hi. we add 1 img to .kra.
it's 200kb. not big. size Width 520 x Height 831.
.kra canbas 1024 x 1024.
first. create .kra with template texture 1024 8bit is 428.6KiB.
second. paste img. 428.6Kib to 1.0MB.
why?

so, it's question.
2.1MB .kra at add image. krita change .kra size 5.8MB.
add image is 861.3KiB.
2.1MB .kra have layer only an 2. use layer style 1. it's pattern overlay.
why bigger file size? strange.

You add a layer, and both layers need to be saved individually. Thus the file size increases. If you export as jpeg or something like that, layers would be discarded and it wouldn't matter, but .kra preserves the layers.

yeah, but bigger.
krita adding 1 layer = more bigger size? no, it's problem with paste image layer.
problem is krita change at small image layer to bigger.

why problem? becouse it is krita size bigger = use an texture image difficult.
if you are have result file. different filesize.
A. use paste image .kra to export file size is many big. A is 3.6MiB.
B. nothing have paste image .kra = export file size is small. B is 2.6MiB.
200KiB image but result file size different 1MiB.
paste image is icon. no tiling carpet. no using layer overlay. not change.

although, solved method is delete paste image. yes, no solved.
only 200KiB, but change bigger result size. 3d or 2d or etc use texture is difficult.
krita is good tools, but file import system, or import file deal is, ah, no good. sorry.

If you open up a .jpg image in krita, it will be expanded because .jpg is a compressed (and lossy) format. Krita maintains image detail and stores image detail for every layer and so the .kra file sizes are large compared to .jpg

e.g If i open a 600 x 600 .jpg file that is 31.5 kB in size, it occupies 2.0 MB in memory and the saved .kra file (single layer) is 962.9 kB. This is to be expected.

oh sorry, we use png. no jpg. no important?
png is lossless. so png is change size many big. krita need big file size. than jpg. so .kra more bigger.
ok, we understand.

so we moved this topics for KDE Bugtracking.
thanks replay.