PNG 32 BPP wrongly displayed…

[Clo]

Pierre

Hello !

• With the 1.95.x versions, I can't display the 32 BPP PNG correctly, they are announced and shown as 24 BPP !
Below, how a sample looks :

   

- At left hand, in GFIE where the chequered pattern is visible.
It's alright processed as 32 BPP (and made in that programme), 106 colours.
- At right hand, the same file in XnView 1.95.2, 82 colours only, and a white BG instead of the transparency

• My settings are OK to display the Alpha channel, but it is not…



• Please, notice that the related menu entries are always greyed out, and I failed to get them active again for a while.

• The original sample can be got HERE

KR
Claude
Clo

[oops66]

Hello Clo,
FYI:I have not your problem (into v1.92.2) if I have:
Options\Read/Write\Read\PNG\ Compose image with alfa 32 = disabled

Then it become more and more interesting to have this kind of help now:
http://newsgroup.xnview.com/viewtopic.php?t=16256

[Clo]

oops66

Hello !

• Thanks, it solves the issue !

• However, I think that this option as it's set is totally illogical, unclear and confusing…
- Besides, there are too many scattered options about the Alpha channel and transparency,
I'ld like them grouped and clear…

BTW : This option in the PNG page acts also for BMP !
Il y a un
(There is a snag)

KR
Claude
Clo

[XnTriq]

• However, I think that this option as it's set is totally illogical, unclear and confusing…
- Besides, there are too many scattered options about the Alpha channel and transparency,
I'ld like them grouped and clear…

+1

In XnView transparency is not edited but only displayed, so far I understand. So I don’t understand the option Tools » Options » General » Read/Write » Read » PNG » Parameters » Compose ...

I'd be happy to give you a definitive answer, but – as mentioned before – I never completely figured out what impact these parameters have, how they “interact” with each other, and why they are available for PNG format only.
What I have to offer is the configuration I finally settled on after going through a fair amount of trial & error work:

• General » Read/Write » Read » PNG
  • Parameters
    [ ] Compose image with transparency
    [ ] Compose image with alpha (32bits)
• View » View
  • Auto Image Size [Fit image to window, large only]
  • Background colour [R128/G128/B128]
  • [x] Use transparent index (<=8bits) or alpha channel

Or does off means to ignore the transparent/alpha maske and display the hidden colors in the RGB channels, which are actually intended not to be visible due to the transparency? Than off as default seems nonsense for me.

Yes, that's my interpretation of Use transparent index (<=8bits) or alpha channel too.
BTW: Just recently the possibility to switch transparency off turned out to be crucial in identifying a problem.

These options have been discussed in many threads. I'd like to bring two of them in particular to your attention, where you will find some comments from Pierre:

• Colours in PNG images not displayed properly
• XnView does not support transparent PNG, ICO, GIF!

I can confirm this inconsistent behavior for v1.91.6 & v1.92 beta 2 on Windows 2000 SP4 with 32-bit PNGs:

• View mode
  • Use transparent index <=8bits is greyed out.
  • You can switch Show Mask and Use alpha channel on & off independently.
  Preview pane
  • Use transparent index <=8bits is not greyed out.
  • When Show Mask is enabled in the context menu, you can't activate Use alpha channel.

We already have an option for that: Use transparent index (<=8bits).
This works for images with 16- and 256-color palettes, but not for monochrome images (2-color palettes):

• 
  [ z00m ]

BTW: How about combining the two separate settings (Use transparent index (<=8bits) & Use alpha channel) to a single option (Use transparency)?

Yes, but I mean an easier way to do that (to avoid to go into the configuration each times only for that).
Maybe a bistable mode (with an hotkey) to toggle between The checkerboard pattern as background and an user defined background color. so only an option to activate\deactivate the "Use checkerboard pattern as background" item. ?

Your words in Pierre's ears...

I would like to suggest that the Use checkerboard pattern as background option be moved to the View menu, and also that it be made available as a command for customizing the toolbar.

[powerman]

XnTriq
Was going to post a couple of PNG's here, but

General » Read/Write » Read » PNG
Parameters
[ ] Compose image with transparency
[ ] Compose image with alpha (32bits)

solved the problem.
Thanks!