1.9.2 Mac: Thumbs corrupted for GIFs and PNGs with alpha channel

[XnSoldier]

title says it all:

PNG file with alpha channel shows up perfectly in viewer but thumnails look like alphachannel is ignored and actually messing up the graphics.

can't provide a file at the moment due to company logo rights.

CC thumbs.jpg (38.28 KiB) Viewed 31 times

creditcards.png (3.17 KiB) Viewed 31 times

Here a GIF. I don't think it has an alpha channel:

amex thumb.jpg (196.38 KiB) Viewed 31 times

amexco.gif (25.76 KiB) Viewed 31 times

[xnview]

no problem here, which thumbnail size do you use? and what do you have in settings>Thumbnail?

[XnSoldier]

Maybe because thumbnail is larger than the original?

no problem here, which thumbnail size do you use? and what do you have in settings>Thumbnail?

Screenshot 2025-07-31 at 01.59.27.png (103.67 KiB) Viewed 17 times

Screenshot 2025-07-31 at 01.59.40.png (87.8 KiB) Viewed 17 times

[xnview]

Maybe because thumbnail is larger than the original?

there is no embedded thumbnail

do you use windows font scaling?