zero_crossingzero_crossingZeroCrossingZeroCrossingzero_crossing (Operator)

Name

zero_crossingzero_crossingZeroCrossingZeroCrossingzero_crossing — Extract zero crossings from an image.

Signature

Description

zero_crossingzero_crossingZeroCrossingZeroCrossingzero_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 ImageImageImageimageimage) is zero, or if at least one of its neighbors of the 4-neighborhood 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_gausslaplace_of_gaussLaplaceOfGaussLaplaceOfGausslaplace_of_gauss), which were possibly followed by a smoothing operator. In this case, the zero crossings are (candidates for) edges.

Execution Information

• Multithreading type: reentrant (runs in parallel with non-exclusive operators).
• Multithreading scope: global (may be called from any thread).
• Automatically parallelized on tuple level.
• Automatically parallelized on domain level.

Parameters

Result

zero_crossingzero_crossingZeroCrossingZeroCrossingzero_crossing usually returns the value 2 ( H_MSG_TRUE) . If necessary, an exception is raised.

Possible Predecessors

laplacelaplaceLaplaceLaplacelaplace, laplace_of_gausslaplace_of_gaussLaplaceOfGaussLaplaceOfGausslaplace_of_gauss, derivate_gaussderivate_gaussDerivateGaussDerivateGaussderivate_gauss

Possible Successors

connectionconnectionConnectionConnectionconnection, skeletonskeletonSkeletonSkeletonskeleton, boundaryboundaryBoundaryBoundaryboundary, select_shapeselect_shapeSelectShapeSelectShapeselect_shape, fill_upfill_upFillUpFillUpfill_up

Alternatives

thresholdthresholdThresholdThresholdthreshold, dual_thresholddual_thresholdDualThresholdDualThresholddual_threshold, zero_crossing_sub_pixzero_crossing_sub_pixZeroCrossingSubPixZeroCrossingSubPixzero_crossing_sub_pix

Module

Foundation