Better Light 7 - Manual (Page 57)

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You can change the pivot point of the contrast buttons by sliding the zero position of the
scale at the bottom of the tone curve. Drag the zero EV marker to the desired location,
then hold the Option key (Alt key on Windows) while the contrast buttons are clicked and
the curve will pivot at the zero position.
Manual Tone Curve Adjustments
Tone curves may also be adjusted manually. On the tone curve graph, there are a number of
round dots. Each of these dots is a control that can be moved using the mouse. Begin by selecting the
number of control points. Click on the Control Point selection button to choose between 5 or 7
control points.
Each click will toggle between the 5 and 7 points options. The graph will instantly
update to reflect the choice. To adjust a portion of the tone curve, click and drag the point on the
curve to the new desired location. The prescan will update as the point is moved to show the result.
The live update makes it easy to achieve the desired effect. As each point is moved, the line connect-
ing the point to the neighboring points will rubber band to maintain a continuous transition in that
section of the tone curve.
Holding down the Control key (Macintosh) or the Alt key (Windows) while click-dragging
a control point will enable a microstepping feature that results in a small screen movement
for a large mouse movement. This allows for very precise control point positioning.
If a radical bump or sharp bend occurs in the curve, adjust the surrounding handles to
maintain a smooth curve and minimize any chance of posterization.
The three buttons at the bottom of the tone graph control the range of manual adjustment
allowed for the curve control points. The button restricts each control point to horizontal move-
ments (+- EV changes) only. The button restricts each point to vertical (+- output value changes)
only. The button allows full xy motion to the point. One restriction on the motion of these points
is that they cannot be moved to left or right, above or below the same position as their neighboring
points. This helps prevent many mathematical problems in creating the curves.
As each control point is moved, two lines are drawn on the tone graph to aid in positioning the
point. One line is a vertical extending down to the EV scale at the bottom of the graph, and the other
is a horizontal line extending across the graph to the output value tone scale on the graph’s left side.
Numeric readouts appear near each scale to aid in precise positioning of the point. As each point is
moved vertically, the output value will change as odd numbers when moving down and even numbers
when moving up the graph. The increment will usually be by 2, except when rounding errors cause
the number to increment by a single number. The numeric readouts, combined with the manual
adjustment restriction buttons makes it easy to create curves very precisely.