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entry variable: $sfthresh -- statmask hard threshold
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default: 0.3

This unmarked entry (second entry after "fthr:")
is only visible if "mask" ($statmaskampflag) is
ticked.

If the stat mask for a pixel is below this
number, the displayed *value* (e.g., complex
amplitude or HDR response amplitude estimate) is
masked to background.

The units of this mask threshold ($sfthresh) will
*not* in general be the same as the units of the
amplitude thresh ($fthresh).

See $fthresh and $fmid help for more details.

Note that the color scale bar and the color scale
bar limits are in amplitude units, not stat mask
units.

The color scale bar in the surface display window
is *not* statmasked, and so only affected by
$fthresh, $fmid, and $fslope.
