Filter editor

Edit a user-defined linear filter or view the contents of a linear system filter. Linear filters use a linear combination of all pixels in a rectangle around the input pixel.

The Filter editor is opened:

when you click the OK button in the Create Filter dialog box,
when you double-click a user-defined linear filter in a Catalog,
selected a filter in a Catalog, and choose Edit Object from the Edit menu in the Main window,
when in a Catalog, you click a user-defined linear filter with the right mouse button in the Catalog, and select Open from the context-sensitive menu.

Options:

Matrix:

The window shows a matrix with the number of rows and columns as specified before when creating a linear filter. The rows and columns of the filter are numbered; cell 0,0 is the center of the filter. If the filter is rather large, scroll bars appear.

To edit values in the matrix:

select a cell at a time and type a value, or
select multiple cells, click the selection with the right mouse button and choose Edit from the context-sensitive menu.
select multiple cells, and choose Edit from the Edit menu.

Description:

Optionally, type a description for the filter. The description is visible on the status bar of the Main window when moving the mouse pointer over a filter in the Catalog.

Gain:

Type a value for the Gain factor yourself, see the example below.

Moving through the matrix by keyboard:

to move up and down in the matrix: press the Arrow Up and Arrow Down keys;
to move to one cell to the right: press the Tab key;
to move to one cell to the left: press the Shift+Tab key.

Example:

When considering a linear filter of size 3x3, the 9 matrix values are multiplied with 9 pixel values in the input raster map, this is summed and multiplied by the gain factor. The result is assigned to the center pixel in the output map.

Tips:

To view the contents of a linear system filter:

click the Customize Catalog button in the standard toolbar of the Main window,
in the Customize Catalog dialog box, select the object type Filter (use the scroll bar) and select the check box Include System Objects,
then, in the Catalog, the linear system filters will appear: AVG3x3, D2FDX2, D2FDXDY, D2FDY2, DFDDN, DFDUP, DFDX, DFDY, EDGESENH, LAPLACE, SHADOW,
you can open a system filter by double-clicking it.

System filters cannot be edited.

To copy the contents of a filter to clipboard:

open a filter,
from the Edit menu in the Filter editor, choose the Select All command, then
from the Edit menu, select the Copy command or press the Ctrl+C keys on the keyboard.

To copy the whole filter editor window to clipboard:

press the Alt+PrintScrn keys on the keyboard.