Resize does not preserve the alpha channel of PNG images

Ask for help and post your question on how to use XnView Classic.

Moderators: XnTriq, xnview

cermini
Posts: 2
Joined: Mon Feb 21, 2011 10:22 am

Resize does not preserve the alpha channel of PNG images

Postby cermini » Mon Feb 21, 2011 11:15 am

1. Resize does not preserve the alpha channel of 32bit PNG images (in a PNG-to-PNG conversion) and does not inform for the loss of it.
2. The status bar ignores the alpha channel of 32bit PNG images - it does not indicate in any way the existence of alpha channel in the selected image.

User avatar
xnview
Author of XnView
Posts: 28291
Joined: Mon Oct 13, 2003 7:31 am
Location: France
Contact:

Re: Resize does not preserve the alpha channel of PNG images

Postby xnview » Tue Feb 22, 2011 4:17 pm

cermini wrote:1. Resize does not preserve the alpha channel of 32bit PNG images (in a PNG-to-PNG conversion) and does not inform for the loss of it.
2. The status bar ignores the alpha channel of 32bit PNG images - it does not indicate in any way the existence of alpha channel in the selected image.

I can't reproduce, "Option/Read/PNG/Compose ...." is checked??
Pierre.

cermini
Posts: 2
Joined: Mon Feb 21, 2011 10:22 am

Re: Resize does not preserve the alpha channel of PNG images

Postby cermini » Wed Feb 23, 2011 6:34 pm

Thanks for pointing this.

Tools -> Options -> General -> Read/Write -> Read -> PNG -> Compose image with alpha (32bits) was checked. By default this option is not checked in XnView v1.97.8. It appears that XnView used settings from previous installation.
If that's the case it is possible that it used a setting, which I made so long ago that I don't remember it at all.

MasterHD
Posts: 2
Joined: Wed Jun 22, 2011 4:34 am

Re: Resize does not preserve the alpha channel of PNG images

Postby MasterHD » Wed Jun 22, 2011 4:44 am

I'm having the same problem resizing PNG's. The alpha layer just turns black for any resample type other than "bilinear" or "nearest neighbor" (and those produce pixelated images that don't look good).
I tried enabling/disabling the "Option/Read/PNG/Compose ...." in every combination. I can't even perform a color depth "transformation" and retain the alpha layer. Am I doing something wrong? I've tried this with xnConvert as well with no luck.

Thanks for any help.

User avatar
xnview
Author of XnView
Posts: 28291
Joined: Mon Oct 13, 2003 7:31 am
Location: France
Contact:

Re: Resize does not preserve the alpha channel of PNG images

Postby xnview » Wed Jun 22, 2011 9:09 am

Is it a 32bits PNG?
Pierre.

MasterHD
Posts: 2
Joined: Wed Jun 22, 2011 4:34 am

Re: Resize does not preserve the alpha channel of PNG images

Postby MasterHD » Sun Dec 11, 2011 12:17 am

The color is 8-bit depth, and all 4 channels (RGBA) are active. But I have since moved on because I didn't realize there was a response here :(
Have you been able to reproduce this problem?

User avatar
xnview
Author of XnView
Posts: 28291
Joined: Mon Oct 13, 2003 7:31 am
Location: France
Contact:

Re: Resize does not preserve the alpha channel of PNG images

Postby xnview » Mon Dec 12, 2011 9:18 am

MasterHD wrote:The color is 8-bit depth, and all 4 channels (RGBA) are active. But I have since moved on because I didn't realize there was a response here :(
Have you been able to reproduce this problem?

No, please send me a picture file?
Pierre.


Return to “Classic - General Support”

Who is online

Users browsing this forum: No registered users and 3 guests