XnView Software

As I examine the program further the number of issues worth reporting grows.
Although nobody uses jpg2000 it's still worth noting that JPEG2000 conversion in xnview produces large files of bad quality - compared to other programs. Making the feature useless. The quality difference is so great that I conclude with certainty that it can only be a bug.

brand2321 wrote: Fri Jan 18, 2019 10:54 pm As I examine the program further the number of issues worth reporting grows.
Although nobody uses jpg2000 it's still worth noting that JPEG2000 conversion in xnview produces large files of bad quality - compared to other programs. Making the feature useless. The quality difference is so great that I conclude with certainty that it can only be a bug.

Have you experimented with the quality settings available in File > Format settings... > Write tab ?

Unfortunately, the above menu is easily overlooked due to a limitation arising from the Qt framework used.

cday wrote: Sat Jan 19, 2019 7:52 am Have you experimented with the quality settings available in File > Format settings... > Write tab ?

It's the same settings that you find in the "export" dialogue, so yes.

brand2321 wrote: Sat Jan 19, 2019 4:18 pm

cday wrote: Sat Jan 19, 2019 7:52 am Have you experimented with the quality settings available in File > Format settings... > Write tab ?

It's the same settings that you find in the "export" dialogue, so yes.

There is a quality difference even for lossless compression?

If possible, could you post an example saved from XnView MP and a reference example from another software? The current forum attachment limit is 2MiB, and you will probably need to place the files in a ZIP or similar archive in order to be able to attach them.

cday wrote: Sat Jan 19, 2019 4:46 pm There is a quality difference even for lossless compression?

Of course. You can try any picture.
Here's an example random instagram pic https://ibb.co/6BVGhtR
A 2mb file, jpg 100% quality, uncompressed. Let's get it down to about 100kb.
I have used faststone for the reference jp2 & image comparison. Below you see the original top left, reduced jpg top right, xnview jp2 bottom left, reference jp2 bottom right. The xnview jp2 file is larger, blurrier and lacks fine detail.


You can also see rainbow colors if you zoom in (bottom right)

Thanks, this is one for Pierre really...

I can confirm your results!

I tested the quality of XnViewMP 0.92 and IrfanView 4.52 (+plugins) and saved a file to jpeg 2000 with 100 kb.
Both programs can compress a picture to your specified filesize limit of 100 kB.
The picture quality of the IrfanView jpeg2000 file show more fine details and looks a little bit sharper.

XnViewMP use the OpenJPEG Library and IrfanView another or commercial library.

yes i use OpenJPEG library, i don't know what is used by Fastone Viewer