- Function File:
`filter`=**fspecial(**`type`,`arg1`,`arg2`) Create spatial filters for image processing.

`type`determines the shape of the filter and can be`"average"`Rectangular averaging filter. The optional argument

`arg1`controls the size of the filter. If`arg1`is an integer`N`, a`N`by`N`filter is created. If it is a two-vector with elements`N`and`M`, the resulting filter will be`N`by`M`. By default a 3 by 3 filter is created.`"disk"`Circular averaging filter. The optional argument

`arg1`controls the radius of the filter. If`arg1`is an integer`N`, a 2`N`+ 1 filter is created. By default a radius of 5 is used.`"gaussian"`Gaussian filter. The optional argument

`arg1`controls the size of the filter. If`arg1`is an integer`N`, a`N`by`N`filter is created. If it is a two-vector with elements`N`and`M`, the resulting filter will be`N`by`M`. By default a 3 by 3 filter is created. The optional argument`arg2`sets spread of the filter. By default a spread of*0.5*is used.`"log"`Laplacian of Gaussian. The optional argument

`arg1`controls the size of the filter. If`arg1`is an integer`N`, a`N`by`N`filter is created. If it is a two-vector with elements`N`and`M`, the resulting filter will be`N`by`M`. By default a 5 by 5 filter is created. The optional argument`arg2`sets spread of the filter. By default a spread of*0.5*is used.`"laplacian"`3x3 approximation of the laplacian. The filter is approximated as

(4/(

`alpha`+1))*[`alpha`/4, (1-`alpha`)/4,`alpha`/4; ... (1-`alpha`)/4, -1, (1-`alpha`)/4; ...`alpha`/4, (1-`alpha`)/4,`alpha`/4];where

`alpha`is a number between 0 and 1. This number can be controlled via the optional input argument`arg1`. By default it is*0.2*.`"unsharp"`Sharpening filter. The following filter is returned

(1/(

`alpha`+1))*[-`alpha`,`alpha`-1, -`alpha`; ...`alpha`-1,`alpha`+5,`alpha`-1; ... -`alpha`,`alpha`-1, -`alpha`];where

`alpha`is a number between 0 and 1. This number can be controlled via the optional input argument`arg1`. By default it is*0.2*.`"motion"`Moion blur filter of width 1 pixel. The optional input argument

`arg1`controls the length of the filter, which by default is 9. The argument`arg2`controls the angle of the filter, which by default is 0 degrees.`"sobel"`Horizontal Sobel edge filter. The following filter is returned

[ 1, 2, 1; 0, 0, 0; -1, -2, -1 ]

`"prewitt"`Horizontal Prewitt edge filter. The following filter is returned

[ 1, 1, 1; 0, 0, 0; -1, -1, -1 ]

`"kirsch"`Horizontal Kirsch edge filter. The following filter is returned

[ 3, 3, 3; 3, 0, 3; -5, -5, -5 ]

Package: image