Automatic GCR software

[Louis Dery]

Hi Gordo,
Very good resumé about ink saving and evaluation and consideration of offerings avalaible!

About "Is the process accomplished outside of the workflow in a separate box?"
What do you think?
What is the future… built-in?

Many RIP workflows allready have ICC DeviceLink compatibility… (Prinergy, Apogee, etc.) but not everyone know how to make it to work and/or have the tool to create ICC devicelink.

Louis Dery
TGLC inc.

 

[gordo]

Hi Gordo,
About "Is the process accomplished outside of the workflow in a separate box?"
What do you think?
What is the future… built-in?
Many RIP workflows allready have ICC DeviceLink compatibility… (Prinergy, Apogee, etc.) but not everyone know how to make it to work and/or have the tool to create ICC devicelink.

Based on my experience speaking with printers....
The preference is to have the reseparation built-in. As you say, many workflows have device link compatibility but not every workflow vendor offers a viable/useable/affordable solution. As a result printers are quite willing to implement a non-built-in solution. The ROI makes it a no-brainer. That being said, they will likely switch to a built-in solution if one does come along from their workflow vendor.
Some don't mind their customers seeing (perhaps through online soft proofing) that they have reseparated the images ("Yeah, we've optimized your images so they look as good as possible") others prefer late binding i.e. their customers don't know reseparation has occurred, since, if done correctly, reseparation shouldn't affect the appearance of the final presswork - so the customer "doesn't need to know."
Plus, if the customer knew what had happened they might request a discount on presswork based on ink savings. :-(

gordo

 

[michaelejahn]

Ink Savers and shorter make ready times

Ink Savers and shorter make ready times

I have read the posts on this thread and would like your help to settle a debate I'm having on when GCR/UCR can be applied, as well as better understand how to calculate the economics of using GCR/UCR technologies.

Applying GCR Debate
I'm a newbie to the print world. My friend is a 20 year prepress veteran. My friend's experience is primarily in programs like PhotoShop, InDesign and Quark, but has experience in print workflows.

When I read about GCR/UCR tedhnologies, it appears to me the GCR/UCR formulas are generic to anything using CYMK inks. My friend insists that GCR/UCR is unique to images being converted from RGB to CYMK color space.

"Retain black (GCR/UCR) is something that happens when the RGB image passes through L*A*B where the black channel that did not previously exist is created before it goes into CMYK. You cannot apply retain black to an image that is already CMYK. To do that, you would have to convert the image from CMYK back to RGB, then BACK through L*A*B to CMYK again. "​

[/QUOTE=pnkearns;101874]

Jahn comments -- Well, that would assume that everyone in the software development world would only be limited to using the ICC aproach, which is not always the case. Yes, it is very popular to use Adobe Photoshop to separate RGB files to CMYK using a custom profile - and this would pass that RGB image through LAB as the Profile connection Space (PCS) - using (most often) Adobe ACE (Adobe Color Engine).

One could also set up a workflow that consumes CMYK images, and then, pssing them back through RGB - or LAB - would make a new CMYK image.

Many Color management vendors do this "plus" some Look Up Table (LUT) conversions - so, this is sort of a hybrid approach - where they use Algorthms and image processing tricks.

At IQColour, we do not happen to depend ONLY on the ICC approach. We pass images through a unique and custom transform - and we also do not use LAB color space as the intermediate space, we use IJK and a custom space that can be read about under the Resources menu at the iqcolour.com web site.

Finally, the examples at IQ Color, Inc., posted in this thread earlier by Michael Jahn are all RGB --> CYMK, even though he implies he has done some CYMK --> CYMK work. So my friend may be right or wrong. [/QUOTE=pnkearns;101874]

Jahn comments - IQColour can convert RGB to CMYK, and CMYK to CMYK. I can post samples here I guess, but most of the samples I have posted thus far have been at the Sterling Ledet "colortheory" forum moderated by Dan Margulis.

Can GCR/UCR be done on an existing CYMK image to reduce ink?

-- why, yes - you can do this using Adobe Photoshop or many of the fine Device Link Profiles (DVL) offered by the many developers - just search Google for Ink Saver - Alwan, GMG, CGS and many others offer solutions...

Can GCR/UCR be done on either RGB or CYMK vector data?

-- why yes, absolutely - you could call this 're-separating'

GATF is cureently doing 2nd set of studies on this subject - they will be comparing different approaches and reporting on many factors related to ink savings and make ready times -- stay tuned !

 

[michaelejahn]

Where to re-separate ?

Where to re-separate ?

Based on my experience speaking with printers....
The preference is to have the reseparation built-in. As you say, many workflows have device link compatibility but not every workflow vendor offers a viable/useable/affordable solution. As a result printers are quite willing to implement a non-built-in solution. The ROI makes it a no-brainer. That being said, they will likely switch to a built-in solution if one does come along from their workflow vendor.
Some don't mind their customers seeing (perhaps through online soft proofing) that they have reseparated the images ("Yeah, we've optimized your images so they look as good as possible") others prefer late binding i.e. their customers don't know reseparation has occurred, since, if done correctly, reseparation shouldn't affect the appearance of the final presswork - so the customer "doesn't need to know."
Plus, if the customer knew what had happened they might request a discount on presswork based on ink savings. :-(

gordo

@ Gordo

In different workflow environments - well - it is always different!

I can think of several instances that people do not want to do this in a RIP, and (like screening or trapping) can certainly see advantages where this ink-saver faster make ready gadget would best be at the RIP stage. I also know that many customer insist on doing conversions on individual images - while others require conversion of PDF files - single or multi-page PDF files.

For example - the editorial photographer at a newspaper transmits images from his camera system from the feild - these images could stay in RGB, placed in some authoring application as RGB - then the image could be made the the appropriate CMYK at the RIP. If the newspaper suddenly switch to a different stock or different press or ink with different Ink Tack (no - not ink TAC) you know, where the inks viscosity has changed - well, these all must be accounted for when one creates a new approach to color separation, agreed ?

On the other hand, there are archives of images that have been stored in CMYK. When anyone famous dies, out come the old images (all the publishers went through this drill when Paul Neuman passed away) - so, there would be an example where we needed to do a CMYK to CMYK conversion - again, perhaps at the RIP, perhaps on an image (with a review of the result in Photoshop)

The challenge in a newspaper environment is of course color ads walking in as PDF - are they PDF/X1a ? Were they made with SNAP in mind, or are they SWOP separations - companies like ALWAN offer an amazing array of options, switches, levers - even the ability to modify UnSharp Masking (USM) - Dynamic conversions - which enable the incoming PDF files to be in nearly any condition and then be "normalized" to a specific press requirement - in this case, 're-separated'.

So - where you put this gadget depends on the workflow - IQColour has customers that insist on RGB to IQ CMYK (via a droplet) - RGB/CMYK to IQ CMYK (via Photoshop Action) and others who want to convert an entire edition of a newspaper - PDF CMYK to new PDF with IQ CMYK

No one can really dictate where the conversion takes place - it is up to the customer.

 

[gordo]

No one can really dictate where the conversion takes place - it is up to the customer.

I agree. What I was trying to simply point out was that those options exist and need to be considered by the customer when choosing a solution. That being said, every printer that I've spoken to (magazine and newspaper), even those that have already implemented a reseparation solution where PDFs exit their workflow, get processed, then re-enter their workflow, have told me that if they could get a viable solution integral with their workflow they would, rightly or wrongly, switch. Simplicity in the production flow, particularly in a newspaper environment, seems to be of paramount importance.
The range of reseparation solutions available from the various vendors is pretty wide - all the way from a simple device link for a few hundred dollars to "all singing all dancing" complex ones that cost tens of thousands. IMHO, printers considering this kind of solution should, when doing their evaluation, separate the workflow part of the vendor's offering from the technical/functional part. i.e. where/when does the processing take place vs did it process it to their satisfaction. Some people many want a drop in solution (even though, from a vendor's POV it's inadequate)- others want levers and switches to fiddle with (even though they may never use them once the system is installed).

best, gordo

 

[michaelejahn]

@ kaiserwilhelm (and any other Newspaper)

Our Newspaper customers have varried workflows - editorial is submitting tagged and 'mystery meat" untagged RGB images - the designers who build ads in house have some level of control and follow the procedure, but submitted ads come in all over the map - SWOOP, some SNAP, some separated with some custom GCR setting applied on images in Photoshop, some as PDF files that have been passed through some Device Linked profile - as I said, this all depends on what they bought 5 years ago (often Acrobat 5, some old moldy rip, who know what clasified or ad system or what pagination / editorial system !)

Anyway - yes, you are correct - anyone could indeed create a custom ICC profile (not sure you can 'export' one from GMG, CGS or Alwan that will "work" with that Fuji Trueflow RIP BTW) - but lest assume you created a 'special' ICC profile (a DVL - Device link Profile) and lets say you could upload it to your rip and lets say that magically all the people that ever submitted a PDF file used the exact same seetings in Photoshop and in InDesign and all made perfectly ready to rumble SWOP files - then, you are absolutely right, when you know what is comong in door "A", and the PDF files are ALL THE SAME - then you can use that single DVL "B" - and live forever happy.

Okay, well, I don't know about you, but i certainly don't live in that world !

This is why CGS and GMG "optimize" - and this is why you need someone like Matt Beals to show up and set up that ALWAN or that Eplical or that SWTICH workflow - depending on what walks in YOUR door - you may indeed need what they like to refer to as a DYNAMIC DVL - where the file is analyzed and then converted.

On the other hand, IQColour takes a different approach, as we do not really use the traditional method of using a CMM and a profile to convert an RGB or CMYK data through LAB color space and apply some ICC profile to it and make a new CMYK data.

Would love to convert some files for you or set you up with a trial so you might test it yourself.

email me at [email protected]

 

[pnkearns]

Ink Savings - Newbie Questions Follow on

Ink Savings - Newbie Questions Follow on

Gordo,

Thank you for your response.

The information is very helpful. I have started to experiment with the TGLC tool you recommended. I am also collecting information on the various GCR software applications recommended in another thread on this board, under the topic thread, "I want to try GCR software but..."

I am still curious though. The examples of GCR I have run across all deal with RGB images --> CYMK + GCR images. The GCR always seems to be shown as part of a RGB image --> CYMK image conversion process. Even the examples of GCR at IQ Color, Inc., posted in this thread earlier by Michael Jahn are all RGB image --> CYMK + GCR image. Is there some reason why GCR on existing CYMK images (CYMK --> CYMK + GCR) or GCR on vector data (RGB or CYMK) seems to be rare?

Again, my thanks for your assistance.

Patrick Kearns
[email protected]
Niyi.org (a future graphic arts online community web site)

 

[pnkearns]

Michaelejahn,

Thank you for your reply. I will check into your recommendations.

Let me repeat a question I asked Gordo above. This is more for my general knowledge than anything else. Is there some reason why GCR on existing CYMK images (CYMK --> CYMK + GCR) or GCR on vector data (RGB or CYMK) seems to be rare?

Again, my thanks for your assistance.

Patrick Kearns
[email protected]
Niyi.org (a future graphic arts online community web site)

 

[gordo]

Let me repeat a question I asked Gordo above. This is more for my general knowledge than anything else. Is there some reason why GCR on existing CYMK images (CYMK --> CYMK + GCR) or GCR on vector data (RGB or CYMK) seems to be rare?

From my experience, the ability to do CMYK-->CMYK reseparations to a level of quality where the presswork maintains its appearance even though the separations are now quite different has only become possible in the past 3-5 years or so.
The primary market for the technology is for newspapers, the second would be publications work. This is because of their need to reduce production costs wherever possible as well as to bring some level of consistency to the separations that go out to the pressroom in order bring some degree of order to production.
Newspapers, I think, more than any other market, receive the greatest variety of files that were not prepared for their production process or who have to deal with a chaotic mix of files purposed for who knows what. Not only that, they're under brutal production time restraints and they don't get a second chance to make good if there's a problem on press. An upset advertiser will cost them dearly.
Unfortunately, again in my experience, newspaper prepress departments tend to be very...how should I put it...unsophisticated...basic....intuitive.... I've only visited about 30 or so prepress departments in newspaper printers in N America and 3 in Australia – these were large metro dailies as well as small town weeklies...every one of which relied on one or more gurus with "golden eyes" to massage the images in PShop so that they would print well. In almost every case, the settings in PShop were the default ones that came when the application was installed. So it's a bit more of an uphill battle to make changes in their process.
That being said, the newspaper market is very keen to get their process turned around and are very rapidly adopting the ink saving technology. The adoption is happening, and it's happening fast.
Same is true for publications printers - but not quite as fast. Many remember being burned by GCR on press in the old days (circa 1970s).
As I think I mentioned, it's not just a case of reseparating images or flats with the application of GCR - there are potential press side issues. For example, in newspaper work Yellow is often laid down first. This helps seal the paper a bit (yellow typically being the largest component of a separation) which in turn reduces the following inks from soaking as much into the paper. That results in a bit more vibrancy in the color. With heavy GCR that yellow functionality is gone. Also, in newspaper work the black ink that's used is pretty close to...soot. Very cheap and poor quality. But with heavy GCR the quality of the black printer is critical to success.
In publications work, as with commercial, yellow is last down. This provides a certain varnish effect to the image and enhances its vibrancy. Heavy GCR would reduce that effect.
That is why I suggest that this solution will likely involve more than just a cmyk transform in prepress. Make sure that is you go this route that either your vendor of choice can support you in the pressroom or that you have the skills yourself or that you have access to a competent consultant.

best, gordo

 

[otherthoughts]

Same is true for publications printers - but not quite as fast. Many remember being burned by GCR on press in the old days (circa 1970s).
As I think I mentioned, it's not just a case of reseparating images or flats with the application of GCR - there are potential press side issues. For example, in newspaper work Yellow is often laid down first. This helps seal the paper a bit (yellow typically being the largest component of a separation) which in turn reduces the following inks from soaking as much into the paper. That results in a bit more vibrancy in the color. With heavy GCR that yellow functionality is gone. Also, in newspaper work the black ink that's used is pretty close to...soot. Very cheap and poor quality. But with heavy GCR the quality of the black printer is critical to success.
In publications work, as with commercial, yellow is last down. This provides a certain varnish effect to the image and enhances its vibrancy. Heavy GCR would reduce that effect.

GCR in the 70s? That's quite some time ago I should think. I submit that GCR in the 70s was just a concept yet to be implemented with any breadth (although much beloved).

I have some trouble with the use of "Vibrancy" to describe the effects of GCR on the Yellow newsprint printing plate. GCR should only affect the neutrals and the blue areas of an image with respect to a yellow printing plates coverage, for it is only therein that a Gray Component exists to be replaced. I suspect that a fuller black printer would provide more "Shape" to the image. The decline in overall, overprint ink film density, particularly in the more neutral shades, resulting in lower reflectance in the shadows and therefore lower gloss might constitute loss of "Vibrancy" if we all agree that it is so.

I have the same issue with the use of "Vibrancy" regarding publications and commercial work. I am just saying that we should all agree to the meaning of a term, so that we are all on the same page.

 

[gordo]

GCR in the 70s? That's quite some time ago I should think. I submit that GCR in the 70s was just a concept yet to be implemented with any breadth (although much beloved).

I have some trouble with the use of "Vibrancy" to describe the effects of GCR on the Yellow newsprint printing plate. GCR should only affect the neutrals and the blue areas of an image with respect to a yellow printing plates coverage, for it is only therein that a Gray Component exists to be replaced. I suspect that a fuller black printer would provide more "Shape" to the image. The decline in overall, overprint ink film density, particularly in the more neutral shades, resulting in lower reflectance in the shadows and therefore lower gloss might constitute loss of "Vibrancy" if we all agree that it is so.

I have the same issue with the use of "Vibrancy" regarding publications and commercial work. I am just saying that we should all agree to the meaning of a term, so that we are all on the same page.

To my knowledge, GCR was introduced with much fanfare in the late 70s and early eighties along with the first digital scanners. It was adopted for the same reasons it is being promoted now. However it fell into disfavor - to the point where ad submission guidelines from the major magazine publishers would state that ads separated using GCR would be rejected. (I was a creative director of a national ad firm at the time and it happened to me). This was not reseparating (a whole other level of complexity) which is what is being adopted now.
GCR replaces the gray component wherever three chromatic colors appear together - not just along the neutral axis. There tends to be a great deal of Yellow, in a UCR separation, used throughout any given image. Reducing the amount of Yellow available through the application of Heavy GCR, will potentially have an affect on presswork – unfortunately I don't believe there has been any independent, published, research done in this area. Which is why I used caveats such as "potential" "possible" "may be" in my posts. I'm speculating on some issues to think/watch out for that may, or may not turn out to be a problem in implementation. I know that the quality of the black printer on press is crucial to success, and I also know that the black ink used in newspaper printing is very often a poor grade of ink. So it becomes an area of potential concern.
I was using the word "vibrancy" to mean the qualitative loss of contrast, gamut, chroma, tone range - which I think is an acceptable use. Similar to how you would the difference between an image printed on uncoated vs coated paper. If you can suggest a better word, I'll use it.


Best, gordon p

 

[otherthoughts]

Gordon, I think we can both agree on the introduction of the GCR time-line. I always liked the idea of GCR myself.

I meant no offense to you with my concerns over the term vibrancy. I agree with the vast majority of what you spelled out in your posts.

I however prefer the terms you used near the end of your most recent post much better "contrast, gamut, chroma, tone range", rather than vibrancy. I just think that these terms are much more commonplace and well defined.

GCR is exactly as you explained it above (although much more elegantly than I).

UCR is Under Color Removal and only affects the neutrals, as you stated. I think we both agree up to here. What I am not sure about is what you meant by the statement, "There tends to be a great deal of Yellow, in a UCR separation, used throughout any given image." I think that what we both want to say here is that whether we are using GCR or UCR (more so w/GCR), our yellow printing plate will print less ink, when compared to a non-GCR/UCR separation. If we both agree here, we are Golden.

 

[Louis Dery]

GCR replaces the gray component wherever three chromatic colors appear together - not just along the neutral axis. There tends to be a great deal of Yellow, in a UCR separation, used throughout any given image. Reducing the amount of Yellow available through the application of Heavy GCR, will potentially have an affect on presswork – unfortunately I don't believe there has been any independent, published, research done in this area.
Quality In Print

Hi Gordo,

Can you tell me from which GCR profile, or application or else are you refering about this more important Yellow reduction compared to Cyan and Magenta?
I’ve tried many images with max GCR (from PerfX) and i always endu up with allmost the same ink reduction for CM and Y.

Louis

 

[gordo]

What I am not sure about is what you meant by the statement, "There tends to be a great deal of Yellow, in a UCR separation, used throughout any given image." I think that what we both want to say here is that whether we are using GCR or UCR (more so w/GCR), our yellow printing plate will print less ink, when compared to a non-GCR/UCR separation. If we both agree here, we are Golden.

Yes I agree. We're golden.

Louis wrote:
"Can you tell me from which GCR profile, or application or else are you refering about this more important Yellow reduction compared to Cyan and Magenta?
I’ve tried many images with max GCR (from PerfX) and i always endu up with allmost the same ink reduction for CM and Y."

I'll use "vibrancy" to avoid being redundant with "contrast, gamut, chroma, tone range" - but that's what I mean with the word.
I think this is where the misunderstanding is happening. What happens on press is not the same as what happens in a separation or on a proofer. Yes, with GCR, Magenta and Cyan are being reduced along with the Yellow. What I'm pointing out is that the Yellow printer does not just have a chromatic role to play in a process separation, particularly in newspaper work, but also to a somewhat lesser degree in commercial offset. If you reduce the amount of Yellow ink being laid down you might reduce this other mechanical role and hence the final "quality" of the reproduction. In newspaper work, Yellow is very often first down with Black last - the opposite of commercial work. Laying Yellow down first helps to seal the absorbent paper helping to reduce Cyan and Magenta from sinking into the paper. you'll see a variation of this effect when commercial printers print a varnish first down on uncoated paper to get greater "vibrancy" in their separations on that type of paper. It helps the ink sit on top of the paper as f the paper were a coated sheet. I'm suggesting that if the Yellow ink is reduced (obviously along with Cyan and Magenta) there will be less Yellow ink to seal the paper. Hence the Cyan and Magenta will likely sink into the paper with the final result losing some potential "vibrancy" compared to a UCR separation.
On the commercial side, because there is usually a large amount of yellow in a separation, it is run last down. If it was run first down on a gloss stock, Cyan and Magenta would have trouble sticking to it. Also, since it makes up such a large proportion of the separation and because it's relatively transparent as an ink - it acts effectively as a varnish to the images on press. Lose that through GCR and the image could end up a bit duller. (Note the amount of Yellow - even in the blues)
Here's an image to illustrate what I'm talking about:

On the left is the original image.
In the center is the Yellow printer from a UCR separation - note the coverage.
On the right is the Yellow printer from a GCR separation - note the reduction in coverage and hence the possible reduction in the Yellow printer's mechanical function - less Yellow to seal the paper, less Yellow to provide a varnish effect.
I'm not saying that one should not do reseparations to apply GCR techniques. I am saying that there is more to the process than a "simple" transform or lever in a workflow. Anyone contemplating this strategy should consider those potential consequences and their response, and vendor support, if an issue arises.

Hope that's a bit clearer.

best, gordon p

 

[meddington]

Hi gordo,

In the scenarios you mention above, had the newsprint/commercial printers undergone custom press profiling, or were they using standar or generic cmyk/GCR separations (adobe defaults)? Would it be your opinion that modern GCR application involving custom press profiles would suffer from the "vibrancy" issue you speak of? After all, in addition to reduction of the achromatic components, there are chromatic adjustments as well to maintain the original measured CIELab values (its more than just black substitution).

And with custom profiling, much is known about the print characteristics of the device...including to a degree how the paper takes ink without a yellow "sealant". GCR applied via icc profiles or DVLs won't alter the cmy separation values to the point where significant deviations in measured cielab occur, and if the press prints as it did on the day of profiling, this should result in the same visual sensation...or at least a result that measures very close to the target cielab values.

Wouldn't any current GCR application have its success weighted more on accurate profiling in addition to the ability of the press/press operators to print consistently toward predetermined targets?

mike

 

[gordo]

My personal experience is too narrow to provide a meaningful answer to your questions. I've seen examples where the instruments indicate a good match but the eyeballs disagree. Also, there is a broad range of vendor offerings, from DLVs derived from industry supplied profiles, to DLVs based on custom profiles that ignore the press condition, to ones where experts go into the pressroom to validate the press condition before running a characterization form. Also, I haven't seen a published comparison of, say, the top 10 solutions out there, where some of this info could be provided. Unfortunately there is no independent organization in this industry that would evaluate and report on the various offerings. Even though the primary market for reseparation is newspapers, the marketing material from several vendors, that I've seen shows the pre and post reseparation being applied to images printed sheetfed offset on gloss coated paper.

Your post does bring up the issue of sign-off. I.e. what constitutes a successful installation of a reseparation solution? Eyeball OK?, Measurement data?, Percent of ink savings? All 3? Or?

best, gordo

 

[Alois Senefelder]

"Compensation by Black - a New separation?"

"Compensation by Black - a New separation?"

Hello - Mr G. Pritchard and Mr M. Meddington

Hopefully of interest the following PDFs


Regards

Alois

 

[Louis Dery]

My personal experience is too narrow to provide a meaningful answer to your questions. I've seen examples where the instruments indicate a good match but the eyeballs disagree. Also, there is a broad range of vendor offerings, from DLVs derived from industry supplied profiles, to DLVs based on custom profiles that ignore the press condition, to ones where experts go into the pressroom to validate the press condition before running a characterization form. Also, I haven't seen a published comparison of, say, the top 10 solutions out there, where some of this info could be provided. Unfortunately there is no independent organization in this industry that would evaluate and report on the various offerings. Even though the primary market for reseparation is newspapers, the marketing material from several vendors, that I've seen shows the pre and post reseparation being applied to images printed sheetfed offset on gloss coated paper.

Your post does bring up the issue of sign-off. I.e. what constitutes a successful installation of a reseparation solution? Eyeball OK?, Measurement data?, Percent of ink savings? All 3? Or?

best, gordo

new blog: Quality In Print

Hi Gordo,

I agree with you about the need of a published comparison of the ink saving offering.
Specially about real tests on press. Many made their GCR in order to save ink or to match idealized characterization data. When comparing theorical numbers or only with a digital proof, this does not show up how it can be used on printing press in real life operation.

About what constitutes a successful installation of a reseparation solution:
–Eyeball OK: this is what advertisers are looking for.
–Measurement data: a way to get an objective validation of the whole thing.
–Percent of ink saving: yes, but the proper way.
–Printability: many can show up % of ink saving in files but this does not validate that it is easily printable in day to day production. Yes pressman have to take care of the black ink when printing, but is this sometimes, beacause of bad GCR algorithm? I’ve seen comparative print run that shows this behavior many times!
–Workflow integration: as simple as possible! This is a must.

About marketing material, you are right. Try to find downloadable images with before and after ink saving, with low TAC at 240 or bellow (other than from our web site).

Have an great year 2009!

Louis Dery
TGLC inc.
TGLC Color Management and Color Control Solutions: PerfX Softwares, Training, Implementation, Certification

 

[gordo]

Hello - Mr G. Pritchard and Mr M. Meddington
Hopefully of interest the following PDFs Regards Alois

Thanks for forwarding the PDFs. I'll have to read the original document more thoroughly. However, at first read I cannot agree with her key conclusion. She writes (my emphasis in bold):
"The tests [SNIP] generated similar results for UCR and for the lowest level of GCR. It is difficult to draw a border between these two separation types. UCR is really a “light type”of GCR or “GCR level 1”
Then:
"Discard the term UCR and use only GCR, as it really only concerns gray component replacement. This would make it easier for people in the business to focus on the process itself instead of trying to understand the difference between the two types of separations, a difference which cannot be seen visually."

Well maybe for the lowest level of GCR - but that's not what people use. Here's an example - rather than use the lightest type of GCR - I've gone to the max to exagerrate the differences - which is also more relevant to the GCR reseparation technology we're talking about.
Below, on the left is the original RGB image. Center top CMY from a UCR separation, center bottom CMY from a GCR separation. Top right the K from the UCR separation and bottom right the K from a GCR separation.

I think that, in fact, the differences can easily be seen visually by anyone.
In the steam-powered days of prepress when GCR first started to be used, it was even easier to tell the difference just by looking at the supplied film. That's how the publications folks could tell the sep was done GCR rather than UCR and thereby reject it.

best, gordo (not affiliated with Kodak)

 

[gordo]

Hi Gordo,

[SNIP]
–Printability: many can show up % of ink saving in files but this does not validate that it is easily printable in day to day production. Yes pressman have to take care of the black ink when printing, but is this sometimes, beacause of bad GCR algorithm? I’ve seen comparative print run that shows this behavior many times!

Hi Louis, I don't think a press knows about algorithms
I think the problem stems from the poor quality of the black ink that is often used in newspaper work. Because the GCR separation has a much larger component of black ink - any issues will therefore be magnified.

best, gordo (not affiliated with Kodak)