I suggest that we should enable krita to export binary images in order to print them out, although I approve of krita's policy that it won't have the ability to edit indexed colors images. Japanese Cartoonists prefer binary images to grayscale images for the purpose of printing them out, because print results of binary images are better than ones of grayscale images. It should have options as a threshold slider with a histogram of a image, like this: https://pbs.twimg.com/media/CbwGlUJUYAAP7Wg.jpg

Reproducible: Didn't try