When i convert from RGB to CMYK i n photoshop total color changes

Discussion in 'Layout, graphics, and prepress Software' started by sash_007, May 13, 2010.

  1. sash_007

    sash_007 Member

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    Hello friends,

    I am really confused about this when i tried to convert RGB TO CMYK in photoshop the whole color changes ?
    also i want to know how can i create pdf of any size with cute pdf writer ?
     
  2. Jeff

    Jeff Senior Member

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    What are your settings under Edit -> Color Settings (or Ctrl + Shift + K on windows photoshop?) and do you have color management setup for your
    monitor/output device?

    If your color management is way off, you may be seeing things incorrectly.

    However, even if your're setup accurately in terms of color management, not all RGB colors can be reproduced exactly in CMYK (bright vivid saturated blues and vivid greens for example will translate into duller CMYK colors.) This is why printers who will be printing process color CMYK (not talking here about expanded gamut added by presses which run additional colors beyond cmyk) commonly require you to do the conversion from RGB to CMYK. The straight mathematical conversion from RGB to "best fit / closest cmyk version of the rgb color" CMYK is just a click of a button or automatic in the RIP. Many times that's fine. However sometimes depending on the RGB colors you've used, which colors are next to which other colors, etc. it takes the designer's or prepress guy's eye to make an artistic decision. Yes this CMYK blue is the mathematical best representation of the RGB color, but it looks to purple to my eye in that sky and needs a hue adjustment. Or this bright RGB green when translated to its closest mathematical CMYK counterpart looks too drab as the background here and needs to be lightened. Etc. So either work in CMYK colors with a display which has a color profile applied, or if you are developing work in the RGB convert and then manually adjust slightly as necessary for a pleasing CMYK version.
    Under Properties, Paper/Quality Advanced, Paper Size, Postscript Custom Page Size I enter the custom sizes I need if it's not a standard sheet size. The dialog box says the limits are 200 inches for me or over 16 feet in one direction - I haven't needed to go beyond that to date.
     
  3. sash_007

    sash_007 Member

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    actually when i see it in adobe Photoshop there is not much of difference but when i view it through nero picture viewer there is a huge difference and i also tried by redoing the design by starting all in cmyk but that dint make any difference

    i am attaching the screenshot of what i see with nero snap viewer

    rgb
    [​IMG]


    cmyk
    [​IMG]

    so is it better to convert rgb jpg to pdf and then to print?
     
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