To sort of paraphrase what Craig is saying, converting solid spot colors is the least common denominator in ECG printing, and pretty much any of the commercial solutions do a minimally competent job. A touch plate can be challenging because it involves a spot overprint, and this is probably the greatest color management challenge in hi-fi, or ECG printing. But it also involves spot color gradients, the next toughest challenge. These values are not directly characterized in a spot color library, so they are modeled based on anything from simpler Lab formulas to spectral modeling based on printed samples of tints and overprints on black (to provide opacity information). The ideal case is to build a 3-D model, such as an ICC profile, of the actual colors involved, but takes a very capable profiling solution. Two well-known solutions lack a true n-color model, but cleverly stitch together a sort of 7-color space from 4-color sectors. These can work well for certain tasks
RGB image conversion is something any ECG solution should do well, yet when I did a test of most of the leading ECG solutions few actually performed well enough for high-quality reproductions, and some were truly dreadful. Flaws included rough gradients and posterization, or flattening of gamut-boundary colors. One leading solution lacks a perceptual rendering table in its profiles, with rather scary outcomes. I can share the results upon request.
There is no "Mike's software," only Mike, a humble worker toiling in the fields of practical n-color and other thankless tasks. I do work with some very good developers.
Craig's advice to try different solutions is good, but it may not be easily done, as these solutions are generally built upon a project that includes the pressroom and your prepress departments. That can be expensive in terms of down time alone, even if the labor is donated by a vendor you have a lot of business with. It might be more practical to submit a variety of files to be converted, and then require a proof (hard or soft) so you can evaluate the results (noting Craig's comment about the inability of Creative Site apps to preview results). This is a very tough test. Also take a "tour" of the solution and evaluate its friendliness and speed.
Mike
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Mike Strickler
MSP Graphic Services
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Original Message:
Sent: 12-17-2024 09:35 AM
From: Craig Maalis
Subject: Candidates for ECG (7-color process) Printing
Hi Jeremy,
Hi Mike, yes, it's been a few years!
There are a couple things to look for when converting to ECG.
If you have touch plates or bump plates with Pantone or any spot color, it increases the complexity as opposed to converting a solid vector artwork.
Photoshop doesn't do a good job of previewing ECG when retouching additional nChannel separations. You might need to work in RGB until you convert at the last moment and then compare your proofs to the actual calibrated monitor in RGB mode. There are software options for this but are fairly expensive last I checked. Also, nchannel icc profiles don't play well in most proofing rips. Message me if you need a workaround.
Also, the color conversion of gradients within a multichannel photoshop file can be a factor.
We did a test with 24 RGB files that had gradients going to ECG with three different softwares. The software all converted, and the gradients were very challenging. Stepping and artifacts within the gradients.
If you are only concerned about converting vector artwork, there are several solutions that will do a fine job. Xgamut by CGS is another option you could look at. It's an easy hotfolder workflow that can fingerprint your press to ECG and then convert on the fly to give you pdfs to ingest into your systems. There is also GMG OpenColor.
It depends on the size of your company, how many files you are pushing through the system and other factors.
We have a VM with 20 processors and loaded with RAM. Pushing through thousands of files per month. Kind of a color geek hotrod...
Good luck with your research. It can be difficult finding people that are experts or those that are willing to share in this.
Give Mike's software a trial and then get a 30-day trial from other vendors so you can compare cost and results of the files you are running through your system.
Last, Idealliance has recently produced some guidance for ECG and you should check into that as well. Here's a link:
https://idealliance.org/specifications/expanded-color-gamut-ecg-project/
Best regards,
Craig
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Original Message:
Sent: 12/12/2024 1:43:00 AM
From: Mike Strickler
Subject: RE: Candidates for ECG (7-color process) Printing
Hi Craig--Long time no talk to!
I just want to note that every commercial ECG solution has at least these two things in common: They do a decent job of converting solid spot colors and they all offer a predictive report in dE, so these are not really differentiators.
Ways in which they can differ include:
- Conversion of spot color tints and overprints
- PDF processing, including flattening and transparency handling, processing of embedding CXF/X-4 color data, processing steps, etc.; ability to process PDF-X4 and X5
- Flexibility in output (Yes, sometimes 7 or even more channels can be useful)
- Flexibility in input, e.g., making and processing multichannel devicelink profiles--including ability to reconvert ECG files for both production and proofing
- Reliance on industry-standard ICC profiles v proprietary color models
- Quality of RGB image conversions (an underrated capability)
- Ease of use
- Processing speed and use of multiple processing queues
- Availability of XML or JSON-based commands for automation
The list is not even close to exhaustive. Digital print presents special challenges, too, for example minimizing output channels to avoid press slowdowns and "click" charges, and the ability to have this calculated automatically without having to consult those predictive reports on every job. This is super-helpful when runs are short and job changeover rapid.
Most ECG solutions are built on pretty old bones, developed up to decades ago with only modest tweaks over the years, so one must really look carefully to see if they are keeping pace with today's needs.
Mike
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Mike Strickler
MSP Graphic Services
Original Message:
Sent: 12-11-2024 06:44 AM
From: Craig Maalis
Subject: Candidates for ECG (7-color process) Printing
Good morning, Jeremy,
I like the Alwan Color Hub system for this.
It does a great job with separations and has the option to predict by deltaE whether you need 4, 5, 6 or 7 plates.
Most ECG doesn't need all 7 based on the color of the spots which saves money.
It also does GCR while accomplishing this.
Good luck!
Craig
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Original Message:
Sent: 12/10/2024 9:38:00 AM
From: Jeremy Reed
Subject: Candidates for ECG (7-color process) Printing
Hello everyone,
I'm looking for some guidance on how to identify 'good' candidates to move from my current mix of spot and 4CP+spot color jobs to ECG. We are a paper packaging printer using wide format sheet-fed litho presses. What tools do you use to ensure that the given PMS colors will be achievable using ECG? What other pitfalls should I look out for? Any tools, tips or other advice as to how you have been able to navigate this process and move work to ECG would be most appreciated.
Thanks!
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Jeremy Reed G7 Expert
Pacific Southwest Container
Modesto CA
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