Graphics Programs Reference
In-Depth Information
strates grading using the Bezier curve to arrive at a similar result, as achieved using
the black and white levels technique:
The factor value (
Fac
) in this node represents the influence of this node on the out-
put. An image can be connected to this socket to specify node influence. A value of
1
will display an influence of 100 percent in the output.
The following screenshot specifies a few common grading effects—invert, posterize,
lighten, and contrast—performed using the
RGB Curves
node:
When using the
RGB Curves
node, we will sometimes need higher precision in ad-
justing the curve points. The default setup makes it tedious to have such precision.
This task can be accomplished by having cascaded RGB Curves nodes with different
factor values as shown in following screenshot. In the following flow, first grade node
with Fac value of
0.25
provides four times higher precision for adjusting shadows,
second grade node with
Fac
value of
0.5
provides twice the precision for highlights,
and third grade node with Fac value of
1
provides default precision for midtones. A
similar flow can be created to have different precisions for
R
,
G
, and
B
channels.
