Trying to recreate the effect on this image, where the border is broken up and partially transparent with the page visible underneath. Curious what this would be called and how to replicate it in GIMP.
It is not an effect, it just an image with transparent parts. In Gimp, you have to:
- make sure there is an alpha-channel on the layer so that erasure creates transparency (instead of filling with background color):
Layer>Transparency>Add alpha channel. When there is no alpha-channel the layer name is in boldface in the Layers list.
- erase whatever, use a layer mask to erase non-destructively (meaning you can always un-erase)
- export to an image format that supports transparency. This means not JPEG, usually, PNG or if you want to be modern, WebP (in Gimp 2.10).
Look into downloadable Gimp brushes . There are a lot of free, decent quality brushes out there that can achieve this effect.