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.