h = fspecial(type)


h = fspecial(type
，
para)

其中
type
指定算子的类型，
para
指定相应的参数；


type
的类型有：


1
、
'average'
averaging filter

为均值滤波，参数为
hsize
代表模板尺寸，默认值为【
3
，
3
】。


H = FSPECIAL('average',HSIZE) returns an averaging filter H of size

HSIZE. HSIZE can be a vector specifying the number of rows and columns in

H or a scalar, in which case H is a square matrix.


The default HSIZE is [3 3].


2
、
 'disk'
circular averaging filter


为圆形区域均值滤波，参数为
radius
代表区域半径，默认值为
5.


H = FSPECIAL('disk',RADIUS) returns a circular averaging filter

(pillbox) within the square matrix of side 2*RADIUS+1.

The default RADIUS is 5.


3
、
'gaussian'
Gaussian lowpass filter


为高斯低通滤波，有两个参数，
hsize
表示模板尺寸，默认值为【
3 3
】，
sigma
为滤波器的标准值，单位为像素，默认值为
0.5.


H = FSPECIAL('gaussian',HSIZE,SIGMA) returns a rotationally

symmetric Gaussian lowpass filter
of size HSIZE with standard

deviation SIGMA (positive). HSIZE can be a vector specifying the

number of rows and columns in H or a scalar, in which case H is a

square matrix.

The default HSIZE is [3 3], the default SIGMA is 0.5.


4
、
'laplacian' 

laplacian filter approximating the 2-D Laplacian operator


为拉普拉斯算子，参数
alpha
用于控制算子形状，取值范围为【
0
，
1
】，默认值为
0.2.

H = FSPECIAL('laplacian',ALPHA) returns a 3-by-3 filter

approximating the shape of the two-dimensional Laplacian

operator. The parameter ALPHA controls the shape of the

Laplacian and must be in the range 0.0 to 1.0.

The default ALPHA is 0.2.


5
、
'log'
Laplacian of Gaussian filter


为拉普拉斯高斯算子，有两个参数，
hsize
表示模板尺寸，默认值为【
3 3
】，
sigma
为滤波器的标准差，单位为像素，默认值为
0.5.


H = FSPECIAL('log',HSIZE,SIGMA) returns a rotationally symmetric

Laplacian of Gaussian filter of size HSIZE with standard deviation

SIGMA (positive). HSIZE can be a vector specifying the number of rows

and columns in H or a scalar, in which case H is a square matrix.

The default HSIZE is [5 5], the default SIGMA is 0.5.


6
、
'motion'
motion filter


为运动模糊算子，有两个参数，表示摄像物体逆时针方向以
theta
角度运动了
len
个像素，
len
的默认值为
9
，
theta
的默认值为
0
；


H = FSPECIAL('motion',LEN,THETA) returns a filter to approximate, once

convolved with an image, the linear motion of a camera by LEN pixels,

with an angle of THETA degrees in a counter-clockwise direction. The

filter becomes a vector for horizontal and vertical motions.
The 
default LEN is 9, the default THETA is 0, which corresponds to a

horizontal motion of 9 pixels.


7
、
'prewitt'
Prewitt horizontal edge-emphasizing filter


用于边缘增强，大小为【
3 3
】，无参数


H = FSPECIAL('prewitt') returns 3-by-3 filter that emphasizes

horizontal edges by approximating a vertical gradient. If you need to

emphasize vertical edges, transpose the filter H: H'.

[1 1 1;0 0 0;-1 -1 -1].


8
、
'sobel'
Sobel horizontal edge-emphasizing filter


用于边缘提取，无参数


H = FSPECIAL('sobel') returns 3-by-3 filter that emphasizes

horizontal edges utilizing the smoothing effect by approximating a

vertical gradient. If you need to emphasize vertical edges, transpose

the filter H: H'.

[1 2 1;0 0 0;-1 -2 -1].


9
、
'unsharp'
unsharp contrast enhancement filter


为对比度增强滤波器。参数
alpha
用于控制滤波器的形状，范围为【
0
，
1
】，默认值为
0.2.


H = FSPECIAL('unsharp',ALPHA) returns a 3-by-3 unsharp contrast

enhancement filter. FSPECIAL creates the unsharp filter from the

negative of the Laplacian filter with parameter ALPHA. ALPHA controls

the shape of the Laplacian and must be in the range 0.0 to 1.0.

The default ALPHA is 0.2.

二、imfilter:对任意类型数组或多维图像进行滤波。