Broken alpha

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Enmoku
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Broken alpha

Post by Enmoku » Sun Aug 02, 2009 5:15 pm

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.

Enmoku
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Re: Broken alpha

Post by Enmoku » Sun Aug 02, 2009 5:26 pm

Apparently the buggyness was kept on image resize, uploaded it here: http://www.mediafire.com/?imninnnyz2o

marsh
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Re: Broken alpha

Post by marsh » Sun Aug 02, 2009 6:29 pm

Does this work with shellext (I don't have it installed)?
Options>General>Operations>[x]Ignore Alpha Channel
(effects conversion of transparent image)

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xnview
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Re: Broken alpha

Post by xnview » Mon Aug 03, 2009 10:03 am

Enmoku wrote: And here's what the image looks like if I remove alpha channel.
Are you sure that alpha is correct?
Pierre.

Enmoku
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Re: Broken alpha

Post by Enmoku » Tue Aug 04, 2009 5:52 am

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).

Enmoku
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Re: Broken alpha

Post by Enmoku » Tue Aug 04, 2009 5:54 am

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.

marsh
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Re: Broken alpha

Post by marsh » Tue Aug 04, 2009 8:19 am

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:

Enmoku
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Re: Broken alpha

Post by Enmoku » Sat Aug 15, 2009 10:45 am

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.

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xnview
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Re: Broken alpha

Post by xnview » Mon Aug 17, 2009 8:36 am

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
Pierre.

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XnTriq
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Re: Broken alpha

Post by XnTriq » Mon Aug 17, 2009 7:45 pm


Enmoku
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Re: Broken alpha

Post by Enmoku » Fri Aug 28, 2009 9:20 pm

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.

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xnview
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Re: Broken alpha

Post by xnview » Sat Aug 29, 2009 9:34 am

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?
Pierre.

Enmoku
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Re: Broken alpha

Post by Enmoku » Sat Aug 29, 2009 11:07 pm

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)

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xnview
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Re: Broken alpha

Post by xnview » Sun Aug 30, 2009 1:45 pm

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)
Pierre.

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