prewitt

Herror ::prewitt_amp ( Hobject Image, Hobject *ImageEdgeAmp ) HImage HImage::PrewittAmp ( void ) const HImageArray HImageArray::PrewittAmp ( void ) const

Detect edges (amplitude) using the Prewitt operator.

::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) `->` Hobject: HImage(Array) ( byte / int2 )
Input image.

`ImageEdgeAmp` (output_object)	(multichannel-)image(-array) `->` Hobject : HImage(Array)* ( byte / int2 )
Edge amplitude (gradient magnitude) image.

Example

read_image(&Image,"fabrik");
prewitt_amp(Image,&Prewitt);
threshold(Prewitt,&Edges,128,255);

Result

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

Possible Predecessors

::gauss_image, ::sigma_image, ::median_image, ::smooth_image

Possible Successors

::threshold, ::gray_skeleton, ::nonmax_suppression_amp, ::close_edges, ::close_edges_length

Alternatives

::sobel_amp, ::kirsch_amp, ::frei_amp, ::robinson_amp, ::roberts

Module

Image filters