QTR-Quadtone RIP

I read in the QTR-User-Guide that all formats(RGB or 16-bit grayscale) 
are converted into 8-Bit grayscale.8-bit is only 256 gradations of the 
brightness.

I know that the Sources(Digicams) does not produce nothing at all 
better under normal conditions. But there is 14-bit 
Consumer Cameras on the Market now which can produce 16384 steps of 
luminance. 

My question: Is the bottle neck the printer-systems anyway? or why 
this limitation on 256 steps?
 

Thanks,

Andreas Engi

> From: andreas_engi
>
> I read in the QTR-User-Guide that all formats(RGB or 16-bit grayscale)
> are converted into 8-Bit grayscale.8-bit is only 256 gradations of the
> brightness.
>
> I know that the Sources(Digicams) does not produce nothing at all
> better under normal conditions. But there is 14-bit
> Consumer Cameras on the Market now which can produce 16384 steps of
> luminance.
>
> My question: Is the bottle neck the printer-systems anyway? or why
> this limitation on 256 steps?

There is no camera that produces 14 bits of real data. In the best DSLR at
the lowest ISO, you'll be lucky to see more than ten. The rest is noise (and
marketing hype).

Bits beyond eight are important in capture, because you may need to apply
strong corrections to the image before use. But most printer drivers only
accept eight bits because, once an image is perfected, eight is enough to
represent the entire dynamic range that any inkjet printer can produce.
There is some evidence that a ninth bit may occasionally be useful for B&W,
under some circumstances, but certainly no more than that. With a true
continuous medium (as opposed to inkjet), and a very low-noise image, one
might be able to detect a tenth bit, but that's not what we're dealing with
here.

--

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@...

Yes. Along with the papers you are printing on.

Regards
Duane



--- In QuadtoneRIP@yahoogroups.com, "andreas_engi" <aengi@...> wrote:

> 
> My question: Is the bottle neck the printer-systems anyway? or why 
> this limitation on 256 steps?
>  
> 
> Thanks,
> 
> Andreas Engi
>

You're limited to 256 values because that's the number of different 
values that can be represented by an 8-bit integer, one of which is used 
to store the value of each channel at a given pixel in an 8-bit image.  
This works out fairly well because your eye needs just over 200 values 
in a gray scale to see continuous tone, it varies a bit from eye to eye 
of course, but 256 values will do it with a little wiggle room.  
Therefore digital output systems generally only use 8-bits because 
that's all that's required for human viewers to see a continuous tone.  
When you're editing, you may need more values than that because editing 
ends up degrading the image (discarding information).  So when doing 
serious editing to an image, it's generally worth it to use a larger bit 
depth, 16, with allows some millions of values to be represented, 
allowing for much heavier editing before degredation becomes apparent.  
But when that data goes to the printer, the printer doesn't need it all, 
and re-maps those 16-bit values into 8-bit values.  Hope that's helpful, 
and makes things a bit clearer.

Peter

dlruckus wrote:

> Yes. Along with the papers you are printing on.
>
> Regards
> Duane
>
>
>
> --- In QuadtoneRIP@yahoogroups.com, "andreas_engi" <aengi@...> wrote:
> >
> > My question: Is the bottle neck the printer-systems anyway? or why
> > this limitation on 256 steps?
> > 
> >
> > Thanks,
> >
> > Andreas Engi
> >
>
>
>
>
>
>
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