Re: [Gimp-print-devel] 3.2 or 4.0 Release criteria

[Thomas T. <tt...@bi...>]

Robert L Krawitz wrote:


>    No, I only put the gray cartridge, I chose UCR separation, correct
>    the saturation. and select "color ink".  The driver do separations
>    in CYMK and add the two extras layers for the ligth cyan and
>    magenta.  Choice of UCR should be better than GGR, but I don't
>    tried the two on the same picture.
> 
> What is UCR separation?  Why would you correct the saturation for
> printing black and white, which has no saturation?

UCR is 'Under Color Reduction'. GCR is 'Gray Component Reduction'. Both
have to do with using CMY instead of black, As far as I remember, GCR
uses more black, and UCR uses more CMY.

With offset printing both have a spec that gives the max ink level.

> Basically, what it sounds like is that the architecture of the Windows
> driver is simply different from ours.

As long as the grey inkt in each nozzle has the same darkness as the
Epson colored ink, this cartridge should give good results. When the
image is made black and white before it is printed, the results may be
even better.

But even better results could be obtained by using the knowledge that
cou can print from the light magenta nozzle without anything getting
magenta. So what it does in the 'Windows Scenario':

Light tints are built up from LC LM and Y - these are light greys.
Darker tints are built up from C M Y - these are medium greys (humm, Y
is out).
Darkest is built by K - which is really black. 

Desaturating your image allows skies to be printed with more 'M and Y'
which may work better than just 'C'. And you use the inks more evenly.

But a different separation, that knows CMY are not colores, sounds even
better.


Thomas