Some questions

Aug 19, 2009 at 11:29 PM


This seems to be a great library!!

I just have a little bit of a problem getting started. I have it doing a round trip over a RGBA...RGBA 8 bit file and it's working great. However if I save the encoded file to disc it can't be read by another program! I have tried a few, Safari, iCab and IAS Viewer. IAS Viewer say it fins a faulty header... Do you know what can be wrong?

I have ported the code to OS X. It basically worked out of the box on a MacBook Pro with a Core 2 Intel CPU.

Also, it would be great if all options were explained somewhere. At least I haven't seen any docs..


Mikael Grev

Aug 21, 2009 at 10:40 PM


Thanks for taking an interest, and for testing on a mac. One more platform to add to the list.

There are two things you should be aware of when you want to read jls files with other applications. First, the jpeg-ls format is not widely supported, even less so as a standalone image format. There used to be a photoshop plugin (by HP) for reading/writing jls files, but I never used it. On windows, the free irfanview can read jls files (it's part of the optional plugin collection). That plugin also uses charls'. code. I know of no web browsers that render jls files.

Jpeg ls shares its header file format with regular jpeg, which could confuse viewers to think it's malformed regular jpeg.

You are not the first to note the lack of documentation. That will be worked on.  Some basics of JPEG-LS are explained on wikipedia: If you want in-depth information, there's the FCD version of the standard at: