Alpha channel is ignored for grayscale PNG

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MaxSt
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Alpha channel is ignored for grayscale PNG

Post by MaxSt »

Examples:

Image

Image

XnView only displays alpha channel for the color image, not for the grayscale one.
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Clo
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Re: Alpha channel is ignored for grayscale PNG

Post by Clo »

:arrow: MaxSt

:) Hello ! Welcome aboard !

• I can confirm that there's an issue ! Here, it's displayed as a full black square,
and shown as “8 BPP” in the status bar… :(

• This image is shown correctly in some other viewers, though, i.e. Imagine and Universal Viewer

:mrgreen: Kind regards,
Claude
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XnTriq
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Re: Alpha channel is ignored for grayscale PNG

Post by XnTriq »

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xnview
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Re: Alpha channel is ignored for grayscale PNG

Post by xnview »

Yes, currently xnview doesn't support alpha for greyscale
Pierre.
MaxSt
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Re: Alpha channel is ignored for grayscale PNG

Post by MaxSt »

Too bad. I hope it can be fixed. PNG is a very common format, it should be supported 100%.

I mean, XnView even reads animation chunks in png, surely reading alpha channel isn't much harder to implement.
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Clo
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Re2: Alpha channel is ignored for grayscale PNG

Post by Clo »

:arrow: MaxSt

:) Hello !

• In fact, the Alpha channel IS supported, but when the pics contain colours hues,
not only grey ones, it seems…
- Since your pic has an A-channel, it might be processed as any 32 BPP PNG -like in other viewers- no matter whether there are colours hues or only grey ones.
Pierre, please ?

:mrgreen: KR
Claude
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MaxSt
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Re: Alpha channel is ignored for grayscale PNG

Post by MaxSt »

Bump?

I'm very happy with all the PNG improvements in 1.97b1, but there is one basic PNG feature left - mode 4 (grayscale+alpha).

PNG mode 4 is still not supported by XnView.
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xnview
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Re: Alpha channel is ignored for grayscale PNG

Post by xnview »

MaxSt wrote:PNG mode 4 is still not supported by XnView.
Yes, i've tried but need a lot of changes... So for the next time perhaps :-)
Pierre.
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ZoNi
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Re: Alpha channel is ignored for grayscale PNG

Post by ZoNi »

Maybe you can somehow use Win Picture Viewer as "engine" for this?

Image
x2088
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Re: Alpha channel is ignored for grayscale PNG

Post by x2088 »

can finish it?

Image
MaxSt
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Re: Alpha channel is ignored for grayscale PNG

Post by MaxSt »

It's much worse now.

See:

Image Image

Only the 1st of the 2 animations is working.
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