A method of retrieving an image for display is disclosed. The image is
stored in a compressed wavelet-based format having blocks encoded
substantially independently. Initially, a representation (1300) of the
image is provided at a first (low) resolution (1302). The user can then
select a portion (1308) of the representation for reproduction at a
predetermined, generally a second (higher), resolution. A first set of
blocks is then identified (1322) corresponding to the selected
portion(1310), which are then retrieved, decompressed and rendered to
display. A second set of blocks (associated with the first set of blocks)
is then identified (1326 1340), retrieved and decompressed. The rendered
first set of blocks is then modified using the decompressed second set
and displayed at the predetermined/second resolution.