BW= edge3(V,'approxcanny',阈值)returns the edges found in the intensity or a binary volumeVusing the approximate Canny method. The approximate Canny method finds edges by looking for local maxima of the gradient ofV.edge3calculates the gradient using the derivative of a Gaussian smoothed volume.

The approximate Canny method uses two thresholds to detect strong and weak edges, and includes the weak edges in the output only if they are connected to strong edges. This method is more likely than the Sobel method to detect true weak edges.

BW= edge3(V,'approxcanny',阈值,sigma)returns the edges found in the intensity or binary volumeV, wheresigmaspecifies the standard deviation of the Gaussian smoothing filter.edge3chooses the size of the filter automatically, based onsigma.

BW= edge3(V,'Sobel',阈值)accepts an intensity or a binary volumeV和returns a binary volumeBWwith1s where the function finds edges inV和0s elsewhere.

The Sobel method finds edges using the Sobel approximation to the derivative. It returns edges at those points where the gradient ofVis maximum.edge3ignores all edges that are not stronger than阈值.

BW= edge3(V,'Sobel',阈值,'nothinning')speeds up the operation of the algorithm by skipping the additional edge-thinning stage. By default, or when'thinning'is specified,edge3适用边缘变薄。