g7 calibrating my epson proofer

[beanz]

I read under the g7 how to guide from idealliance that I can g7 calibrate my proofer. I am with the understanding that if i g7 my proofer, it will output similarly to my g7 press.


according to the guide, I will output the test print with the p2p target through my proofer (without using any color management), then do the fan graph method to make C M Y K adjustments curves to my RIP.


however, I cannot see where I can apply my changes to the rip. I am using prinect workflow (signa, meta).

There is a process calibration under the calibration manager but this is only available if i choose the supra setter as my output device, but not when i select my epson proofer as output device.


I hope someone out there can help

 

[Stephen Marsh]

I personally would use ICC device profile and ICC devicelink profile for inkjet proofing simulations (or proprietary colour tables if offered by the RIP).

RGB input is colour managed to the press simulation profile, which is then colour managed to the proofer device profile.

CMYK colour may or may not be colour managed or assumed to be in the press simulation profile, which is then colour managed to the proofer device profile.

Colour management based on characterisation data from a chart such as an ECI chart is the way to go.

An inkjet proofer is a colorimetric device, not a tonal based device (yes, one can use tone curves in some RIP software however it is not the same thing as a press). Why some insist on making this more complicated than it needs to be is beyond my understanding.


Stephen Marsh

 

[ColorGeek]

Stephen is correct, most proofer RIP's would be configured with ICC (or device link) profiles - not curves - to get the color in-tolerance to the GRACoL color space. I find frequently that people don't know the difference between GRACoL and G7. You do not have to use the G7 approach (measuring P2P chart(s) and generating curves) in order to get a proof that would "qualify" for the IDEAlliances G7 Master Printer program. Typically, the curves are used in for the platesetter RIP/workflow and the inkjet RIP is configured with the actual GRACoL ICC profile - or a custom press profile, if the press (after being curved) wasn't capable of hitting all criteria (LAB for paper white, solids, overprints AND gray balance (NPDC)) for GRACoL.

Having said that, there are some instances where I utilize a G7 approach for inkjet RIP's. For instance, if I don't want to limit my output device to the GRACoL color space - because I'm not trying to match a GRACoL press but would rather take advantage of the full gamut of my printing device/ink/substrate combination. In this case, I would use the media profile as both the destination/output AND reference/simulation. If you do this, the gray balance will probably be a little whack. So, after you calibrate and profile, you then print the P2P and generate curves which will be applied on top of the ICC transform and fix it - this works great in RIP's like Onyx or EFI.

I would say that the color functionality you have available to you is very limited in your current software. I would suggest a more robust inkjet proofer RIP, so that you have all of these approaches at your disposal. I highly recommend EFI Fiery XF, contact me offline if you'd like to setup a 30-day trial.

 

[Correct Color]

In this case, I would use the media profile as both the destination/output AND reference/simulation.

Why?

If I'm understanding you correctly, you're printing to a profile and also using that same profile as a proofing condition?

Am I missing something? Why do that?

(Edited to add:

I am with the understanding that if i g7 my proofer, it will output similarly to my g7 press.

By the way, just in case these guys didn't make it clear: That is completely incorrect. Your Epson uses different primaries than your press. It may very likely not even be a simple CMYK device. But if it is, it's CMY and K are not the same CMY and K as your press. You need to characterize the thing correctly with an ICC profile, and once you do, then you can send it files in Gracol color space -- or any other color space you want -- and as long as the colors are in gamut, and your media white is correct, you'll get an accurate proof.)


Mike Adams
Correct Color

 

[gordo]

I read under the g7 how to guide from idealliance that I can g7 calibrate my proofer. I am with the understanding that if i g7 my proofer, it will output similarly to my g7 press.

No. G7 is a method to bring an output device into grey balance. If the primary hues between two devices are different then their G7 grey balance would be the same but all the other colors would be different.

 

[Stephen Marsh]

http://www.idealliance.org/specifications/gracol/g7-vs-gracol

This is not helped by articles such as this:

http://www.piworld.com/post/g7-high-speed-aqueous-inkjet-yes-you-can-mary-schilling/


Stephen Marsh