Plate Calibration - Harlequin RIP - Edit From Calibrated/Uncalibrated

[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.

[Ulrich]

Hello again @Slammer

Back then, I also failed to load other pre-built Intended Press curves than those available for selection in the calibration dialog. (With newer versions may already FOGRA 51 and 52 already be offered?).
What does not matter, because i worked with manual input. But I vaguely remember that there is a possibility at the HQ-RIP to read measured values directly from a measuring instrument (presumably in the form of a CSV file?). Maybe additional Intended-Press-Curves can also be implemented as CSV-data from one-channel-patches (and not via ICC profile)?


-------------------------

after all something for the record regarding linearization or not:

With great pleasure I want to praise Gordo's professional competence, his wisdom and kindness and last but not least his truly exceptional teaching skills for the rest of my life as loud as I can.

Yet:
We are about to receive a new make of plate (from the same manufacturer) and have been "warned" that recalibration may be necessary for the established processes.

As there are: Three printing machines with their own calibration curves for uncoated and coated. If, in fact, it becomes necessary for the new product to require a recalibration, then this can be done with only one(!) correction (the linearization curve) instead of at least six, because in the various processes, so to speak, only the zero point is to readjust, the "peculiarities" (states) of the different machines (and thus the need to adjust each individually different from each other) remain in their relationship to each other ...

Or have I thought incorrectly about that?

Best regards

Ulrich

[gordo]

We are about to receive a new make of plate (from the same manufacturer) and have been "warned" that recalibration may be necessary for the established processes.

As there are: Three printing machines with their own calibration curves for uncoated and coated. If, in fact, it becomes necessary for the new product to require a recalibration, then this can be done with only one(!) correction (the linearization curve) instead of at least six, because in the various processes, so to speak, only the zero point is to readjust, the "peculiarities" (states) of the different machines (and thus the need to adjust each individually different from each other) remain in their relationship to each other ...

Or have I thought incorrectly about that?

Best regards

Ulrich

As I said before, there may be exceptional cases where a two curve (plate linearization+press) method may be appropriate. My problem is when industry experts just say "do it this way" without explaining why. Each shop needs to evaluate what works best for them by understanding the consequences of their choice.
In most cases for most shops applying a linearization curve and then curving that curve makes no sense.
In most cases shops do not use different curves for each press. Instead they average the difference and just use one press curve for the different presses.
There are always exceptions. For example, I have been to printshops that have hundreds of press curves - not just for different presses and papers but also different customers. I think that's crazy - but they feel it works for them.