Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Paul D. DeRocco" 
<pderocco@i...> wrote:
> > From: Tom Husband [mailto:thusband@s...]
> >
> > When printing a 16 bit file does the printer convert it to 8 bit?
> > I've been trying to get the author of Qimage to allow processing of
> > 16 bit grayscale files.  Qimage has a feature called "print to file"
> > where you don't send the file to the printer but to another
> > location.  It's a great feature but it takes a grayscale 16 bit file
> > and converts it to 8 bit RGB.  Anyway, Mike Chaney has responded with
> > the following, "I'd also have to question why you'd want to print 16
> > bits/channel when printing to file because printers cannot accept
> > anything but 8 bit data (even when using a RIP). As far as I know,
> > and unless things have changed recently, all printers (the hardware
> > itself) are based on 8 bits/channel even when dealing with grayscale."
> >
> > I was thinking that it might happen when using the Roark curves and
> > the Epson drivers but how about using QTR?
> 
> What goes across the cable to the printer (at least for Epson) is dots, not
> 8-bit or 16-bit data. Standard printer drivers convert the image to dot
> patterns, but only accept 8-bit data. Alternative software, like a RIP,
> could in theory use all 16 bits, but I couldn't tell you if QTR does. For
> B&W, it's possible that an extra bit or two might be useful on some media,
> but it's doubtful that you'd see the difference for color.
> 
> --
> 
> Ciao,               Paul D. DeRocco
> Paul                mailto:pderocco@i...

Both Mac and PC print systems are based on 8 bit pixel data.  So everything
that gets sent through print commands will be truncated to 8bit pixels.

I would doubt this makes any visible difference -- our eyes just can't
distinguish even 256 grays on paper.  I also think all the conversion to
printer dots is the limiting factor by far.  Another thing to consider is that
smooth areas of an image have lots of pixels and what you see is a blend
of adjacent pixels not individual pixels -- a result of dithering, ink bleed,
and eye resolution.

Roy