%二維DCT變換
function y = dct_2D(x)
%獲取圖像矩陣大小
size_x = size(x);                      
height = size_x(1,1);                  
width = size_x(1,2);                   
%計算所需計算的2的次方的矩陣
h2 = ceil(log2(height));             
w2 = ceil(log2(width));              
%實際計算的矩陣大小(h,w)
h = 2^h2;                             
w = 2^w2;                             
%得到補0的矩陣
X = zeros(h,w);
X(1:height,1:width) = x;      
%可分離，一維一維計算
%中間結果Y
Y = zeros(h,w);                       
for i=1:h
    Y(i,:) = dct_1D(X(i,:));
end
%最終結果y
y = zeros(h,w);                       
for i=1:w
    y(:,i) = ( dct_1D(Y(:,i)') )';
end