Channel, Histogram, And Curves - Kodak PROFESSIONAL RFS 3600 User Manual

Channel, Histogram, and Curves

These functions behave consistently with their implementations in
Photoshop version 5.0 and later.
Adjustments to the curve and the use of the White, Gray, and/or Black
pointer buttons and Auto Balance functions cause the histogram to change;
but changes to the histogram do not cause the curve to change.
The X- and Y-axis tone curves are based on brightness, with shadows at 0%
and highlights at 100%. You create up to 4 new points on the tone curve
by:
Clicking in the grid.
Command-clicking (Macintosh) or control-clicking (Windows) on the
desired position on the Before image. The brightness value for the pixel
you've clicked appears on the curve at that input brightness level.
Points on the curve are fixed until you move or delete them. Move a point
by dragging it to a new location; delete a point by dragging it off the side of
the curve.
Make the appropriate Channel choice to perform the histogram and curve
functions on All colors, or separately on the Red, Green, or Blue channel.
(If you are working in CMYK, these channel values are still shown in RGB.)
In the histogram, above the Input and Output sliders, the x-axis range
contains values from 0-255, and the y-axis is the relative number of pixels
with each of these values. Suppose you had an image that was "flat" in
color, but nicely exposed; you would have a histogram with a hump in the
middle. Perhaps the lowest value on x-axis is 40 and the highest is 200,
indicating that the image does not have a lot of dynamic range.
You can now use the Input and Output sliders to increase your contrast
range to a full range of values as follows:
Drag the white slider on the Input scale to the position where the hump
in the curve in this example ends at 200 on the x-axis. This causes the
software to take the values at 200 and remap them to a new value of
255. This action remaps all the values from 40-200 to a new range of 40-
255.
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