pcontourextensionrect

Performs rectangular-shaped extension of end points.

Synopsis

pcontourextensionrect length height [-m mask] [im_in|-] [im_out|-]

Description

pcontourextensionrect extends all contour end points by a rectangle (or a parallelogram in 3D) defined by the size length x height (or length x height x height for 3D). A contour chain is a sequence of connected non null pixels with 1 pixel thickness. A end point is a contour point with only 1 neighbor. For a 3D extension, the depth is equal to the height.

For example, the 2D contour on the left is extended to the contour on the right if length=4 and height=1.

                     xxxx
    xxxx    ->   xxxxxxxx
                     xxxx

For the current 3D version, height is not taken into account. The extension is only 1 pixel height and depth.

Warning: if the contour is not 1 pixel thickness, the operator may have unpredictable behavior. It might be necessary to use the operator ppostthinning to guaranty 1 pixel thickness.

Parameters

length is the length, counted in pixel unit, of the extension in the sense of the contour.
height is the thickness, counted in pixel unit, of the extension in the orthogonal sense of the contour.

Inputs

im_in: a 2D or 3D grayscale image (Img2duc or Img3duc).

Outputs

im_out: an image of the same type as the input image.

Result

The number of end points.

Examples

Closes contours yielded by a simple edge detection of tangram.pan by using an extension of the end points:

   psobel tangram.pan b.pan
   pbinarization 60 1e30 b.pan c.pan
   pskeletonization c.pan d.pan 
   ppostthinning d.pan e.pan
   pcontourextensionrect 3 3 e.pan f.pan
   plabeling 8 f.pan out.pan

C++ prototype

Errc PContourExtensionRect( const Img2duc &im_in, Img2duc &im_out, int height, int length );

Version française

Extension des points terminaux dans la direction du contour.

Author: Régis Clouard