Apple Color 1.5 - Manual (Page 307)

Grain Reduction
Reduces grain and noise in an image by averaging adjacent pixels in that frame according
to the values specified in the Master, Red, Green, and Blue Scale parameters. Edge
detection can be used to preserve sharpness in areas of high-contrast detail via the Edge
Retention parameter, and a sharpening operation can be applied after grain reduction
to boost overall detail. Because some shots have noise that’s more apparent in specific
color channels, you can make independent adjustments to each channel. This node has
six parameters:
• Master Scale: Averages the adjacent pixels of every color channel in the image to reduce
grain and noise, at the expense of a certain amount of image softness.
• Red Scale: Selectively averages pixels in the red channel.
• Green Scale: Selectively averages pixels in the green channel.
• Blue Scale: Selectively averages pixels in the blue channel.
• Edge Retention: Uses edge detection to isolate areas of high-contrast detail in the image
(such as hair, eyes, and lips in an actor’s close-up), and excludes those areas of the
image from the Grain Reduction operation to preserve the most valuable image detail
from softening. Higher values preserve more of the original image in these areas.
• Post Sharpening: Applies a Sharpening Convolution filter after the Grain Reduction
operation to try and restore some lost detail once the grain has been softened. Use
this parameter sparingly—if you set this too high, you’ll end up reintroducing the grain
you’re trying to reduce.
Hue
Rotates the hue of every pixel in the entire image. This node has one parameter:
• Shift: The amount by which you want to shift the hue. This is not done in degrees, as
is represented in the Vectorscope. Instead, you use a value from –1 to 1, where –1, 0,
and 1 place the hue at the original values.
Invert
Inverts the image. Useful for creating “positives” from the image negative. Also useful for
reversing a grayscale image that you’re using as a matte with the Alpha Blend node, to
reverse the portions of the matte that will be solid and transparent.
Lift
Lift uniformly lightens or darkens the entire image, altering the shadows, midtones, and
highlights by the same amount. This node has four parameters:
• Lift: Adjusts the red, green, and blue channels simultaneously, for an overall change
to image brightness.
• Red Lift: Adjusts the red channel only, enabling color correction based on a lift
adjustment for that channel.
307 Chapter 11 The Color FX Room