Digital BW, The Print

Austin,

That is my original question. If the Epson driver in "Black" ink mode 
can produce a slightly darker 100% patch, why can't the Piezo driver 
be adjusted to produce an equally dark 100% patch? There may be a 
good reason for this that I am not aware of, but with the many 
requests for deeper blacks I have always been puzzled by this 
apparent failure to get the most out of the black ink.

Would it be a reasonable assumption that by selecting "Black" in the 
ink setting of the Epson driver that no dithering is applied?

Back in Post #2095 I wrote:

"I ran a test image of a 1" 100% black square four times on the same 
piece of paper. Once on Torchon and once on Hahnemule Photo Rag 
188gsm. I scanned the 8 patches together with my Linoscan 1400 and 
its cheesy software. In Photoshop I applied a levels adjustment layer 
and brought the white and black points in to slightly outside the 
ends of the histogram. I then selected each square and did a 
histogram. Here is what I got:

Torchon: Luminosity - Mean, Std. Dev., Median 

Piezo Ink and Driver: 94.28, 21.88, 90
Piezo Ink and Epson Driver Black Only: 67.26, 9.68, 66
MIS VM Ink and Neutral Curve, Epson Driver RGB: 69.00, 11.40, 67
MIS VM Ink and Epson Driver Black Only: 64.70, 8.81, 64

Hahnemule Photo Rag: Luminosity - Mean, Std. Dev., Median

Piezo Ink and Driver: 89.17, 11.92, 87
Piezo Ink and Epson Driver Black Only: 64.18, 7.50, 63
MIS VM Ink and Neutral Curve, Epson Driver RGB: 64.34, 7.23, 64
MIS VM Ink and Epson Driver Black Only: 64.33, 7.91, 63

This information is obviously meaningless as an absolute value but 
should be a reasonable comparison. On Torchon the MIS VM black is 
slightly darker. On the Photo Rag I would say they are the same. The 
difference in Std Dev on the Torchon is probably surface related."

Are the higher standard deviations of the Piezo ink and drive 
combinations indications of the possible use of a dither pattern? The 
luminosity values were on a 0 to 255 scale.

Martin


--- In DigitalBlackandWhiteThePrint@y..., "Austin Franklin" 
<darkroom@i...> wrote:
> 
(snip)
> >
> > Austin, this is an interesting subject. Under some circumstances,
> > I'm seeing dithering at 100%K, we noticed it recently with
> > Steve's 7000 with the RGB driver. Also, do you you how the Epson
> > driver changes density at 100% on different media settings
> > if not by dithering?
> 
> But shouldn't 100% black be just that, no matter what the media?  
At least
> that's what I'd want it to be!  If, for what ever reason, someone 
decides to
> map 100% to less than that, then, of course, it has to apply some 
dither
> pattern to decrease the density.