Harmony Curves - Use Single or CMYK calibration

[David Ingram]

Hello again!

I've been given the task of figuring out harmony curves for our prinergy Workflow system.
We are a busy commercial shop and currently output linear to almost all our plates.

We do need to dial in for Uncoated though, because we are getting too much gain on uncoated (mostly cardstock for this 1 big customer)

IS it better to create Harmony curves:
1) using a single curve to affect all 4 plates
2) Using a curve for each plate

also. is it better to go from an uncalibrated state for testing? Or should we
baseline 1st. We use only thermal plates so they have to go on press to develop, and be brought up to color before we can take a reading on the sheet.

TIA for any advice. Also if anyone could show me the #s of a working harmony curve or a picture as it pertains to uncoated i would be most grateful.

 

[Mark_S]

Curves

Curves

We used a curve for each plate.
Attached is our Harmony 175 line uncoated curve.
We use this in place of our old 133_uncoated x-curve.

I'm pretty sure we started from uncalibrated.

hope this helps. Mark

 

[David Ingram]

Thank You So Much Mark!

Thank You So Much Mark!

I come from doing 12+ years of film, but now im in a shop where we go direct to plates that develop on the press, and are really faint when imaged. No chance to calibrate the plate or measure it until its on press. This extra wrinkle is bugging me cause i used to keep my old shops AGFA Select Set 5000 SF and ECRM VR 18 in perfect calibration, and would usually compensate the IMAGE, in software depending on the process where the piece was going.

Here, everything is thermal, everything is CTP, can't measure till its too late it seems.

Again thank you very much for the info.

 

[jminrod]

We output using a curve (CMYK) It was based on GRACOL 7. 1 way to test is to reroute your 1bitt Tiff that would go to plate and check the screen percentage in photoshop, this will eliminate the wasted plates for testing. We also plate all of our uncoated jobs using 150 line screen. another thing that seemed to help us was using less nodes in the harmony curve. Example 10% - 90% by tens didnt work as well as 25%, 50%, 75% this allows harmony to create a more consistent curve. Hope it helps

 

[pga2]

David

Firstly - the printing conditions that were used to develope the colour profile you use when converting rgb to CMYK defines the lab ink colour and TVI(dot gain) that your press should be set up to.

Secondly - it is the result on the sheet that matters - and this not only about lab and TVI - but about overprints and print sequence.

The numbers for Harmony plate correction should be worked back from the press - ie what do the 25% 50% and 75% digital patches from say photoshop measure when they are printed with the ink at the correct lab values. I think in the US the increase is about 17 - 20% on the 50% ie 50% digital dot should measure 67 - 70%. Someone mentioned G7 and thats agood starting point.

Peter

 

[eduardo]

another thing that seemed to help us was using less nodes in the harmony curve. Example 10% - 90% by tens didnt work as well as 25%, 50%, 75% this allows harmony to create a more consistent curve. Hope it helps

This is a good idea. I used 2%,5% ... and lost a long time to do it smother, without bands. Thanks

 

[magnetas]

hya,

do you guys have any curves for like 105 lpi? we use a kodak trendsetter newz we print newspapers