes sense in the world of editing. Let’s see this from a different perspective.

You just watched a movie which has left you awestruck. You are spellbound by the visual effects and just cannot sleep ignoring the brilliant scenes that flash up in your mind again and again.

Does it happen to you too? AS we all are under lockdown so I decided to watch some movies and picked Avengers: End Game. The movie again filled me with the same excitement that I had experienced when I saw it for the first time.

But this time what captured my attention are those super stunning visual effects. I just cannot keep my mind off of that and decided to search about that and while looking I found out some clips of the movie before editing.

The big battle footage was shot in front of a green screen but what we saw in reality was something else. That entire background that left us speechless was just a green and blue screen. Exciting, isn’t it?

But do you know what these blue and green screens are? Why are they used?

Let’s head on to the blog to find all the answers.

Reasons to have Blue Color in Chroma - Walking man on green screen

What is Green screen and Chroma keying?

The colored background which is removed using the software is called the ‘Green Screen’. The background is usually in green or blue color because they are far away from the skin tone of human beings.

Chroma keying is the digital process of removing the green or blue screen using the digital software. It comes under the post production process and once you remove the background color, can add desired image or video.

You must be thinking why the screens are either green or blue. As we all know about the RGB model and how digital applications like television, computers, digital cameras make use of it. So these colors are used popularly.

Why is red color not used in chroma?

Human skin tone already contains a good amount of red color and if red is used as a chroma screen it will be interposed with shadows. This is the reason red is not used as a chroma screen and green and blue is heavily preferred by professionals.

Reasons to have Blue Color in Chroma - Blue Chroma Screen

Why is Blue Color in Chroma?

Chroma Key Blue is the alternative color used for green screens – it is also known as Chroma Blue and is valued at approximately 2728C in the Pantone color matching system (PMS).

Shooting with Blue

All colors in our visual range are made up of a combination of the three primary colors red, blue, and green. In the chroma shoot or blue screen process, an actor or object is filmed against an evenly lit (i.e. entirely one color) blue screen.

  • In the composting process, the blue color in chroma or blue element (i.e. the background screen) is removed via a color separation process.
  • The screen is blue in color because blue is the smallest competent in the color of human skin (i.e. skin color has more red and green elements) so that when the blue color is removed, it does not affect the appearance of the skin.
  • This of course also means that the actor cannot wear certain blue clothing or the object cannot have blue parts.

With advancement in digital technology, it has completely replaced the traditional composting processes; the color of the background screen is becoming less important as greater accuracy in color separation can be achieved with computers.

In the television series Lois & Clark: The New Adventures of Superman, the Man of Steel was filmed against a green screen for the flying shots to prevent his blue tights from disappearing into the composited background.

Reasons to have Blue Color in Chroma - Blue Chroma Image

Early Days of the Blue Screen

These blue screens were first created by RKO Radio Pictures back in the 1930’s. Blue screen first appeared in 1940 in the movie The Thief of Bagdad in the scene where genie comes out of a bottle flying.

The blue screen was an evolution in the chroma keying field as the intensity of blue color matched the intensity of neon green color and it gave new elements to professionals to experiment with.

Reasons to have Blue Color in Chroma - Green Chroma Screen

Important Technique for Chroma Shoot

A chroma key subject during chroma shoot must not wear clothing similar in color to the chroma key color(s) (unless intentional), because the clothing may be replaced with the background video. An example of intentional use of this is when an actor wears a blue covering over a part of his body to make it invisible in the final shot.

This technique for chroma shoot can be used to achieve an effect similar to that used in the Harry Potter films to create the effect of an invisibility cloak. The actor can also be filmed against a chroma key background and inserted into the background shot with a distortion effect in order to create a cloak that is marginally detectable.

Let me give you a quick example for this.

There is a popular movie of the year of 2002 very well known as Spider-Man and I’m sure that you must have watched this movie. There is a scene in this film where both super hero (Spider-Man) and super villain (Green Goblin) are in the air. To make this scene realistic, green and blue screens were used to shot the scenes of both the characters respectively.

For Spider-Man greenscreen was used and for Green Goblin bluescreen was used. Now you can clearly recognize the reason of filming with different colored screens. The main reason was that the costume of Spider-Man was having red and blue colors in it on the other hand the costume of super villain goblin was in green color.

Because of presence of blue and green colors in their costumes, it became difficult for the team to shot in front of a same screen. If they were shot in front of green screen then goblin would have been partially erased from the film and same could be happen in front of blue screen.

Hope you got it.

Reasons to have Blue Color in Chroma - Green Chroma Setup

Importance of Blue and Green Colour

Blue color is generally used for both weather maps and special effects because it is complementary to human skin tone.

The use of blue is also tied to the fact that the blue emulsion layer of film has the finest crystals and thus good detail and minimal grain (in comparison to the red and green layers of the emulsion.)

In the digital world, however, green has become the favorite color because digital cameras retain more detail in the green channel and it requires less light than blue. Green color not only has a higher luminance value than blue color but also in early digital formats the green channel was sampled twice as often as the blue, making it easier to work with.

Reasons to have Blue Color in Chroma - Green Chroma Image

Which Colour Option to Choose?

According to various post-production courses institutes – the choice of color is up to the effects artists and the needs of the specific shot in the post-production industry.

Green: In the past decade, the use of green has become dominant in film special effects. Also, the green background is favored over blue for outdoors filming where the blue sky might appear in the frame and could accidentally be replaced in the process.

Red is usually avoided due to its prevalence in normal human skin pigments but can be often used for objects and scenes which do not involve people 🙁

Magic Pink: Occasionally, a magenta background is used, as in some software applications where the magenta or fuchsia key value #FF00FF is sometimes referred to as “magic pink”.

Tips to avoid confusion between colors

With better imaging and hardware, many companies are avoiding the confusion often experienced by weather presenters, who must otherwise watch themselves on a monitor to see the image shown behind them, by lightly projecting a copy of the background image onto the blue/green screen. This allows the presenter to accurately point and look at the map without referring to monitors.

Use a retro reflective curtain

A newer technique is to use a retro reflective curtain in the background, along with a ring of bright LEDs around the camera lens. This requires no light to shine on the background other than the LED’s, which use an extremely small amount of power and space unlike big stage lights, and require no rigging.

  • This advance was made possible by the invention of practical blue LED’s in the 1990s, which also allowed for emerald green LED’s.

Do you know about another form of color keying? Well Thermo-Key is there that is slightly invisible to human eyes because of the presence of light spectrum.

One more interesting thing about this type is that it works with infrared as the key color. This key color used by Thermo-key is non-replaceable at the time of post-processing.

What’s the difference between a green screen and a blue screen?

Professionals employed in the post production industry were using green screens for a long period of time. While both the colors are used as screens, there are certain reasons why filmmakers are moving towards blue screens from green one.

Know what are some basic differences between green and blue screen!

Use of digital camera

When a cameraman uses a digital camera to shoot a video they prefer green screen. Green screen gives better luminescence over blue color. Green screen gives out less noise over blue while doing the keying process.

Color Spill

When the green or blue screen is removed during the keying process, some color gets spilled around the object, especially to the edges. A thin line gets stuck to objects which look really odd. Blue screens often have a less spill than green screen and correcting blue spill is relatively easier than spill caused due to green screen.

Luminosity

Blue color has less luminosity than green color and thus Blue color screen is preferred when shooting for a low light scene.

Prevalence of blue

Blue is present in most of the objects around us. For example, you can see people wearing blue more often than green and using a screen of a color which is dominantly present around you is not a good option.

Professionals, that is why majorly use green color as it is not heavily present in the surrounding and this is also the major reason why screens of red or yellow color don’t even exist 😮

Reasons to have Blue Color in Chroma - Chroma cutting

How to key a green screen scene in your favorite software?

  • Keying in After Effects

After Effects is one such software that produces one of the finest keying results. There are several methods of working with green footage in after effects but Adobe provides a built in preset that helps you get quick fine results.

The software comes with a built in keyer called Keylight. It is a powerful present developed by the same company which has developed Nuke, The Foundry.

  • Keying in Premiere Pro

Premiere Pro was the flagship project of Adobe under a non-linear video editing domain. Similar to After Effects, Premiere Pro also comes with a powerful keying option. The chroma keying effects produced by the software are fantastic.

However the only thing which is a drawback here is you have to do a lot of manual masking which would be relatively easier in After Effects.

  • Keying in Final Cut Pro

FCP or Final Cut Pro has a casual workflow for green screen which is useful for novice video editors and Youtubers who are in search of quick solutions.

You only need to add your green footage to the timeline and apply the keyer effect, the software will do everything else for you. It will automatically carry out the green screen and refine the entire look for you.

 You can also manually refine the edges with simple controls.

Reasons to have Blue Color in Chroma - Green Chroma Shooting

The Current scenario – Faking at its best!

Digital revolution has turned everything and the green screen has been one of the best technological developments!

The consistent and dynamic changes in the industry have made green screen part of every commercial business. Green screens are no more limited to Hollywood or big budget movies.

Now the professionals don’t need to spend millions of dollars to bring the professional look. They can shoot a scene in their boundaries using the green screen and then immediately using the leading software can transform into something else, something more beautiful!

Check out below to know about big budget bollywood movies that have used green screen at its best!

Author’s Note:

So, this was all about chroma keying, Green and Blue screen. If you are also fascinated with these things, let me tell you, the Post Production and Video editing industry is filled with such exciting and interesting things.

ADMEC brings one of the best and professional quality courses in video editing and post production domain. You’ll experience the best training under the guidance of professional faculty.

Join now to experience the best of the city. Stay tuned with us for more informative blogs, till then, keep exploring !

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