Yes, the latest crop of ink-jets look pretty darn good in normal viewing
situations. My dad recently won first place in a local photo competition
with an all-digital print, taken on a Olympus D600L, manipulated (very
slightly) on a PowerMac, and printed on an 1440 dpi Epson StylusColor 800.
But there is still a great difference between photographs and ink-jet
prints. I boils down to:
1) the "DPI" myth: "1440 DPI" means the printer can place individual cyan,
magenta, yellow, or black dots on a 1440 DPI grid. It DOES NOT mean that
the dots it places are actually little squares, 1/1440th of an inch on a
side, nor does it mean it can place arbitrarily colored dots on that grid.
Effective resolution is no better than the area in which all four inks can
be displayed, or 720 DPI.
2) the dynamic range myth: Even DPI/4 makes the assumption that each
four-dot cell can have a value, or intensity, from Dmin to Dmax, which is
not true. To make fully saturated or extremely light colors, the printer
must "dither" or utilize adjascent 1/720th cells, further reducing the
effective resolution to 360 DPI or less.
3) the "magazine quality" myth: "lines per inch" are not "dots per inch"!
Traditional printing is measured much in the way that resolving power of a
lens is measured, by the density of high-contrast alterations, which is
"lines per inch" (or lines per mm in the civilized world :-). It takes AS A
MINIMUM two rows of dots to make a line: one row of black dots, and one row
of white dots, thus the printers *effective* DPI is at best twice the
printer's LPI. Newspaper photos are perhaps 50 lpi, most magazines are
perhaps 127 lpi, better "National Geographic" magazines are perhaps 155
lpi, the finest, expensive "graveure" technique magazines are perhaps 170
lpi.
4) the "dots vs grain" myth: no consumer-grade inkjet printer delivers
"continuous tone" prints, which is what a photograph is. (Dye-sublimation
prints and Iris ink jet prints with certain formulations can deliver
contone prints.) It is argued that the grain of a photograph or negavite is
"equivalent" to a certain DPI, but this is only even vaguely true for
continuous tone devices, because the dot-matrix printer has a combination
of dot grid and dither grid to consider. The dither grid is rarely
specified, and (as pointed out above) is generally MUCH coarser, by a
factor of four or more, than the marketeer's advertised DPI. In addition,
film grain is stochastic, or random, and so is much less distracting than
dot grids or most dither grids.
5) the "longevity" myth: not really a myth, just not talked about. People
glibly say, "You've got the file, just re-print when it fades in a year or
so." Tell that to the client you sell the print to! Ink jet prints don't
last. Period. (Okay, okay -- certain Iris formulations are rumored to be
"archival," but they cost as much or more than Cibas!)
Thus, printing with a 300 DPI image potentially gives you National
Geographic quality, and all but maxes out the capabilities of a so-called
1440 dpi printer.
Sure, at arm's length, a print from a $200 ink-jet printer looks great --
albeit on paper that costs as much or more than photographic paper, but
take a loupe to it, or set it in a sunny window for a while, and you'll see
why photographs aren't going to disappear any time soon!
: Jan Steinman <mailto:jans@xxxxxxxxxxx>
: 19280 Rydman Court, West Linn, OR 97068-1331 USA
: +1.503.635.3229
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|