Hey everybody,
Is it possible to have some indication regarding images's alpha channel directly in the lister thumbnail view?
Like a label assignment by adding a small icon?
Or maybe already show the alpha background within the lister?
Thank you!
You could set a background image (or solid color) in the file display, so you can see when parts of the images show through to the background.
The Description column will also tell you the bit depth of images. 32 bpp usually means there is an alpha channel.
Regarding the background color - How do I set it up? right now I see the alpha as white in the file display, while the bg color is grey.
Regarding the column display - is it possible to utilize the depth information to create an icon that shows up on the alpha images? as it's easier to spot
Thanks Leo!
Set Preferences / File Display Modes / Thumbnails / Fill Color to transparent.
You could use a label filter to do that. I'd make it check the file extension first to avoid calculating the extra information when it isn't needed.
https://www.gpsoft.com.au/help/opus12/index.html#!Documents/Prefs/Label_Assignments.htm
use this to create background for Lister:
checker.zip (2.3 KB)
All you need then is a properly configured transparent thumbnailer (Mystic Thumbs is the one I use but there are others) and you will see the white from the space.
You only need that if you want transparent pdf thumbnails. Things like PNG and GIF are built in to Opus with transparency support.
Thank you both !
Absolutely loving the flexibility of OPUS <3 !! a friend for life 
@Leo
Do not want to take anything away from Opus at all, but transparent PDFs are vital for me. Will Opus cope natively with transparent PSD and LZW compressed Tiff files?
Nobody mentioned any of these formats until now in the thread. You're complicating things unnecessarily, is all.
In the absence of an answer to my perfectly reasonable and genuine question, I will have to take it as a "no", then.
I didn't answer that because I don't know the answer off the top of my head, and you already have a solution for your needs, which are most likely not the same needs as the person who started the thread, so it seemed an odd tangent.
There's nothing wrong with installing Mystic Thumbs. It's a good piece of software, if you need what it does. There's also nothing wrong with recommending it for situations where it is needed.
My point was just that it isn't needed for the usual file formats people want alpha channels for, and recommending people install it out of the blue, when none of the formats it handles were being discussed, and without explaining when/why it's useful, complicates things unnecessarily.
If you have a genuine question about something, it's better to start a new thread for it rather than throw it on the end of an existing thread about something else.