The image used, avoiding textual annotation and other data.
The filtered image. Wavelet scales 4 and 5 were retained, and here we see the sum of these two images.
The image in FITS format (32-bit real) was wavelet transformed (à trous method), mr_transform -n 6 -x echoc.fits echocard , and the output images translated to GIF in IDL.
To probe further
Image and Data Analysis: The Multiscale Approach, J-L Starck, F Murtagh and A Bijaoui, Cambridge University Press, 1998.