Jpeg 2000 Fun Facts : Bypass Encoding
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Aaron Boxer
May 27, 2017, 4:05:15 PM5/27/17
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Hi Folks,
Those of you who use Jpeg 2000 in their work flow may be familiar with bypass encoding.
For those who aren't, using the bypass encoding mode can speed up decoding of Jpeg 2000 images by up to 40-50 %.
Bypass works by reducing encoding complexity in part of the encoding pipeline, at the cost of a slight increase
in compressed file size. Bypass speeds up encoding as well.
As I understand, bypass is most popular in the archive community - it isn't allowed for cinema and broadcast Jpeg 2000
streams, and it is not recommended for artificial imagery such as medical images.
At the present time, the only open source codec that can encode in bypass mode without any corruption to the resulting image
is Grok codec: https://github.com/GrokImageCompression/grok
It is also the only open source codec that can guarantee lossless encoding in bypass mode,
for single or multiple quality layers.
So, if you're currently using bypass mode in your work flow, or if you would like to try it out, check this project out.
You can visit the wiki here: https://github.com/GrokImageCompression/grok/wiki/2.-Command-Line-Interface
for a guide to the various command line parameters for the encoder and decoder.
If you have any issues or questions, you can post on project's Github issue page : https://github.com/GrokImageCompression/grok/issues
At this time, the codec has no known security or image corruption issues.
Kind Regards,
Aaron
Those of you who use Jpeg 2000 in their work flow may be familiar with bypass encoding.
For those who aren't, using the bypass encoding mode can speed up decoding of Jpeg 2000 images by up to 40-50 %.
Bypass works by reducing encoding complexity in part of the encoding pipeline, at the cost of a slight increase
in compressed file size. Bypass speeds up encoding as well.
As I understand, bypass is most popular in the archive community - it isn't allowed for cinema and broadcast Jpeg 2000
streams, and it is not recommended for artificial imagery such as medical images.
At the present time, the only open source codec that can encode in bypass mode without any corruption to the resulting image
is Grok codec: https://github.com/GrokImageCompression/grok
It is also the only open source codec that can guarantee lossless encoding in bypass mode,
for single or multiple quality layers.
So, if you're currently using bypass mode in your work flow, or if you would like to try it out, check this project out.
You can visit the wiki here: https://github.com/GrokImageCompression/grok/wiki/2.-Command-Line-Interface
for a guide to the various command line parameters for the encoder and decoder.
If you have any issues or questions, you can post on project's Github issue page : https://github.com/GrokImageCompression/grok/issues
At this time, the codec has no known security or image corruption issues.
Kind Regards,
Aaron
Antonin Descampe
Jun 13, 2017, 9:19:26 AM6/13/17
to IIIF Discuss
Hi,
Thanks Aaron, it's good to see that your AGPL fork of OpenJPEG is doing well.
For those interested, I take this opportunity to signal that OpenJPEG, the open-source (BSD) JPEG 2000 ISO Reference Software also guarantees lossless encoding (with or without bypass mode): the bug has been fixed today in Master branch and a new release will be made shortly.
More details on all improvements (including speed) currently being made to OpenJPEG is available here: https://groups.google.com/d/msg/iiif-discuss/XlZKwG-NiQ4/5G5r6jEiAgAJ
Kind regards,
Antonin
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