Alpha channel is ignored for grayscale PNG

[MaxSt]

Examples:





XnView only displays alpha channel for the color image, not for the grayscale one.

[Clo]

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…

Kind regards,
Claude
Clo

[XnTriq]

Incorrect display of a png image

[xnview]

Yes, currently xnview doesn't support alpha for greyscale

[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.

[Clo]

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 ?

KR
Claude
Clo

[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.

[xnview]

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

[ZoNi]

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

[x2088]

can finish it?

[MaxSt]

It's much worse now.

See:



Only the 1st of the 2 animations is working.