This plug-in creates a transparent layer on top of the active layer highlighting the parts
of the image with maximum local contrast, thus the parts witch are in perfect focus.
It also show which parts of the image are unrecoverable under,- and overexposed.
Finally, if there is transparency in the layer(s), the plug-in will indicate areas
with no image information.
It is optional to sample only the active layer or all visible layers.
If the image contains a lot of detail (or noise), completion will take longer.