1.3.1: Export to Jpeg-XL bug

[Kadet]

XnView: MP 1.3.1 - 64 bit and older
Windows 10 and Windows 11 64bit
AMD processor

When the program starts, everything is fine at first.
But after a while (do more or less some stuff in program), when I click Export and choose the JPEG-XL tab, some images in the output window show something strange or black instead of the correctly encoded image.

[masterjp]

I have an idea, why you get these colour errors in the export preview with jpeg XL.
I get these errors with 32bit colour depth files or pictures in XnViewMP in older versions.

Please try to convert your picture in 24 bit colour depth
before you export the picture to JPEG XL.

[Kadet]

After few tests...
When XnView start on tab with picture 24 bits, preview bug happens on 32 bits pictures.
If start in 32 bits, error is on other deep bits.

[xnview]

sorry could you explain how to reproduce?

[masterjp]

Here is a sample file. I think the alpha channel/transparency is the problem.

[xnview]

no problem, the preview is correct

[masterjp]

I can reproduce the problem.

Here is a video: https://www.dropbox.com/s/ewxjk7ny0uuh4 ... g.mkv?dl=0

Steps:
--------
1. Copy both png files in a directory.
2. Open the directory in browser mode
3. Open the file 32_bit_picture.png from browser mode
4. Export dialog and select jpeg xl (=everything is fine!)
5. Close Export dialog without saving file
6. Use the next picture button in the bar below the menu
6. The Layers_32bit.png open in viewing mode
7. Use Export dialog again and the preview is damaged

32bit_picture.png

This is the picture file with problems, but it is important to open the upper file in export dialog first!

Layers_32bit.png

[Kadet]

sorry could you explain how to reproduce?

1. Open XnView MP.
2. Open the directory in (a) browser mode or (b) with picture in tab (24 or 32 bits)
3. Open any picture from browser mode if 2.a
4. Export dialog and select jpeg XL (everything is fine!)
5. Close Export dialog without saving file
6. Change color deep 24 --> 32 or 32 --> 24 bits
7. Use Export dialog again and the preview is damaged

Or if You have mix pictures 24 and 32 bits and first time You try export to jxl 24 bits picture and then try export some 32 bits picture you will see the bug.

[xnview]

ok, i can reproduce, but it seems that output file is correct, the problem is loading. I can reproduce with 'Batch convert' too

[Kadet]

...but it seems that output file is correct...

Not always. When I was testing this, I once save a bad image.

[xnview]

...but it seems that output file is correct...

Not always. When I was testing this, I once save a bad image.

Even if you restart XnView?

[Kadet]

...but it seems that output file is correct...

Not always. When I was testing this, I once save a bad image.

Even if you restart XnView?

Now I don't remember. I was a few weeks ago.

[Kadet]

Sorry, now I know about what You ask.
Yes, After restart XnView image was broken.

[xnview]

Thanks to your detailed description I can reproduce the problem.

[corr]

This image is always broken when I create a JXL from it.