How to use a Chroma Key Background – Lighting, Setup & Post Production Techniques

October 3, 2010 · 4 comments

in Equipment,Photoshop,portraiture,Tutorials

Chroma key is a technique used mainly in the film industry for separating actors from the background, so that another background can be added in post production.

There are two type of Chroma key backgrounds – Blue and Green. These colours are used because the colours are not present in skin colour. You should choose a chroma key colour which is not present in your foreground subject that you want to “cut out”.

How to light the subject and the chroma key backdrop

Lighting the backdrop
Use two lights at 45 degree angles about 1,5 metres from the background.
If you are using flash lighting, do not over light the background, as this will wash out the colour and saturation.
Use your light metre to ensure that the background is lit evenly – this is the most important part of your set up. If this is not done properly, it will be much harder to extract the subject in post production.

Lighting the subject
Place you subject approximately 1,5 – 2 metres in front of the backdrop. This is important so that the colour of the backdrop does not bleed, or spill over onto the subject.
Keep the lighting soft on your subject, by using two lights – one light of each side of the subject. Position the lights pointing away from the subject into umbrellas, and angle them to bounce reflected light onto the subject.
If possible, use a back light on the subject to further prevent colour spill from the backdrop.

Taking the Photo
Zoom in on your subject as much as possible to help define the edges of you subject.

Post Production
How to remove the background in Photoshop

There are several ways of removing the Chroma Key background in Photoshop, but one of the quickest and easiest ways is by using the Extract feature.

Step 1: Open the image in Photoshop

Step 2: Duplicate the image by pressing Ctrl + J

Step 3: Extract the subject
Click Filter, then Extract, to open the Extract pop up window.
First, select a brush size big enough to cover the edges of the subject. Next tick the Smart Highlighting box. Press Ctrl + to zoom in. To zoom in more, keep pressing the +.
Use the Highligher Tool to paint an edge around the subject. Make sure you cover the edges completely, especially on fuzzy areas like hair.

Step 4: Fill the Selection
Use the Fill Tool to fill the selection and click OK.

Step 5: Place the subject on the new background

Open the new background image on which the subject will be placed.
Select the image with the extracted subject, and using the Move Tool, drag the subject to the image of the new background. Once you are happy with the positioning of the subject, flatten and save the image by selecting Flatten Image on your Layers Menu.

That’s it! Have fun using a Chroma Key background!

These images were shot on a Chroma Key backdrop at an Abobe event at Monte Casino in September.

{ 4 comments… read them below or add one }

louis berber August 23, 2012 at 8:57 am

Do you know where we can find chroma key backdrops here?

rikkihibbert August 23, 2012 at 8:59 am

Hi Louis – Singer Photographic in Randburg.

Hadassah Mack October 16, 2012 at 9:54 am

hey hey hey…can we use any old backdrop for chroma key or does it have to be…I don’t know…chroma key? lol I hope m question makes sense.

rikkihibbert October 16, 2012 at 5:36 pm

Hi Hadassah, a chroma backdrop is ideal, but if you can’t get one, use a backdrop colour that not on your subject matter.

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