0.99.6:Extract Alpha Channal wrong with a 8-bit indexed PNG

Older bugs which are supposed to be fixed in 0.84. *** Please try to reproduce your bug and confirm the bug fix. ***

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Mapaler
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0.99.6:Extract Alpha Channal wrong with a 8-bit indexed PNG

Post by Mapaler »

XnView: MP 0.99.6 - 64 bit
OS: Windows 10- 64bit

Neither removing the alpha channel nor extracting the alpha channel is correct with this 8-bit index png.
111.png
↓This is the source image
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xnview
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Re: 0.99.6:Extract Alpha Channal wrong with a 8-bit indexed PNG

Post by xnview »

this image file doesn't contain alpha channel but a transparent index that you can change in 'edit colormap'
Pierre.
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Mapaler
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Re: 0.99.6:Extract Alpha Channal wrong with a 8-bit indexed PNG

Post by Mapaler »

xnview wrote: Tue Jan 04, 2022 4:46 pm this image file doesn't contain alpha channel but a transparent index that you can change in 'edit colormap'
But it can extract RGB channels.
Why not convert to a 32-bit image and then extract the Alpha channel ?

And I found 'edit colormap' does not establish a record of modifications and cannot be undone after reading the index file of other images.
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xnview
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Re: 0.99.6:Extract Alpha Channal wrong with a 8-bit indexed PNG

Post by xnview »

:bugconfirmed: Thanks to your detailed description I can reproduce the problem.
Pierre.
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xnview
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Re: 0.99.6:Extract Alpha Channal wrong with a 8-bit indexed PNG

Post by xnview »

This problem is supposed to be fixed in XnView MP 0.99.7. Please check and confirm the bug fix here.
Pierre.