-------------------------------------------
entry variable: $bwslope -- contrast adj sigmoid slope
default: 12.0
-------------------------------------------
left-click "contr:" label -- toggle $linearflag
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The "contr:" entry sets the slope of the contrast
sigmoid function used to map image data to
display brightness.

A higher number for "midpt:" increases contrast.
Use midpoint ($bwmid, "midpt:" entry) to set
inflection point of sigmoid.  For linear map, set
linearflag TRUE

                         1.0
display =  -----------------------------------
            1.0 + exp(-bwslope*(image-bwmid))

To invert contrast, use a negative number for
$bswlope ("contr:" entry).

A left-click on the bold "contr:" label toggles
between the standard sigmoid function vs. a
linear function mapping image data to display
brightness.
