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Preview Alpha Channel in XnView Classic is broken
Posted: Wed Sep 30, 2020 5:10 am
by esenthel
Latest release broke previewing images with alpha channels.
Press M to see alpha channel (show mask menu) doesn't always work, sometimes you need to press Ctrl+H first (Use Alpha Channel)
Re: Preview Alpha Channel in XnView Classic is broken
Posted: Tue Oct 06, 2020 10:21 am
by xnview
could you send me a picture file where it doesn't work?
Re: Preview Alpha Channel in XnView Classic is broken
Posted: Fri Oct 23, 2020 4:34 am
by esenthel
In latest version 2.49.4
Please use any image that has alpha channel, BMP, PNG, TGA, any
Then set zoom to be less than 100%, for example 50%,
Then press M key to show alpha, it won't work
Zoom in at 100%, alpha starts to work
In options I have "High Quality Zoom \ Reduce = ON"
Re: Preview Alpha Channel in XnView Classic is broken
Posted: Fri Oct 30, 2020 7:24 am
by xnview
it works here
Re: Preview Alpha Channel in XnView Classic is broken
Posted: Sun Nov 08, 2020 7:01 am
by esenthel
Re: Preview Alpha Channel in XnView Classic is broken
Posted: Tue Nov 10, 2020 9:53 am
by xnview
I can't reproduce, could you send me the file used, and which settings do you have in options>View?
Re: Preview Alpha Channel in XnView Classic is broken
Posted: Sat Nov 28, 2020 4:49 am
by esenthel
The problem happens with any/all images that have alpha channel.
Re: Preview Alpha Channel in XnView Classic is broken
Posted: Tue Dec 01, 2020 11:49 am
by xnview
it's crazy, it works correctly here
Re: Preview Alpha Channel in XnView Classic is broken
Posted: Thu Dec 03, 2020 5:30 am
by esenthel
Could it be related to Windows?
I have the latest version: Win 10 Home, ver 2004, os build 19041.508
But I've tested an older version, 2.37 just now, and it doesn't suffer from the same problem.
So I think something got broken in your code.
It was working fine just couple releases ago.
Is there a way to download older versions of your software? (v 2.48, 2.47 or something)
I could tell you between each release where the problem occurred, and you could check your code base for changes in that time frame, to see which change broke this function.
Re: Preview Alpha Channel in XnView Classic is broken
Posted: Fri Dec 04, 2020 10:07 am
by xnview
esenthel wrote: Thu Dec 03, 2020 5:30 am
Could it be related to Windows?
I have the latest version: Win 10 Home, ver 2004, os build 19041.508
no it's XnView
Is there a way to download older versions of your software? (v 2.48, 2.47 or something)
http://download.xnview.com/old_versions
Re: Preview Alpha Channel in XnView Classic is broken
Posted: Sat Dec 05, 2020 10:15 pm
by XnTriq
I'm not able to reproduce this issue with XnView Classic v2.49.4 and
966_1578623403.png or any other 32-bit PNG. However, we had a
similar report a couple of years ago.
Related:
Recommended settings
Re: Preview Alpha Channel in XnView Classic is broken
Posted: Sun Dec 06, 2020 1:55 pm
by esenthel
I've tested a bunch of versions:
2.39 works great, no issue
2.40 has different problem, black background and white pixels on the border

- 2.40.png (16.54 KiB) Viewed 2580 times
2.41+ has problems with alpha sometimes visible, sometimes RGB, depending on zoom < or > 100%
Something got broken between 2.39 and 2.40
Attaching the entire XnView.ini file with settings, maybe you can do tests with it.
My Windows DPI Settings in 125%
Re: Preview Alpha Channel in XnView Classic is broken
Posted: Sun Dec 06, 2020 10:00 pm
by XnTriq
Hello esenthel
I ran XnView v2.49.4 with the INI you provided (Windows DPI = 120%) and opened
flour-flower-png-transparent-png-images-pluspng-2.png in fullscreen, edit and preview. Although I watched
your screen recording again and made sure to follow the steps outlined in one of your previous posts…
esenthel wrote: Fri Oct 23, 2020 4:34 amIn latest version 2.49.4
Please use any image that has alpha channel, BMP, PNG, TGA, any
Then set zoom to be less than 100%, for example 50%,
Then press M key to show alpha, it won't work
Zoom in at 100%, alpha starts to work
In options I have "High Quality Zoom \ Reduce = ON"
… everything works as expected
Related:
Transparent pixels dont get filtered correctly