An image process system tiles an image data array, processing the tiles in
a predefined order. Each tile of image data is processed by applying a
predefined family of transform layers to the tile of image data so as to
generate successive sets of transform coefficients. Each set of transform
coefficients include edge coefficients positioned at outside boundaries
of the set of transform coefficients and non-edge coefficients positioned
at interior locations of the set of transform coefficients. The sets of
transform coefficients include a last set of transform coefficients,
produced by the last transform layer, and one or more earlier sets of
transform coefficients. The transform filters used include a short edge
transform filter that is applied to image data at boundaries of the tile
and to coefficients positioned at and near boundaries of each of the
earlier sets of transform coefficients so as to generate the edge
coefficients, and a long interior filter that is applied to image data at
interior locations of the tile and to coefficients at interior locations
of the earlier sets of transform coefficients so as to generate the
non-edge coefficients. The edge transform filter has a shorter filter
support than the interior transform filter, and both the edge transform
filter and the interior transform filter are applied only to image data
within the tile and only to transform coefficients within the earlier
sets of transform.