Creating a B&W CMYK tiff with just two colours

Discussion in 'Design and Graphics' started by irishgrizzly, Apr 8, 2008.

  1. irishgrizzly macrumors 65816

    irishgrizzly

    Joined:
    May 15, 2006
    #1
    I'm trying to create a black and white photo that will print in four colour, but will only use black and a little cyan to give it depth. I was told to open in photoshop, convert to grayscale, back to CMYK, then have a layer above with a flat colour (100 black 40 Cyan) with the Hue blending mode turned on. Flatten and save. However looking at the values I still have yellow and magenta in there. Anyone know what I'm doing wrong?

    Thanks
     
  2. jerryrock macrumors 6502

    jerryrock

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    #2
    I really don't understand your workflow, but there is an easier way to obtain the same effect. With the original RGB image (I don't know why you work in CMYK), go to image/adjust/black & white and check the tick box for "Tint". Slide the hue slider to obtain a cyan tint and adjust the saturation of the tint.
     
  3. Jim Campbell macrumors 6502a

    Jim Campbell

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    #3
    Right. I think I understand ... you're not looking for a cyan tint to a greyscale image, you want the black to be replicated at 40% on the cyan plate, to give what printers like to call a "rich black" ... yes?

    I think that the easiest way to achieve this is to leave your image as a greyscale TIFF and create a new colour swatch for "rich black" in InDesign or Quark that's made up of C40M0Y0K100. You can then tint the TIFF on the finished document from within your DTP app of choice, although you will need to check the trap settings of black for the document and ensure that black is set to Overprint and not Knockout.

    You'd need to run out separations to make sure that works, BTW.

    I was just about to have a go for you when I discovered that InDesign CS3 (v5.0) doesn't appear to work with 10.5.2.

    (Something else I'll have to waste time fixing. Not terribly impressed with this Leopard update, so far.)

    Cheers!

    Jim
     
  4. Jim Campbell macrumors 6502a

    Jim Campbell

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    #4
    Alternatively ...

    Brought to you from memories of days gone past ...

    Open your grayscale document.

    Go: Channel -> New Spot Channel -> Colour C40M0Y0K0 and Solidity 100

    Copy the contents of your Grey channel and paste into the Cyan channel.

    Create a second Spot Channel -> Colour C0M0Y0K100 Solidity 100.

    Paste your image into this one too.

    Now, delete your Grey channel and Save As -> DCS 2.0 (check the Spot Colours option).

    This is the only format I ever found that reliably preserved spot colour information without trying to helpfully split your colours across all four plates.

    Note for future reference that this also supports PANTONES if you go Channel Options -> Colour -> Colour Libraries

    You may have to experiment with the dialogue that comes up next - I haven't done this in a while. ISTR that the defaults worked OK, but you will still need to output some separations to make sure that it's doing what you want (ie - the proper b/w image on the black plate and a 40% tint of the same on your cyan plate).

    I hope that's some help ...

    Cheers!

    Jim
     
  5. killmoms macrumors 68040

    killmoms

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    #5
    ...I use IDCS3 just fine in 10.5.2. Maybe something else is wrong? :confused:
     
  6. MechaSpanky macrumors 6502

    MechaSpanky

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    #6
    2 color image

    [snip]

    The reason he is working in CMYK is because there is no printer in the world can print RGB. All RGB images are converted into CMYK before they are printed. When you convert images from RGB into CMYK there is a chance that the colors will shift and appear darker and duller than what is intended. Many people work in RGB because many Photoshop filters will only work in RGB mode but they are always aware of the differences between the RGB color spectrum and the CMYK spectrum. The only time CMYK isn't used is if the client decides to use spot colors instead of CMYK. Spot colors still don't use RGB.

    irishgrizzly

    What you need to do is
    1). Take your desired photo and change it from CMYK to Grayscale (keeping a copy of the original as CMYK just in case).
    2). Then change the image from Grayscale back to CMYK. Now you should have a CMYK image that looks like it is a grayscale.
    3). Next, click on the "Channels" tab and you should see four channels. You will want to click on the Yellow channel and select all and delete. Then do the same for the Magenta channel. This will give you a two color image, consisting of only Cyan and Black.
    4). Now if you want to adjust the color, you need to make sure you are working in that colors Channel, not all of the channels.

    Normally you don't want to mess around with an images channel but in some cases you have to. I hope this helps.
     
  7. Jim Campbell macrumors 6502a

    Jim Campbell

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    #7
    Haven't started InDesign up since I updated from 10.4.11. I get as far as the starting up screen and it announces that it's quitting back to the Finder.

    The 5.0.3 updater hasn't worked either. Time for a clean reinstall and see what happens, I guess.

    Cheers!

    Jim
     
  8. MacBoobsPro macrumors 603

    MacBoobsPro

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  9. Jim Campbell macrumors 6502a

    Jim Campbell

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    #9
    Nope. Fortunately, I cloned the entire HDD on my Mac before upgrading the OS. I've just booted from the 10.4.11 back-up on my external drive and -- guess what -- InDesign launches and operates just fine.

    Boot from the internal, running 10.5.2 and it won't. The only things that have been installed since the back-up was made are Apple's own updates via Software Update.

    The exact same story with the laptop.

    Once again, I am less than impressed with Leopard thus far.

    +EDIT TO ADD+ Hmph. Old news it seems. All have to do is Erase & Install Leopard (and then update it to 10.5.2 again, because the earlier versions don't play nice with my wifi) and then reinstall CS3 again.

    So that's another half a day wasted just to get my system to perform the way it did before I started down this upgrade path. Jeez. ++EDIT ENDS++

    Bah.

    Jim
     
  10. jerryrock macrumors 6502

    jerryrock

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    #10
    I do have a degree in graphic design.

    There is no inherent advantage to working in CMYK with Photoshop, there are the disadvantages that you have mentioned. The LCD monitor can not display the full CMYK color gamut. So your argument that the color will be more accurate (less dull) is void. The modern digital press can accurately translate color information from wide gamut RGB to CMYK. There is no need to convert digital photos from RGB to CMYK.
     
  11. JasonElise1983 macrumors 6502a

    JasonElise1983

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    #11
    I'm going to jump in on this one. Yes MODERN DIGITAL PRESSES can convert rgb to cmyk, but the op did not say he was printing on a modern digital press. He most likely is printing offset since he is trying to control what colors print where so efficiently...offset pressed can not RIP rgb files correctly and the pre-press people will write you hateful emails/post-it notes if you send them rgb images. that's why if you preflight something in InDesign, it give an error if an image is rgb...because that's not the norm. that's like saying you could design a website at 1900 x 1200 pixels wide because that is what modern monitors use. too bad 90+% of the population can't view it. (i know...strange analogy)

    -JE
     
  12. Jim Campbell macrumors 6502a

    Jim Campbell

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    #12
    Which is why I work with Gamut Warning on. Plus, CMYK display is closer to CMYK output than RGB display is.

    I have over ten years' experience in print design that directly contradict that statement. Plus, I have no idea how you think any press is going to be able to accurately translate a simulated 40% Cyan tint in an RGB document into an accurate split for four colour print.

    And how much experience in pre-press production? Because I have a ton of it, and I cannot agree with pretty much any part of your statements ...

    Cheers

    Jim
     
  13. jerryrock macrumors 6502

    jerryrock

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    #13
    Jim, please read this recent article:

    http://www.ppmag.com/reviews/200703_rodneycm.pdf

    This is not just my opinion. I am sure you think you have the ultimate answer, but it is always good to be open to new options.
     
  14. Jim Campbell macrumors 6502a

    Jim Campbell

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    #14
    Of course I don't think I have the "ultimate answer", and much of what is in that article is very interesting, but the newer technologies are an edge behind which many, many print operations trail by a variable number of months or years.

    In this specific instance, the OP wanted to get a CMYK image that split to two specific plates in specific percentages and did not generate any superfluous coverage on either the magenta or yellow plates.

    I will say again, that I do not see how simulating a cyan tint on an RGB image will give the result that the OP said he wanted. Assuming that there is some kind of software voodoo that will magically give a 40% cyan overprint on black from an RGB image with no trap information (which, personally, I doubt), then your advice would have to assume that the OP's printer was using the latest, dog's b*ll*cks software and hardware.

    The advice offered by everyone else on this thread centres on getting a good result from pretty much any press. As such, that advice was sound, whereas yours made an assumption that was, potentially, unhelpful to say the least.

    Cheers

    Jim
     
  15. PixelFactory macrumors regular

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    Chicago
    #15
    While you can send RGB files to a printer, I find that most images will print faded with poor color quality. The article is talking to photographers who just don't work in cmyk.

    For the OP. The method i use is this.

    1. open the RGB file and duplicate it (Image -> duplicate)
    2. Convert the duplicate to greyscale (I prefer to use the Black & White function first).
    3. select all and copy the greyscale image and covert to CMYK
    4. paste into the black channel and delete all the info in the CMY channels
    5. Copy your original file (the one still in color) and paste into the Grayscale (should create a new layer)
    6. Change the blending mode to multiply on the new layer
    7. Image -> adjustments ->channel mixer on the new layer

    At the top you'll see a drop down menu with your channels (CMYK), in the MYK channels, zero everything out, in the Cyan channel you can adjust the sliders to your liking.

    it's a little convoluted but it gives great results
     
  16. PixelFactory macrumors regular

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    #16
    There is no software that will do what the OP wanted using just an RGB file. The article's audience is photographers who in most cases never use cmyk.

    Is CMYK workflow voodoo for the new breed of graphic designers? I've been in the industry for over 15 years and would NEVER send a file in RGB to press. Too many variables for things to go wrong.
     
  17. Jim Campbell macrumors 6502a

    Jim Campbell

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    #17
    Can I ask why you are addressing these remarks to me? I'm just curious, since you seem to be responding to points made by jerryrock ... my own points agree entirely with your own as far as the general incompatibility of CMYK and RGB colour spaces is concerned for the vast majority of printers and presses.

    Cheers!

    Jim
     
  18. PixelFactory macrumors regular

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    #18
    Not arguing, just agreeing. :)
     
  19. durija macrumors 6502

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    Seattle
    #19
    Why not just make a duotone with black and cyan? Very easy to control the amount of cyan. If you're not used to working with duotones, just be sure to save it as a eps or it won't separate correctly. I think this is by far the simplest way to go.
     
  20. IgnatiusTheKing macrumors 68040

    IgnatiusTheKing

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    #20
    I use InDesign CS3 daily on two different machines running 10.5.2, without problem.
     
  21. Jim Campbell macrumors 6502a

    Jim Campbell

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    #21
    *Sigh* Allow me to modify my original statement, then: InDesign CS3 has stopped working on my system since I upgraded to 10.5.2. YMMV.

    Cheers!

    Jim
     
  22. heehee macrumors 68020

    heehee

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    #22
    Weird, my InDesign CS3 works fine right from when Leopard first introduced, 10.5.0 to 10.5.1 to now 10.5.2.
     
  23. IgnatiusTheKing macrumors 68040

    IgnatiusTheKing

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    #23
    Just letting you know that it isn't a bug with Leopard or CS3, but some quirk of your system. Just trying to help...
     
  24. MechaSpanky macrumors 6502

    MechaSpanky

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    #24
    RGB vs CMYK

    jerryrock,

    I'm surprised that as a graphic designer you haven't had any problems with your files once they reach the printer. Truth be told the printer converts all of your images from RGB to CMYK and then charges you or your company for doing it. Depending on the type of work you do, RGB to CMYK conversions can make a huge difference.

    You said "The LCD monitor can not display the full CMYK color gamut."

    Who said anything about what kind of monitor he has? Not everyone uses LCD monitors. Plus, in the end a printer does not print RGB images. The printing process uses CMYK, not RGB.

    Yes there are some modern digital presses that can convert RGB images into CMYK but still in the end you have to have a CMYK image so why not do it right from the start. I have never seen a printer who says "we prefer RGB images". Most printers require CMYK images and if you send RGB images, they will charge you an extra fee to convert them to CMYK (which you should have done from the start). Even if the digital press can convert images from RGB to CMYK, most of the time their conversion isn't as good as what can be done in Photoshop.

    Jim Campbell,

    I completely agree with you. From reading your posts, I can tell that you are someone who has an intimate knowledge of things that many people have no idea about, like creep, impositions, and pagination. So many of the designers today have no clue what happens when their files get to the printer. A truly good designer knows and understands the printing process.
     
  25. jerryrock macrumors 6502

    jerryrock

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    #25
    Mechaspanky,

    The printer I deal with prefers RGB for photos and there is no extra charge for doing so. The machine is a Xerox iGen Digital Press. I send a color proof with my digital file and the conversion is done by the printer. Converting the RGB photo file to CMYK is destructive and you cannot get the detail back once it is gone.

    Your CMYK converted file is also being converted again when it reaches the press to comply with their printer icc profile (in the case of digital press). This is why my printer prefers the original RGB photo file.

    I am not saying that everything sent to the printer should be RGB, just photo files. I still use CMYK for all my other graphic elements, but use Pantone color matching.

    There are several ways to get to and end product and this is all I was trying to point out. I didn't expect to be attacked for my workflow or method. It is what my client and printer prefer and the method that obtains the best color output for my situation.

    Jerry
     

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