數(shù)字圖像處理 Matlab 退化模型示例(example0507)

1、>> f=checkerboard (8);>> imshow (f)>> PSF=fspecial ('motion', 7, 45);>> gb = imfilter( f, PSF, ' circular' );>> noise = imnoise(zeros(size(f),'gaussian',0,0.001);>> g = gb + noise; F Gb Noise G% 可用MATLAB的fspecial建立PSF模型 %¤PSF = fspecia

2、l(motion,len,theta) %¤Len 移動(dòng)的像素?cái)?shù) %¤Theta運(yùn)動(dòng)方向(逆時(shí)針) >> help fspecial FSPECIAL Create predefined 2-D filters. H = FSPECIAL (TYPE) creates a two-dimensional filter H of the specified type. Possible values for TYPE are: 'average' averaging filter 'disk' circular averaging

3、filter 'gaussian' Gaussian lowpass filter 'laplacian' filter approximating the 2-D Laplacian operator 'log' Laplacian of Gaussian filter 'motion' motion filter 'prewitt' Prewitt horizontal edge-emphasizing filter 'sobel' Sobel horizontal edge-emphasizi

4、ng filter 'unsharp' unsharp contrast enhancement filter Depending on TYPE, FSPECIAL may take additional parameters which you can supply. These parameters all have default values. H = FSPECIAL ('average', HSIZE) returns an averaging filter H of size HSIZE. HSIZE can be a vector specif

5、ying 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. H = FSPECIAL('disk',RADIUS) returns a circular averaging filter (pillbox) within the square matrix of side 2*RADIUS+1. The default RADIUS is 5. H = FSPECIAL('gaussian',

6、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. H =

7、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. H = FSPECIAL('log',HSIZE,SIGMA) returns a rota

8、tionally 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. H = FSPECIAL('motion&#

9、39;,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, w

10、hich corresponds to a horizontal motion of 9 pixels. 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. H = FSPECIAL('sobel'

11、;) 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. H = FSPECIAL('unsharp',ALPHA) returns a 3-by-3 unsharp contrast enhanc

12、ement 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. Class Support - H is of class double. Example - I = imread('cameraman.tif'

13、;); subplot(2,2,1);imshow(I);title('Original Image'); H = fspecial('motion',20,45); MotionBlur = imfilter(I,H,'replicate'); subplot(2,2,2);imshow(MotionBlur);title('Motion Blurred Image'); H = fspecial('disk',10); blurred = imfilter(I,H,'replicate'); s

14、ubplot(2,2,3);imshow(blurred);title('Blurred Image'); H = fspecial('unsharp'); sharpened = imfilter(I,H,'replicate'); subplot(2,2,4);imshow(sharpened);title('Sharpened Image'); See also conv2, edge, filter2, fsamp2, fwind1, fwind2, imfilter. Reference page in Help bro

15、wser doc fspecial>> help imfilter IMFILTER N-D filtering of multidimensional images. B = IMFILTER(A,H) filters the multidimensional array A with the multidimensional filter H. A can be logical or it can be a nonsparse numeric array of any class and dimension. The result, B, has the same size a

16、nd class as A. Each element of the output, B, is computed using double-precision floating point. If A is an integer or logical array, then output elements that exceed the range of the given type are truncated, and fractional values are rounded. B = IMFILTER(A,H,OPTION1,OPTION2,.) performs multidimen

17、sional filtering according to the specified options. Option arguments can have the following values: - Boundary options X Input array values outside the bounds of the array are implicitly assumed to have the value X. When no boundary option is specified, IMFILTER uses X = 0. 'symmetric' Inpu

18、t array values outside the bounds of the array are computed by mirror-reflecting the array across the array border. 'replicate' Input array values outside the bounds of the array are assumed to equal the nearest array border value. 'circular' Input array values outside the bounds of

19、the array are computed by implicitly assuming the input array is periodic. - Output size options (Output size options for IMFILTER are analogous to the SHAPE option in the functions CONV2 and FILTER2.) 'same' The output array is the same size as the input array. This is the default behavior

20、when no output size options are specified. 'full' The output array is the full filtered result, and so is larger than the input array. - Correlation and convolution 'corr' IMFILTER performs multidimensional filtering using correlation, which is the same way that FILTER2 performs filt

21、ering. When no correlation or convolution option is specified, IMFILTER uses correlation. 'conv' IMFILTER performs multidimensional filtering using convolution. Notes - On some Intel Architecture processors, IMFILTER can take advantage of the Intel Performance Primitives Library (IPPL), thus accelerating its execution time. IPPL is activated only if A and H are both two dimensional and A is uint8, int16 or sin