Use the Custom colour channel option to select the colour to be extracted from the key-in clip. This option can give good results when keying transparencies, particularly by experimenting with the Softness and Colour Spread values.

To create a key by extracting a custom colour:

1. In the Keyer, do one of the following:
   • Click Keyer to show the Keyer menu.
   • Click Colour to show the Colour menu.
2. Click Channel.

   The Channel controls appear.

   
   

   (a) Channel Mode box  (b) Average Colour pot  (c) Softness field  (d) Colour Spread field  

3. Select Custom from the Channel Mode box.
4. Click the Average Colour pot.

   The cursor changes to a colour picker.

5. Click the image to select a single colour, or drag the colour picker across a region to obtain the average of the colours encountered by the colour picker. Try selecting different colours in the background area to get the best result.
   TipTo keep shadows, click just outside them. To remove shadows, click inside them.
6. Adjust the softness for the key using the Softness field.

   Increasing softness raises the level of grey in the matte. Lowering it makes the matte sharper.

7. Adjust the colour spread for the key using the Spread field.

   Increasing the colour spread value extends the range of colours extracted from the key-in clip.

8. Click Result to see the result of your key.
   NoteTo improve the key at this point, try adjusting it with the histogram. See Adjusting the Luminance of the Key.

For floating-point images, you can use a node in Batch or the Modular Keyer to create a 16-bit key by extracting a custom colour. See Keyer-Channel Node.