This is a freely programmable filter based on a filter matrix. It works the following way:
The filter matrix is applied to every pixel of the image. The center of the matrix lies always on the current pixel. Now the pixels corresponding to the matrix entries are read and multiplied with matrix value. The matrix values must be in the range from -99 to +99. All results are added and the sum is divided by the divisor Div.. The value Bias is added to this result. If the option Clip is selected, overflows - that are results smaller than 0 and larger than 255 - are corrected. The result after all these operations replaces the current pixel.