Filters

User-defined standard deviation filters

There is no standard standard deviation filter stored on disk. You always have to define a standard deviation filter yourself, either through the Filter dialog box or by an expression on the command line of the Main window.

Using the Filter dialog box:

To define your own standard deviation filter:

Open the Filter dialog box,
for Filter Type, select: Standard Deviation,
specify the size of the filter.

Using the command line (advanced):

To define your own Standard Deviation filter, type the following expression on the command line of the Main window:

OUTMAP

MapFilter(InputMapName, FilterStandardDev(rows,cols))

where:

OUTMAP	is the name of your output map.
MapFilter	is the command to start the Filter operation.
InputMapName	is the name of your input map.
FilterStandardDev	is the command to define a standard deviation filter.
rows	are the number of rows of your standard deviation filter.
cols	are the number of columns of your standard deviation filter.

Example:

To use a standard deviation filter which considers each 7 vertically neighbouring pixels:

in the Filter : dialog box, choose for Filter type: Standard Deviation,
specify 7 for the number of rows and 1 for the number of columns,
on the command line, use a filter definition of: FilterStandardDev(7,1).

Tip:

Both the number of rows and the number of columns defining the filter size must be odd values.