pnonmaximasuppression

Performs non-maxima suppression for edge detection.

Synopsis

pnonmaximasuppression [-m mask] [im_in1|-] [im_in2|-] [im_out|-]

Description

pnonmaximasuppression finds the non maxima values from the magnitude gradient image im_in1. Maxima values are gradient magnitude that are maximum in the orthogonal direction of the gradient.

The direction image im_in2 contains pixels that are set with Freeman codes.
The Freeman codes are:

   2D        3D
              z-1:	   z:		    z+1:
 1 2 3      2  3  4	10 11 12	 19 20 21
 0   4      1  0  5	9     22	 18 13 14
 7 6 5      8  7  6	25 24 23	 17 16 15

Note: the output border values (size 1x1x1) are set the input image border values. im_out.

The output image is of the same type as the input image.

Inputs

im_in1: a grayscale image.
im_in2: a byte image (Uchar image).

Outputs

im_out: an image of the same type as im_in1.

Result

Returns SUCCESS or FAILURE.

Examples

Extracts contours from the tangram.pan image:

   pexponentialfiltering 0.7 tangram.pan i1.pan
   pgradient 1 i1.pan i2.pan i3.pan
   pnonmaximasuppression i2.pan i3.pan i4.pan
   ppostthinning i4.pan i5.pan
   pgradientthreshold 0.03 i2.pan
   seuilhaut=`pstatus`
   pbinarization $seuilhaut 1e30 i5.pan i6.pan
   pgradientthreshold 0.2 i2.pan
   seuilbas=`pstatus`
   pbinarization $seuilbas 1e30 i5.pan  i7.pan 
   pgeodesicdilation 1 1 -1 i6.pan i7.pan out.pan

C++ prototype

Errc PNonMaximaSuppression( const Img2duc &im_in1, const Img2duc &im_in2, Img2duc &im_out );

Version française

Suppression des points non maxima dans une image d'amplitude de gradient.

Author: Régis Clouard