gray_skeleton — Thinning of gray value images.
gray_skeleton applies a gray value thinning operation to the input image Image. Figuratively, the gray value “mountain range” is reduced to its ridge lines by setting the gray value of “hillsides” to the gray value at the corresponding valley bottom. The resulting ridge lines are at most two pixels wide. This operator is especially useful for thinning edge images, and is thus an alternative to nonmax_suppression_amp. In contrast to nonmax_suppression_amp, gray_skeleton preserves contours, but is much slower. In contrast to skeleton, this operator changes the gray values of an image while leaving its region unchanged.
Note that filter operators may return unexpected results if an image with a reduced domain is used as input. Please refer to the chapter Filters.
Image to be thinned.
* Seeking leafs of a beech tree in an aerial picture: read_image(Image,'forest') gray_skeleton(Image,Skelett) mean_image(Skelett,MeanSkelett,7,7) dyn_threshold(Skelett,MeanSkelett,Leafs,3,'light')
gray_skeleton 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>). If necessary, an exception is raised.
nonmax_suppression_amp, nonmax_suppression_dir, local_max