Digital BW, The Print

Steve,

On Monday, December 22, 2003, at 06:47  PM, Steve Kale wrote:

> Carl/Roy
>
> Some observations after another evening playing around with this and 
> hopefully a lot
> better understanding.
>
> Using EEM and just focusing on the warm curve for now, Default Ink 
> Limit set at 75%
> (tough on the eyes to place this one) and capping the LK at 60%, I get 
> a much lower
> cross over point into the use of the LK ie 25 rather than 35.  
> (Capping LK at the
> default 75% makes little difference to this number, ie 26%.)  I also 
> set boost at 95
> rather than 90.
Seems low for EEM with matte K, but not impossible.  Did you arrive at 
the 25% by  finding that the measured density of the 100% patch of the 
LK wedge was equal to the measured density of the 25% patch of the K 
wedge on the print of the ink separation file (printed in calibration 
mode with default ink limit set to 75 for all inks in the calibration 
profile)?
>
> Am I right in seeing the selection of this 25% point as being the 
> point at which QTR
> switches from using LK to K to produce shades of gray, ie only LK is 
> used from 0 to
> 25 and only K is used from 26 to 100, or is it not an abrupt 
> switchover?

No it is not an abrupt switch, the two inks are blended and you can see 
the transition by running the graph_curve script with your .quad warm 
curve file (from the curvedropbox).

>
>
> The unlinearised density values were:
>
> 0.039 0.087 0.153 0.224 0.305 0.375 0.464 0.548 0.632 0.705 0.783 
> 0.862 0.949 1.
> 041 1.124 1.210 1.295 1.374 1.456 1.548 1.666
>
> And the linearized density values were:
>
> 0.040 0.089 0.138 0.189 0.243 0.293 0.361 0.420 0.479 0.541 0.610 
> 0.689 0.770 0.
> 855 0.938 1.031 1.148 1.242 1.361 1.496 1.623
>
> I was surprised to see the dMax difference but both of these seem to 
> be jumping
> around with different readings and as the ink settles.  I would expect 
> the two 100%
> figures to be the same.

Mine usually are about the same dmax or higher after linearization.
>
> Wouldn't the lower use of LK make it easier to cool this curve rather 
> than one with
> Gray_Ink_Val LK set to 35?

I don't know, perhaps Roy can address this.

>
> Cheers
>
> Steve

Carl