Name

prewitt_amp — Detect edges (amplitude) using the Prewitt operator.

Synopsis

prewitt_amp(Image : ImageEdgeAmp : : )

Description

prewitt_amp calculates an approximation of the first derivative of the image data and is used as an edge detector. The filter is based on the following filter masks:

  A =
        1       1       1
        0       0       0
       -1      -1      -1

  B =
        1       0      -1
        1       0      -1
        1       0      -1

The result image contains the maximum response of the masks A and B.

Parameters

Image (input_object) (multichannel-)image(-array) → object (byte / int2 / uint2)

Input image.

ImageEdgeAmp (output_object) (multichannel-)image(-array) → object (byte / int2 / uint2)

Edge amplitude (gradient magnitude) image.

Example

read_image(Image,'fabrik')
prewitt_amp(Image,Prewitt)
threshold(Prewitt,Edges,128,255)

Result

prewitt_amp always returns 2 (H_MSG_TRUE). If the input is empty the behaviour can be set via set_system('no_object_result',<Result>). If necessary, an exception is raised.