What is Green Screen and How does it Work?

What is Green Screen and How does it Work?

In big blockbuster films, we all know that the fantastical background looks underwhelming on set. With the use of green screen, filmmakers are creating worlds with an unbelievable sense of authenticity. Green screen is common and practical now with the rise of digital filmmaking.

Green Screen is a visual effects technique where two images or video are layered together. The green screen lets you drop in whatever background images you want behind the actors or foreground. It’s used in film production to relatively place the desired background behind the subject/actor. When a background isn’t available and impossible to create like a fictional, historical, futuristic, alien or even just hard-to-access location green screen comes to the rescue.

After the Shot, the Compositors take over:

The new background is composited (2 images or video streams are layered mutually) into the shot.

The chroma key singles out the decided color (green screen) and digitally removes it by rendering it transparent. Lets the other image to show through.

When used with more sophisticated 3D animation techniques, this process can add a new element (fire, rain, smoke, etc.) to complex moving shots.

Click on below Video: Use Green Screen to Create Composites in Photoshop!

Why is Green Screen used?

You can make use of any background color technically. A vibrant, almost neon green is the standard choice because it is a distinctly different color on the subject from anything (e.g. the clothes, hair, eyes, accessories).

The critical rule is no matching colors. The background has to be a different color from the main subject. Otherwise, if the actor is wearing a bright green tie in front of a green screen, then he will end up with a transparent layer down his chest where the tie is.

How to Set Up Green Screen in Shot

1. No Reflective Surfaces

Avoid any green and reflective surface from the shot. Don’t allow the actor to wear or hold anything green color or else the particular portion will become transparent once chroma-keyed. Any shiny objects will pick up the green from the screen and also be rendered transparent.

2. Allow Depth

For an entire shot of your actor, you will need to back up the camera to allow the full figure shot and a good separation between the green screen and the subject (At least 6 feet to avoid).

Depending on the lens, you will typically want 25-30 feet depth shot that don’t shoot off the edges of the background for a full-length.

3. Light and Softly

Light the green screen as smoothly as possible to give a smooth gradient and texture. The more even the lighting, the more comfortable and better it will be to manipulate the material.

Keep the green screen clean and smooth to maintain a consistent color range. If the screen is fabric, make sure there aren’t any lines. If coated, keep extra paint on hand to touch up any scratches.

4. Light Separately

The green background should be little separately from the subject to avoid:

The subject casting shadows and a green screen hue bouncing off the subject which creates problems when removing the background.

This is why you will need at least six feet of separation between subject and background.

5. Keep Camera Position Still

When green screen shots – Keep your camera in a static form. Lock the camera, so the subject doesn’t look like it’s bouncing or vibrating against the background when the camera moves slightly.

Your subject will look like it’s shrinking in relation to the background.

Use motion trackers and motion control for more sophisticated 3D shots, but it’s a lot more work for the VFX artists.

Use Chroma Key Software

Research and consider software based on the shots needed, the editing system and user experience. Your options for Chroma Key software will depend on the type of shot.

Arena Sayajigunj offers an excellent opportunity for students who are interested to learn more the Green Screen and how does it work on more professional level, please sign up today for our VFX Courses.

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