User Manual

3 Apply sharpening by doing one of the following:
 Using that node’s contextual menu, uncheck Enable Channel 2 and Enable Channel 3,
which correspond to the U (Cb) and V (Cr) channels, leaving only Channel 1 (Y) enabled.
Then, open the Blur palette, and drag the ganged Radius sliders down to sharpen the
Y channel.
 You can also just open the Blur palette, ungang the Radius sliders, and drag the red
slider down to sharpen the Y channel, since any control with three gangable sliders
will automatically assign those sliders to whichever channels are used by the currently
selected Color Space.
(Before) The original image, (After) Sharpening
applied to only the Y’ channel of the image
As you can see, while the Blur palette ordinarily provides separate R, G, and B controls that can
be unganged from one another, the Color Space submenu lets you apply sharpening to the
channel definitions of other colorspaces, providing many other corrective and creative
possibilities with the same controls.
Supported Color Spaces for Conversion
The Color space submenu available when you right-click a node in the Node Editor
supports four different color spaces that you can set each node to work within.
When you choose a color space other than RGB, all channel-specific controls
(the Custom curves, Soft curves, RGB Lift/Gamma/Gain sliders, and RGB mixer) operate
on the particular channels of that color space, rather than the default YRGB channels.
By switching color spaces, you can achieve very different kinds of adjustments by
swinging values among mathematically different axes.
YUV converts the image into Y’, Cb, and Cr channels. The Y’ channel governs
luminance, while the Cb and Cr are color difference channels that work within the
broadcast model of color.
Chapter – 127 Channel Splitting and Image Compositing 2880