Might add more
-To increase screen resolution in GIMP:
: lemme check.....this is for Mac but it might be the same schematic for Windows or Linux, I'm not very sure.
go to FILE>NEW
on the CREATE A NEW IMAGE window click on ADVANCED OPTIONS.
there's a little chain link next to the X RESOLUTION AND Y RESOLUTION. click to make sure the chain link is whole and not broken. then change the numbers to something between 300 and 600 pixels/inch. so long as the chain link is whole, whichever resolution number you change will change the other without you having to do it
hope it helps