<< Dye-sub prints manage fairly convincing
tone by bleeding the edges of the dots together--and they also look
fairly sharp even though the print resolution is around 200 dpi. >>
Yes, one can consider dye-sub as printing 200 dots per inch, and each dot can
have different tones (I believe it is 256 tones, but I can't remember for
sure).
On the other hand, the "digital" negative that we have discussed recently
(such as output from a printer) is different. If you have 600 dpi, for
example, it does not mean you can print 600 dots per inch where each dot can
have different tones. Each dot can be either black or white, or simply cyan
and white, or magenta and white....
To simulate continuous done with traditional screening, several dots are
combined. For example. If you use 10 dots in each direction, the combined
"superdots" now have 100 pixels to use, so you will have 100 tones (+ white)
for each superdot. The trade off is, of course, you now only have 60 (600 /
10) superdots per inch. So you now have 60 lpi (lines per inch) and each
"superdot" can have 100 tones. So there is always a trade-off between
resolution and number of tones.
Using dithering algorithm provides a smoother transition of tones, but the
trade off is basically the same. You trade smoothness for sharpness (details).
That is why I have always said that a 1200 dpi printer is extremely low in
resolution (mathematically you can have 120 lpi with 100 tones each dot (low
in tone), or 75 lpi (low in sharpness) with 256 tones for each dot), but if
your image / composition does not rely on fine details (things like hair
lines), then it will work nicely for you. You can go higher in resolution, but
your emulsion / coating and the combination of the whole process might not
support it as we have discussed before.
Dave