The printing of simulated spot colour with CMYK screens.

[Deleted member 16349]

I have a question to printers and it relates to the issue of printing simulated spot (or Pantone) colours with CMYK screens.

It seems there are some issues about this but I have a specific question.

If you had to print two or three of these simulated spot colours, directly in line with each other around the plate cylinder and in line with the control patches, would you have a problem getting a predictable result for all of them?

The example is framed this way because if one would only print a singe simulation, it would be easier for the press operator to move densities to get a reasonable result. If one has more than one of these simulations in line with each other, it would not be so easy to cheat by moving the densities.

Anyhow, I thought this would be an interesting question.

Thanks for any comments.

 

[chevalier]

Can you provide a visual aid to supplement your question? I encounter this a lot and I think I understand your question but don't want to provide bad feedback.

 

[Deleted member 16349]

Can you provide a visual aid to supplement your question? I encounter this a lot and I think I understand your question but don't want to provide bad feedback.

I don't really have a visual aid but I will try to explain it better.

Let's say we have two, three or more large rectangles that are lined up in a column on the plates and each rectangle is to be printed with a different Lab colour value. Kind of like printing packaging or labels but all the rectangles are different colours. For this example, the more different the colour the better.

Or like windows on a building. They all line up.

I hope this helps.

 

[gordo]

[snipped]I have a question to printers and it relates to the issue of printing simulated spot (or Pantone) colours with CMYK screens.

If you had to print two or three of these simulated spot colours, directly in line with each other around the plate cylinder and in line with the control patches, would you have a problem getting a predictable result for all of them?

The example is framed this way because if one would only print a singe simulation, it would be easier for the press operator to move densities to get a reasonable result. If one has more than one of these simulations in line with each other, it would not be so easy to cheat by moving the densities.

I was involved with some testing of this during the development of a commercial spot color simulation solution (4/C, 5/C, 6/C, 7/C process) and found that the simulations had close to the same variation as single spot colors. We used the technology one year to print our annual report using a different overall flat screen build simulation of a different spot color for each page (which fits your description) and had no issues. I've never heard a customer say they had a problem with that in live production.

Of course there are probably a number of reasons why this might be so. For example, we used FM screening (20 and 10 micron), our software screen tint builds, production printing was packaging and labels which tend to have a more averaged out over the sheet distribution of process ink usage, etc.

 

[chevalier]

The honest answer is "it depends". You need not even involve spot colors into the problem. Simply ganging up multiple items that are designed to be CMYK sans spot color conversions in this configuration causes problems. If you stack a blue item, a purple item and a green item on top of each other the same battle usually ensues. It really depends on the configuration, the press conditions and the press operator.

The central problem that I find in simulating any spot color is getting all parties involved to accept the fact that a precise match is unlikely even outside of the scenario that you describe. I advocate that one should generate a best alternative color within the (typically CMYK) gamut being utilized and make that the new target. This typically doesn't go over very well with anyone except prepress. The customer wants an exact match to their spot color (usually not achievable) and the press operator wants a spot color (usually not cost acceptable).

 

[chevalier]

@gordo

It sounds as if you had near laboratory level conditions, near unlimited access to computer resources and very knowledgable human resources to maximize the potential of success.

I definitely accept that if a plant is extremely organized, has the resources required and has the proper procedures in place that minimizing variances to those similar to printing with spot ink colors is possible. The problem is that is not the norm out in the wild.

 

[Deleted member 16349]

I was involved with some testing of this during the development of a commercial spot color simulation solution (4/C, 5/C, 6/C, 7/C process) and found that the simulations had close to the same variation as single spot colors. We used the technology one year to print our annual report using a different overall flat screen build simulation of a different spot color for each page (which fits your description) and had no issues. I've never heard a customer say they had a problem with that in live production.

Of course there are probably a number of reasons why this might be so. For example, we used FM screening (20 and 10 micron), our software screen tint builds, production printing was packaging and labels which tend to have a more averaged out over the sheet distribution of process ink usage, etc.

Thanks Gordon. I was not really thinking about the variability of the print during production. It was a question that was aimed more at the predictability of the colour when choosing the CMYK screen combinations for those multiple simulated colours. I have no doubt that the Kodak spot colour simulation would be effective due to the LUT approach I think it uses. But other than that Kodak technology, I figured that just the regular colour management methods normally used would be a problem.

 

[gordo]

@gordo

It sounds as if you had near laboratory level conditions, near unlimited access to computer resources and very knowledgable human resources to maximize the potential of success.

I definitely accept that if a plant is extremely organized, has the resources required and has the proper procedures in place that minimizing variances to those similar to printing with spot ink colors is possible. The problem is that is not the norm out in the wild.

We tested the system at commercial printers scattered around Canada, the US, Australia, Singapore, and the UK.
Most, but not all of the printers were trained on how to optimize their printing by the product development team I was part of. If you want to maximize the potential of success, as in any endeavour, you will need to invest some resources in developing some expertise. But it is quite doable and in fact has been done commercially for near a decade that I know of.
Here's a photo of one of the presses I tested on. It prints millions of breakfast cereal boxes (note the pressman's hair net):

A manual ink key setting Planeta. Hardly state-of-the-art. LOL

 

[Deleted member 16349]

We tested the system at commercial printers scattered around Canada, the US, Australia, Singapore, and the UK.
Most, but not all of the printers were trained on how to optimize their printing by the product development team I was part of. If you want to maximize the potential of success, as in any endeavour, you will need to invest some resources in developing some expertise. But it is quite doable and in fact has been done commercially for near a decade that I know of.
Here's a photo of one of the presses I tested on. It prints millions of breakfast cereal boxes (note the pressman's hair net):

A manual ink key setting Planeta. Hardly state-of-the-art. LOL

Looks like a lab press to me. At least the kind of labs I would be allowed into.

From your earlier comment regarding FM screens in your tests. I suspect that made a very big benefit.

By the way, I don't think the guy is wearing his hair net properly. It is not covering all his hair. Report him! What is this in my cereal?

 

[chevalier]

A manual ink key setting Planeta. Hardly state-of-the-art. LOL

Embarrassing. A lesson learned in jumping to conclusions.

If you want to maximize the potential of success, as in any endeavour, you will need to invest some resources in developing some expertise. But it is quite doable and in fact has been done commercially for near a decade that I know of.

I could not agree with you more. My commentary is based on my experiences and not what is possible.

 

[Ret Heidelberg Instructor]

Ret Heidelberg Instructor

Ret Heidelberg Instructor

I have a question to printers and it relates to the issue of printing simulated spot (or Pantone) colours with CMYK screens.

It seems there are some issues about this but I have a specific question.

If you had to print two or three of these simulated spot colours, directly in line with each other around the plate cylinder and in line with the control patches, would you have a problem getting a predictable result for all of them?

The example is framed this way because if one would only print a singe simulation, it would be easier for the press operator to move densities to get a reasonable result. If one has more than one of these simulations in line with each other, it would not be so easy to cheat by moving the densities.

Anyhow, I thought this would be an interesting question.

Thanks for any comments.

I was involved with a test that we tried on a SM52 Anicolor press some time ago. We took a QM DI file of a Pantone chart with numerous Pantone colors (forget the exact number) but it filled a 13 by 18 inch sheet with Pantone numbered patches. The results were amazing and because of the nature and consistency of the Anicolor print quality, I maintain that you could achieve excellent results. For example, you could take various corporate colors such as IBM blue, Waste Management Corporate Green, Campbells Soup Red and any other well known Corporate color. Line them on a sheet and with assigned pre-press values to create the CMYK screening and in my opinion the results would be more than acceptable. I hope this answers the question you proposed.

 

[Deleted member 16349]

I was involved with a test that we tried on a SM52 Anicolor press some time ago. We took a QM DI file of a Pantone chart with numerous Pantone colors (forget the exact number) but it filled a 13 by 18 inch sheet with Pantone numbered patches. The results were amazing and because of the nature and consistency of the Anicolor print quality, I maintain that you could achieve excellent results. For example, you could take various corporate colors such as IBM blue, Waste Management Corporate Green, Campbells Soup Red and any other well known Corporate color. Line them on a sheet and with assigned pre-press values to create the CMYK screening and in my opinion the results would be more than acceptable. I hope this answers the question you proposed.

It does not answer my question exactly but I totally agree and understand why the Anicolor press will perform this way. It is superior in this respect to the conventional press designs. With the Anicolor one can get a characteristic print conditions which is predictable which one can not get with conventional presses. It shows what the potential is for presses with respect to predictability of print.

This same level of performance can be obtained with other types of press designs that don't use anilox rollers and have the ability to run and adjust normal inks etc. The Heidelberg TOK press design comes close. I would have loved to have Heidelberg test my ITB technology on one of their old TOK presses. Consistent printing, not affected by water, etc. and predictable prepress to make the plates. But that is not likely to happen since Heidelberg does not do those kind of experimental tests. Or so their engineers have told me.

Thanks for commenting on the Anicolor performance.

 

[turbotom1052]

If I may jump in on this; if it is a simple question of can you run a multitude of simulated spot colors in line of each other on a cmyk form and have accurate results?

The answer is yes.

When you look at a cmyk Pantone conversion chart or book - digital or otherwise - the values for each color (cmyk) are listed and depending on your media, you may even get a swatch that can be used at press for matching. The representations of each Pantone color can vary in accuracy mostly depending on which color it is, but matching the target swatch on press is usually quite achievable. On a decent press, there shouldn't be too much ink starvation as I have seen entire image area solids lay down beautifully. So the question of whether or not the images are in line shouldn't be an issue. It's more so as to whether or not the imitated color looks like the Pantone color to begin with.

The cmyk values Pantone calls out to imitate the spot color is usually the problem in matching it and I have seen prepress come closer to matching an actual color by customizing the values over what is actually recommended. The idea is to shift your densities on press as little as possible (run the numbers) and let prepress decide what the colors should be, not the press. That way you can run the correct densities across the sheet for ideal trapping, drying, image quality, etc., job after job.

could not have said it better myself!!!

 

[Deleted member 16349]

The cmyk values Pantone calls out to imitate the spot color is usually the problem in matching it and I have seen prepress come closer to matching an actual color by customizing the values over what is actually recommended. The idea is to shift your densities on press as little as possible (run the numbers) and let prepress decide what the colors should be, not the press. That way you can run the correct densities across the sheet for ideal trapping, drying, image quality, etc., job after job.

This is what I was expecting but did not know how many printer have the problem. Yes they can be matched but usually only when prepress has to make custom values.

Since my questions was trying to imply if the matches could be obtained without custom values being made, I would say that your comment is stating that the matches can not be obtained without added customization.

I hope I understood your comment and thanks.

But in your example, you are initially using the Pantone suggestion for the cmyk values. I think most people would expect them not to be perfect since they would not represent your press and inks, etc.

Does anyone use the Lab values for the spot colour and then somehow pick the cmyk values form a source that represents how your separations are made?

 

[gordo]

Custom recipes are required to do CMYK simulations of Pantone colors for several reasons but the most important is that they must be generic since they cannot reflect the print characteristic of specific individual printshops. Pantone is a lot of things but they are not psychic.

In the steam-powered days printers could use their own color atlas (The Print Guide: The Color Atlas - helping designers to specify color) to derive a CMYK recipe to simulate a spot color by doing a side by side visual or measured comparison. It is possible to do the same thing using software - i.e. have custom recipes based on a given print characteristic then change the characteristic and have the recipes update automagically - but I don't know if that capability is available commercially.

You can use CIEL*a*b* values and an ICC profile to generate custom recipes (as one solution does), or use CIEL*a*b* values and a LUT (as a competing solution does).

You can also implement a spot color simulation based on a 4/C inkset or use an extended process inkset (5, 6, or 7/C process). Generally with an extended process inkset only 3 colors are used in the simulation recipe.

 

[BeauchampT]

I find that your raw supplies make a real difference.

We run an ink that, depending on the screening, gobbles up water significantly. This leads to some...unpredictable....dot gain in certain screen combinations. If I ran a blue, a purple, and a red in line with each other, the magenta ink would give me real issues as the dot gain would be way off for one colour and spot on for another.

As a side point...we ran FM and i did notice that this helped stabilize some of those color match issues on press. I rather liked it (although we didn't stick with it).

 

[gordo]

I find that your raw supplies make a real difference.

We run an ink that, depending on the screening, gobbles up water significantly. This leads to some...unpredictable....dot gain in certain screen combinations.

I don't know if this applies to your experience, but...
Pantone spot colors aren't typically formulated to be halftone screened or overprinted. When I worked with spot color simulation using an extended process ink set I, or the customers I worked with, worked closely with the ink supplier so that they formulated the inks so that they would work the way conventional process inks worked. Unfortunately, not every ink supplier "got it" which sometimes meant that the printshop had to source a different ink supplier.