At present, local interpreters aren’t great at this. Not all interpreters behave the same way, so a general suggestion is to have a height or width of 700 or so pixels (~700 pixels should be the longer side). I’ve been doing this for a while, and it’s fine, though a higher resolution image scaled to fit would be nice. I believe that’s coming, but I’m not sure when.
TLDR; try a width of 700-720 pixels for a wide image. Try a height of 700 pixels for a tall image.
This is a game in Lectrote displaying a 700 x 525 image.
Web releases scale very well, but it’s a complex process getting there. If you end up trying that out, I can help.