Matching Press to Proof

[MitchtheMitch]

We have been G7 certified for going on 5 years now. We use a digital press and an Epson Inkjet printer for 95% of our hard copy proofs. We use ORIS PressMatcher to make 4D color corrections targeted to GRACoL (one customer requires us to target FOGRA) specifications on both proofing devices. We use Color Path Sync from FujiFilm to calculate our press curves also targeted to GRACoL. For the most part the press can get a satisfactory match to the proof, but a lot of times there are CMYK color builds in areas like page headers, color gradiations, brand colors, banners, etc. We struggle to match those specific color build from press to proof. Photographs are pretty spot on but as you all are very aware there is much more to color printing than just photos. How can me more accurately proof our presswork. I know that we have the ability to run an ECI2002 or IT8 form on our offset press then use the profile generated from that printed chart as our target in to color correct against in ORIS. So, is that the right direction? How are other printers calibrating their proofers to match their presses?

Thanks everyone

 

[DYP]

What digital press? And what color rendering intent are you using when print proofs?

 

[MitchtheMitch]

DVP: we use an Indigo 5600 and an Epson 9900 for our proofs. I believe our rendering intents are set to Perceptual

 

[DYP]

You probably should be using colorimetric for proof printing. Try Relative with NO black point compensation. You can also test the Absolute as well. But you defiantly what to use Perceptual.

 

[Correct Color]

Mitch,

I'll second what DYP said. Perceptual rendering intent is not intended for proofing use, ever. Two problems: First is that as defined by the ICC, perceptual rendering intent is supposed to move all colors, in or out of gamut, in order to make images more perceptually pleasing. Great to reduce clipping, but it can play hell with just the types of areas you're describing. Second is that the perceptual rendering intents are so vastly different between profile-making engines that you also have no idea without some pretty careful testing if that's even truly the way they work.

Best and most accurate in your situation would probably be AbsCol. What it will do is print the new whitepoint -- from your proofing paper to the new media white -- but your Epson should be able to handle that.

I'd try that first, and if for whatever reason you still have issues, try RelCol as DYP said.

If you still have issues, it could be how you define the color builds. That can be an issue as well.


Mike Adams
Correct Color

 

[David Milisock]

As far as proofing goes there are a few things to remember, only the dead see everything the same way all the time, the blind have fairly stable vision but for the rest of the people the perception of color can and does vary. In 41 years on presses of all types I've never seen a proof EXACTLY MATCHT THE PRESS.

​My advice on rendering is relative colorimetric for conversions from a space to a space that have close total ink values, absolute colorimetric for simulating other media.

As far as wide gamut spaces like Aobe RGB or Prophoto RGB to a narrow space like any real CMYK I use perceptual rendering, it's like putting D cup breasts into a B cup bra, no right way to do that.

 

[MitchtheMitch]

Mitch,

I'll second what DYP said. Perceptual rendering intent is not intended for proofing use, ever. Two problems: First is that as defined by the ICC, perceptual rendering intent is supposed to move all colors, in or out of gamut, in order to make images more perceptually pleasing. Great to reduce clipping, but it can play hell with just the types of areas you're describing. Second is that the perceptual rendering intents are so vastly different between profile-making engines that you also have no idea without some pretty careful testing if that's even truly the way they work.

Best and most accurate in your situation would probably be AbsCol. What it will do is print the new whitepoint -- from your proofing paper to the new media white -- but your Epson should be able to handle that.

I'd try that first, and if for whatever reason you still have issues, try RelCol as DYP said.

If you still have issues, it could be how you define the color builds. That can be an issue as well.


Mike Adams
Correct Color

Okay I will generate a profile using Absolute rendering intent on the CMYK-CMYK conversions. Should I leave the RGB-to-CMYK conversions at Perceptual or also change that to Absolute?

Thanks!

 

[Kent Chung]

Hello Mitch,

For proofing, it's usually done with Absolute rendering intent when you want the proof to have dots on the proofing paper on the paper area of the printed file, simulating the source icc profile's white point.

However, if you are running the RIP with different source and destination icc profile, you'll want to use the relative rendering intent to avoid adding dots to the paper area.



For RGB to CMYK conversions, it really depends on how you are treating the RGBs for proofing and printing. If you leave RGB files in your PDFs to be handled by ORIS, then you'll have to make sure you do the same setting on the proofer software to match what the ORIS does to the RGBs.

Can you clarify a little bit on the ORIS and Fuji ColorPath Sync though? Am I correct that you are only using the ORIS for proofing on the inkjet and using FujiColorPath Sync with only curve adjustments by G7 method and not a Devicelink transformation for your Press adjustment? The reason I'm asking this is that the G7 method is a gray calibration tool and not a color management tool. Your digital press is gray calibration but it is, with a very high probability, NOT color matching to the GRACoL or FOGRA to an average delta E of your acceptable range.

Hope this helps a bit.


Kent

 

[Stephen Marsh]

We have been G7 certified for going on 5 years now. We use a digital press and an Epson Inkjet printer for 95% of our hard copy proofs. We use ORIS PressMatcher to make 4D color corrections targeted to GRACoL (one customer requires us to target FOGRA) specifications on both proofing devices. We use Color Path Sync from FujiFilm to calculate our press curves also targeted to GRACoL

Presuming that lighting conditions and differences between OBA in the proof and press sheet have been taken into account… Is your Indigo really printing to the same specification as the proofing system is targeting?

My guess is that your proof is much closer to the reference conditions (GRACoL, Fogra) than your Indigo is.

Use colour management to simulate your proofing target conditions on the Indigo press, you could do this with ORIS Press Matcher. This should get you close to the proof if they are both simulating the same reference.

You could also profile the output of your Indigo (which is conforming to a reference print via colour management) and simulate that with the inkjet, however that would not be my ideal choice if you are printing to reference conditions.


Stephen Marsh