Digital BW, The Print

dfaprinting wrote:

>-
>
>If you link the many black ink channels into one color (K), then BO 
>becomes that entire K color. So it all depends on how the RIP deals 
>with linking and mixing the inks. When you send a magenta to the RIP, 
>you don't have to tell it which magenta to use, the RIP just fits it 
>to the nearest point in the LUT, and spits out the correct amount of 
>one or more channels. Same should apply to the 3 black channels, once 
>mixed, you should get a continuous tone from the start point to the 
>end point, and won't have to worry about whether it is using light, 
>medium or full black ink (or any combination of those). And yes the 
>mixing can make quite a mess out of your limits, but that's another 
>topic of discussion.
>
>  
>
On the Wasatch SoftRip that's all very nice sorted out for RGB and CMYK 
streams. The 9600 has the Cc, Mm, Kk, partition point choices. And the 
greyscale will use the Kk (I do expect but haven't checked as I do not 
have a 9600) as it is, so a warm black without neutralisation. The 9800 
will get Kkk partition point choices.

The Scanvec Amiable RIP didn't use the k at all so far for the 9600. 
This month there's a version available though that has it. Still a warm 
black you get that way.

So, it isn't just about the use of the Kkk's in greyscale mode but the 
neutralising and/or toning as available in Advanced B&W mode that I do 
not see appear in RIPs.  With good profiled color printing it shouldn't 
be a problem to use neutral RGB c.q. duotone RGB for similar results. 
Though the B&W quality will not exceed QTR or Advanced B&W printing. And 
many designers will be disappointed when their greyscale files in PDFs 
don't print neutral.

On top of that the greyscale images are either having gamma or dotgain 
added and CM in the RIP is reserved for color only. So the perceptual 
quality will suffer if compared to what we are already having despite 
the partitioning + linearisations that's available in the RIP.  There 
may be exceptions where perceptual adjustments are done on the greyscale 
data, I don't know whether they exist.

Little would be needed to make greyscale neutral and more perceptually 
correct. I would love to see the first report here of a Postscript RIP 
that has some sliders to get there. Ergosoft's Posterprint is the most 
likely winner.

The graphic industry heritage of most RIPs is still showing in many 
aspects of their B&W handling. Somewhere on the web there is an article 
on CcMmYK(k) Silkscreen Printing. Unheard off before that inkset was 
used in inkjet printing. The competition didn't have that quality so why 
worry. At best you heard: OK, we can print an extra red separation for 
that reproduction as I can't make it with CMYK. Maybe we will see better 
B&W offset printing due to digital B&W printing. They have to.

Ernst