Printing xcf files with alpha channels results in semi-transparent result
GIMP version: 2.10.20, 2.10.18
Operating System: Linux (Mint 20)
Package: 2.10.20 = flatpak, from gimp.org, 2.10.18 = Mint repo
Description of the bug
I design and print clear water-slide decals in GIMP. The newer versions of GIMP, 2.10.20, 2.10.18, and maybe a bit older, do not print the decals properly. Attached is an xcf file that printed properly in my older version of GIMP (sorry, I don't recall the version - I installed it when I installed Kubuntu 20.04)clear.xcf. This image consists of a transparent background layer (to act as a "container") and several layers consisting of imported images, each image having an alpha channel.
In the past these layers would print properly, i.e. the pixels with alpha=0 will not print, and pixels with alpha=1 print with no transparency. In newer versions of GIMP the pixels with alpha=1 print semi-transparent, as if the image is merged down automatically while printing. Converting to PNG before printing does not help.
Is the bug reproducible? Always
- Create an xcf image containing two layers - bottom fully transparent, top opaque
- print on clear decal paper (I don't know of another way to test than to go through the whole process) You need to spray a clear coat over the decal, let it dry, then use water to slide off the decal.
- Note: decal paper is not cheap, and the process is time consuming
The water slide decal should be fully opaque except where the pixels were intentionally made transparent.
The image that should be opaque is semi-transparent.
I'll help in any way. I'm desperate since I rely on GIMP to print clear decals. I installed GIMP 2.10.20 on my wife's Windows machine and got the same result - so it's not a printer driver issue.