About stationary wavelet transform

Hi all.. I have a doubt in stationary wavelet transform. In DWT, we are applying low pass and high pass filter and decimated by 2. So that we are getting reduction in the resolution (i.e) size is reduced to half (for all 4 bands). In SWT, we are not decimating, so that we are getting all bands as same resolution as original image.In this where interpolation comes..and what is the function of interpolation here???... I may be wrong in my concept...If so really sorry for that..Please explain about this... Thanks a lot in advance..