Digital BW, The Print

>... If you want RGB color to be maintained then you
> must use a color printing workflow. 
> The disadvantage with this for the most part is that 
> too much color ink is used resulting in color casts and metamerism.
> Most of the efforts for B&W printing focus on reducing the amount 
> of color ink.


I think the 2400 with carbon in the yellow cart may allow a limited RGB
workflow that uses minimum color inks.  I would assume that less LK and LLK
would be used in a RGB mode as opposed to ABW mode, but with no yellow ink,
and only carbon to get to yellow, a neutral tone will have to be produced by
only carbon and the minimum color pigments.

I am not proficient in profiling software, but it would be an interesting
experiment to see if just a standard RGB profiling software package could
deal with a 2400 "Y=Carbon" inkset.

To get some idea of the quality that such an approach might result in, I
made a PS curve to adjust a grayscale test strip to print relatively neutral
with the Y=Carbon variation.  The curve is a simple one with only 3 internal
points per curve -- at 25%, 50% and 75%.  It was put into an ICC using Roy's
Create ICC-RGB program.  A grayscale 21-step test strip printed with it
looks very good (printed on Kirkland glossy).  

I suspected the highlights might be where the largest differences would
appear.  So, I scanned those of the Y=Carbon (EZW) variation in both ABW and
RGB modes.  The link below is to the scanned image.  For comparison, a 2400
OEM ABW mode test strip was also scanned.  I have also included the Lab A &
B distribution of the test strip.  See
http://home1.gte.net/res0a2zt/2400_RGB_Y=EZW.jpg  

Using the Photoshop histogram's Standard Deviation measure to be objective,
the ABW Y=EZW has the lowest (best) reading.  The RGB Y=EZW is second best.
And the standard full inkset ABW mode is, according to this measure, the
roughest (due to the higher color content I assume).

Visually, the prints all look good.

I will not have time until next week to see what the range of this RGB
approach might be, and frankly, I'd use ABW mode for most.  However, if some
profiling software can deal with the Y-Carbon variation, it might be
interesting and useful for some images, like split toning.

Paul
www.PaulRoark.com