How to choose a print standard ?

[danremaley]

Press dot gain

Press dot gain

A 50% in file should read 70% on paper at press. This is optical and mechanical gain, including any plate curves. photoshop converts all RGB to CMYK with -20% gain (in the midtones). the proof adds the gain back in to represent the press gain.
If you print with 15% gain (50+15=65%) you print too sharp.
If you print with 26% gain (50+26=76%) you print too heavy.
I developed a simple method to print to gray balance while at GATF, please contact me off-line and I can share it with everyone - "google me' for more information.

Dan Remaley
412.889.7643
[email protected]

 

[Achenk]

Thanks for information all....

 

[meddington]

A 50% in file should read 70% on paper at press. This is optical and mechanical gain, including any plate curves. photoshop converts all RGB to CMYK with -20% gain (in the midtones). the proof adds the gain back in to represent the press gain.
If you print with 15% gain (50+15=65%) you print too sharp.
If you print with 26% gain (50+26=76%) you print too heavy.
I developed a simple method to print to gray balance while at GATF, please contact me off-line and I can share it with everyone - "google me' for more information.

Actually, ISO 12647-2 specifies approx. 14% tvi at midtone for paper type 1 & 2 (Curve A). This is based upon results from positive plates exposed by film (150 lpi, round dot measured with Status E w/ polarization). For negative plates (exposed by film), the standard is Curve C, or appox. 20% TVI. With CTP, its now left to the discretion of the user whether to follow the legacy practices of their geographical area for positive or negative plate types when defining which curve to use as a target So theoretically, with a 4% tolerance, a given printer can print anywhere from 10-24% gain at midtone and still claim conformance to ISO12647-2. Kind of silly actually (and part of the reason for the NPDC metric of G7 to remove ambiguity). Note that for CTP imaged linear at 150 lpi round dot, the inherent gain is closer to 14%.

 

[zcto7]

Wow, its a good thing I didn't try to hit a 50% patch on paper

I think i'll try to go the NPDC route, I still don't fully understand it yet, but I have to read up on it on my own free time (and with 2 jobs is scarce!)

If that doesn't work i'll try configuring Navigator with the instructions Dan left, with some sort of target gain.