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Application Note: #011
Date: Nov. 03, 05
Written By: Eitan Abramovich
Approved by: Shay Rosenzweig
How to Create and use Manual Linearization Profiles
in Matan PhotoPrint Server
Introduction
When printing BMP images with Matan's thermal printing technology, we
might have difficulty printing “light shadows”. The Sprinter can not generate
shades from 5% to 15/20%; and “dark shadows” from 85-95%, depending on
the media type.
In order to fix this problem we need to RIP images and use Color
Management with the PhotoPrint Server.
There are two procedures for handling Color Management:
• Color Correction (by using ICC Profiles)
• Linearization Profiles (also called Linearization Tables).
In order to create ICC Profiles, expensive professional tools are required. The
Linearization Profiles can be made in a relatively simple way, either by using
measurement tools or manually.
The generation of the linearization curve is an important step in printer color
characterization. The typical purpose of the linearization curves in
conventional four color ink printing is to compensate for dot overlapping and
dot size variations and therefore to accommodate the non-linearity of the
printing process.
In the following sections we will learn how to create and use Manual
Linearization Profiles.
Note: This document is an elaboration of the Manual Linearization Profiles
section in AppNote10 Sprinter Color Management.pdf, describing and
explaining the Manual profile creation process in greater detail.
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Creating a Manual Linearization Profile
Preparation
Before starting, we need to print (without any color management) a CMYK
color patch table like the below one (swatches.eps), and examine the results.
In most cases, the 5% patch will not appear at all, the patches around 10-25
% will be print around 5-15%, and patches around 85-95% will be printed
around 95-100%.
This printing test will be used as a reference in the following stages.
Creating a manual Linearization Profile
After we have located and have examined the problem we can start building
the profile.
• On the PhotoPRINT main menu, select Setup and then Color Profiler. The
Color Profiler dialog will open.
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• Set the Setup configuration name, Media name, RIP Resolution and the
Screen Type and press the OK button.
• The main Color Profiler dialog will open.
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• Click on the Find Ink Limit… button. The Find Ink Limit dialog will appear..
These settings are basically for ink printers so do nothing (leave the
default dialog settings) and press the OK button.
• The Not yet done text next to the Find Ink Limit… button in the main
wizard dialog will be replaced by Done.
• Next, click the Linearization… button to open the Linearization dialog.
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• Set the output linearization file name.
• Set the "Step size" to 5% step or 10% step – depending on your CMYK
color patches.
• For a manual Linearization Profile uncheck the Use Densitometer box.
• Create a new linearization file by clicking New. A successfully generated
message will appear.
• The created Linearization Profile uses a straight linear 45 degrees curve
for all the separations and will not influence the print shades at this stage.
• Click OK.
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• Click the Edit… button (which is now active) to open the Density
Adjustment dialog.
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• In this step, you need to adjust the points on the curve according to the
actual print output of your patches test table, so that the curve reflects the
current output. The software will make the necessary adjustments.
This is done either by dragging points on the curve up and down, or by
selecting the labels on the X-axis and editing their values in the Output
field. It is good practice to start at 5% and work your way up to the 95%
point.
For example: if you see on your test print that the 25% point prints like
20% - enter a 20.000 value at the 25% point.
One more example: in the printing test you will probably notice that the 5%
patch doesn't print at all. This means that you have to push down the
curve to the 0% point.
However, it is forbidden to enter two identical values. The curve must start
at 0% and gradually climb up to 100%.
So at this point enter a low value, such as 0.001.
At the second point, (10%) enter the value that is visible on the printing
test.
Continue to enter the values gradually until the 95% point.
Note: The curve should not contain any points that fall below a previous
value. If such a point is measured, edit the curve so that the point is
above the previous point on the curve.
• Click Reset to return the curve to its original values.
• On the Channel drop down menu switch to Magenta and repeat the above
procedure.
• Do the same with Yellow and Black. When finished press the OK button.
• The curves for each channel will probably not be similar, since each color
might behave a bit differently.
• Press OK twice and exit from the Color Profiler dialog.
• The new Linearization Profile you just made is ready for use.
Matan Digital Printers Ltd. – 11 Amal St., Park Afek, Rosh-Ha’ayin, 48092 Israel
Tel: 972-3-9039939 , Fax: 972-3-9039947, [email protected]
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Using and Editing the Linearization Profile
• Select the SprinterB setup.
• Select Default Job Properties… from the Setup menu.
• Select the Color Management Tab.
•
•
•
•
Uncheck the Perform color correction check box.
From the drop down menu "Linearization table" select the desired profile.
Choose "None" for working with no profile.
It is possible to import an existing file (as from a previous version) from a
different directory by selecting "Add"
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• When you create a new profile it is automatically saved in the correct
directory and will appear on the drop down list.
• Press the OK button.
• RIP the CMYK swatches.eps again – but now with the new profile that you
just created.
• Print the file and examine the results.
You will probably notice the big improvement in the screen shades values.
• If the results are not satisfying, edit the profile by opening the Color
Profiler dialog again; choose the correct profile and select Edit.
RIP the file again, print it out and examine it.
• Repeat the steps above until you get the most satisfying results.
Matan Digital Printers Ltd. – 11 Amal St., Park Afek, Rosh-Ha’ayin, 48092 Israel
Tel: 972-3-9039939 , Fax: 972-3-9039947, [email protected]
w w w . m a t a n p r i n t e r s . c o m