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Filters for black and
white documents
 Filter functions are used
for removing unwanted noise, lines or speckle with a defined size.
Additionally, they are powerful tools for automatically moving
information to different raster layers. Note that this function is
available for black / white images only. All filters can be performed
either on the whole image or on selected areas. To start a filter on a
selected area, the following procedures:
Select an area with any of the selection tools and click the FILTER tool
or use EDIT, FILTER. For filtering the whole image, follow the previous
procedure without selecting an area. Filters should be used with care,
since they can remove information of real value. This happens to any
pixel configuration which matches the properties of the chosen filter.
The pixel configuration looks like noise to the program, but instead is
real information. Use the Undo command if you suspect this has happened
after filtering, or specify a destination layer for removed graphics for
easy verification.
As mentioned previously, PixEdit may not only remove graphics matching
the specified filter, but may also be used as a layer separator,
automatically separating graphics with given properties onto different
layers. For example, you may want to separate thin and thick contour
lines into two different layers in a scanned map, and remove all text
with a specific size to a third layer. By carefully selecting parameters
for the different filters, you may save manual processing when
information in scanned maps or other types of documents needs to be
separated.
Filter types
The following filters may be configured to remove the graphics matching
the filter specification, or to move it to another layer:
Single Pixels: Removes or moves single pixels only, or single
pixels attached to lines.
Lines: Removes or moves lines whose thickness lies between two
thickness values. Useful for layer separation of contour lines in
scanned maps.
Objects: Removes or moves objects within two specified numbers of
pixel values.
Object extent: Removes or moves objects with an extent between
two specified pixel values.
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