changes_from_vm7_0.txt

JPEG2000实现的源码

                        CHANGES IN VM7.1 FROM VM7.0
                       ============================

Multi-Component changes
-----------------------
  * Merged all three component transforms into a single object.

  * Moved weight gain calculations from forward info object to component 
    object and provided a mechanism for communicating those component weight 
    gains to the info object.

  * As a result of above two changes, all three component transforms 
    (`-Mycc', `-Mtdt' and `-Mlin') can be independently switched for each 
    tile.

  * Modified image input so that multiple components can be specified using 
    a wild card character system.  See the new usage for `-i' and the the 
    new option `-i_subset' for more details.

  * Modified the `-Mtdt' option to allow user defined third dimensional 
    wavelets.

  * The optimum `-Fweights' table reported in the WG1N1587 core experiment 
    is included in "components/ColorVisualWeights".  As reported in that 
    core experiment, this weighting table is highly recommended for 
    compression of color imagery.


VPW change
----------
  * The ebcot_send_bit_stream() routine now always calls 
    optimize_bitstream_layer() instead of estimate_layer_threshold() when 
    the `-Cvpw' option is used.  This eliminates inconsistencies between the 
    `-Cvpw' and `-Fweights' implementation.


Bug/Warning Fixes
-----------------
  * Scan based processing:

    -Now always uses set_buffer_threshold() instead of 
     estimate_layer_threshold() for non-optimized layers.

    -Corrected recycling errors in and around calls to the arithmetic 
     coders return_units routine (resulted in very poor performance in 
     VM7.0 for some cases).

    -Corrected several type cast warnings.

  * Multi-Component transforms:

    -An extra "sum +=" line was removed from the invert_lin_xform() routine.

    -Corrected core dump which resulted with various combinations of `-Mycc'
     and `-Frev'.

    -Corrected several type cast warnings.

  * Modified assertion which failed for images compressed with 
    `-Comit_tile_length' and one tile.