Detect zero crossings in an image.
::zero_crossing 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 smoothing operator. In this case, the zero crossings are (candidates for) edges.
|
Image (input_object) |
image(-array) -> Hobject: HImage(Array) ( int2 / int4 / real ) |
| Input image. | |
|
RegionCrossing (output_object) |
region(-array) -> Hobject * : HRegion(Array) |
| Zero crossings (as region). | |
::zero_crossing usually returns the value H_MSG_TRUE. If necessary, an exception is raised.
::laplace, ::laplace_of_gauss, ::derivate_gauss
::connection, ::skeleton, ::boundary, ::select_shape, ::fill_up
Region processing
