Discrete Wavelet Transform, why downsample ?

[everyone0]

Discrete Wavelet Transform, downsampling and wavelet coefficients

Hi All,
i was reading about DWT in image processing, i found that in the analysis a signal is decomposed into levels, each level is downsampled by a factor of 2, is there any physical meaning or a certain reason to downsample an image or a signal by a factor of 2 ? , and the other question is what does the wavelet coefficients represent in a signal?
thanks in advance.

 

[yok]

The down sampling is to ensure that the transformed image subspace resolution after DWT is still same as the original image spatial resolution. This is referring to dyadic wavelet transform.