In this assignment we will learn about the advantages and difficulty with using green screens in photography. Green screens have been used in cinema since the 30's. it is used widely in television, modern digital filmmaking and photography. In the video production world it is called a "Chroma Key" or "Color Key".
With software like Photoshop green screen removal is a possibility for any photographer. The advantage is you can remove the green screen and add any background image you prefer, all during the post process. Some of the difficulties are correct lighting of the screen as well as avoiding the screen color in clothing. That is why green or blue is used most widely, people rarely wear neon green or blue clothing. Although with these methods literally any color can be edited, removed, changed.
With still photography the biggest challenge is creating a clean selection or mask for the subject. Light hair/clothing can pick up green glow from the screen called "spill light", it's literally green light shining off the wall onto our subjects. Also, variation in the green tone can make processing difficult, strive for even lighting of the wall. Watch for shadows being cast by your subject onto the wall.
The process for green screen in photoshop is first to create a good selection of the screen, then refine the selection, then you can replace the background. Work through the tutorial below and check out the link at the bottom of the page for expert tips on screen refinement.
Green Screen Assignment Details:
You assignment is to take 3 photographs using the green screen and edit out the background, replacing it with a different background.
- Take 1 photo with a single person
- Take 1 photo with 2 people
- Take 1 photo with 3 people
- Edit out the green screen with the process below
- Replace the background with something different, an island, the himalayas, outer space, brick wall, or a simple gradient or flat color
- post the 3 image results to your blog when complete
Assignment Grading Rubric:
- 2 Points - All 3 photos represented
- 2 Points - Backgrounds replaced, screen removed properly
- 2 Points - Creative use of backgrounds. People "interact" with background ( if background is dark forest, people act scared / if background is outer space, people act like they are weightless, etc... use your imagination!) or the background is removed and replaced with a simple gradient or color background to add focus to a portrait photo.
- 2 Points - Photos are in focus
- 2 Points - Photos show proper exposure
- Bonus Points: Add Lightsabers
How To Remove A Green Screen:
Open up your photo in Photoshop...
Create your initial selection by going to Select > Color Range
To see the selected area, chose Quick Mask preview mode. I've also checked the Invert box to invert the selection. That way, the colors I choose will be masked out, and the remainder will be actually be the selected region. Click on the left-most eyedropper tool and click on the image in the green area. To fill in the entire green area, click on the middle eyedropper and continue clicking in other areas of the background to add those colors to the selection.
Hit ok and your selection will be loaded...
Next you will refine the edge by using the refine edge feature. Go to Select > Refine Edge...
As shown here, I've chosen to view the resulting image on a white background, so it's easy to see how the settings will be applied. There is also a new Smart Radius setting that tells Photoshop how far out to look for adjoining details. I've also used the Paint Edge tool (just to the left of the Edge Detection box) to paint around acoustic foam where I want CS5 to look a little further out. Lastly, I've chosen output to New Layer with Layer Mask. With this setting, CS5 will automatically duplicate the Background layer and add the mask. Adjust the settings for the best results based on your image...
Hit ok and you will have a layer with your selection masked out...
Next replace your background, you can use a nice gradient or another photograph even. Refine and edit your layers for the best results.
If your image needs finer selection editing (such as areas where green stays in hair/clothing) read the tutorial link below for expert tips:

































































