Spot detection

Level for spot detection.

This number defines a threshold of the intensity change for a pixel to be considered as a false intensity jump. If this happens then that pixel becomes a candidate for a spot, which will then be removed. The larger is this number, the smaller will be the spot detection sensitivity meaning that only very distinct spots will be detected.
Typical range is for this parameter is 20...35

Level for spot clearance.

When the spot is detected, the pixels on its perimeter are checked to be different enough from the intensity in the spot.
This parameter defines the threshold for such comparison. If the intensity difference is smaller than the threshold the pixel is counted as bad.
Normally this parameter is about 2/3 of Level for spot detection.
Set it lower for easier spot detection.

Required perimeter clearance.

This factor defines a relative amount of bad pixels in the perimeter.
Spots without perimeter clearance are ignored.
Can be from 0 to 32.
Zero means absolute perimeter clearance, without bad pixels.
Set it higher for easier detection of spots over uneven backgrounds.

Spot fullness factor.

The larger is this number, the more pixels with intensity jumps are required in the spot. Smaller values allow for thin spots like scratches, hairs etc. If you process cartoons set this number higher than 20; otherwise some thin lines of the video contents may become identified as spots.
Can be from 0 to 32.

Debug spot removal

If you check this option, the spots will not be removed but enclosed in rectangles. Red rectangles mark the spots that are subject for removal. Blue rectangles mark the spots that were detected but identified as moving objects. Those spots that were detected but have no perimeter clearance or area fullness are not marked.
Also, this mode will highlight those cells from the motion table where the motion threshold is exceeded.