Matlab滤波函数

Matlab滤波函数
Matlab's fspecial function, usage, image processing
Matlab's fspecial function usage
The fspecial function is used to establish predefined filtering operators:
H = fspecial (type)
H = fspecial (type, para)
Where type specifies the type of operator, and para specifies the corresponding parameter;
The type of type has:
1,'average'
Averaging filter
For mean filtering, the parameter hsize represents the template size, and the default value is [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
For circular region mean filter, the parameter is radius, represents the region radius, the default value is 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
For Gauss low-pass filtering, there are two parameters, hsize represents the template size, the default value is [33], sigma is the standard value of the filter, the unit is pixel, the default value is 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, H, or, a, scalar, in, which, in, case, H, is, a
Square matrix.
The, default, HSIZE, is, [3, 3], the, default, SIGMA, is, 0.5.
4,'laplacian', filter, approximating, the, 2-D, Laplacian, operator
For the Laplasse operator, the parameter alpha is used to control the shape of the operator. The range of values is [0, 1], and the default value is 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, to, 1.0.
The, default, ALPHA, is, 0.2.
5,'log'
Laplacian of Gaussian filter
For the Laplasse Gauss operator, there are two parameters, hsize represents the template size, the default value is [33], sigma is the standard deviation of the filter, the unit is pixel, and the default value is 0.5.
H = FSPECIAL ('log', HSIZE, SIGMA), returns, a, rotationally, symmetric
与标准偏差的大小hsize高斯拉普拉斯滤波器
σ（正）。

hsize可以是一个向量，指定的行
在H或标量中的列，在这种情况下h是一个方阵。

默认是5 hsize [ 5 ]，默认是0.5西格玛。

6、'motion”
运动滤波
为运动模糊算子，有两个参数，表示摄像物体逆时针方向以θ角度运动了Len个像素，Len的默认值为9，θ的默认值为0
H = fspecial（'motion，Len，θ）返回一个滤波器近似，一
与图像卷积，Len像素的相机的线性运动，
以逆时针方向的θ度角。

这
滤波器成为水平运动和垂直运动的矢量。

这个
默认的莱恩是9，默认θ是0，它对应
9像素的水平运动。

7、'prewitt”
Prewitt边缘强调横向滤波器
用于边缘增强，大小为【3 3】，无参数
H = fspecial（'prewitt”）返回3*3滤波强调通过垂直梯度逼近水平边。

如果你需要
强调垂直边，转置过滤器H：H。

[ 1 - 1 - 1；0 - 0 - 0；1 - 1 - 1 ]。

8、'sobel”
水平边缘强调滤波器
用于边缘提取，无参数
H = fspecial（'sobel”）返回3*3滤波强调水平边利用近似a的平滑效果
垂直梯度。

如果您需要强调垂直边，转置
过滤器H：H。

[ 1 - 1 - 2；0 - 0 - 0；1 - 2 - 1 ]。

9、'unsharp”
锐化增强滤波器
为对比度增强滤波器。

参数α用于控制滤波器的形状，范围为【0,1】，默认值为0.2
H = fspecial（'unsharp，α）返回一个3×3的锐化对比
增强过滤器。

fspecial创建从锐化滤波器
带参数α的拉普拉斯滤波器的负性。

α控
拉普拉斯的形状，必须在0到1的范围内。

默认alpha是0.2。