nonmax_suppression_dir — 使用方向图像抑制边缘上的非最大点。
nonmax_suppression_dir(ImgAmp, ImgDir : ImageResult : Mode : )
nonmax_suppression_dir suppresses all points in the
regions of the image ImgAmp whose gray values are
not local (directed) maxima. ImgDir is a direction image
giving the direction perpendicular to the local maximum (Unit:
2 degrees, i.e., 50 degrees are coded as 25 in the image). Such
images are returned, for example, by edges_image。Two modes
of operation can be selected:
Each point in the image is tested whether its gray value is a local maximum perpendicular to its direction. In this mode only the two neighbors closest to the given direction are examined. If one of the two gray values is greater than the gray value of the point to be tested, it is suppressed (i.e., removed from the input region. The corresponding gray value remains unchanged).
Like 'nms'. However, the two gray values for the test are obtained by interpolation from four adjacent points.
ImgAmp (输入对象) singlechannelimage(-array) → object (byte / uint2 / real)
Amplitude (gradient magnitude) image.
ImgDir (输入对象) singlechannelimage(-array) → object (direction)
Direction image.
ImageResult (输出对象) image(-array) → object (byte / uint2 / real)
Image with thinned edge regions.
Mode (输入控制) string → (string)
Select non-maximum-suppression or interpolating NMS.
默认值： 'nms'
值列表： 'inms', 'nms'
nonmax_suppression_dir 在所有参数正确时返回 2 ( H_MSG_TRUE )。 The behavior with respect to the input images and
output regions can be determined by setting the values of the flags
'no_object_result', 'empty_region_result', and
'store_empty_region' with set_system。如有必要，则抛出异常。
edges_image,
sobel_dir,
frei_dir
threshold,
hysteresis_threshold
S.Lanser: “Detektion von Stufenkanten mittels rekursiver Filter nach
Deriche”; Diplomarbeit; Technische Universität München, Institut
für Informatik, Lehrstuhl Prof. Radig; 1991.
J.Canny: “Finding Edges and Lines in Images”; Report, AI-TR-720;
M.I.T. Artificial Intelligence Lab., Cambridge; 1983.
基础