CMYK TIFF is 4 bytes/pixel ?

Discussion in 'Digital Photography' started by Alfred Molon, Jun 27, 2005.

  1. Alfred Molon

    Alfred Molon Guest

    Just noticed that a CMYK TIFF file has a size of four times the pixel
    count, instead of three. What are the bytes used for - cyan, magenta,
    yellow and what else ?
     
    Alfred Molon, Jun 27, 2005
    #1
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  2. Alfred Molon

    Bill Hilton Guest

    Alfred Molon asks ...
    K is black, that's the extra byte.

    Bill
     
    Bill Hilton, Jun 27, 2005
    #2
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  3. Black.

    K is short for Key ... which is black.

    -dansken
     
    David Knudsen, Jun 27, 2005
    #3
  4. Alfred Molon

    winhag Guest

    BlacK
     
    winhag, Jun 27, 2005
    #4
  5. Alfred Molon

    Bill Hilton Guest

    Alfred Molon writes ...
    Alfred, if you're going to be doing much CMYK work then I recommend the
    book "Professional Photoshop" by Dan Margulis. It's pretty much an
    advanced book but explains CMYK in much more detail than any other book
    I've read. Here are a couple of links that may help you decide if it's
    what you need.

    http://www.ledet.com/margulis/articles.html
    http://www.photoshophalloffame.com/Dan_Margulis.html

    Bill
     
    Bill Hilton, Jun 27, 2005
    #5
  6. Alfred Molon

    Alfred Molon Guest

    Is it a luminance information byte, or simply an additional colour
    component, i.e. is CMYK a four-dimensional colour space ?
     
    Alfred Molon, Jun 27, 2005
    #6
  7. No, it's subtractive color space. When you add CMY you get black.

    Here's a very good example of it.

    http://dx.sheridan.com/advisor/cmyk_color.html



    *********************************************************

    "I have been a witness, and these pictures are
    my testimony. The events I have recorded should
    not be forgotten and must not be repeated."

    -James Nachtwey-
    http://www.jamesnachtwey.com/
     
    John A. Stovall, Jun 27, 2005
    #7
  8. Alfred Molon

    Jim Guest

     
    Jim, Jun 27, 2005
    #8
  9. Alfred Molon

    Bill Hilton Guest

    Alfred Molon writes ...
    Yes, it's four dimensional, matching up with the four colors in the
    press. In theory you could combine C,M and Y to get black but in
    practice it is typically muddy and not pure black, hence the extra
    'color'. Note that each RGB triplet *exactly* defines one color but
    with four variables you can combine them different ways to get the same
    color. Since black ink is cheaper than the colored inks there are
    tricks pre-press pros use to use more black and still get the same
    color. This is one reason RGB is easier to work with.

    Go to Photoshop's Help files and enter a search on CMYK for some good
    basic info on this color mode and how to use it.

    Bill
     
    Bill Hilton, Jun 27, 2005
    #9
  10. Alfred Molon

    Bill Hilton Guest

    Alfred Molon writes ...
    Alfred, if you're still working on CMYK images you might find some
    interesting info in this article, which describes how a guy did the RGB
    to CMYK conversions of images for his self-published book. I
    remembered your CMYK post when I read it, hope it's of interest,
    especially the part describing soft proofing and the edits necessary to
    the CMYK files to try to better match the RGB colors.

    http://www.luminous-landscape.com/essays/100-books.shtml ... the CMYK
    conversion steps are described about 2/3's the way thru the article, if
    you don't want to read it all.

    Bill
     
    Bill Hilton, Jul 8, 2005
    #10
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