close_edges_lengthclose_edges_lengthCloseEdgesLengthCloseEdgesLengthclose_edges_length (Operator)

名称

close_edges_lengthclose_edges_lengthCloseEdgesLengthCloseEdgesLengthclose_edges_length — 使用边缘振幅图像闭合边缘间隙。

签名

close_edges_length(Edges, Gradient : ClosedEdges : MinAmplitude, MaxGapLength : )

描述

close_edges_lengthclose_edges_lengthCloseEdgesLengthCloseEdgesLengthCloseEdgesLengthclose_edges_length closes gaps in the output of an edge detector, and thus tries to produce complete object contours. This operator expects as input the edges (EdgesEdgesEdgesEdgesedgesedges) and amplitude image (GradientGradientGradientGradientgradientgradient) returned by typical edge operators, such as edges_imageedges_imageEdgesImageEdgesImageEdgesImageedges_image or sobel_ampsobel_ampSobelAmpSobelAmpSobelAmpsobel_amp.

Contours are closed in two steps: First, one pixel wide gaps in the input contours are closed, and isolated points are eliminated. After this, open contours are extended by up to MaxGapLengthMaxGapLengthMaxGapLengthMaxGapLengthmaxGapLengthmax_gap_length points by adding edge points until either the contour is closed or no more significant edge points can be found. A gradient is regarded as significant if it is larger than MinAmplitudeMinAmplitudeMinAmplitudeMinAmplitudeminAmplitudemin_amplitude. The neighboring points examined as possible new edge points are the point in the direction of the contour and its two adjacent points in an 8-neighborhood. For each of these points, the sum of its gradient and the maximum gradient of that points three possible neighbors is calculated (look ahead of length 1). The point with the maximum sum is then chosen as the new edge point.

注意

Note that filter operators may return unexpected results if an image with a reduced domain is used as input. Please refer to the chapter 滤波器.

执行信息

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

参数

EdgesEdgesEdgesEdgesedgesedges (input_object) region(-array) → object

Region containing one pixel thick edges.

GradientGradientGradientGradientgradientgradient (input_object) singlechannelimage → object (byte / uint2)

Edge amplitude (gradient) image.

ClosedEdgesClosedEdgesClosedEdgesClosedEdgesclosedEdgesclosed_edges (output_object) region(-array) → object

Region containing closed edges.

MinAmplitudeMinAmplitudeMinAmplitudeMinAmplitudeminAmplitudemin_amplitude (input_control) integer → (integer)

Minimum edge amplitude.

默认值： 16

建议值： 5, 8, 10, 12, 16, 20, 25, 30, 40, 50

值范围： 0 ≤ MinAmplitude MinAmplitude MinAmplitude MinAmplitude minAmplitude min_amplitude ≤ 255

最小增量： 1

建议增量： 1

MaxGapLengthMaxGapLengthMaxGapLengthMaxGapLengthmaxGapLengthmax_gap_length (input_control) integer → (integer)

Maximal number of points by which edges are extended.

默认值： 3

建议值： 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 20, 30, 40, 50, 70, 100

值范围： 1 ≤ MaxGapLength MaxGapLength MaxGapLength MaxGapLength maxGapLength max_gap_length ≤ 127

最小增量： 1

建议增量： 1

示例（C）

sobel_amp(Image,&EdgeAmp,"sum_abs",5);
threshold(EdgeAmp,&EdgeRegion,40.0,255.0);
skeleton(EdgeRegion,&ThinEdge);
close_edges_length(ThinEdge,EdgeAmp,&CloseEdges,15,3);

结果

close_edges_lengthclose_edges_lengthCloseEdgesLengthCloseEdgesLengthCloseEdgesLengthclose_edges_length returns 2 ( H_MSG_TRUE) if all parameters are correct. If the input is empty the behavior can be set via set_system('no_object_result',<Result>)set_system("no_object_result",<Result>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>)set_system("no_object_result",<Result>). If necessary, an exception is raised.

可能的前置算子

edges_imageedges_imageEdgesImageEdgesImageEdgesImageedges_image, sobel_ampsobel_ampSobelAmpSobelAmpSobelAmpsobel_amp, thresholdthresholdThresholdThresholdThresholdthreshold, skeletonskeletonSkeletonSkeletonSkeletonskeleton

替代算子

close_edgesclose_edgesCloseEdgesCloseEdgesCloseEdgesclose_edges, dilation1dilation1Dilation1Dilation1Dilation1dilation1, closingclosingClosingClosingClosingclosing

参考文献

M. Üsbeck: “Untersuchungen zur echtzeitfähigen Segmentierung”; Studienarbeit, Bayerisches Forschungszentrum für Wissensbasierte Systeme (FORWISS), Erlangen, 1993.

模块

Foundation

算子