Part of Unit: Advanced Post-Production Techniques & Compositing
Lesson Plan Overview / Details
This lesson is an introduction to chroma key. Students will learn how chroma key works and the history of chroma key. Some basic chroma key editing tips will be discussed.
- One Class Session
- 55 Minutes
California Career and Technical Education Standards
- AME.FS.10.6 Know the appropriate skills and vocabulary of the art form.
- AME.FS.4.1 Understand past, present, and future technological advances as they relate to a ...
- AME.FS.5.4 Use the elements of the particular art form to observe, perceive, and respond.
California Academic Content Standards (Reinforced)
- ELA.11-12.LS.C.1.3 Interpret and evaluate the various ways in which events are presented and inform...
- ELA.11-12.LS.ODOC.1.10 Evaluate when to use different kinds of effects (e.g., visual, music, sound, gra...
Objectives and Goals
- Students will learn what Chroma Key is
- Students will learn how Chroma Key works
- Students will learn about the history of Chroma Key
- Students will learn some Chroma Key basics
Activities in this Lesson
- Anticipatory Set - Hooks / Set
What is chroma key?
Show the Stargate Studios Virtual Reel 2009 (4 Min)
Who can describe the process of chroma key?
Chroma key compositing (or chroma keying) is a technique for compositing two images together in which a color from one image is made transparent revealing another image behind it.
This technique is also referred to as color keying, green screen, and blue screen.
It is commonly used for weather forecast broadcasts, wherein the presenter appears to be standing in front of a large map, but in the studio it is actually a large blue or green background.
The meteorologist stands in front of a blue screen, and then different weather maps are added on those parts in the image where the color is blue.
This also works for green screens.
Blue and green are considered the colors least like skin tone.
Chroma is the Greek word for color. Chrominance or chroma is one of the two components of a television signal.
The other component is luma, which represents the brightness in an image (the "black and white" or achromatic portion of the image)
- Chroma Key History - Check Understanding
This following video provides an excellent visual history of chroma key.
- Show “History of Chroma Key” video (6 min)
- Have Students write 10 key points from the video.
- Ask students to share their key points with the class.
- Keep a list on the board of new items until ideas are exhausted.
- Have students keep this list in their notes or journal for future reference.
- Chroma key Basics - Lecture
Good chroma key techniques are required regardless of the equipment being used.
Each manufacturer has proprietary controls and parameters for adjusting the colors and tolerances which makes the discussion more difficult.
There are several techniques in common to all methods of keying, which include:
- Lighting the chroma key wall (paint, fabric, paper or mat) evenly so the color is consistent but not light too brightly.
- Lighting the talent with three-point lighting.
- Keeping the talent far enough from the screen to avoid casting shadows.
- Clothing must be contrasting to the color of your screen
- Textures with fine details on the edges like curly hair, loose earrings, and frilly fabric are difficult to key because of the complex variation in contrast and opacity.
Chroma key effects can be created live using a video switcher hardware, or in post-production using chroma key software filters.
The following video demonstrates how to adjust the chroma key filters in three popular video editors; Adobe Premiere, Sony Vegas, and Final Cut Pro.
Play movie, “How to get the perfect green screen key” (5 min)
- More Resources for further study - Other
This PDF slide show is a detailed look at chromakey from the International Film School in Sydney (IFSS). http://www.ifss.edu.au
You may want to use this if your students are advanced and will appreciate the detail.
Download "Chroma key: Technology and Technique"
This is the link to the file:
- Chroma key PDF Slide show [ Download ] Chroma key: Technology and Technique
- Assessment Types:
- Teacher-Made Test, Quick Quiz
- Convert the student generated list from the "History of Chroma Key" movie into a quiz.
- Allow students to use their notes.
- The technique referred to as color keying, green screen, and blue screen are also knows as _________? (chroma-key)
- Blue and green are considered the colors least like__________. (skin tone)
- What is the Greek word for color? (chroma)
- What is the Greek word which represents the brightness in an image? (luma)
- Why must clothing be contrasting to the color of your screen? (to avoid keying off of the clothing making the clothing invisible)
- Why are textures with fine details on the edges like curly hair difficult to key? (Detailed and high contrast edges are complex and have too much variation.)