Plate Calibration - Harlequin RIP - Edit From Calibrated/Uncalibrated

[gordo]

The only difference to your recommendation is that he uses a linearization (curve 1), too, which really does not matter in this case.

You probably say "12 noon" instead of just "noon" (the 12 is redundant) ;-)

In lean manufacturing terms the 2nd most common wastes is excess processing. Excess processing is a sign of a poorly designed process. A redundant step like applying a curve to linearize plates before applying a second curve to affect tone reproduction in presswork is an example of excess processing.

You gave a good reason for why linearizing the plate is probably a carry over from the old film to plate days and that is no reason to continue doing it. So, I'm just being more adamant about removing redundancy and making the process as simple and variable free as possible.

 

[Ulrich]

I totally agree to your strategy to make a clean up concerning redundant steps!

The only reason I said, that it does not matter that Andy has worked with the linearization curve in this actual case is this, my understanding (no scientific or mathematical knowledge) of the process we are talking about:

Working with the Harlequin RIP the use of a linearization curve has nothing to do with the compensation curve the RIP is generating for the print with the input from a target (curve 3, intended press) and curve 4 (actual press curve). Although the RIP generates another compensation curve (for linearization of the plate) and “combines” both compensation curves at least, but that combining happens probably in a simple addition compared with a more complex
algorythm which is used for generating the compensation-curves.

I understand the generating of each compensation curve as autonomously processes.

The proof for this thought is simple: a plate only with curve 1 (linearization) and curve 3 (intended press/target) will lead to the same result as a plate made only with curve 1.
The use of curve 3 only make sense with a curve 4 (actual press). Following this argument the use of curve 4 also make sense only with a curve 3 together and therefore a plate made only with curve 4 and curve 1 leads to the same result as a plate only with curve 1. And that is the proof that the use of a linearized curve (1) does not affect the compensation curve made from the input from the curves 3+4.

If so... unfortunately I can not proof it anymore by testing. But from this thoughts I find the courage to claim that in this special case it does not matter and has no influence that Andy got a result +5-8 above target by working with curve 3+4 (and 1). Did he got the same results he got from the linearized print without a linearized plate he had got also +5-8 only by using curves 3+4...

Ulrich

 

[Slammer]

Always good to see something about calibration with the HQN rip. I do have a question though.
All the information I can find points to the tab "intended press" as being set manually with for, for instance, "Forgra 39" values, however if you add the Fogra 39 ICC in color management the intended press tab is greyed out, does this mean that the values for Fogra 39 in the color tab are being used as intended press?

 

[Martin Mueller]

You have to decide how you want to calibrate your printing process, with the ICC-Profile FOGRA 39 or with dot gain values of the "Intended Press FOGRA 39". You can read these needed dot gain values on pages 43/44 in the attached "MediaStandard_Print2018" PDF document, provided by the German BVDM (German Printers&Media Association).

Best regards
Martin

 

[Ulrich]

Slammer
I do not know, but would be very skeptical, because an ICC profile does not contain one-to-one information - no densitometric values - about tone value increases (but colorimetric values, only indirectly can from the Lab values to the tabulated one colour-patches be generated conclusions which, strictly speaking, are not accurate enough to serve as calibration values ...).

In german language look here for that topic:
https://www.hilfdirselbst.ch/foren/D...51.html#458051

I can not look, because I have no access to the software: Did I understand you correctly that Intended Press is now greyed out, if you deposit an ICC profile on "Color"?

If so then your assumption would be suspected, but for the above mentioned reason should already include an inaccuracy


Best

Ulrich

 

[Martin Mueller]

Just to clarify, I would recommend to use dot gain values for press calibration (actual & intended) in the HQ-RIP. It is easy to do and understand.

 

[Slammer]

Yes, if fogra39 is active in Color then nutendes press is Greyed out, which begs my question. Where would you then get your Target blaues from without banging them in value for value.

 

[Slammer]

Stupid german Auto Orte t

 

[Slammer]

Autokorrektur

 

[Slammer]

Autocorrect

 

[Martin Mueller]

Yes, if fogra39 is active in Color then nutendes press is Greyed out, which begs my question. Where would you then get your Target blaues from without banging them in value for value.

Sorry, but it is necessary to type in the tone values for intended and actual press under "edit from uncalibrated target" for "printing press" in the HQ-Rip.

 

[Slammer]

Just to clarify, I would recommend to use dot gain values for press calibration (actual & intended) in the HQ-RIP. It is easy to do and understand.

I am struggling to Understand where the hqn Gets the intended values from if you dont have them in the system i cant just pull fogra39 intended Target values out of Thin air

 

[realaqu]

here is my way to do the calibration, I do not use intend or actual press option, just 2 steps, any inputs?
1 I always use uncalibrate target to linearize the plate
2 use a software named curve4 to generate tvi curves for each press and paper, not the one from calibration manager.

 

[gordo]

here is my way to do the calibration, I do not use intend or actual press option, just 2 steps, any inputs?
1 I always use uncalibrate target to linearize the plate
2 use a software named curve4 to generate tvi curves for each press and paper, not the one from calibration manager.

You don't need to linearize the plate.
You do need to have a tone curve target and you do need the press current tone response from uncurved plates.

 

[realaqu]

You don't need to linearize the plate.
You do need to have a tone curve target and you do need the press current tone response from uncurved plates.

One reason is if we do the G7 calibration we have to use linearized plate to print p2p target

Another reason, We use polyester plate, each roll has slightly difference, around 2%, measured by techkon spectroplate, that is the reason why I calibrate each roll, looks like the plate is not stable to me

 

[gordo]

One reason is if we do the G7 calibration we have to use linearized plate to print p2p target

Another reason, We use polyester plate, each roll has slightly difference, around 2%, measured by techkon spectroplate, that is the reason why I calibrate each roll, looks like the plate is not stable to me

From the how to G7 method instructions (my emphasis):

5.7 Pre-adjust the plate-making system at 50% (optional)

If possible, adjust the CtP exposing unit’s focus, exposure energy, or other physical parameters (including plate development) until a 50% file value measures 50% on plate. CAUTION: Do not adjust the CtP calibration curves to achieve this condition unless delta calibration values can be added to the pre-calibration values after the calibration run. (This is easier in some RIPs than others.)
Note that it is usually simpler to leave the CtP system in a completely un-calibrated state for the first run, even if 50% does not measure exactly 50% on plate.
5.8 Make plates for the calibration run
Produce a set of ‘un-calibrated’ plates of the calibration form using exactly the same workflow as you would for regular work.

They do not say to linearize the plates first. Have they changed the method?

 

[realaqu]

From the how to G7 method instructions (my emphasis):

5.7 Pre-adjust the plate-making system at 50% (optional)

If possible, adjust the CtP exposing unit’s focus, exposure energy, or other physical parameters (including plate development) until a 50% file value measures 50% on plate. CAUTION: Do not adjust the CtP calibration curves to achieve this condition unless delta calibration values can be added to the pre-calibration values after the calibration run. (This is easier in some RIPs than others.)
Note that it is usually simpler to leave the CtP system in a completely un-calibrated state for the first run, even if 50% does not measure exactly 50% on plate.
5.8 Make plates for the calibration run
Produce a set of ‘un-calibrated’ plates of the calibration form using exactly the same workflow as you would for regular work.

They do not say to linearize the plates first. Have they changed the method?

Quote From 2018 techkon guide to G7 page 10, because our plate is not that stable, for safe reason, we use linearized plate as guide instructed.

https://www.techkonusa.com/2018-printers-guide-to-g7/


Preparation of the Press Form

The press form can be downloaded from www.idealliance.org, or you can make your own form. The forms at

www.idealliance.org provide good guidelines for placement of elements. Most important is that there should be at

least 2 P2P51 targets on the form. You will notice that these are located on left and right, and top and bottom of the

sheet. The form should be imaged as a linear plate. Before running, we want to measure the plate with a plate reader

and make sure we have a linear plate. Acceptable tolerances for a linear plate are generally +/- 2%. If for some

reason you do not have linear plate or choose to run with a non-linear plate make sure to record the values on the

plate so that you can return the plate to this condition should your platesetter drift. (Over linearization can cause

printing issues). Keep in mind different line screens and screening types will require different curves.

 

[gordo]

Quote From 2018 techkon guide to G7 page 10, because our plate is not that stable, for safe reason, we use linearized plate as guide instructed.

https://www.techkonusa.com/2018-printers-guide-to-g7/


Preparation of the Press Form

The press form can be downloaded from www.idealliance.org, or you can make your own form. The forms at

www.idealliance.org provide good guidelines for placement of elements. Most important is that there should be at

least 2 P2P51 targets on the form. You will notice that these are located on left and right, and top and bottom of the

sheet. The form should be imaged as a linear plate. Before running, we want to measure the plate with a plate reader

and make sure we have a linear plate. Acceptable tolerances for a linear plate are generally +/- 2%. If for some

reason you do not have linear plate or choose to run with a non-linear plate make sure to record the values on the

plate so that you can return the plate to this condition should your platesetter drift. (Over linearization can cause

printing issues). Keep in mind different line screens and screening types will require different curves.

Thanks for the link and the quote.

Notice that he doesn't say why the plate should be linear - i.e. pre-curved.
Then he says that you may have chosen to run with non-linear plates. Which effectively means that you can do G7 without linearizing the plates first.

There is no inherent value or benefit in linearizing the plate first. However doing so may cause problems since you will end up curving curves. Multiple curves can result in shadestepping/banding as well as cause added complexity in the workflow since you have to manage the application of two curves instead of one.

That being said, if the plate response changes then there is no effective difference whether you're starting with a linearized or non-linearized plate. You either adjust your linearization curve in the first case or you just adjust your tone reproduction curve in the second case.

N.B. There may be exceptional cases where a two curve method may be appropriate however IMHO that should not be the standard procedure.

 

[realaqu]

Thanks for the link and the quote.

Notice that he doesn't say why the plate should be linear - i.e. pre-curved.
Then he says that you may have chosen to run with non-linear plates. Which effectively means that you can do G7 without linearizing the plates first.

There is no inherent value or benefit in linearizing the plate first. However doing so may cause problems since you will end up curving curves. Multiple curves can result in shadestepping/banding as well as cause added complexity in the workflow since you have to manage the application of two curves instead of one.

That being said, if the plate response changes then there is no effective difference whether you're starting with a linearized or non-linearized plate. You either adjust your linearization curve in the first case or you just adjust your tone reproduction curve in the second case.

N.B. There may be exceptional cases where a two curve method may be appropriate however IMHO that should not be the standard procedure.

what about in our case, each roll of our plates is slightly different, 2% diffenrence, linearizion can make whole process stable to a known status.

 

[gordo]

what about in our case, each roll of our plates is slightly different, 2% diffenrence, linearizion can make whole process stable to a known status.

Linearizing does not make the process stable. Laser energy, processing etc makes it stable. Yes, in order to create a linearization curve you need to know the status of the plate. However, what the dot tone values are on the plates is only important for checking that the plates are imaging consistently. It doesn't actually matter what those tone values are. In production what matters is what the tone values requested in the original file end up being delivered on the press sheet. I.e. Requested tone value in the file vs resulting target tone value on the press sheet. It is up to the dot gain compensation software to figure out what the requested tone value should be changed (remapped) to in order to deliver the correct target tone value on the press sheet.