🚀 go-pugleaf

In one sense, grayscale characters *are* higher resolution.  Why?
Because the human eye can trade intensity resolution for spatial
resolution.  

The basic problem with low-resolution characters is that there are not
enough pixels to go around, i.e., there is not enough spatial
resolution.  In signal processing terms, a sufficiently high frequency
cannot be represented.  (What is ``sufficiently high''?  Well, the human
eye (most human eyes, I suppose I should say) typically cannot
distinguish lines closer together than one minute of arc, which comes to
about 60 cycles per degree of visual angle, i.e., 60 alternations from
black to white.  (This is called ``grating acuity'' in the vision
research.))

But jaggies are really a question of being able to distinguish an offset
of one line from another, not just distinguish two lines as being
separate.  This is called ``vernier acuity'', and it is about five times
higher than grating acuity, i.e., 12 seconds of arc.  Furthermore, with
practice, it can be reduced to 6 seconds of arc. Some trigonometry will
show you that 6 seconds corresponds to 1800dpi at 18" (which is normal
reading distance) and 12 seconds to 1200dpi -- and most typesetters are
manufactured in this range.  (Incidentally, halftoning sometimes
requires more resolution than text; hence, it is not pointless to
manufacture machines with higher resolution.)

Anyway, the edge information that is lost by using grayscale fonts is
recovered by the human eye.  If it didn't, grayscale characters would
appear to be amorphous blobs, but in fact, they are more readable.  By
increasing our intensity resolution, we also increase our spatial
resolution, because of the eye.

There are lots of references on all this, if anyone is interested.
(And if anyone reading this is doing active research on
letterforms/image processing/signal processing/human vision, I'd
love to hear from you.)

karl@umb.edu