Digital BW, The Print

John said:  "...From the length of the toe for the 2200 there are about 30 or so steps less than 255 available..."
 
I don't know about the 2200, but if you were addressing the 7600/9600 I would suggest that what you are seeing is a limitation of the Epson drivers and not the printer.
 
Tom Baker

johnglodge <john.lodge@...> wrote:


It makes good sense for the software to be completely 16 bit. That
means that profiles and image file are 16 bit. These are most usually
not floating point so that at the ends of the scale the relative
errors are large if 8 bit. Having only one meaningful limitation makes
the outcome far more predictable.

The only limitation that should be felt is that of the printer.

Here; it is not magic, a set of halftone paterns are enumerated and
appear, when covering a reasonably sized swatch to be one density or
another, but with different sqirt amounts and dot gain the enumerated
list of densities may not even be monotonic; let alone able to map the
full range of a 8 bit number. As well particulaly with pigment
printers there is an ink maximum past which the density decreases. The
profiling software needs to be smart enough to reject some patterns
to get a stable monotonic function to use in printing.

From inspection of the Epson NCA grayscale one finds a flat black toe
so that even Epson is not finding sufficient enumerable patterns to
fill the 8 bit space. From the length of the toe for the 2200 there
are about 30 or so steps less than 255 available.

...John

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Joe Berndt
wrote:
> Tyler,
> 
> Yes, IJC/OPM is completely 16 bit, image files that are 16 bit
remain 16
> bit and all 8 bit files are internally converted to 16bit . We
drive the
> printer with this 16bit data.
> 
> OPM uses it�s own method to connect and print to the printer, it
completely
> by-passes the Epson driver and all system related printing methods.
> 
> OPM actually opens a direct handle to the printer and steams the data
> directly to it. 
> 
> Joe Berndt
> 
> 
> 
> On 1/13/05 10:46 AM, "Tyler Boley" wrote:
> 
> > 
> > I'm getting out of my element here, but my understanding is that all
> > printer drivers make 16 bit ramps internally. Also, many profiles,
> > even color, use 16 bit LUTs. Of course IJC/OPM probably does not use
> > icc profiles in the strictest sense, but if their "profiles" use LUTs,
> > that's probably where that statement applies.
> > So some of this would not be extremely informative, until you see
this-
> > "(16-bit files remain 16-bit)".
> > That answers the question.
> > Tyler
> > 
> > ---- In DigitalBlackandWhiteThePrint@yahoogroups.com, "bwbonkers"
> > 
wrote:
> >> > 
> >> > OPM/IJC from Bowhaus uses 16 bit for printing.
> >> > 
> >> > I quote from their website:
> >> > 
> >> > ...All of IJC/OPM profiles and rendering algorithms operate in 16-
> >> > bit, over 65 million shades of gray, resulting in smoother
gradations
> >> > and transitions. IJC/OPM internally converts all 8-bit grayscale
> >> > files to 16-bit during printing to take advantage of the 16-bit
> >> > profiles and rendering algorithms (16-bit files remain 16-bit)....
> >> > 
> >> > Peter.
> > 
> > 
> > 
> 
> 
> 
> 
> [Non-text portions of this message have been removed]






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