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Thread: CMYK Conversion

  1. #1
    Kirk Gittings's Avatar
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    CMYK Conversion

    Teach me something here please.

    This question primarily concerns the reproduction of my "twilght" architectural images that have very rich almost irridescent blues.

    See www.gittingsphoto.com/fmsetgallery.html?gallery=New%20Architecture%20Projects 6th image down as an example of an image I have had problems with.

    Until recently, when a magazine asked for a file, I always just gave them my RGB files from my scans and let them do the conversion to CMYK. Results were always acceptable from both local and national magazines. A couple of times recently, with small local magazines, I was asked for files converted to CMYK which I supplied. The blues in these reproductions were clipped significantly vs. files I had supplied other magazines as RGB files. Same images. What am I missing here? What am I doing wrong when I convert to CMYK vs. magazines which are doing the conversion from my RGB files?.
    Thanks,
    Kirk

    at age 67
    "The woods are lovely, dark and deep,
    But I have promises to keep,
    And miles to go before I sleep,
    And miles to go before I sleep"

  2. #2
    Moderator Ralph Barker's Avatar
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    CMYK Conversion

    Assuming you mean the magazine repro clipped the blue, as opposed to it appearing that way in your CYMK file, it sounds more like a printer issue to me. Some adjustments to the CYMK file may be needed to match the type of press the magazine is printed on, but the AD at the magazine should know what adjustments to make. Additionally, some presses will have color issues introduced by ads that may be running in the same signature. When there's a conflict, the ad typically gets preference.

    I'd suggest talking to the AD at the mag, or the printer contact if the AD isn't up to speed.

  3. #3

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    CMYK Conversion

    The blues in these reproductions were clipped significantly vs. files I had supplied other magazines as RGB files. Same images. What am I missing here? What am I doing wrong when I convert to CMYK vs. magazines which are doing the conversion from my RGB files?.

    Check your profile intent - the default is Perceptual and most users who work in RGB only never change that. Perceptual is fine for RGB editing, but can easily leave certain colors, especially the blues, out of cmyk gamut at conversion. The more vibrant the blue, the worse it gets clipped.

    If this is the case, try changing it to Relative Colorimetric.

    Specifically:

    1. Go to Edit and open Color Settings

    2. Click on More Options

    3. Under Conversion Options:

              a) Under Intent select Relative Colorimetric

              b) Check Black Pont Compensation

    Leave all other options as they are for now and see if this helps.

    If not, ask the publications in questin which CMYK space are they using specifically and try matching it under Working Spaces in the same Color Settings dialog (first group of options). You can also experiment with Grays, Spots and other options.

    But if you've gotten this far with no results, I can only advise you to try and talk to the art director in one of those publications that did conversion for you.

    Regards,

  4. #4
    Kirk Gittings's Avatar
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    CMYK Conversion

    To be honest the magazines are happy, but I am not. I should be able to reproduce my blues.

    Thanks guys. Ralph, it is showing up on the monitor too. Good point. Marko, I think there is something to the rendering intent and I will play with that.

    ASMP recently offered two workshops here on converting files for publication and unfortunately i missed both of them.

    With some of these local magazines, I think we are all on the same learning curve but coming at the problems from different perspectives. Some still prefer film, because they get a more predictable result than files from inexperienced photographers. However more and more prepress production is being pushed back up the chain to photographers. There are things that I have never had to worry about which I do now.
    Thanks,
    Kirk

    at age 67
    "The woods are lovely, dark and deep,
    But I have promises to keep,
    And miles to go before I sleep,
    And miles to go before I sleep"

  5. #5

    CMYK Conversion

    Kirk,

    Blues like this are one of the very hardest colors to match with offset printing. I suggest that the next conversion you do you make it a test. (or test one that already didn't reproduce well) You can do this globally or on selections. Be careful in selections as you can change the sky and not the reflections of the sky and get an unnatural result.

    In PS, go:

    Image > Adjustments > Selective Color > Blues > then diddle with the Magenta slider - you'll see a big difference as you do this. Click the preview on and off to watch the changes. Try all the sliders and experiment. Save copies of different variations and have proofs made. The press people will most likely have a digital contract proofing system (we'd hope). If you are on real good terms with one of the mags they might do the test print for you. Tell them you want your pictures to be better for them. You could gang several variations on one page so you're only making one proof. Even if you have to pay for it it'll be $100 well spent.

    You can also experiment with a Pantone process color guide and compare the "numbers" in PS to the swatch in front of you but contract proofs are way better. But this will give you some idea of what CMYK = 79, 21, 7, 0 looks like in ink.

  6. #6
    Abuser of God's Sunlight
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    CMYK Conversion

    are you using Convert to CMYK, or are you converting to a CMYK profile? Blatner and Fraser recommend doing the latter. If you have a cmyk profile that you plan to use for these magazines you can kill 2 birds with 1 stone. supposedly this does a more accurate, lossless conversion ... but i haven't done side by side comparisons.

  7. #7

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    CMYK Conversion

    What a terrific photograph! The contrasting blues and whites are really neat.

    Before drawing conclusions, I would contact the magazine and trace every step in their workflow. What did they do to your image.

    Did you send a sample along with the file, so they would know what's possible, and what you intended? Can one do this in this type of situation?

  8. #8

    CMYK Conversion

    Also in "Color Settings" see what CMYK setting you've selected. In "Working Spaces" one of the "web" settings is most likely gonna be close for you. The magazines are most likely printed on a web press. There's also dot gain adjustments but don't change from the default settings until you ask for a better number for a particular job.

    If you need or want more precision you need to prepare each submission with correct settings for the particular publication. That will require a talk with the art directors or production supervisors and maybe even the printing rep. or pre-press person. Then when you send XYZ Magazine a file you adjust your color settings for their requirements before you convert.

    All this might be more trouble than you need to go through unless its a cover or big spread. But the good thing is that once you get the lines of communication open and your settings right you can confidently send files that reproduce well.

    And you thought you were a photographer! Over the last few years you've taken on about six new and different jobs - ain't it great.

  9. #9

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    CMYK Conversion

    What magazines print your deep blue skies "clean" in the first place? Cause I've yet to find a CMYK process that can do it...

  10. #10
    Kirk Gittings's Avatar
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    CMYK Conversion

    Thanks Neil. Frank believe it or not, the magazine, "Texas Architect" did a great job with the blues in that very image and great reproductions of my blues from the Hanley-Wood publications, Su Casa, New Mexico Magazine, and some books that did that image too.

    By the way my workflow on images like that these days-

    halogen lit,

    Fuji NPS daylight film asa 100,

    no filter,

    scan 16 bit Adobe RGB 98 with 4990 or Nikon 8000 with Silverfast and do a rough global color correction,

    fine tune color in PS with various tools but primarily the Color Mechanic Pro plug-in, the go to plug-in, an architectural photographers best friend.
    Thanks,
    Kirk

    at age 67
    "The woods are lovely, dark and deep,
    But I have promises to keep,
    And miles to go before I sleep,
    And miles to go before I sleep"

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