[jonah]

Confusion between px and dpi are common for people who haven't done work for both screen and print:

Screens are more accurately measured in PPI (pixels per inch) while the smallest elements a printer can produce (more akin to each of the 8 bit sub-pixels on a screen) are measured in DPI (dots per inch). Since ink is 1 bit more smaller elements (dots) are needed in some sort of dithered pattern to represent grays and colors.

Using halftone screening [1] the image elements are called lines and so a 600dpi printer is capable of producing 85–105 LPI (lines per inch)[2].

The lines per inch of print are more analogous to the pixels per inch of a screen than dots per inch are.

So, that 96ppi LCD and the 600dpi printer have around the same information density for practical purposes.

[1] http://en.wikipedia.org/wiki/Halftone [2] http://en.wikipedia.org/wiki/Halftone#Resolution_of_halftone...

[bzbarsky]

Interesting. Do printers use halftone screens for pure black-and-white content as well?

[jonah]

If it's pure crisp black like text, then no.

Sometimes pure black is printed incorrectly and looks "fuzzy" with dots around the edges - in that case it is rendered with a halftone screen.