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Broken alpha

Posted: Sun Aug 02, 2009 5:15 pm
by Enmoku
Here's an image (another game screenshot) that displays rather strangely in XnView:
Image
And here's what the image looks like if I remove alpha channel.
Image

(Unfortunately the buggy(?) file is about 7MB in size and I don't have a host that would accept it (photobucket converts it to jpg automatically.)

Zooming close enough (150% or more) also fixes the issue. Converting the file to PNG with ShellEx creates a mostly white image that's completely broken (zooming doesn't help anymore and there's no alpha channel to remove). Converting to other formats (that I tested) behaves in similar fashion to the original BMP while conversion to JPG "fixes" it.

If the grayness is correct, then zooming close enough and the gray disappearing is the buggy part. Also, the PNG losing the alpha channel (if there ever was one) is another issue.

Re: Broken alpha

Posted: Sun Aug 02, 2009 5:26 pm
by Enmoku
Apparently the buggyness was kept on image resize, uploaded it here: http://www.mediafire.com/?imninnnyz2o

Re: Broken alpha

Posted: Sun Aug 02, 2009 6:29 pm
by marsh
Does this work with shellext (I don't have it installed)?
Options>General>Operations>[x]Ignore Alpha Channel
(effects conversion of transparent image)

Re: Broken alpha

Posted: Mon Aug 03, 2009 10:03 am
by xnview
Enmoku wrote: And here's what the image looks like if I remove alpha channel.
Are you sure that alpha is correct?

Re: Broken alpha

Posted: Tue Aug 04, 2009 5:52 am
by Enmoku
xnview wrote:
Enmoku wrote: And here's what the image looks like if I remove alpha channel.
Are you sure that alpha is correct?
That's what the file had. As I said, it was game screenshot (one that the game itself produced), so only thing I know of correctness is how it is displayed and how it should (I know what the game looks like).

Re: Broken alpha

Posted: Tue Aug 04, 2009 5:54 am
by Enmoku
marsh wrote:Does this work with shellext (I don't have it installed)?
Options>General>Operations>[x]Ignore Alpha Channel
(effects conversion of transparent image)
No such option, and that wouldn't explain why some formats preserve the alpha channel and others (PNG) don't, unless it was a format specific setting, but PNG options didn't have anything related to alpha/transparency.

Re: Broken alpha

Posted: Tue Aug 04, 2009 8:19 am
by marsh
Enmoku wrote:
marsh wrote:Does this work with shellext (I don't have it installed)?
Options>General>Operations>[x]Ignore Alpha Channel
(effects conversion of transparent image)
No such option, and that wouldn't explain why some formats preserve the alpha channel and others (PNG) don't, unless it was a format specific setting, but PNG options didn't have anything related to alpha/transparency.
It exists in newest version. With a completely different bmp sample, the following option is ideal for me:
Options>General>Read/Write>Read>PNG>[x]Compose image with transparency.
From topic FAQ index:

Re: Broken alpha

Posted: Sat Aug 15, 2009 10:45 am
by Enmoku
marsh wrote:Options>General>Read/Write>Read>PNG>[x]Compose image with transparency.
This option is not present in ShellEx.

And regardless of that, the conversion is not the issue, but the buggy display.

Re: Broken alpha

Posted: Mon Aug 17, 2009 8:36 am
by xnview
Enmoku wrote:And regardless of that, the conversion is not the issue, but the buggy display.
But the display is not buggy, it's the file

Re: Broken alpha

Posted: Mon Aug 17, 2009 7:45 pm
by XnTriq

Re: Broken alpha

Posted: Fri Aug 28, 2009 9:20 pm
by Enmoku
xnview wrote:
Enmoku wrote:And regardless of that, the conversion is not the issue, but the buggy display.
But the display is not buggy, it's the file
If the display isn't buggy, then why does the greyness disappear when zoomed close enough? If it was only the file, the buggyness should be present regardless of zoom level.

Re: Broken alpha

Posted: Sat Aug 29, 2009 9:34 am
by xnview
Enmoku wrote:
xnview wrote:
Enmoku wrote:And regardless of that, the conversion is not the issue, but the buggy display.
But the display is not buggy, it's the file
If the display isn't buggy, then why does the greyness disappear when zoomed close enough? If it was only the file, the buggyness should be present regardless of zoom level.
Perhaps due to smooth resize. Please resend the file?

Re: Broken alpha

Posted: Sat Aug 29, 2009 11:07 pm
by Enmoku
Disabling HQ zoom did make the quirky alpha remain.

Here's a reduced size version of it that exhibits the bug with HQ zoom on as requested, though: http://www.mediafire.com/?zmq2u0yeyql (~600kB)

Re: Broken alpha

Posted: Sun Aug 30, 2009 1:45 pm
by xnview
Enmoku wrote:Disabling HQ zoom did make the quirky alpha remain.

Here's a reduced size version of it that exhibits the bug with HQ zoom on as requested, though: http://www.mediafire.com/?zmq2u0yeyql (~600kB)
I don't see any problem, i have no grey, you can take a look at the alpha channel (M key)