Function Reference
— 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.
'disk'
Circular averaging filter.
'gaussian'
Gaussian filter.
'log'
Laplacian of Gaussian.
'laplacian'
3x3 approximation of the laplacian.
'unsharp'
Sharpening filter.
'motion'
Moion blur filter of width 1 pixel.
'sobel'
Horizontal Sobel edge filter.
'prewitt'
Horizontal Prewitt edge filter.

The parameters that need to be specified depend on the filtertype.

Examples of use and associated default values:

           f = fspecial('average',sze)           # sze can be a 1 or 2 vector
                                                 # default is [3, 3].
           f = fspecial('disk',radius)           # default radius = 5
           f = fspecial('gaussian',sze, sigma)   # default sigma is 0.5
           f = fspecial('laplacian',sze, sigma)  # default sze is [5, 5]
                                                 # default sigma is 0.5
           f = fspecial('log');
           f = fspecial('motion', length, angle) # default length is 9
                                                 # default angle is 0 (degrees)
           f = fspecial('sobel');
           f = fspecial('prewitt');

When sze is specified as a single value the filter will be square.