Version 8.0.2

Version 8.0.2

New in Version 8.0.2

Apart from some important bug fixes, this version adds the following incremental features:
  1. The "Cplex-EST" method for complexity constrained encoding, that is particularly valuable with the HT block coding algorithm of the new HTJ2K standard, can now be supplemented with so-called "background statistics". The four primary compression demo-apps "kdu_compress", "kdu_buffered_compress", "kdu_v_compress" and "kdu_vcom_fast" all accept a new "-bstats" argument that can be used to specify a file with background statistics, or to accumulate statistics from content to generate such a file. The background statistics are extremely easy to use, not only in the demo-apps but also in code, requiring almost no change to any existing application. They server to add a lot of robustness to the statistical forecasting methods of the "Cplex-EST" algorithm when operating in a low memory configuration -- typically "Cplex={6,EST,0.25,0}". There is no harm in using background statistics, since the forecasting strategies have only a very weak dependence on them, but they can make a significant difference to worst case compression performance, retaining the benefits of deterministic encoding complexity, while achieving essentially the same performance as a full encode (encoding all coding passes), under almost any conditions.
  2. The behaviour of quality-layer constrained rendering of multi-layer HTJ2K codestreams (or JPH images) has been changed to reflect the fact that the HT block coding algorithm defined by the HTJ2K standard is not significantly quality scalable. Now, when you attempt to render such content with a reduced number of quality layers, you will at least decode the first HT Cleanup pass of every code-block that provides one, which may lead to very similar visual performance as decoding without any quality constraints. This is fine, since the HT block decoder is vastly faster than the original JPEG 2000 block decoder anyway. Content containing both original and HT code-blocks will be treated in a heterogeneous way during quality constrained decoding/rendering. This behaviour avoids any surprises for users of applications that support all types of JPEG 2000 content.
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