thanks for reminding me, I finally got around to looking at it. In order to obtain a good-quality picture, I had to scale up the resolution quite a bit. Exporting with 100 dpi and a width of 5.9 inch (which results in 590 pixels) the black-on-white text is not reproduced nicely. It gets worse when cranking up the dpi. With 1000 dpi and an export width of 5.9 inch (which results in 5900 pixels) the quality is good. However, to get to the desired number of pixels, a second step has to follow which reduces the exported image to 1/10. It’s a hack, it’s a workaround, but at least it is doable and should be possible to be accomplished programmatically (using ImageMagick or something similar).
The XL Toolbox uses the Windows graphics API to draw the exported image in memory. It’s strange that the font is drawn so differently depending on the resolution. It might have something to do with Windows trying to anti-alias small fonts (for example), but I never managed to change the aliasing and other settings; the corresponding commands just would not be respected by the graphics API. Unfortunately, there is little one can do aobut the drawing issues, it is purely a Windows thing…
Hope you can somehow get your desired workflow up and running!