Roberts filter

Use the Process > Edge Detection Filters > Roberts... command to quickly highlight the edges of objects. The Roberts filter belongs to the so called edge detection filters, i.e., filters that you can use to only select the contours in an image and ignore everything else.

The dialog box that is opened when you use an image processing operation is made up in the same way for every operation. Click here to switch to a description of this dialog box.

Exactly what happens?

The Roberts filter registers transitions from light to dark pixels. It belongs to the class of non-linear filters for edge detection. It is made up of simple derivative filters.

Two 3x3 matrixes will be calculated. Only the difference in brightness of 2 values in both diagonals will be taken into consideration for each pixel. This filter is a very quick edge detection filter, due to the small number of calculations.

Filter matrix

The filter uses two matrixes, by means of which the values a and b are calculated. The resulting intensity value is a+b.

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