pgeodesicerosion

Synopsis

Description

pgeodesicerosion performs the erosion of the pixels of the image im_in as long as those pixels belong to a null area specified in the image im_msq. im_msq is an image of bytes or a region map used as a binary mask. All the non null pixels correspond to a true value for the mask. The structuring element is specified by its type num_se and its size halfsize.

Geodesic erosion of point p corresponds to the operation:

   if im_msq (p)=0
      erosion(p) = MIN(neighbors of p specified by the structuring element)
   else
      erosion(p) = im_in(p).

Whereas, conditional erosion is defined as :

   pinverse msq.pan i1.pan
   por in.pan i1.pan i2.pan
   perosion hs i2.pan i3.pan
   pmask i3.pan msq.pan out.pan 

For the color images, the lexicographic order is used: initially by using band X, in the event of equality by using the band Y then band Z.

Parameters

• num_se specifies the type of the structuring element:

  case of 2D:

  • 0: diamond (4-connexity)
  • 1: square (8-connexity)
  • 2: disc
  • 3: horizontal line (-)
  • 4: vertical line (|)
  • 5: right oblique line (/).
  • 6: left oblique line (\).

  case of 3D:

  • 0: bipyramid (6-connexity)
  • 1: cube (26-connexity)
  • 2: sphere
  • 3: line along X (-)
  • 4: line along Y (|)
  • 5: line along Z
• halfsize specifies the half-size of the structuring element. For example, a half-size of 1 for a square gives a structuring element of size 3x3.
• iteration specifies the number of iterations. If iteration=-1, then geodesic dilation is carried out until idempotence.

Inputs

• im_in: a gray level or a color image.
• im_msq: an image of bytes or a region map.

Outputs

• im_out: an image of the same type as im_in.

Result

Returns SUCCESS or FAILURE.

Examples

• Performs edge detection based on hysteresis thresholding:

   
     pgradient 1 tangram.pan i1.pan i2.pan 
     pbinarization 0 80 i1.pan i3.pan
     pbinarization 0 30 i1.pan i4.pan
     pgeodesicerosion 1 1 -1 i3.pan i4.pan i5.pan
     pinverse i5.pan out.pan
  

See also

C++ prototype