Manages the information associated with JPEG2000
RGN (encoder-side region of interest) marker segment.
Tile- and component-specific forms are allowed (in
fact, required for a complete code-stream description).
The cluster name is "RGN", but you are recommended
to use the macro
RGN_params, in functions which take a cluster name like
kdu_params::access_cluster.
The following attributes are defined. For an explanation
of pattern strings, consult the comments appearing
with
kdu_params::parse_string.
-
Macro =
Rshift; Pattern = "I" — Region of interest up-shift
value. All subband samples which are involved in the
synthesis of any image sample which belongs to the
foreground region of an ROI mask will be effectively
shifted up (scaled by two the power of this shift value)
prior to quantization. The region geometry is specified
independently and is not explicitly signalled through
the code-stream; instead, this shift must be sufficiently
large to enable the decoder to separate the foreground
and background on the basis of the shifted sample amplitudes
alone. You will receive an appropriate error message
if the shift value is too small. Default is 0.
-
Macro =
Rlevels; Pattern = "I" — Number of initial (highest
frequency) DWT levels through which to propagate geometric
information concerning the foreground region for ROI
processing. Additional levels (i.e., lower frequency
subbands) will be treated as belonging entirely to
the foreground region. Default is 4.
-
Macro =
Rweight; Pattern = "F" — Region of interest significance
weight. Although this attribute may be used together
with
Rshift, it is common to use only one or the other. All code-blocks
whose samples contribute in any way to the reconstruction
of the foreground region of an ROI mask will have their
distortion metrics scaled by the square of the supplied
weighting factor, for the purpose of rate allocation.
This renders such blocks more important and assigns
to them relatively more bits, in a manner which is
closely related to the effect of the
Clevel_weights and
Cband_weights attributes on the importance of whole subbands. Note
that this region weighting strategy is most effective
when working with large images and relatively small
code-blocks (or precincts). Default is 1, i.e., no
extra weighting.
rgn_params {Java: Rgn_params}