TIFF-RGB vs TIFF-CMYK

Discussion in 'Photoshop' started by viv, Jan 22, 2006.

  1. viv

    viv Guest

    My fellow Photoshop users:

    I need to submit a piece of artwork for a book cover, with the
    following specs: TIFF file format, CMYK colorspace, 300 dpi.

    The final finished work at 300 dpi CMYK looks fine, and so I saved it
    as a TIFF and it looks fine in Photoshop. But when I call it up using
    the native Windows Picture viewer , it's much much darker and the
    color scheme is totally different (more golden and metallic versus
    red-orange) . Ditto if I call it up in MS Paint, although if I use
    Internet Explorer it looks the way it does in Photoshop: i.e, the way
    I want it.

    If I change the colorspace to RGB, however, everything looks fine no
    matter which application I use to view it.

    This leads me to ask the following three questions:

    1) Will the TIFF-CMYK version print up it the way it looks in
    Photoshop or the way it looks in the other applications? Or in each
    the way it appears in them? (My printer is down for repairs, so I
    can't do my own test.).

    2) Is there a way I can save my artwork at the required specs and make
    it look the same no matter which application I use to view it?

    3) What accounts for this difference in the first place?

    Thankin advance for for any help or suggestions.

    viv
     
    viv, Jan 22, 2006
    #1
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  2. viv

    C J Southern Guest

    Welcome to the world of colour management :)
    It depends ...

    If it's safe to assume that you're not using a calibrated monitor then
    already what you're seeing isn't how it really is. The differances may or
    may not be significant, depending on the intent of the artwork. Apart from
    that, you *should* be OK if CMYK is REALLY what they want (most printers
    these days have RGB interfaces - even though the physical ink is CMYK) - but
    if it's going to be handled by "the big boys" then you should be OK. Having
    said that, if what you're submitting is only a component of the cover then
    I'd be suspicious - far more likely that your contribution will be part of
    an effort by others as well - which makes me think the RGB will more likely
    be required - just a guess though.
    Not that I can think of.
    You've created a file that describes the image in terms of
    cyan-magenta-yellow-black then tried to view it on a device that requires
    Red-Green-Blue. It's a bit like writing a page in German then trying to read
    it in English when you don't have all the exact-meaning words to translate
    perfectly between the two languages.


    Hope this helps.
     
    C J Southern, Jan 22, 2006
    #2
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  3. viv

    Mike Russell Guest

    [CMYK image looks different in Photoshop. and Windows Picture viewer]
    More than likely Photoshop is providing a more accurate display. It is
    worth some effort to calibrate your monitor. Use Adobe Gamma if you have a
    CRT, or a calibration device if you have an LCD monitor.
    This is a complex problem - Photoshop is attempting, by use of color
    management, to make an accurate conversion for you. Windows Picture is not,
    or possibly it is converting using using a different color management
    procedure.
    Photoshop uses an accurate conversion for viewing CMYK images, Windows
    Picture does not.

    If possible, talk with your printer to get an idea of what profile to use.
    In the absence of other information, and as a rough starting point, for
    American offset press use SWOP v2 coated or uncoated, depending on the type
    of stock used.
     
    Mike Russell, Jan 22, 2006
    #3
  4. viv

    viv Guest

    Still a little confused here, because Windows Picture *will* display
    the CMYK artwork as I'd like to see it printed if I save it in some
    format other than TIFF--say JPG. Same for the other applications. Only
    in TIFF-CMYK is the color scheme radically different, whereas in
    JPG-CMYK everything is the same across the board, no matter what the
    application.

    What does the TIFF format do to CMYK files to make them look different
    than CMYK files saved to JPG?

    Thanks for the interesting responses so far.

    viv
     
    viv, Jan 22, 2006
    #4
  5. viv

    Mike Russell Guest

    [CMYK difference in appearance between apps]
    I can't explain that. Your original post said that RGB looked the same in
    both apps, and that CMYK was different between PS and WP.
    Again, no explanation. CMYK should look about the same, whether saved in
    TIFF or jpg.
     
    Mike Russell, Jan 22, 2006
    #5
  6. viv

    Mike Russell Guest

    Viv,

    Your email bounced, so I'm posting here re the screenshots you sent. This
    is definitely a curious problem.

    Perhaps you could send me the files, or cropped sections of them?

    Mike
     
    Mike Russell, Jan 22, 2006
    #6
  7. viv

    C J Southern Guest

    Mike,

    I never have any occasion to work in CMYK (my printers are all RGB interface
    (even my Epson 7800)) - so this was new territory for me, but ...

    I wanted to test out what Viv was saying - interestingly, I chose a scene
    where I'd photographed my 2 kids in a forrest - so lots of leafy greens in
    the background. As soon as I converted the image to CMYK I lost about 1/2
    the saturation from the greens - kids clothing and skin tones were
    unaffected - not sure if this is what Viv is seeing?

    If you immediately (and repeatedly) do a Ctrl-Z to flick back and forth
    between the two colourspaces it's really quite pronounced - I wouldn't have
    expected it to be anywhere near going out of CMYK gamut - so I'm interested
    in anything you come up with.

    As a side note, I still have real doubts that Viv needs CMYK - her comment
    about "not being able to check because her printer is down" raises a red
    flag - I very much doubt many (any?) home type users would have a CMYK
    interfaced printer.

    Viv (if you're reading this) - to answer your question about saving the work
    in a way that will give you the same colour regardless of where it's opened
    .... you can't do this in CMYK format because it's what's termed a "device
    dependant" format - which (in English) tells the printer how much ink to
    use, but doesn't define what the characteristics of the ink are (eg an Epson
    Magenta ink may be a different hue to a Canon Magenta ink - if you use the
    same amounts, you get a different result). You'll need to get it looking as
    good as possible on the screen (and hope that your screen isn't too far out
    of colour calibration) then save the file in a device-independant format
    like LAB colour - assuming that they can open such a file at the other end
    (won't be a problem if they have photoshop).

    Hope this helps.
     
    C J Southern, Jan 22, 2006
    #7
  8. viv

    Laura K Guest

    Greens and blues show the biggest difference between the two color spaces.
    CMYK drastically reduces the colors available, particularly in the green-blue
    range.
    There's a good explanation and graphic example here:
    http://jura.wi.mit.edu/bio/graphics/photoshop/colman.htm
     
    Laura K, Jan 22, 2006
    #8
  9. viv

    C J Southern Guest

    Thanks Laura - I figured that logically that must be the case - I just
    didn't appreciate that CMYK was so - how to put this nicely - "limited".

    Cheers,

    Colin
     
    C J Southern, Jan 22, 2006
    #9
  10. viv

    viv Guest

    The artwork is for a bookcover and to quote exactly the publisher's
    specs:
    ------------------------------
    TIFF (.tif) file format

    CMYK colorspace

    300 dpi resolution

    Match the dimension of the final trim size, plus an 1/8" bleed on the
    top, right and bottom sides (i.e. A cover for a 6" x 9" book would
    need to be submitted at 6.125" x 9.25").

    ----------------------------
    This afternoon I copied the files to disk, then took them over to a
    colleague's with a suitable printer.

    The Photoshop version of the TIFF/CMYK artwork printed up exactly as
    it looked on screen. (In fact, it turned out much better than I
    anticipated, with great detail and no banding [my most serious
    concern], and I could not be happier.)

    Printed from within Windows Picture Viewer, however--well, it printed
    out exactly as it looked, being far darker and more metallic looking.
    (If Mike Russell received my scans he'll know what I mean.)

    Another oddity: when I go to open the picture from within Photoshop's
    Open/Look In [Folder location], the preview thumbnail looks the way it
    does in Windows Picture viewer, but when it opens up in Photoshop, it
    looks fine and exactly the way I want it.

    Tomorrow I'll ftp the file into the Publisher's art department, then
    try to ascertain how it looks on their end.

    The last time I did this everything was in black and white, so I never
    had any color distortion. Guess I should let that be a lesson.

    My thanks to all responders and if anything else suggests itself,
    please post it.

    viv
     
    viv, Jan 22, 2006
    #10
  11. viv

    Laura K Guest

    Can you fedex that print to the printer? I would and tell them to "match" it
    -- it will become what's known as a "match print." You're telling them "this
    is the way it has to look when it's printed."
    The printer will then make any adjustments they need to make so that what
    comes off the press "matches" what you sent them. They can do that a lot
    better than you can because they know their press and the inks they use and
    what they have to do to the digital version to get it right when it comes off
    the press.
    You can also ask them to send you a proof before they start the press run and
    fedex that to you for approval.
    If they're close by, you can do a press check -- go down when they're putting
    it on the press and make sure that what comes off is what you want.
    The match print is really the best way to go.
     
    Laura K, Jan 22, 2006
    #11
  12. viv

    tacit Guest

    There are many things going on here, each of which may be confounding
    you.

    First, as Mike and others have already said, Photoshop does color
    management and other programs do not. Photoshop will show you a better
    approximation of how your file will look on press...

    ....IF you have properly calibrated your system. If you have not, then
    you're likely using more or less random color profiles, and what the job
    will look like on press is a crapshoot.

    Second, your printer, which I assume is an inkjet printer, *will not*
    match a printing press. The CMYK inks used by a consumer inkjet printer
    do not match in tone the inks used on a printing press; the cyan ink in
    particular is more blue in a consumer inkjet printer than SWOP cyan
    printing ink.

    Third, you say that the way the image looks is different if you save as
    a JPEG. If you are using Save for Web to save a JPEG, then Save for Web
    automatically converts to RGB. If you are not, then likely you are
    saving your color profile in the TIFF, but you are not saving the color
    profile in the JPEG.

    Generally speaking, your printer should be able to make what is called a
    "random proof" of your image. Do not trust what you see on your screen
    or what you print on a consumer-grade inkjet printer. The only way you
    can truly know what the image will look like on press is to have your
    printer make you a contract proof, which is a proof made by a special
    technique that is designed to represent how the image will look opn a
    printing press. Getting a proof is a normal, ordinary part of the normal
    workflow for doing graphic arts jobs destined for professional
    reproduction on a printing press. That proof, not your screen and not a
    printout on your inkjet printer, is your Bible; that proof is how your
    image is going to look, and you should make your evaluation and your
    color adjustments based on that proof.

    Talk toy our printer. This dialog is the single most valuable thing you
    can have when you begin to do work for press. Your printer should be
    able to tell you more than what you've said in this thread; they should
    be able to give you the separation parameters for converting your image
    to CMYK, and they may even have profiled their proofing device and their
    press, and if they have, they can give you profiles to use. (Assuming
    you have calibrated your system, that is.)
     
    tacit, Jan 23, 2006
    #12
  13. viv

    tacit Guest

    The CMYK gamut is very limited compared to RGB; many colors in RGB can't
    be reproduced in CMYK.

    However, the reverse is also true. The CMYK gamut is not contained
    entirely within the RGB gamut; there are colors in CMYK (including very
    dark blue-blacks, certain deep fire-engine reds, and pure CMYK yellow,
    that can't be reproduced in RGB. This means that your monitor, which is
    an RGB device, can not show you a perfectly accurate representation of a
    CMYK image.

    This is part of the reason that a contract proof of some sort is
    essential when you're worried about color reproduction on press.
     
    tacit, Jan 23, 2006
    #13
  14. viv

    Mike Russell Guest

    From: "Laura K" <>

    .....
    Laura has it exactly right. Particularly for something like a cover, you
    want a proof before committing to a full print run. This costs a hundred
    dollars or so, but is worth it, and many printers will insist on it before
    doing a run.

    I've been looking at the images, and the CMYK numbers are identical in both
    images, so the difference in appearance is not due to any problems with the
    actual color numbers, but with Windows Picture Viewer's handling of CMYK
    files. Specifically, the tiff image appears much darker in WPV than in
    Photoshop.

    I used Photoshop to save a second copy of the tiff, this time embedding the
    SWOP v2 coated profile. WPV's display of that image was much brigthter,
    and matched its own jpg interpretation, as well Photoshop's interpretation
    of the jpg and tiff images.

    My conclusion is that WPV's default working spaces for CMYK depends on the
    image format, and tif uses a much darker image.

    It's poor practice to embed a profile in a CMYK image, so I would not
    recommend that you embed the profile, but do take Laura's advice about a
    proof.

    There are a couple of other problems with your image that can be easily
    improved. There is indeed banding in the magenta and cyan channels, and
    this may show up in the final result. The banding probably occurred because
    you created your original image in RGB mode and converted to CMYK. A second
    problem is that you are not making use of pure yellow - since you are
    representing a figure silhouetted against a sunburst effect, CMYK's pure
    yellow will add impact. The third problem is that your image is not
    trapped - any slight misalignment will create a colored cyan and/or magenta
    outline around the image.

    The first two problems, banding and impure yellow, are probably due to
    converting from RGB to CMYK, and may be fixed by laying out the image in
    cmyk as follows. Create a new CMYK image of the same size as your final
    image, and paste your artwork into a new layer that is set to *darken mode*.
    In the bottom background layer, recreate your radial gradient going from
    CMYK(0,0,100,0) to the original red-orange color, approximately
    CMYK(0,77,100,0). Save the layered verison of your image, and then flatten
    it and trap it before saving it as a tiff file for printing. The result
    will be a perfect gradient from pure yellow to red-orange.

    If you do not have the original artwork, convert a copy your image to RGB,
    set your CMYK settings to a Custom CMYK of Max GCR, and copy the K channel
    to the clipboard - paste this into the new layer as your artwork.

    Trap is a little more involved. You could print the figure in pure black,
    and it would probably look just fine, but as long as you're paying for CMYK,
    you may as well go for a rich black such as CMYK(100,53,0,100). So we need
    to choke the cyan and magenta plates, and trap the yellow plate to prevent
    fringes due to misalignment.

    One way to do this is a variation of the procedure in the PS manual: "To
    adjust overlapping spot colors".

    Use levels to set the black plate to 100 percent, then load the black plate
    as a selection. Use Select>Modify>Expand to expand by a point or so, and
    then select the cyan plat, hit delete to choke the artwork - effectively
    making it slightly smaller. Repeat with the magenta plate. Leave yellow
    alone, and instead flatten your image and then do an Image>Trap to expand
    the yellow. Your Greek traveller will now be immune to fringing, and at the
    same time have a rich black.

    If your cover is the only colored art on the page, you could do this as a
    two color magenta black job on colored yellow stock. Ask your printer if
    this is available as an option. It may save you money, and will require
    only that you eliminate the yellow and cyan plates.

    And Laura's advice is probably the most important of all: sign off on a
    paper proof before printing.
     
    Mike Russell, Jan 23, 2006
    #14
  15. viv

    Mike Russell Guest

    The image in question is black line art of a walking man set against a
    sunburst in the form of a yellow to orange radial gradient.
     
    Mike Russell, Jan 23, 2006
    #15
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