%載入原始圖像
load sinsin;
% 圖像編碼
nbcol = size(map,1);
cod_X = wcodemat(X,nbcol);
% 畫出原始圖像
subplot(221)
image(cod_X)
title('原始圖像');
colormap(map)
% 使用sym4在第3層對X進行SWT分解
[ca,chd,cvd,cdd] = swt2(X,3,'sym4');
% 輸出分解圖像
for k = 1:3
    % 對第k層進行圖像編碼
    cod_ca  = wcodemat(ca(:,:,k),nbcol);
    cod_chd = wcodemat(chd(:,:,k),nbcol);
    cod_cvd = wcodemat(cvd(:,:,k),nbcol);
    cod_cdd = wcodemat(cdd(:,:,k),nbcol);
    decl = [cod_ca,cod_chd;cod_cvd,cod_cdd];
    % 畫出第k層圖像分解系數
    subplot(2,2,k+1)
    image(decl)
    title(['SWT 分解: 低頻系數和高頻系數(level. ',num2str(k),')']);
    colormap(map)
end