zero_crossingzero_crossingzero_crossingZeroCrossingZeroCrossing (Operator)

Name

zero_crossingzero_crossingzero_crossingZeroCrossingZeroCrossing — Extrakt zero crossings from an image.

Signature

Description

zero_crossingzero_crossingzero_crossingZeroCrossingZeroCrossing 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_gausslaplace_of_gaussLaplaceOfGaussLaplaceOfGauss), which were possibly followed by a smoothing operator. In this case, the zero crossings are (candidates for) edges.

Parallelization

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

Possible Predecessors

laplacelaplacelaplaceLaplaceLaplace, laplace_of_gausslaplace_of_gausslaplace_of_gaussLaplaceOfGaussLaplaceOfGauss, derivate_gaussderivate_gaussderivate_gaussDerivateGaussDerivateGauss

Possible Successors

connectionconnectionconnectionConnectionConnection, skeletonskeletonskeletonSkeletonSkeleton, boundaryboundaryboundaryBoundaryBoundary, select_shapeselect_shapeselect_shapeSelectShapeSelectShape, fill_upfill_upfill_upFillUpFillUp

Alternatives

thresholdthresholdthresholdThresholdThreshold, dual_thresholddual_thresholddual_thresholdDualThresholdDualThreshold, zero_crossing_sub_pixzero_crossing_sub_pixzero_crossing_sub_pixZeroCrossingSubPixZeroCrossingSubPix

Module

Foundation