Eight-point discrete Hartley transform as an edge operator and its interpretation in the frequency domain

3 x 3 edge operators have been commonly used for their simplicity. This paper presents a novel interpretation of the 8-point discrete Hartley transform (DHT) as a new edge operator. The basis functions of the 8-point DHT formulate the 3 x 3 DHT masks that are closely related to the Frei-Chen edge masks. New interpretation in the frequency domain is introduced and application of the 3 x 3 DHT masks to edge detection of a two-dimensional image is shown.