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Thread: Halftone angle correction in Fiery?

  1. #1
    GarethO is offline Senior Fiery Forum Contributor GarethO is on a distinguished path
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    Default Halftone angle correction in Fiery?

    I have been noticing issues with print quality and ran a series of tests.

    The issue turned out to be with the halftone pattern applied in the RIP.

    We are running a Canon C6000 Imagepress with an A1100 server.

    The gradation adjustment prints printed straight out of the machine do not have a pattern or any issues, so I know it is not the printer at fault.

    The issue arises when the pattern is applied in the RIP.

    The worst and most obvious issue, is that there is magenta in the yellow channel.

    The lesser, but still serious issue is that the yellow and magenta channels seem to use the same angle. The red and blue channels are also at the same angle.

    (here is a scan of the pattern)

    How do I remove the magenta from the yellow channel, what angles should the RIP be applying and how do I adjust to those angles?
    Last edited by GarethO; 10-01-2014 at 11:08 AM.

  2. #2
    shmegenke is offline Fiery Forum Expert Contributor shmegenke is on a distinguished path
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    If you have the Graphic Arts Package on this system, you should be able go into the color setup via CWS and make the changes via "Halftone Simulation" then select the screen via the driver or job properties in CWS.
    See screenshot below.

    For the Magenta in Yellow channel problem, where did that color chart come from?

    If you send a CMYK job with only 100% yellow do you still see the problem?



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  3. #3
    GarethO is offline Senior Fiery Forum Contributor GarethO is on a distinguished path
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    Thanks for your reply. No we do not have the graphic arts package. It would be nice, but an expense we don't really need. Surely I don't need an add-on to get a correct halftone?


    That pattern was printed via PS test page in Command Workstation. But I get the same results printing CMYK targets sent to the Fiery.

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    oxident is offline Fiery Forum Expert Contributor oxident is on a distinguished path
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    Even I'm absolutely not familiar with Canon this looks like a huge problem. 50% yellow should definitely not contain any magenta.

    Maybe there's a problem with the color workflow setting in general or the output profile in specific. Did you make any changes within color setup?
    What kind of output and simulation profile do you use?
    IC-306 v3.01 FS100 Pro / KM C6000, IC-308 v2.1 FS150 Pro / KM C71hc / SD-513, IC-414 / KM C754
    CWS 5.8 SP2, Windows 10 x64

  5. #5
    GarethO is offline Senior Fiery Forum Contributor GarethO is on a distinguished path
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    So I changed the output profile and so far it doesn't make a difference.


    I did manage to get the halftone a bit better by changing the diffusion to high res / high res.


    The issue with the colour (magenta in yellow) seems to be completely at the RIP end. When I print via the driver, turn colourwise off or to none and make acrobat control colour the colours are amazing compared to the RIP output.


    I will look into this further.

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    Please list out your current color settings on the Fiery. The CMYK Simulation profile can also affect this - for example if you are using SWOP coated, it will almost certainly contaminate the yellows, in order to compensate that the yellow toner is much brighter than the yellow ink defined in SWOP coated profile.

    If you are not trying to simulate any other CMYK device, but simply want to take advantage of the full gamut of your printer, try printing with CMYK Simulation: None.

    Regards,
    Greta.

  7. #7
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    Default Halftone Simulation

    Just to clarify some of the questions above - Halftone Simulation (included in Graphic Arts Package) is only a simulation - it simulates the halftone of another printer. It does not change the original screening pattern that we use to print to your Canon printer.

    To change the printer screening, you need to go to Image Quality tab, and select 'Printer's halftone'. Under this dropdown you should see options like 'Resolution, Gradation, Error diffusion', etc. These are different screening patterns specific to your Canon printer. Other models may have different options.

    These options won't change your muddy yellows though, for that see my post above.

    Hope this clears things up!

  8. #8
    GarethO is offline Senior Fiery Forum Contributor GarethO is on a distinguished path
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    I tried what you mentioned re the source profile Greta and that has cleaned up the process colours amazingly. I assumed incorrectly that the Fiery would convert embedded source profiles if they were present. Selecting none is very confusing. It was a good idea to add that check box in the newer Fiery versions.


    I am not sure why the angles are strange for my halftones, but that is an engine issue, which I have addressed, it has nothing to do with this forum so I wont go into detail.


    My issue now is magenta in Pantone Process Yellow C.


    Inspecting a Pantone target in Acrobat Pro shows the spots are correctly embedded. However when I print with "spot color matching" selected and leave the printer to manage colour there is magenta in the Pantone Process Yellow C, which according to my Pantone book should be 100% yellow.


    Target here ftp://ftp.onyxgfx.com/TechSupport/Sa...ss%20Color.pdf


    When I inspect the spots in Command Workstation I think I am using outdated ICCs and may need to update my spot LUTs. Is this possible?

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    Default RE: Halftone angle correction in Fiery?

    Coming to this a little late. Can you tell me again what you told Greta? Specifically, what profiles are you choosing for CMYK, RGB, and what is your output profile.

    The PDF you sent will not use spot colors on the Fiery unless you add the "PC" colors from that PDF. Modern pantone coated library such as you will use from Adobe Create Suite will have the extension "C", like "PANTONE Coated C".

    You are seeing M your yellow again at least possibly due to your CMYK source profile since the spot "PANTONE Y PC" is not being looked up as a spot color.

    Tell me your profiles and I can better tell you what's happening.

    ~Lou

  10. #10
    GarethO is offline Senior Fiery Forum Contributor GarethO is on a distinguished path
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    Thanks for your help.

    That target is not a proper pantone i.e. PC rather than C, but it still happens with a correctly embedded Pantone Process Yellow C files like this one.

    My settings are;

    Source
    CMYK : None
    RGB : None, Absolute
    Spot color matching checked

    Output : Canon iPR C7000VP/C6000 Plain(N) v1F

    Calibration Neusiedler 100gsm

    I have Pantone Plus libraries loaded and at the top of the list.

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