Chroma Keying and Working with Green Screens > Creating and Refining a Key in the Master Keyer >

# Generating Mattes

Use the Matte controls in the Master Keyer to generate and refine a matte for your chroma key.

To generate and refine a matte:

1. In the Master Keyer menu, select Matte from the Sampling box.
2. Set the view to Result or Matte view.
3. Click the Primary Sample colour pot and then sample the image. Click the image to sample a single pixel.

   The Auto CC button is enabled and the initial pure colour value for the key is set.

4. Click the Secondary Sample colour pot and then sample the image. Sample an area where you do not want any softness in the matte.
5. Drag in the Mix field to adjust the mix between the primary and secondary sample. Drag right to include more of the secondary sample or left to include less.
   TipYou can adjust the mix at any time as you develop the key.
6. Gesturally refine the matte. In the image window, click an area of the matte that you want to refine—only those parameters that pertain to the area you click appear. Parameters are displayed in order of importance, from top to bottom (those that are brightest and at the top have the greatest effect on the image). You can then modify a parameter by dragging its highlighted slider.
   - To add softness, drag a slider to the right.
   - To remove softness, drag a slider to the left.

   The red indicator shows the original value and the yellow indicator shows the current value.

7. To modify more than one parameter, move the mouse between the parameters to highlight a parameter, or drag the pen vertically. When you highlight the parameter you want to adjust, drag the slider.
   TipIf you do not like the result, you can click Undo to reset parameters directly after you complete the operation. There is only one level of undo in the Keyer menu.
8. When you are finished modifying the displayed parameters, click another area of the image without highlighting a parameter to hide them. Alternatively, you can press any key, such as spacebar or Esc.

   The parameters are no longer displayed.

9. Repeat steps 6 to 8 in other parts of the matte to further refine it. Only the parameters that apply to the problem area will appear.
10. To scroll through the image and display the pertinent parameters, Option-drag the image without clicking it. The parameters update as you drag. You can then modify the displayed parameters by clicking the image and dragging the highlighted slider.

NoteTo reset matte parameters, click the Reset button, next to the sampling box. All matte parameters are reset, except the Mix field and the key colour.

After you have generated your matte, perform basic colour spill removal.

#### Related Information

- Creating and Refining a Key in the Master Keyer
- Chroma Keying and Working with Green Screens