ksvd算法代码matlab
时间: 2023-09-30 20:07:56 浏览: 74
以下是KSVD算法的MATLAB代码:
```matlab
function [D,X] = ksvd(Y,D,X,K)
% Initialize dictionary D
D = normc(randn(size(Y,1),K));
for iter = 1:100
% Update sparse codes X
for i = 1:size(X,2)
X(:,i) = omp(D,Y(:,i),[],K);
end
% Update dictionary D
for j = 1:K
ind = find(X(j,:));
if ~isempty(ind)
E = Y(:,ind) - D*X(:,ind);
[U,S,V] = svds(E,1);
D(:,j) = U;
X(j,ind) = S*V';
end
end
end
end
```
其中,输入参数Y是样本数据,D是字典矩阵,X是稀疏编码矩阵,K是字典矩阵中的列数。该算法的迭代次数为100次。在每次迭代中,首先更新稀疏编码矩阵X,然后根据更新后的稀疏编码矩阵X来更新字典矩阵D。在更新字典矩阵D时,使用了奇异值分解(SVD)来更新字典矩阵的每一列。
相关问题
KSVD算法 matlab代码
以下是KSVD算法的MATLAB代码实现:
```matlab
function [D,X,err] = ksvd(Y,D,X,param)
% Input:
% Y - Signal observation (m x n matrix)
% D - Initial dictionary (m x K matrix)
% X - Coefficient matrix (K x n matrix)
% param - Algorithm parameters structure
%
% Output:
% D - Learned dictionary (m x K matrix)
% X - Sparse coefficient matrix (K x n matrix)
% err - Error history (vector)
% Initialize error vector
err = zeros(param.max_iter,1);
% Loop over iterations
for i = 1:param.max_iter
% Sparse coding
X = omp(D'*Y, D'*D, param.sparsity);
% Dictionary update
for k = 1:param.K
% Find samples that use atom k
I = find(X(k,:));
if ~isempty(I)
% Compute error matrix
E = Y(:,I) - D*X(:,I) + D(:,k)*X(k,I);
% SVD of error matrix
[U,S,V] = svds(E,1);
% Update dictionary and coefficient matrix
D(:,k) = U;
X(k,I) = S*V';
end
end
% Compute error
err(i) = norm(Y - D*X,'fro')^2;
% Check for convergence
if i > 1 && abs(err(i) - err(i-1)) < param.tol
break;
end
end
end
function X = omp(Y, D, K)
% Solve OMP problem
% min ||x||_0 subject to y = D*x
[m,n] = size(Y);
X = zeros(size(D,2),n);
for i = 1:n
% Initialize residual and index set
r = Y(:,i);
omega = [];
% Loop over sparsity level
for j = 1:K
% Find index with largest projection
[~,k] = max(abs(D'*r));
% Add index to index set
omega = [omega;k];
% Solve least squares problem
X(omega,i) = pinv(D(:,omega))*Y(:,i);
% Update residual
r = Y(:,i) - D(:,omega)*X(omega,i);
% Check for convergence
if norm(r) < 1e-6
break;
end
end
end
end
```
其中,`param`是一个包含算法参数的结构体,具体内容如下:
```matlab
param.K = 128; % Dictionary size
param.sparsity = 10; % Sparsity level
param.max_iter = 50; % Maximum number of iterations
param.tol = 1e-6; % Convergence tolerance
```
使用方法如下:
```matlab
% Load signal data
load('signal_data.mat');
% Set algorithm parameters
param.K = 128;
param.sparsity = 10;
param.max_iter = 50;
param.tol = 1e-6;
% Initialize dictionary and coefficient matrix
D = randn(size(Y,1),param.K);
X = zeros(param.K,size(Y,2));
% Run KSVD algorithm
[D,X,err] = ksvd(Y,D,X,param);
```
KSVD算法图像修复
KSVD算法是一种基于字典学习的图像修复算法,其主要思想是通过学习一组字典,将待修复图像分解为若干个基础元素的线性组合,从而实现图像的修复。下面是KSVD算法图像修复的步骤:
1.准备数据:将待修复的图像转化为矩阵形式,并将其分解为若干个小块。
2.初始化字典:随机生成一个字典,并对其进行归一化处理。
3.迭代更新字典:对于每个小块,使用KSVD算法更新字典,使其更好地适应数据。
4.稀疏编码:对于每个小块,使用更新后的字典进行稀疏编码,得到其系数矩阵。
5.重构图像:将每个小块的系数矩阵与更新后的字典相乘,得到重构后的小块,最后将所有小块拼接起来,得到修复后的图像。
下面是使用matlab实现KSVD算法图像修复的示例代码:
```matlab
% 读取待修复图像
img = imread('lena.png');
% 将图像转化为矩阵形式,并将其分解为若干个小块
patch_size = 8;
patches = im2col(img, [patch_size patch_size], 'sliding');
% 初始化字典
dict_size = 256;
dict = randn(patch_size^2, dict_size);
dict = normc(dict);
% 迭代更新字典
num_iter = 50;
for i = 1:num_iter
% 稀疏编码
coef = omp(dict, patches);
% 更新字典
dict = ksvd(patches, dict, coef);
end
% 重构图像
coef = omp(dict, patches);
patches_rec = dict * coef;
img_rec = col2im(patches_rec, [patch_size patch_size], size(img), 'sliding');
% 显示修复前后的图像
figure;
subplot(1, 2, 1);
imshow(img);
title('Original Image');
subplot(1, 2, 2);
imshow(img_rec);
title('Reconstructed Image');
```