Input and Output Value Domains: The
horizontal bar (x-axis) represents input values (they are
value levels from 0 to 255). The vertical bar (y-axis) is
only a scale for output colors of the selected channel.
The control curve is drawn on a grid and
goes from bottom left corner to top right corner. Pointer x/y
position is permanently displayed in top left part of the
If you click on the curve, a Control point
is created. You can move it to bend the curve.
If you click outside of the curve, a control point is also
created, and the curve includes it automatically.
So, each point of the curve represents an 'x' level,
corresponding to an 'y' color. If, for example, you move a
curve segment to the right, i.e to highlights, you can see
that these highlights are corresponding to darker output
tones and that image pixels corresponding to this curve
segment will go darker.
With color channels, moving right will decrease saturation
and can reach the complementary color.
To delete all control points (apart from both ends), click
on the Initialize Channel button. To
delete only one point, move it onto another point or to grid