如何在 MATLAB 中显示多级 wavedec2

Question

图像的4级离散小波变换计算完成后，如何在matlab中显示这个多级变换？以及如何绘制相应的 DWT 系数的直方图？

这是我目前所做的：

I = imread('image.png');
N = 4;
[C,S] = wavedec2(im2double(I),N,'haar');
A = appcoef2(C,S,'haar',1);
[H1,V1,D1] = detcoef2('all',C,S,1);
[H2,V2,D2] = detcoef2('all',C,S,2);
[H3,V3,D3] = detcoef2('all',C,S,3);
[H4,V4,D4] = detcoef2('all',C,S,4);

Answer 1

我会这样做：

N = 4;

img = imread('image.png');
img = im2double(img);

[C,S] = wavedec2(img,N,'haar');

for i = 1:N
    lvl = ['Level ' num2str(i)];

    A = appcoef2(C,S,'haar',i);
    [H,V,D] = detcoef2('all',C,S,i);

    figure('Name',['Images (' lvl ')']);
    % Eventually, you can define a colormap for your images...
    % colormap(pink(255));
    subplot(2,2,1); imagesc(A);
    title('Approximation')
    subplot(2,2,2); imagesc(H);
    title('Horizontal Detail');
    subplot(2,2,3); imagesc(V);
    title('Vertical Detail');
    subplot(2,2,4); imagesc(D);
    title('Diagonal Detail'); 
    suptitle(lvl);

    % tweak the histogram bins as you prefer
    figure('Name',['Histograms (' lvl ')']);
    subplot(2,2,1); hist(A(:),32);
    subplot(2,2,2); hist(H(:),32);
    subplot(2,2,3); hist(V(:),32);
    subplot(2,2,4); hist(D(:),32);
    suptitle(lvl);
end

实际上，由于我在数字图像处理方面不是很熟练，所以您可以调整我的示例以使其适合您的需要。

如何在 MATLAB 中显示多级 wavedec2

how to display multi-level wavedec2 in MATLAB

matlab

image-processing

dwt

wavelet-transform