plabeling

Performs region labeling.

Synopsis

plabeling connexity [-m mask] [im_in|-] [rg_out|-]

Description

plabeling builds regions from a set of connected pixels that have exactly the same pixel value. Two pixels p1 and p2 of the input image im_in are labeled with the same label value in the output region map rg_out if:

p1 is a neighbor of p2 (according to the connexity value).
im_in[p1] = im_in[p2].

A region is defined as a set of connected pixels with the same label. The label value is set randomly from 1 to the number of regions.

If im_in is already a region map, the plabeling relabels the region so as to minimize the number of used labels.

Notice: Pixels with label value = 0 are not considered as part of region. Thus, the region 0 does not exist.

Parameters

connexity specifies the neighbor relation between pixels (4 or 8 for 2D; 6 or 26 for 3D).

Inputs

im_in: a grayscale image, a region map or a graph.

Outputs

rg_out: a region map or a graph.

Examples

Builds the skeleton by influence zones (skiz):

   pbinarization 100 1e30 tangram.pan i1.pan
   pdistance i1.pan i2.pan
   plabeling 8 i1.pan i3.pan
   pwatershed i3.pan i2.pan i4.pan
   pboundary 8 i4.pan out.pan

Result

Returns the number of region or FAILURE.

C++ prototype

Errc PLabeling( const Img2duc &im_in, Reg2d &rg_out, int connexity );

Version française

Etiquetage des régions homogènes d'une image.

Author: Régis Clouard