In 2D the discrete wavelet transform (DWT) of an image using lifting based 5/3 filter, if I perform a row-wise operation first then perform column-wise operation then I will get 4 sub-band LL, LH and HL and HH.

  • During reconstruction, that is IDWT, should I maintain the order in reverse direction that is column first and then row?
  • Or any order I can maintain?
  • In JPEG 2000 there is no order information found in the header. Then how I can main the order during reconstruction?

For each single level of a isotropic or square DWT, the row/column order is not important. Note however that there exists an alternative decomposition, termed anisotropic, rectangular, that does all rows first, then all columns (or the converse) which results in a different subband organization. This is described in the overview of 2D wavelets: A panorama on Multiscale Geometric Representations (arxiv) in Section 3: 2.3.2. Separable orthogonal wavelets.

[EDIT: Added references to related questions]

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    $\begingroup$ Thanks you sir. But in MATLAB simulation i found that: when I am doing DWT(using 5/3 le gal filter) of an image first row wise then column wise and get 4 sub-bands. My doubt is in IDWT process, when I perform just reverse order of DWT process, that is column first and then row we get exact reconstruction, but if i perform first rowwise reconstruction and then column wise we are not getting proper reconstruction. What is the resion? $\endgroup$ Jan 21 '17 at 2:22
  • $\begingroup$ Please help me to share my code. I cannot add here because it is toolong. $\endgroup$ Jan 23 '17 at 11:47

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