Standard image dithering by averaging is performed by using the Average command from the Mathematics menu or by clicking on the button

The size of the averaging area is indicated in the opened dialog box. You can select the square matrix of averaging (3х3, 5х5, etc.). Selection of a large averaging area leads to a significant image dithering.

The algorithm can be explained using an example of a one row profile. The value of the point is replaced by the arithmetic average of the values of all points located nearby (for example, the values of the nearest neighbors). The row profile before and after filtering using a template with three points is given in the illustration below. As a result of filtering, the sharp peak is leveled and the steep slope looks more acclive.