Does wavedec2 and waverec2 support complex valued array inputs?

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Johnathan Le
Johnathan Le am 19 Apr. 2023
Bearbeitet: Johnathan Le am 19 Apr. 2023
I'm trying to use the wavedec2 and waverec2 functions on a complex valued image and I'm finding that the reconstructed image is not match the input image. Using dwt2 and idwt2 seems to work with the same complex valued array however.
%% works
[cA,cH,cV,cD] = dwt2(Image,'haar');
test = idwt2(cA,cH,cV,cD,'haar');
norm(Image - test,2) %% returns 1.27e-12
%% does not work
[c,s] = wavedec2(Image,1,'haar');
test = waverec2(c,s,'haar');
norm(Image - test,2) %% returns 6.79e+03

Antworten (1)

Walter Roberson
Walter Roberson am 19 Apr. 2023
The documentation for wavedec2() does not say that the input, X, must be real-valued.
However, the output vector is defined as being real-valued, and is defined as having a particular size, and those conditions together imply that you cannot reconstruct a complex matrix
  1 Kommentar
Johnathan Le
Johnathan Le am 19 Apr. 2023
Bearbeitet: Johnathan Le am 19 Apr. 2023
Thank you for replying to the question. The documentation does say that the output vector is real-valued but I do get complex-valued wavelet coefficients when inputing a complex-valued matrix. Furthermore, it doesn't make sense to me why dwt2 and idwt2 work for complex-valued inputs while wavedec2 and waverec2 do not work when specifying wavedec2 and waverec2 to do a single level wavelet transform.

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