• Status Closed
  • Percent Complete
  • Task Type Bugs
  • Category Plugins
  • Assigned To No-one
  • Operating System All players
  • Severity Low
  • Priority Very Low
  • Reported Version Version 3.2
  • Due in Version Undecided
  • Due Date Undecided
  • Votes
  • Private
Attached to Project: Rockbox
Opened by Unhelpful - 2009-04-23
Last edited by Unhelpful - 2009-04-23

FS#10162 - Problems with subsampled chroma in jpeg viewer plugin

I noticed while working on jpeg loading+scaling for core that the plugin’s code for handling chroma subsampling had some oddities - it used the first (luma) component’s subsampling values to decide how the image was subsampled, but these values are stored separately per-component, and luma is almost never subsampled. I added code to fail on loading any really bizarre cases (subsampled luma, or the chroma channels having different subsampling), and to check the second component, rather than the first, for subsampling information. While the decoder is now initializing properly (to the best of my knowledge) for chroma-subsampled images, these images are still not displayed correctly. Patch with my (unsuccesful) fixes + some debug output attached, as well as some sample images. All four images should look roughly the same (subsampling is very obvious at this low resolution) but bees-40.jpg is the only one which displays correctly for me.

Closed by  Unhelpful
2009-04-23 06:09
Reason for closing:  Invalid
Additional comments about closing:   Warning: Undefined array key "typography" in /home/rockbox/flyspray/plugins/dokuwiki/inc/parserutils.php on line 371 Warning: Undefined array key "camelcase" in /home/rockbox/flyspray/plugins/dokuwiki/inc/parserutils.php on line 407

I was interpreting the command-line option for cjpeg (and the flags in the file, as well) backwards, this is not a real bug.


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