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I need to convert a CMYK page into just black using photoshop, please help.

Discussion in 'Printing & Print Design Forum:' started by Acknowledged74, Sep 15, 2012.

  1. Acknowledged74

    Acknowledged74 New Member


    I have a 68pp magazine which is part colour but mainly black and white.

    The printer have told me that everything is fine accept one page that looks black but is actually made up of CMYK colours. It has exported Tiff files from another piece of software on it.

    I need this to be just K so that it only needs one plate for printing, will changing the file to Grayscale in Photoshop CS2 achieve this?

    Otherwise what would be my best option?

    Really appreciate any advice, its got to be with them Monday and I'm pulling what little hair I have left out over this.

  2. TDesignCo

    TDesignCo Member

    Hi - yes you could change the file in Photoshop to grayscale, or if its a PDF convert it in Acrobat Professional (if you have this?) by either converting the whole page or changing the black to 100k

    Hope this helps
  3. Acknowledged74

    Acknowledged74 New Member

    I've got the files only on Photoshop unfortunately, the actual publication is on InDesign Cs5.5 and I 'place' the psd file into the required pages.

    I was told that Grayscale would be fine but I've read stuff to the contrary elsewhere, and the printers is closed now.

    We are sure Grayscale is fine, because when I export it and run a colour pippet of it its picking up the CMYK again, or is that just because I have CMYK on?

    Sorry just panicking.
  4. TDesignCo

    TDesignCo Member

    In the pallet you are looking for a K value only, Photoshop displays CMYK or RGB by default. So as long as CMY is O O O then all good!
  5. Acknowledged74

    Acknowledged74 New Member

    When in Grayscale mode it only shows K so I don't know if CMY are blank?
  6. Acknowledged74

    Acknowledged74 New Member

    As soon as say open a new file which is in CMYK and run the pippet over the Grayscale file it picks up something in all CYMK, is this just a Photoshop thing because the other one is in CMYK or because the Grayscale file actually has colours in it?

    Really hope that makes sense. Its a little confusing that different people and different resources saying different things on this.

    If its in Grayscale can it only have K in it?
  7. Acknowledged74

    Acknowledged74 New Member

    OK I've deleted the CMY channels completely so K is at 100% - surely that should cover it?
  8. Acknowledged74

    Acknowledged74 New Member

    Nope InDesign won't accept that, tut. So back to Grayscale, thought I had it licked for a minute there.
  9. bigdave

    bigdave Moderator Staff Member

    I photoshop open your file. Across the top of the file it will tell you what colour mode the document is in:

    (I use CS6 so my screen is slightly different to what you will see in CS2)

    To change the colour profile of an image go to the top tool bar image>mode>grayscale:

  10. Acknowledged74

    Acknowledged74 New Member

    Sorry i haven't been clear I'm using CS2 which doesn't have the CMYK along the top. I have already converted to Grayscale, what I need to know is IF this will only use one plate in litho print process? Simply that.
  11. Katedesign

    Katedesign Well-Known Member

    You should be fine. If you have a printer print separations for the offending page (from Indesign) and if nothing comes out on 3 of the 4 sheets you've cracked it!

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