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.
Image (input_object) |
image(-array) -> object : int2 / int4 / real |
Input image. |
RegionCrossing (output_object) |
region(-array) -> object |
Zero crossings (as region). |
zero_crossing2 usually returns the value TRUE. If necessary, an exception is raised.
laplace__, laplace_of_gauss, derivate_gauss
connection, skeleton, boundary, select_shape, fill_up