G7 Digital press

[Carl Couchman]

I am looking into using G7 on an HP Indigo press. My understanding is that NPDC curves are used. Exaclty where are the curves entered. A few consultants suggested that profiles are all that is needed instead of curves. If we are installing profiles in the RIP how do we make profiles to the G7 method? By that I mean we have Monaco Profiler gold and can make profiles but how do we use it to make G7 profiles?

 

[meddington]

If we are installing profiles in the RIP how do we make profiles to the G7 method? By that I mean we have Monaco Profiler gold and can make profiles but how do we use it to make G7 profiles?

You don't.

Profile the press in its current state...whatever that may be, but least a consistent state. Making it "G7" would be done via the workflow as a whole. I.e.The files you send to the device would ideally be using a Gracol/SWOP profile, and your indigo front end would convert from gracol to your custom profile, therefore emulating the characteristics of the gracol profile on you indigo print. Not to tricky.

What ive found on our indigo (5000) is that the default curves are rather light in the highlights and that the solids might need slight density adjustments to optimize the match to ISO 12647-2. I have gone the route of traditional G7 first...applying G7 curves on press to optimize gray balance and tonality. This in and of itself will make an improvement, but then profiling on top of that is the ideal. This might not be necessary in your case, but I found it helpful.

Performing regular color adjusts, lut generations and verifications will help keep everything in line, plus you have the ability to perform the G7 process via curves again should drift occur. This can minimize the need to re-profile, though this isn't a difficult task to perform either.

 

[Carl Couchman]

Mike,

Great info thanks. A few more questions.

I.e.The files you send to the device would ideally be using a Gracol/SWOP profile
By this do you mean embedded profiles, or selecting input profiles?


I have gone the route of traditional G7 first...applying G7 curves on press to optimize gray balance and tonality....
How and where are the G7 curves applied? This happens on the press itlelf not in the RIP right?

Performing regular color adjusts, lut generations and verifications.......
Im not familiar with LUT generations. Again is this on press? Perhaps if you steer me I can convey it to our press operator.

Again so grateful for your generous help.

Carl

 

[meddington]

I.e.The files you send to the device would ideally be using a Gracol/SWOP profile
By this do you mean embedded profiles, or selecting input profiles?

Either by honoring the embedded profile, or defining a Gracol/SWOP profile as the default input profile at the Rip.

"How and where are the G7 curves applied? This happens on the press itlelf not in the RIP right?"

Curves (or Luts) can be defined in the job properties/color control tab of an individual job. Once defined, they can be saved and selected as default curves within the ticket template of an individual hotfolder...so file sent will have this Lut as default when it Rips.

"Im not familiar with LUT generations. Again is this on press? Perhaps if you steer me I can convey it to our press operator."

Lut generation is a linearization procedure to compensate for dot gain and is accessed from the Adjustments menu on the press console. Hopefully you press op is familiar with it.

 

[degolf]

G7 and HP 5000

G7 and HP 5000

Does anyone have a more detailed procedure on 'curving' applying the G7 curves on the Indigo Luts on press. I have Curve2 and want to adjust for best gray balance. I have noticed that my Magenta is off using everything default for press calibration. Is the best route to adjust Magenta SID to get curve more inline with others.

Thanks,

David Egolf

 

[Bloodsaler]

You can see my test result.But all the document wrote in Chinese.Hope the data can help you.
My digital proof test math NPDC curve,but the b* value of yellow color upto 100.I want to know why?