QTR-Quadtone RIP

Hi Paolo

 > on K for limit 30 i have L=24
 > on C and M for limit 90 i have L=35 ---> on K i have L=35 for limit 15
 > on Y,LC,LM for limit 90 i have L=45 ---> on K i have L=45 for limit 10
 >
 > so i created a curve with
 > C limit 45 (half of 90) and denisty = 15/30*100 = 50
 > M copy corve from C
 > LC limit 30 (90/3) and denisty = 10/30*100 = 33
 > Y copy corve from LC
 > LM  copy corve from LC

I'm not sure if I follow that although the end result might be okay! 
It's not clear from what you have written but you should compare the 
100% patch for C printed at your chosen limit (90) with the equivalent K 
value on the reprinted ink separation page with the ink calibration bar 
set at 30 (your chosen limit for K).

Then calculate as follows:
The 100% patch for C on the limit 90 print measures L=35 which is 
equivalent to the 50% K patch on the limit 30 print
Therefore first partition = 50
The 100% patch for LC on the limit 90 print measures L=45 = 33% K 
'patch' (ie somewhere between the 30% & 35% patches) on the 30% limit print
Therefore second partition = 33

You are correct with your sub-division of the duplicated inks.

As a general comment, the limits and densities for the non-K inks seem 
high to me particularly for 2880dpi but I don't have an R260 so can't 
judge. Are you sure you are getting clearly visible separation between 
patches at 90%? If not, you should reduce the limits to a point where 
you are getting good separation.

You are at a disadvantage using a scanner as opposed to a densitometer 
or similar. For example the Dmax for eboni on EAM should be in the 
region of 16-17, not 24.

 > why you choose :
 > GRAY_HIGHLIGHT=4
 > GRAY_SHADOW=8
 > GRAY_OVERLAP=16
 > GRAY_GAMMA=1

These are the defaults - no need to change them unless there is a 
particular issue.

 > a last question : have i to print with 1440 dpi on EAM ?

No, 2880dpi is fine as long as the inks are limited correctly.

regards
Howard

paolovertullo wrote:
> Hi Howard
> just to see if i have understood well
> 
> I scanned the ink_limit_pattern and misured the L value with photoshop
> and found that 
> 
> on K for limit 30 i have L=24
> on C and M for limit 90 i have L=35 ---> on K i have L=35 for limit 15
> on Y,LC,LM for limit 90 i have L=45 ---> on K i have L=45 for limit 10
> 
> so i created a curve with 
> C limit 45 (half of 90) and denisty = 15/30*100 = 50
> M copy corve from C
> LC limit 30 (90/3) and denisty = 10/30*100 = 33
> Y copy corve from LC
> LM  copy corve from LC
> 
> why you choose :  
> GRAY_HIGHLIGHT=4
> GRAY_SHADOW=8
> GRAY_OVERLAP=16
> GRAY_GAMMA=1
> am i supposed to make some other considerations ? 
> a good starting point wasn't 
> GRAY_HIGHLIGHT=10
> GRAY_SHADOW=10
> GRAY_OVERLAP=
> GRAY_GAMMA=1
> 
> Here my new .qidf i named the curve with your name :-)
> 
> PRINTER=QuadR260-MIS
> CURVE_NAME=MK-EAM-HOWARD_1
> GRAPH_CURVE=YES
> N_OF_INKS=6
> DEFAULT_INK_LIMIT=30
> BOOST_K=35
> LIMIT_K=30
> LIMIT_C=45
> LIMIT_M=45
> LIMIT_Y=30
> LIMIT_LC=30
> LIMIT_LM=30
> N_OF_GRAY_PARTS=3
> GRAY_INK_1=K
> GRAY_VAL_1=100
> GRAY_INK_2=C
> GRAY_VAL_2=50
> GRAY_INK_3=LC
> GRAY_VAL_3=33
> GRAY_HIGHLIGHT=4
> GRAY_SHADOW=8
> GRAY_OVERLAP=16
> GRAY_GAMMA=1
> GRAY_CURVE=
> N_OF_TONER_PARTS=0
> TONER_HIGHLIGHT=10
> TONER_SHADOW=10
> TONER_GAMMA=1
> TONER_CURVE=
> N_OF_TONER_2_PARTS=0
> TONER_2_HIGHLIGHT=10
> TONER_2_SHADOW=10
> TONER_2_GAMMA=1
> TONER_2_CURVE=
> N_OF_UNUSED=0
> COPY_CURVE_M=C
> COPY_CURVE_Y=LC
> COPY_CURVE_LM=LC
> 
> a last question : have i to print with 1440 dpi on EAM ?
> 
> many many thanks
> Paolo
>