Web : Convolutions

   KERNEL                             DESCRIPTION


laplacian                     3 x 3 Laplacian edge detection 
                                         
   0  -1   0  
  -1   4  -1  
   0  -1   0  

laplac5                       5 x 5 Laplacian edge detection 

  -1  -1  -1  -1  -1 
  -1  -1  -1  -1  -1 
  -1  -1  24  -1  -1 
  -1  -1  -1  -1  -1 
  -1  -1  -1  -1  -1  

laplac7                       7 x 7 Laplacian edge detection

  -1 -1 -1  -1 -1 -1 -1
  -1 -1 -1  -1 -1 -1 -1
  -1 -1 -1  -1 -1 -1 -1
  -1 -1 -1  48 -1 -1 -1
  -1 -1 -1  -1 -1 -1 -1
  -1 -1 -1  -1 -1 -1 -1
  -1 -1 -1  -1 -1 -1 -1

gauss                         7 x 7 Gaussian kernel 
     
   1  1  2  2  2  1  1 
   1  2  2  4  2  2  1 
   2  2  4  8  4  2  2 
   2  4  8 16  8  4  2 
   2  2  4  8  4  2  2 
   1  2  2  4  2  2  1 
   1  1  2  2  2  1  1 

hipass3                       3 x 3 High Pass Filter 

  -1 -1 -1 
  -1  9 -1 
  -1 -1 -1 

hipass5                       5 x 5 High Pass Filter 

   0 -1 -1 -1  0 
  -1  2 -4  2 -1 
  -1 -4 13 -4 -1 
  -1  2 -4  2 -1 
   0 -1 -1 -1  0 

sharpen3                      3 x 3 Sharpening Filter 
                              (Combines high and low pass filtering) 
  -1 -2 -1
   2  4  2 
   1  2  1 
 
lopass3                       3 x 3 Low Pass Filter 

  1  2  1 
  2  4  2 
  1  2  1 

lopass5 
                              5 x 5 Low Pass filter 
  1  1  1  1  1 
  1  4  4  4  1 
  1  4 12  4  1 
  1  4  4  4  1 
  1  1  1  1  1 

variance3                     3 x 3 Variance Operator
                              Finds variance of 3x3 neighbourhood 
  1  1  1 
  1  0  1 
  1  1  1 
 
variance5                     5 x 5 Variance Operator 
                              Finds variance of 5x5 neighbourhood  
  0  1  1  1  0 
  1  1  1  1  1 
  1  1  0  1  1 
  1  1  1  1  1 
  0  1  1  1  0  

variance7                     7 x 7 Variance Operator 
                              Finds variance of 7x7 neighbourhood  
  0  0  1  1  1  0  0 
  0  1  1  1  1  1  0 
  1  1  1  1  1  1  1 
  1  1  1  0  1  1  1 
  1  1  1  1  1  1  1 
  0  1  1  1  1  1  0 
  0  0  1  1  1  0  0  

denoise                        3 x 3 Noise removal 
                               Pixel replaced by area average if       
   1   1   1                   pixel value is less than lower
   1   0   1                   limit.
   1   1   1  

erode                          For pixel value:       Set to:
 (by hits)                        < threshold         original minimum

                                  >= threshold &&     original value
                                  (# adjacent pixels
                                  >= threshold) >
                                  hits.

                                  >= threshold &&     original minimum
                                  (# adjacent pixels
                                  >= threshold) <
                                  hits.

dilate                         For pixel value:        Set to:
 (by hits)                        >= threshold        original value

                                  < threshold &&      original maximum
                                  (# adjacent pixels
                                  >= threshold) >
                                  hits.

                                  >= threshold &&     original minimum
                                  (# adjacent pixels
                                  >= threshold) <
                                  hits.

binary skeleton                Reduces image area to a skeleton.
                               Works on binary images only.

test                           Experimental program used to 
                               determine proximity of neighboring
                               pixels having certain preset values.
                               Replaces all pixels having value outval
                               with distance to nearest pixel having
                               value: inval.