I have a graphic (not photo) that I wish to reproduce way taller than it is. I actually want to quadruple the resolution (say from 2000x3000 to 4000x6000 (double linear, quadruple surface).
Is there a way to do this in GIMP? Like … extrapolate or the likes?
It all depends on what the graphic is. As you may know, I love Inkscape. However, if the tracing is poor and you don’t want to fix the trace or recreate the graphic in Inkscape, you could scale in GIMP and clean up using G’MIC.
Again, it depends. If your image is a JPG with compression artifacts, when you enlarge the image, the artifacts will worsen. In that case, you would filter the artifacts first and then re-scale.
You did not share your image, probably for a good reason. Please share a small crop and discuss what problems you have been facing in your workflow. Otherwise, we are just guessing.
You have fine lines and test, that gets rely fast ugly if you scale it.
If possible try to ask the one who created it to provide a version in a higher resolution.
If that is not possible scale the image in GIMP like afre wrote. If you have the logo in the lower right corner as vector file scale that separate and replace the one in the jpeg.
There are AI image scale tools, that I haven’t testet. But perhaps it’s an option: https://bigjpg.com/
Maybe you don’t need to scale it. If you make the physical image bigger, it will be looked from further away so you need less resolution, and it all evens out. Your 2000x3000 image is a 250DPI image on a Letter format, so not that bad already. You can of course scale it up in Gimp, but this is just a matter of where the bur will come from: Gimp’s upscale or the print driver upscale.
I am familiar with the concept of “longer distance - lower resolution”, but we talk about an A4 image that needs to be blown up to two meters on the long side …
distance for the reader will be about one meter, so … 120 dpi nevertheless
If you’re mainly concerned about clean edges and willing to use a gimp plugin, g’mic has a few filters which may help by searching for “upscale”. In theory “upscale [edge]” can do a reasonable 8x scale, but there are no guarantees of course…