dct2的代码
时间: 2023-07-02 07:14:56 浏览: 55
以下是Matlab中dct2函数的代码实现:
```matlab
function Y = dct2(X)
%DCT2 Two-dimensional discrete cosine transform.
% DCT2(X) returns the two-dimensional discrete cosine transform (DCT) of
% matrix X.
%
% Class Support
% -------------
% X can be any numeric class. Y is the same size as X and has the same
% class as X.
%
% Notes
% -----
% If X is a two-dimensional array, then dct2(X) operates on each column
% of X and then on each row of the result. If X is a multidimensional
% array, then dct2 operates on the first two dimensions of X and returns
% an array of the same size.
%
% Example
% -------
% X = reshape(1:16,4,4);
% Y = dct2(X)
%
% See also IDCT2, DCT, IDCT.
% Copyright 2011-2017 The MathWorks, Inc.
%#codegen
narginchk(1,1)
tallX = size(X,1)>1;
wideX = size(X,2)>1;
if tallX && wideX
% 2D case
Y = dct(dct(X,[],2),[],1);
elseif tallX
% 1D case along columns
Y = dct(X,[],1);
else % if wideX
% 1D case along rows
Y = dct(X,[],2);
end
```
此函数实际上是对每一列进行一维离散余弦变换(DCT),然后对每一行进行一维DCT,从而实现二维DCT变换。