zakezuke said:
I noticed this once when on my ip3000 I was running out of a color,
probally magenta. I was printing some lyrics and wanted some cyan and
others black. All the colors were skewed due to the lack of the
magenta including the black text, which I found very odd as it was text
and assumed that was covered by the bci-3e black.
I don't understand the rhyme or reason of the driver choosing go to
color or dedicated black.
The Canon print engine in these models is document oriented, so they do
not discern the difference between black and colour within a single
document. It converts the entire document and then uses either black or
colour inks for the document based on its minimum requirements.
HP print engines are object oriented and can print black text with black
ink, and colour graphs with the colour inks, all within the same
document.
I'm told 80% is the usual threthhold, but
when I observe things like this happening I simply have no idea.
The 80% threshold relates to photos and how the Canon iP3000 will lay
down the pigment-based black ink for very dark areas since the CMY black
is not as dark.
The iP4000 improves photos very slightly by using a dye-based black for
photos. But after viewing photos from both printers, it makes little
difference with glossy paper since Canon papers are nanoporous and
adsorb the ink below the surface. The final print is very glossy and the
pigment ink is barely noticed.
HP photo paper is of the swellable type, and the ink tends to sit near
the surface. The final print is very glossy, but at first appears etched
because the heavy layer of CMY to make black is thick and takes a while
to be adsorbed by the photo paper.
This is why Canon prints are so much more water resistant to HP prints.
You can actually run a Canon print under water, and gently wipe it dry.
But HP prints must be allowed to dry without wiping it or the ink will
be smudged. Once allowed to fully dry for 24 hours, HP prints are
generally smudge resistant. But fresh out of the printer they may smudge
with moist fingers.