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UCR using ICC color Profiles

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  • #16
    What do You mean by profiles You have been experimenting with? An ICC profile characterizes a given printing process. There exist standard ICC profiles, which can be applied to printing processes aligned to ISO 12647 family of standards, Gracol or SWOP specifications, and so on. If your process is aligned to some standard such as ISO 12647, you can use the standard profile which characterizes it as well as the process is aligned to the norm. If your process isn't aligned to some standard, it can be characterized by its custom ICC profile. An ICC profile characterizes a given process, i.e. it links CMYK and CIE L*a*b* for a particular combination of inks, substrate and printing press. The use of standard profiles presumes the use of inks conforming to ISO 2846 norm, paper conforming to one of the ISO Type 1-5, and press aligned to some (e.g. ISO 12647) norm aims. Experimenting with different profiles for one printing process isn't right because each profile is meant to characterize the process it was created for.

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    • #17
      I think he means he is experimenting with different device output profiles for his printer.

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      • #18
        Originally posted by arossetti View Post
        I think he means he is experimenting with different device output profiles for his printer.
        Okay, but profiles are meant to describe the behavior of one particular process (printer/press, substrate and ink). Applying different profiles to one printing process does not make sense since profiles are meant to characterize particular processes. For example, for a given aimed CIE L*a*b*, ISO Coated and ISO Uncoted Yellowish profiles will provide different CMYK recipes because those two processes (one using coated bluish paper, and one using yellowish paper) will require different CMYK inputs in order to achieve the same color, precisely quantified in CIE L*a*b* coordinates.
        Applying different profiles to one printing process is the exact opposite of the intended use. Applying different profiles to one printing process will give you different CMYK recipes for given aimed CIE L*a*b*, and non of them will achieve the aim since non of the profiles actually characterizes the given process.
        Last edited by ddonevski; 04-28-2017, 02:14 PM.

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        • #19
          So I can't speak for OP but what it sounds like is he has created several profiles for one press/ink/paper combo testing out different baked in GCR settings. I experiment all the time with creating different profiles for the same press/ink/media to see if I can get the same visual results while saving ink.

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          • #20
            Originally posted by ddonevski View Post
            What do You mean by profiles You have been experimenting with? An ICC profile characterizes a given printing process. There exist standard ICC profiles, which can be applied to printing processes aligned to ISO 12647 family of standards, Gracol or SWOP specifications, and so on. If your process is aligned to some standard such as ISO 12647, you can use the standard profile which characterizes it as well as the process is aligned to the norm. If your process isn't aligned to some standard, it can be characterized by its custom ICC profile. An ICC profile characterizes a given process, i.e. it links CMYK and CIE L*a*b* for a particular combination of inks, substrate and printing press. The use of standard profiles presumes the use of inks conforming to ISO 2846 norm, paper conforming to one of the ISO Type 1-5, and press aligned to some (e.g. ISO 12647) norm aims. Experimenting with different profiles for one printing process isn't right because each profile is meant to characterize the process it was created for.
            I have been trying out ICC Profiles based on Different paper types and Different levels of GCR.

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            • #21
              Oh... if so, it makes sense

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              • #22
                Originally posted by Nutech Shroff View Post

                I have been trying out ICC Profiles based on Different paper types and Different levels of GCR.
                So your profiles are different profiles made by some profile creation software?

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                • #23
                  The links to the articles posted by Stephen give plenty of historical background to the use of UCR/GCR but another paper by two Swedish researchers indicates that there is very little difference in the implementation these days (see link below). As the articles report these separation techniques have been around for a long time. In the pre-desktop age GCR was known by a host of other names e.g. Crosfiled called it Polychromatic Colour Replacement - PCR (or something like that). 'Ink saving' algorithms used in today's RIPs might use similar principles but you would have to ask an engineer about that as they are working with a greater number of inks.

                  I would add that the promise of saving ink is qualified by the fact that it is really only significant when you are using a lot of it in the first place. In other words, if your publication is a long run with lots of dark (low key) saturated images then saving ink might be significant cost saver however, if it is a catalogue of weddings dresses with little else then savings will be marginal. The shrinking run-length of todays publications is also a factor to be considered. These techniques were developed in an age when printing was done on a truly industrial scale and many publications had run-lengths in the millions.

                  'Advantages' can also be 'disadvantages'. For example, having less ink might reduce problems associated with high TAC and colour stability but it also gives you less room to compensate on the press by playing around with the amount of ink flowing onto the substrate. Of course, in this day and age of colour managed workflows age old practices like this have been eliminated ;-)

                  If I rummage through my archive of presentations I used as a teacher for many years I might find one that lists ALL of the advantages as well as disadvantages. For now, it's going on the 'to-do' list.

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                  • #24
                    Originally posted by ddonevski View Post
                    ...The thing is, we only need three variables (CIE L*a*b* or XYZ) to specify the color, but we have four inks at our disposal. The presence of K, in addition to the ability to render dark colors not obtainable by CMY alone, also provides the ability to replace some of the CMY combinations (gray component present in them) with K....
                    Great premiere post, ddonevski. I'd say that sums it up very well. Welcome to the forum!

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                    • #25
                      Originally posted by ddonevski View Post

                      How does this contradict my statement? We agree that they (UCR and GCR) differ in how far from absolute neutrals they introduce Black. UCR operates in near neutrals and is therefore a subset of GCR. GCR takes it (in addition to near-neutrals) a little further and applies black farther from near-neutrals, or as You stated, "It applies wherever the 3 chromatic (CMY) colors print together.".

                      I can't see any disagreement between our statements.
                      I did not intend to contradict your statement. My post was to clarify and add to it. Apologies if that wasn't clear.
                      Last edited by gordo; 04-28-2017, 07:31 PM.

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                      • #26
                        ddonevski
                        I have read your post, that is a very interesting topic for me and please explain more about the dynamic ink saving software:
                        "...Static ink saving software: Static ink saver typically uses a pre-calculated device link (input CMYK to output CMYK) and applies it consistently, regardless of image content.

                        Dynamic ink saving software: Dynamic ink saver analyzes the local activity for each pixel to determine the amount of GCR. Image areas with high local activity mask possible noise and therefore allow greater amounts of GCR. Smooth image areas are prone to the appearance of visible artifacts and therefore allow smaller amounts of GCR...."

                        If I right understood, the dynamic ink saving software will put high amount of GCR in high ink CMY area and smaller amount of GCR in lower ink CMY area, am I right? Is it the way that Alwan Color Hub works?
                        I have tried by putting high GCR in destination CMYK colorspace in "convert to profile" function of Photoshop. In this function, I can adjust the curve that I will not use GCR in <20% dot area, and set high GCR from 20% to 70% dot area.
                        So could you please tell me how advantage of the dynamic ink saving software (I suppose Alwan Color Hub) compared to the way I did in Photoshop?

                        Thank you!
                        Regards,
                        DeltaE

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