Could someone explain me Contourlet decomposition level?

Hi, I don't understand Contourlet decomposition level. Please explain me the following codes in MATLAB. nlevels=[0,2,3,4] nlevels=[0,1,3] nlevels=[2]

Answer 1

[Hari]

Hi Farhad,

I understand that you would like to know about the Contourlet decomposition levels in MATLAB and how they are represented by the code snippets nlevels=[0,2,3,4], nlevels=[0,1,3], and nlevels=[2].

Contourlet decomposition is a multi-scale and directional decomposition technique used in image processing to capture the intrinsic geometrical structures of images. It involves applying a Laplacian Pyramid followed by a Directional Filter Bank.

The "nlevels" variable specifies the number of decomposition levels at each scale in the Contourlet transform. Each element in "nlevels" corresponds to a scale, and its value indicates the number of directional subbands at that scale.

For nlevels=[0,2,3,4]:

• The first element 0 indicates no directional decomposition at the coarsest scale.
• The second element 2 indicates 2 directional subbands at the second scale.
• The third element 3 indicates 3 directional subbands at the third scale.
• The fourth element 4 indicates 4 directional subbands at the finest scale.

For nlevels=[0,1,3]:

• The first element 0 indicates no directional decomposition at the coarsest scale.
• The second element 1 indicates 1 directional subband at the second scale.
• The third element 3 indicates 3 directional subbands at the finest scale.

For nlevels=[2]:

• The single element 2 indicates 2 directional subbands at the only scale considered for decomposition.

Refer to the documentation of Contourlet Transform for more details on its properties and usage:

https://www.mathworks.com/matlabcentral/fileexchange/8837-contourlet-toolbox

Hope this helps!