Setting threshold levels for the overlay image

Scanning overlays

Setting threshold levels for the overlay image

When comparing the two scans, ScanBackground uses default threshold values to determine which pixels of the overlay are displayed as transparent, opaque or used in the anti-aliased edge inbetween the transparent and opaque regions.

The default threshold levels used by ScanBackground will normally produce satisfactory results. However, if required, you can select new threshold levels. The procedure is described below:

Choose Tools > Overlay Controls.

: The Overlay Controls dialog box is displayed, containing default threshold values:

Pixels that have a difference more than the Alpha Threshold value are rendered transparent.

Pixels that have a difference less than the Image Threshold value are rendered opaque.

Pixels that have a difference inbetween the two threshold levels are anti-aliased.

: A larger difference between the Alpha Threshold and the Image Threshold, gives a smooth anti-aliased edge. A smaller difference, gives a harder edge.

: Note, you cannot have an Image Threshold value greater then the Alpha Threshold value.

Enter new values in either of the fields and press Return. The overlay in the Splice Window is redisplayed using the new threshold values.

Scanning overlays

Setting threshold levels for the overlay image