zero_crossing2 ( Image : RegionCrossing : : )

Detect zero crossings in an image.

zero_crossing2 returns the zero crossings of the input image as a region. A pixel is accepted as a zero crossing if its gray value (in Image) is zero, or if at least one of its 4-connected neighbors has a different sign.

This operator is intended to be used after edge operators returning the second derivative of the image (e.g., laplace_of_gauss), which were possibly followed by a smoothin operator. In this case, the zero crossings are (candidates for) edges.


Parameters

Image (input_object)
image(-array) -> object : int2 / int4 / real
Input image.

RegionCrossing (output_object)
region(-array) -> object
Zero crossings (as region).


Result

zero_crossing2 usually returns the value TRUE. If necessary, an exception is raised.


Possible Predecessors

laplace__, laplace_of_gauss, derivate_gauss


Possible Successors

connection, skeleton, boundary, select_shape, fill_up


Alternatives

threshold__, zero_crossing1



Copyright © 1996-1997 MVTec Software GmbH