Truly Lossless JPEG2000 Compression

This posting used to have the tag “– Except for Grayscale?” appended to the end of the title. That is no longer needed; see the bottom of the post for an explanation. We have been implementing University of Michigan’s DLXS software, and DLXS uses JPEG2000 for its image masters. We have been investigating reports of perceived changes in images in the conversion from our old media server to DLXS, and along the way I discovered an important fact: the default parameters for two popular JPEG2000 codecs results in an irreversible transformation. Here is how to address that.

Following Up on Adobe Photoshop and JPEG2000

The discussion has died down on Jack Nack’s blog posting about the future of JPEG2000 support in Photoshop. Since I last updated my own commentary on the issue, there have been a few more comments, including one by Erich Kesse from the University of Florida. Jack has added a few follow-ups to comments left on his blog, including this one at the bottom of Erich’s comment:

[Thanks for the detailed feedback. I would note that regardless of what Adobe does with JPEG 2000, other developers can create JPEG 2000 reading/writing plug-ins for the app. --J.]