You are speaking of what is referred to as "dot gain". The picolitre
measurement is not a size, per se, but a volume of ink. Therefore the
dot gain of the paper will determine the size of the "flat" dot. Plain
paper certainly has a fairly large dot gain, but specially
coated inkjet papers are designed to control dot gain. You are
correct that some use dot gain to "smooth" the edges of the dots, but
they do not typically "fill in" the whole area other than in darker
areas. The dots typically are found intermingled with one another
and with some white paper substrate.
Take a look as a print under a loupe and you'll see.
Dye inks tend to have higher dot gain than pigment color inks, because
they are designed to penetrate and spread in the fiber of the paper
which pigments sit on top of the paper for the post part. It all
comes down to careful control on the dot volume. They is in part why
profiles are created for different paper types.
There is a certain loss of color fidelity or accuracy with a four
color system (even one with low dye load inks). That is why many
inkjet manufacturers have added greens or blues, oranges or reds. The
making of blue from cyan and magenta, and red from magenta and
yellow somewhat limits the gamut available, so by adding a "true blue
and red, or green and orange, often allows for several advantages. Less
dots have to be laid down since, for instance, every blue dot is
equivalent to several cyan and magenta dots. That speeds up the
printing process. Further, the blue might be one that is out of
gamut for a mix of magenta and cyan. It is also more profitable for
the inkjet company, since they sell a lot more ink cartridges when
the printer has 7 or 8 or more involved. It also makes counterfeiting
or 3rd party copies more difficult, and makes the profiles more
"ego-centric" to the specific colors of the OEM inks.
Overall, for most applications, however, the idea of a simple four
color printer using a very small dot size and 4 full dye load inks,
makes sense in terms of use of raw materials, and fade resistance.
Art
SleeperMan wrote: