Filter

Dialog box

Filtering is a process in which each pixel value in a raster map is replaced with a new value. The new value is obtained by applying a certain function on each input pixel and its direct neighbours.

Dialog box options:

Input raster map:

Select an input raster map or an input map list. Open the list box and select an input map or map list, or directly drag a raster map or map list from a Catalog into this box.

When you select an input map list, the operation will be performed on all raster maps in the map list.

Filter type:

Select the type of filter to use: linear, average, majority, rank order, median, pattern, binary, or standard deviation.

Predefined:

When you selected as the Filter type: Majority or Rank Order:

select this check box if you want to use a standard predefined Majority filter (Majority, MajUndef, MajZero) or a standard predefined Rank order filter (Med3x3, Med5x5) on disk.

Clear this check box if you want to construct your own majority or rank order filter.

Filter name:

For linear, predefined majority, predefined rank order and binary filter types: select the name of an existing filter on disk.

When you selected as the Filter type: Linear; you can also create your own linear filter by clicking the create button .

Rows Columns:

Type values for the number of rows and columns to define the filter size. Row and column values must be odd values but do not need to be the same.

Rank:

For user-defined rank order filters: optionally, specify the rank order number of the considered pixels that should be used as output value.

Threshold:

Optionally, specify a threshold value. An output value of the filter will only be used if the difference between the original and new pixel value is smaller than or equal to the threshold. If the difference between the original and new pixel value is larger than the threshold the original value will be used.

Undefined:

For a user-defined majority filter: optionally, select this check box to replace only undefined values.

Output raster map:

Type a name for the raster output map that will contain the filtered values.

If you selected an input map list, then you can type a name for the output map list; all raster maps in the output map list will obtain this name followed by _1, _2, _3, etc.

Domain:

Accept the default domain, or select another domain for the output map(s), or create your own domain.

Value range:

Accept the default value range, of specify your own range of possible values in the output map(s).

Precision:

Accept the default precision of output values, or specify your own precision.

Description:

Optionally, type a description for the output map or the output map list. The description will appear in the status bar of the Main window when moving the mouse pointer over the map in a Catalog, and in the title bar of a map window when the output map is displayed. If no description is supplied, the output map or the output map list will use its own definition as description.

When you selected a single raster map as input:

When you selected a map list as input:

For more information and some examples on using standard or user-defined filters from the Filter dialog box, refer to Filters : user-defined filters.

See also: