Digital BW, The Print

**I posted this on the piezo board but realize I should have posed 
it to a wider audience, apologies to those who receive both***

I need a little help straightening something out in my head :)
I thought I understood the relationship between an indiv. ink's 
density and limit in regard to the Total density. However, when I 
try to add things up they don't come up how I thought.
I am talking about the K7 inks in particular.
I am also looking at this through the raw data found in QTR (in the 
quad files).

If I understand this correctly a linearized profile has the TOTAL 
density increasing in a LINEAR fashion from paper white to max 
black. In the case of K7, max black is a combination of 5 inks as 
seen here:
http://www.inkjetmall.com/NK7-visual.jpg 

I know these might not be exact but I found these 

The seven dilutions are as follows:
K7 Shade #1: 100.0%
K7 Shade #2:  32.0%
K7 Shade #3:  16.0%
K7 Shade #4:  10.0%
K7 Shade #5:   6.0% 
K7 Shade #6:   2.5%
K7 Shade #7:   0.6%
 

The one variable I don't have is the ink limit for each ink. 
However, it seems they might all have the same ink limit.....

I thought if you added up the amount of ink laid down for a given 
ink density, you would get the total density. If there is more than 
one ink you need to add it on as well. If a 21 step wedge is printed 
on a linearized profile, the density readings are linear.
However, applying this to actual data seems to render an exponential 
type fit instead of a linear one.  

I hope I explained that at least in some sort of digestible form. 
So, could someone set me straight on how the individual ink limits 
and densities add up to Total Density?

If I can get this clear in my head I think I might have a better 
idea of the whole concept.

Much appreciated for any help! 
Thanks
Scott

I am not an NK7 user so I am likely off base here, but if the NK7-
visual.jpg is a true representation of the ink partitions, then I 
can't see how this inkset can ever achieve a very good dMax with 4 
lighter gray shades also firing at dMax.  A very low ink limit at 
dMax to minimize this problem would adversely affect the rest of the 
ramp because the ink limits are applied across the entire shade range 
of the ink.

QTR linearizes density or L between paper white and dMax (which 
greatly opens up the dark end of the ramp).  You of course can apply 
any gamma you want between paper white and dMax.



--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "schrochem" 
<schrochem@...> wrote:
>
> **I posted this on the piezo board but realize I should have posed 
> it to a wider audience, apologies to those who receive both***
> 
> I need a little help straightening something out in my head :)
> I thought I understood the relationship between an indiv. ink's 
> density and limit in regard to the Total density. However, when I 
> try to add things up they don't come up how I thought.
> I am talking about the K7 inks in particular.
> I am also looking at this through the raw data found in QTR (in the 
> quad files).
> 
> If I understand this correctly a linearized profile has the TOTAL 
> density increasing in a LINEAR fashion from paper white to max 
> black. In the case of K7, max black is a combination of 5 inks as 
> seen here:
> http://www.inkjetmall.com/NK7-visual.jpg 
> 
> I know these might not be exact but I found these 
> 
> The seven dilutions are as follows:
> K7 Shade #1: 100.0%
> K7 Shade #2:  32.0%
> K7 Shade #3:  16.0%
> K7 Shade #4:  10.0%
> K7 Shade #5:   6.0% 
> K7 Shade #6:   2.5%
> K7 Shade #7:   0.6%
>  
> 
> The one variable I don't have is the ink limit for each ink. 
> However, it seems they might all have the same ink limit.....
> 
> I thought if you added up the amount of ink laid down for a given 
> ink density, you would get the total density. If there is more than 
> one ink you need to add it on as well. If a 21 step wedge is 
printed 
> on a linearized profile, the density readings are linear.
> However, applying this to actual data seems to render an 
exponential 

> type fit instead of a linear one.  
> 
> I hope I explained that at least in some sort of digestible form. 
> So, could someone set me straight on how the individual ink limits 
> and densities add up to Total Density?
> 
> If I can get this clear in my head I think I might have a better 
> idea of the whole concept.
> 
> Much appreciated for any help! 
> Thanks
> Scott
>