清空筛选条件
清空筛选条件

Error in using waverec2

2 次查看（过去 30 天）
kash
kash 2013-2-28
I have a code below,where i used 2 level decomposition and added noise to image ,wen reconstructing i am not getting original image ,please assist
X = imread('cameraman.tif');
[C,S] = wavedec2(X,2,'haar');
A1 = appcoef2(C,S,'haar',1);
A2 = appcoef2(C,S,'haar',2);
[H1,V1,D1] = detcoef2('all',C,S,1);
[H2,V2,D2] = detcoef2('all',C,S,2);
lev=[A1,H1;V1,D1];
figure('name','One_level_Decomposition','numbertitle','off'), imshow(uint8(lev))
q=[A2,H2;V2,D2];
q1=[q,H1;V1,D1];
figure('name','Two_level_Decomposition','numbertitle','off'), imshow(uint8(q1)),title('Two_level_Decomposition')
J = imnoise(q1,'salt & pepper',0.02);
G=J(:)';
p=waverec2(G,S,'haar')

请先登录，再回答此问题。

采纳的回答

Wayne King
Wayne King 2013-2-28
You add noise to the image, then denoise in the wavelet domain, then reconstruct.
Like this:
load sinsin;
Y = X + 18*randn(size(X));
[thr,sorh,keepapp] = ddencmp('den','wv',Y);
xd = wdencmp('gbl',Y,'sym4',2,thr,sorh,keepapp);
subplot(221)
imagesc(X); title('Original Image');
subplot(222);
imagesc(Y); title('Noisy Image');
subplot(223)
imagesc(xd); title('Denoised Image');

更多回答（2 个）

Wayne King
Wayne King 2013-2-28
Why do you expect that after you have added noise to the coefficients and then inverted the wavelet transform that you would obtain the original image?
That will never happen. The wavelet transform (like the Fourier transform) is an invertible transform. If you modify the coefficients (in the wavelet domain or in the Fourier domain) and then invert the transform, you will end up with a different signal (image).
  1 个评论
kash
kash 2013-2-28
ok wayne is it possible to reconstruct from this variable q1
q1=[q,H1;V1,D1];

请先登录，再进行评论。

Wayne King
Wayne King 2013-2-28
Yes, but you don't need to use anything other than the C,S vectors
load woman;
[C,S] = wavedec2(X,2,'haar');
Xnew = waverec2(C,S,'haar');
max(max(abs(X-Xnew)))
You see perfect reconstruction
  3 个评论
显示 1更早的评论
kash
kash 2013-2-28
not perfect reconstruction,nearly 70% is enough

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Image Analysis 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by