QTR-Quadtone RIP

Is there a new chart throb application. If than can ypu please give a link for it.

Sent from Yahoo Mail on Android

From: Alan Vlach <alanvlach@...>;
To: <QuadtoneRIP@yahoogroups.com>;
Subject: Re: [QuadtoneRIP] UV transmisison characteristics of Epson K3 inks
Sent: Mon, Mar 10, 2014 3:07:11 PM

Roy,

Chartthrob has a new function to create a negative curve. It is applied to a positive image and inverts it while applying the curve. I plugged this curve into a QTR profile and didn't get what I was expecting.

Anyway, I created this curve using the chartthrob negative function:

I created this QTR profile using the above curve:

# QuadToneRIP curve descriptor file

#

# PRINTER=QUAD3800 Salted Paper

# TPF100 Ink limit =100

PRINTER=QUAD3800

CALIBRATION=no

GRAPH_CURVE=yes

N_OF_INKS=8

DEFAULT_INK_LIMIT=100

LIMIT_K=35

#BOOST_K=80

LIMIT_C=35

LIMIT_M=1

LIMIT_Y=35

LIMIT_LC=1

LIMIT_LM=1

LIMIT_LK=35

LIMIT_LLK=1

# Describe usage of each ink

# All inks must be listed

# Gray Partitioning Information

N_OF_GRAY_PARTS=1

GRAY_INK_1=K

GRAY_VAL_1=100

GRAY_INK_2=

GRAY_VAL_2=

GRAY_INK_3= ;

GRAY_VAL_3=

GRAY_INK_4=

GRAY_VAL_4=

GRAY_INK_5=

GRAY_VAL_5=

GRAY_INK_6=

GRAY-VAL_6= ;

GRAY_INK_7=

GRAY_VAL_7=

GRAY_INK_8=

GRAY_VAL_8=

GRAY_HIGHLIGHT=0

GRAY_SHADOW=0

GRAY_GAMMA=1.5

GRAY_CURVE=/Users/windeking/Desktop/Curves/Chartthrobnegtest.acv

COPY_CURVE_C=K

COPY_CURVE_M=K

COPY_CURVE_Y=K

COPY_CURVE_LC=K

COPY_CURVE_LM=K

COPY_CURVE_LK=K

COPY_CURVE-LLK=K

And printed this step wedge:

<21step_gamma2.2.jpg>

I expected to get this result:

But this is what printed:

As you can see the 0% or 255 value printed white instead of black. The gradient at the top of the wedge showed the darks printing till the very end where it printed white again.

I opened the step wedge in photoshop and applied a levels layer which changed the output value from 255 to 254:

I printed this image and got the expected result.

I'm also curious about the choppy look on the right hand side of the gradient.

Thanks for all your help,

Alan