Linearization Target Problem

General Color & Graphics Color Science & ICC Profiles
1

Hello;
I have printed a linearization Target for a CMYK Press, I decided to use it in creating my new TestChart to print on Press.

But I found out that performing linearization inside RIP(Not inside profile) is better solution.

Now I have printed my Linearization TestChart by Press and I measured it two formats: LAB and Spectral values

but now I need to have these values in percentage because my RIP accept percentage of CMYK color separately instead of LAB or … values:
img29.picoodle.com/img/img29/4/7 … 09619f.jpg
1-How should I convert them to percentage?

Again I measured my TestChart via Measure Tool 5, it has an option to measure density, I measured my Color Patches density but I can not convert them to percentage for example I have this value:
1.67D (For Black)
1.47D (For Magenta),…

2-What is maximum possible Density?(2D, 3D,…?)

3-How should I convert these Densities to percentage?

Regards.

2

You need to read dot gain on sheet.
Density for Coated should be about:
Wet density readings
K 1.85
C 1.30
M 1.40
Y 1.05

Then make sure Plates are outputing at linerized dot 5% = 55 25% = 25% ect…

then output a plate for each Color like number below.

2%
5%
10%
20%
25%
50%
75%
80%
85%
90%
95%
100%
Run on machine to density and tehn read dot gain on sheet. these are your natural press curves.

then establish your desired curve

K 50% = 72%
CMY 50% = 70%

this should give you a nice nuetral gray.

3

He won’t know what densities he should be running to, as this will depend on stock and ink being used.

Initially you need to check that your plates are linear (50%=50%) and if they don’t then you need to input the values you have and generate a compensation curve to bring them (ideally) to within 1% of desired dot values.

Then output a suitable test form and get your press minder to run a range of ink weights from high to low (within reason) from one side of the sheet to the other. You can then go through and check your solid LAB values to find the closest match to your standard (I’m assuming G7). Once you have found the closest LABs you can then take density readings from these patches and there are your ideal ink weights for that stock/ink combination.

Next up is to run your test form again but now you can run to your new ink weights all the way across the sheet.

From these sheets you read your presses natural got gain values and make a separate compensation curve for use with those inks & stock. Obviously you need to reference the standard again in order to know what your desired TVI values should be (for Coated I’m guessing around 14-17% @ 50%).

Hope that helps
:slight_smile: