Version 1.0

Description

iMovie plugin effects for blue screen, green screen, and compositing. Includes 2 free effects!

This iMovie plugin package contains effects for compositing operations, including blue screen and green screen effects, as well as clip blending and combining. It also includes a number of effects for extracting masks from clips. These masks can be tweaked, processed, and then used in compositing. IMPORTANT: Please read the special README file which accompanies this plugin for instructions on how to use this plugin.

Notes

WHAT IS A MASK? A mask (also known as a matte) is a black and white image (or clip) whose value at each pixel determines it's opacity (or alpha) value. So a white pixel would indicate an opaque pixel, black a transparent one, and grey values varying degrees of transparency. If a color image is used as a mask, only the red component of the image will be used.

HOW DOES COMPOSITING WORK? In compositing, two images (or clips) are combined in one of several ways using a mask. The most common way is to place one image (the foreground) over another (the background). Where the mask indicates transparency, the background image will show through the foreground. Other compositing modes include adding and subtracting the images, still using the mask to control the operations.

WHAT IS BLUE/GREEN SCREENING? Also known as chroma keying, or just keying, blue screening (and the same applies to green screening) is a special kind of compositing, where the mask is calculated from the foreground image. Where this image is blue (or green for green screen), the mask is considered to be transparent. This technique is useful when shooting film and video, as a blue or green screen can be placed behind the object being shot and some other image then inserted in that space later.

ISSUES WITH BLUE/GREEN SCREENING USING DIGITAL VIDEO. Blue and green screening rely entirely on the color of each pixel to determine where the edge between the object and the blue/green screen is. Since the DV standard used in iMovie is a compressed format, color is stored only at every fourth pixel. This makes it challenging to come up with good clean edges for the extracted mask. The effect in this plugin attempt to compensate for this, but there will always be cases where it is very difficult to extract a clean mask.

SHOOTING TIPS FOR BLUE/GREEN SCREEN. The most important factor affecting the quality of a blue/green screen is how the footage was shot. Make sure the object is well lit, does not include the color of the screen (i.e. if you are shooting an object which has some blue in it, use a green screen, not a blue screen). Also make sure that the object is lit so it stands out from the screen. Often this is done by having a light behind the object so it is rim-lighted, giving it a sharp edge. Make sure the screen is flat with no wrinkles and is as uniformly lit as possible. Shadows on the screen can cause problems unless you intend to include their effect in the composite.

DOING BLUE/GREEN SCREEN AS A TWO-PASS PROCESS. In addition to the blue and green screen effect, this plugin includes effects for extracting blue and green screen masks. The idea is that the mask can be extracted and tweaked using the Mask Tweak effect, then used with the foreground and background clips in a Composite effect. Additionally, the mask can be tuned using the various brightness/contrast and level adjustment effects available in our other plugins. One very useful approach is to use black or white markers from the Labels & Overlays plugin to "plug" the holes in a dirty mask.

Contents

Blend (Free)
Blue Screen (Free)
Blue Screen Mask
Blue Screen Mask, Smooth
Blue Screen, Smooth
Combine
Composite
Green Screen
Green Screen Mask
Green Screen Mask, Smooth
Green Screen, Smooth
Mask Extract, Blue, Highlights
Mask Extract, Blue, Midtones
Mask Extract, Blue, Shadows
Mask Extract, Green, Highlights
Mask Extract, Green, Midtones
Mask Extract, Green, Shadows
Mask Extract, Intensity, Highlights
Mask Extract, Intensity, Midtones
Mask Extract, Intensity, Shadows
Mask Extract, Red, Highlights
Mask Extract, Red, Midtones
Mask Extract, Red, Shadows
Mask Tweak