User guide

KeylightThe Foundry

TUTORIAL

Tutorial 2: Fine Tuning a Key

Tutorial 2: Fine

Tuning a Key

Using the images from the film The Saint, you will learn how to fine tune the

key pulled in Tutorial 1. You will learn how to:

• Use Status to judge the quality of the key.

• Use the Screen Strength to improve the background.

• Use the Despill Bias to remove more blue spill.

1. Drag the SaintFG.tif and SaintBG.tif pictures onto the timeline. Apply

Keylight to the blue screen layer. Pick the Screen Colour by clicking and

dragging a rectangular area on the blue screen in the composition win

dow.

Note

These steps were covered in greater detail in the previous chapter.

2. Before we do anything else we need to look at the quality of the key so

far. On first inspection, the composite looks pretty good, but it’s hard to

judge. To see any potential problems more clearly, switch the Render

control to Status as shown in

Figure 67.

Figure 67. Status showing grey pixels in the background.

Here we can see that the windscreens are a mixture of black and grey

pixels. The black pixels tell us that pure background will be seen here in

the final composite. The grey pixels tell us that there will be a mix of

foreground and background pixels. What we want is a clean background

showing through the windows, but with some reflections in the side win

dow preserved. In other words we need mostly black pixels with a few

grey ones.

3. Figure 68 shows the Status view that we’re aiming for. The background

has been cleaned up and we still have some reflections in the side

window. To get this you should increase the Screen Strength from 100 to

106.

Figure 68. Improved background with Screen Strength.