Filter Weights

The weight for each element of the filter kernel. After entering weights, you can normalize the filter to unit weight by clicking the [Normalize] button.

Rotation Angle

The Rotation Angle specifies a rotation of the weights entered into the dialog. Use this to rotate the filter kernel without calculating new weights. For example, consider the filter typed into the sample dialog above,. This shows a 3x3 gradient filter pointed toward the right. Applying this filter produces an image containing the "east gradient". Setting Rotation Angle = 90 would change this to a North or South oriented gradient without having to recalculate or retype the 9 weights in the dialog.

Normalize

The Normalize check box normalizes the filter to have a sum of all weights equal to 1.0. Another way to say this is that it causes the filter kernel to be scaled to unit volume underneath the weight profile.

Use Cursor ROI

If you check this item, only the region inside the Image Cursor is filtered.

tip

Be wary of using the Normalize option when the filter weights sum to 0 as in the above example. Many operators such as gradient filters normalize to 0 whereas a sharpening filter, for example, normalizes to a value of 1.