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leonbloy / pngj

PNGJ : pure Java library for high performance PNG encoding
http://hjg.com.ar/pngj/
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Investigate filtering strategies #16

Closed leonbloy closed 9 years ago

leonbloy commented 9 years ago

From hgonzalez@gmail.com on September 06, 2012 11:49:39

Perhaps We could make better with the filtering choosing strategy. Some ideas:

  1. GIve more felxibility to the user for setting heuristic parameters. Perhaps even the strategy itself (as a custom objet)
  2. Investigate libpng in this regard (see png_write_filtered_row in pngwutil.c ) Is it useful to include some "inercy" in the filter selection?
  3. What about using entropy instead of sum of errors?
  4. What about encoding simultaneously with all 4 filters to different streams and choosing one of them every N rows (sounds crazy, but...)?

Original issue: http://code.google.com/p/pngj/issues/detail?id=16

leonbloy commented 9 years ago

From hgonzalez@gmail.com on October 01, 2012 10:38:56

Labels: -Priority-Low Priority-Medium

leonbloy commented 9 years ago

From hjg.com.ar@gmail.com on April 23, 2014 19:44:23

quite work done here, including point 4 (commit 67cf2832e9)

class PixelsWriterMultiple implements all those ideas - needs a little more working

Status: Fixed
Owner: hjg.com.ar@gmail.com