Grass Valley 1200 Operation Manual User Manual

Page 189

5-9

Advanced Chroma Keying

If the foreground scene appears too neutral, you can shift its
hue by pressing the

[HUE ANGLE]

soft button to choose

SUPPRESS

, and then adjusting the

(FOREGROUND HUE SUPPRESS

ANGLE)

soft knob. This control is useful for correcting colors

that have become distorted by mixing with the background
color. This adjustment works especially well on transparent
portions of the foreground, such as a glass of red wine that
became magenta as a result of mixing with the background
color.

Now examine the foreground edges for dark or light lines,
indicating that the background key hole size or position does
not match the foreground fill. If the edges exhibit this
problem, press

[EXIT]

to move to the Chroma Key main menu,

and then select

[KEY EDGE]

to move to the Key Edge menu.

Select

above the

[V EDGE PROC]

soft button, then select and

adjust the

(KEY SIZE)

(KEY SOFTNESS)

, and

(KEY POSITION)

soft

knobs to minimize the lines along the edges of the key.

Use the

[EDGE CONTROL]

soft button to switch between a

multiplicative key and an additive key. Use whichever looks
best. A multiplicative key works best for smoke because it
softens the appearance of the key. An additive key works
better when you prefer to see greater detail in the key.

If there is still some noise in the background, try switching

EDGE PROC]

to the

[TEMPORAL]

position to enable temporal

filtering. This may remove a small amount of noise, but it may
also cause motion artifacts, so you may want to roll the tape
and watch for them.

10. To add shadows to the new background, adjust the Keyer

(GAIN)

knob. Then press

[EXIT]

to return to the main Chroma

Keyer menu, and select

[SHADOW PROC>]

. In this menu, turn

[SHADOW PROC] ON

. Set

(SHADOW GAIN)

and

(SHADOW OPACITY)

to100%, and adjust

(SHADOW CLIP)

until nearly all of the

background is black. Then reduce

(SHADOW GAIN)

until the

shadow density looks best. Lastly, touch up the Keyer

(GAIN)

knob to reduce shadow noise while preserving the key edge.

This completes the advanced chroma key adjustments.