QTR-Quadtone RIP

--- In QuadtoneRIP@yahoogroups.com, Franco Laeri <franco.laeri@...> wrote:
> 
> as a newcomer to QuadToneRIP I am trying to create profiles for my 
> printer-paper combination (Epson R2400-Hahnemuhle FineArt Pearl 285 
> g/m^2), and I am afraid not to understand some basic concepts, like the 
> <Black Boost> setting in the Curve Creator.
>  In my printer-paper case I choose to truncate at a K-ink 
> level of 45% leading to a luminosity L* of 17.6. L* then slowly taperes 
> off to reach the lowest level of 5.5 at the 75% K-ink level. 

If your 17.6 L* to "5.5" L* level is correct, it doesn't seem a very
gradual taper. It represents going from an approximate density of
d'log 1.62 to one of d'log 2.22. That's considerable.

> Up to now it was 
> my understanding that boosing the blacks is intended to increase dMax 
> and should limit is action to the dark black image tones, but leaving 
> the middle grays unaffected.

That's my understanding also.

> 
> Is my understanding wrong? Is somebody suggesting the alternative 
> approach of linearizing with <Black Boost> set to zero and only after 
> linearizing setting the <Black Boost>-level to a higher value, for 
> example 75% ? What do the long time experts think?

I'm no expert Franco but it seems to me that you would want to use or
not use the black boost from the very beginning step in curve
building. Once you have your maximum useable d'max as set by limit
plus any boost you might choose, linearizing should space out the
steps appropriately. I don't know if the black boost function was
intended as a means of increasing ink lay down at the dense end for
inks and papers requiring extra large amounts of black or if it is
only really intended as a control for slight variation to gain best
d'max after determining the coarse limit setting or perhaps some other
purpose entirely. Roy might have some input on that.

In my case,I prefer to begin with 100% limit and zero boost and only
use the boost if it can contribute something to the d'max after I have
coarse set the limit and before linearizing. That may be all wrong
from other's perspective but it's what I currently do. I'd be
interested in other's thoughts as well.

Regards
Duane
 
 
> I am most grateful to learn from you!
> 
> 
> Franco Laeri
> 
> franco.laeri@...
>