6 Replies Latest reply on May 13, 2009 1:38 PM by Lou Dina

    Newbie CMYK question - alternate profiles?

    David4322

      I am converting a whole series of images to CMYK for printing, in Photoshop CS3. All the originals are RGB 8 bit. I am surprised at the range of the results (as viewed on monitor) I am getting. It seems many images hardly change at all with conversion, some change moderately, and some are skewed a great deal. The moderate ones I am able to compose actions with adjustments that approximate the appearance under RGB. Some of the worse ones are so bad as to not be viable with any adjustments I have been able to make so far.

       

      In particular, several of the files with large areas of blue sky are very badly affected - while others that also have large blue skies are almost completely unaffected and look great. The difference seems to be that those whose sky shade is closer to cyan display well, where those which are a saturated shade closer to true blue look terrible - dull and dark and lose all their luminosity, becoming a much darker shade of slate blue-grey. I also get contrasty bright halos surrounding trees in 2 cases.

       

      Also, on a few,  large areas of saturated green foliage in the background seem to lose much of their yellow, causing the images to be much less zippy overall. Same thing with large red, orange, and lavendar areas, but this does not impact the image appearance as badly.

       

      It doesn't make a lot of sense to me that the conversion would just pull so much yellow out of the saturated backgrounds (cmYk after all...), and leave the whites and other zones unaffected (so that if I just try to add the yellow back in, I lose the whites and other areas skew). Can this be minimized with any other settings or techniques?

       

      Also: I have heard there may be numerous CMYK color profiles which can be applied as alternates when converting. How can I obtain and install these profiles? Will they alter the display characteristics with congruent press results?

       

      Thanks for help with this!

        • 1. Re: Newbie CMYK question - alternate profiles?
          Lou Dina Level 3

          David,

           

          You leave out a LOT of information that is important if you want a good response.  Converting to "CMYK" means little.  Every CMYK is different, depending on the printing device, paper, ink, etc.

           

          In "general", CMYK doesn't do a very good job on blues, bright reds, and light pastels, but this is a very general statement.  Tell us what RGB profile you are starting out with, what CMYK profile you are converting to, the rendering intent, and what software created the CMYK profile, or whatever information you have.

           

          A monitor can display a MUCH wider dynamic range than a typical CMYK output space, and usually had a wider gamut (at least overall) than most CMYK color spaces.  If you are printing to an inkjet on a wide gamut glossy paper, you will have one result.  If printig to a low gamut matte paper on an inkjet or press, it's a whole different situation.  And Newsprint.....well, that's another situation altogether.

           

          If your original RGB image has a super bright, wide dynamic range, super saturated colors, and is in a super wide color space, such as ProPhoto RGB, then you may be flabbergasted when you see the difference in print or in soft proof, especially if you send your file to low dynamic range matte fine art papers or a press using uncoated stock.

           

          Give us more info and perhaps we can give you more useful guidance.

           

          Lou

          • 2. Re: Newbie CMYK question - alternate profiles?
            David4322 Level 1

            Thanks for the response Lou.

             

            I am working in Photoshop CS3, in Windows Vista, on a Gateway laptop with a generic PnP monitor.

             

            Image mode for originals:

            RGB  8 bits/channel

             

            From color settings:

             

            RGB: sRGB IEC61966-2.1

            CMYK: U.S. Web Coated (SWOP) v2

             

            I have not been aware of these settings. I probably just accepted default settings.

            I just changed RGB setting to Adobe RGB (1998) to play with it, having read the characteristics. The CMYK drop down has a dozen or so options, but I do not know enough to choose.

             

            The project is high saturation colorful custom business card designs. Most of the source images are photographic - tropical, nature, etc. - high quality photography combined with product images. The destination uses Heidelberg plate presses, ganged. Printing to 14 pt. stock, usually glossy both sides, occasionally uncoated.

             

            See my first post for indications of what I'm seeing on my monitor, and what color corrections I'd like to achieve.

             

            Thanks very much for any suggestions

             

             

            P.S. Just for curiosity, if the CMYK colorspace is so problematic for blues and bright colors, why is it the ubiquitous standard in printing?

            • 3. Re: Newbie CMYK question - alternate profiles?
              Lou Dina Level 3
              David,

               

              "From color settings:

              RGB: sRGB IEC61966-2.1

              CMYK: U.S. Web Coated (SWOP) v2

               

              I have not been aware of these settings. I probably just accepted default settings.

              I just changed RGB setting to Adobe RGB (1998) to play with it, having read the characteristics. The CMYK drop down has a dozen or so options, but I do not know enough to choose."

               

              Welcome to the world of color management.  It's a deep and complex subject, especially at first.  It is not unusual to be a bit disappointed when comparing an incredibly bright monitor view of an image (especially if the image is very bright, contrasty and saturated) to what it will look like in print.  It's physics, man.  There is NO way you are going to get some of those colors in print, period.

               

              "The project is high saturation colorful custom business card designs. Most of the source images are photographic - tropical, nature, etc. - high quality photography combined with product images. The destination uses Heidelberg plate presses, ganged. Printing to 14 pt. stock, usually glossy both sides, occasionally uncoated."

               

              If you are interested in achieving the best possible color and range, you will need to embark on some study and learning.  Every device has its limits as regards to the color that can be reproduced.  Ink on paper (regardless of the ink colors chosen) will usually be a bit dim and dull compared to a backlit monitor, which has higher dynamic range, saturation, etc.  That's part of why slides or screen presentations look so lively compared to prints.  The fact that you are in a dark room also helps make them "pop".

               

               

              P.S. Just for curiosity, if the CMYK colorspace is so problematic for blues and bright colors, why is it the ubiquitous standard in printing?'"

               

              Well, you can't use just Red, Green and Blue inks to print a continuous tone image.  How would you get yellows and light colors?  So, they take the opposite of RGB (which is CMY) and use those "subtractive colors" as the basis for printing.  They add black ink to keep text, lines, etc, in registration, and also to give a truer black, since CM and Y don't give a good solid black (in theory they do, but in reality, no).  It doesn't help that ink dyes and pigments aren't totally pure, which also reduces the possibilities.  Sometimes, inkjets add light inks to help out pastels, or they add other primary colors to give better reds, greens, blues, oranges, purples, etc.  But the basis of printing ink on paper is CMYK.

               

              If you want to learn more, go to my site and read my articles on color management.  You can also read Real World Color Management.  It's tough to explain it all without a solid grounding in the basic principles.   My website is www.DinaGraphics.com.  Click on the Color Management heading and dig in.  I think I few links may be a dead at the moment and I am working with my web host to get them working.

               

              Lou

              • 4. Re: Newbie CMYK question - alternate profiles?
                David4322 Level 1

                Thanks again for the response. I'll look at your site.

                 

                "There is NO way you are going to get some of those colors in print, period."

                 

                Yes, I know that. 85-90% as good as your average National Geographic mag would be a great result for me.

                 

                "The project is high saturation colorful custom business card designs. Most of the source images are photographic - tropical, nature, etc. - high quality photography combined with product images. The destination uses Heidelberg plate presses, ganged. Printing to 14 pt. stock, usually glossy both sides, occasionally uncoated."

                 

                Do you have any actual suggestions about fine-tuning or improving performance?

                 

                Goals: a) getting non-cyan blue skies to tanslate better. b) not losing so much yellow in the greens, or putting it back without losing my whites.

                 

                Methods: a) is messing with CMYK profiles worthwhile - will it have much effect on this? How to choose? b) any other techniques to achieve those goals?

                 

                David

                • 5. Re: Newbie CMYK question - alternate profiles?
                  Lou Dina Level 3

                  David,

                   

                   

                  "85-90% as good as your average National Geographic mag would be a great result for me."

                   

                  First, how do you know whether you are getting 85-90% as good as National Geographic or not?  When you compare a monitor display to a soft proof or print, it almost always looks weak.  It's like listening to two sets of speakers side by side.  One sounds good until you hear a really superior sound system.

                   

                  "The project is high saturation colorful custom business card designs. Most of the source images are photographic - tropical, nature, etc. - high quality photography combined with product images. The destination uses Heidelberg plate presses, ganged. Printing to 14 pt. stock, usually glossy both sides, occasionally uncoated."

                   

                  Do you have any actual suggestions about fine-tuning or improving performance?

                   

                  I am assuming you are converting from RGB to the standard US Web Coated SWOPv2 profile in Photoshop.  That CMYK profile is based on coated stock for an average magazine...pretty good, but not the best achieveable. When converting, look at both Perceptual and Relative Colorimetric rendering intents, and choose the one that looks best.   (be sure to use black point compensation with RelCol intent).  After the file is converted, you have crammed all your original colors into a new "container" that is smaller overall.  You can then make some tweaks to your CMYK file in Photoshop to make it look a bit better and bring back some of the saturation and dynamic range you lost, but you cannot create colors that do not exist in that color space.  It's like taking a 12 ounce glass of water and pouring it into an 8 oz glass.  Not all the liquid will fit into the smaller glass, no matter what you do.  You also need to be careful that you do not exceed the total ink limit for your press.

                   

                  Goals: a) getting non-cyan blue skies to translate better. b) not losing so much yellow in the greens, or putting it back without losing my whites.

                   

                  Methods: a) is messing with CMYK profiles worthwhile - will it have much effect on this? How to choose? b) any other techniques to achieve those goals?

                   

                  I wouldn't mess with the CMYK profile.  I'd tweak the file after conversion, by using a curves adjustment layer.  You can also try a saturation adjustment layer, selective color adjustment layer, or other techniques.  Blues are, unfortunately, a weakness of CMYK.  So are pastels.  All you can do is get the most out of the destination color space.

                   

                  Rick McCleary wrote a good book called CMYK 2.0 (available on Amazon) which discusses the entire process.  It can't easily be communicated on a forum.  It's too much information.

                   

                  Hope this helps.

                   

                  Lou

                  • 6. Re: Newbie CMYK question - alternate profiles?
                    Lou Dina Level 3

                    David....a few last thoughts.  I assume you probably know this, but it is important and bears repeating.

                     

                    The selection of your destination profile (whether press, inkjet, lightjet, digital press, etc) is important to good color.  Ideally, you want to use "an accurate, well-built, custom profile on a well calibrated device".  An accurate printer profile establishes the boundary of printable colors on the device, but it also contains large lookup tables that help you "re-map" colors from a different color space during conversion.  So, when you send jobs to a press, you would ideally like to have a custom press profile for the specific press, paper, etc.  That profile will normally only be accurate for that press and paper combination, and that assumes your commercial printer has a well calibrated, well maintained press, exercises excellent process control, and handles all the files properly.  There are a LOT of links in this chain. Many commercial printers do not actually profile their press...they profile their proofer instead, and supply "contract proofs" to their customers.  Once the customer signs off on the proof, it is then the printer's job to match their own proof on press (within tolerances usually specified by SWOP, which are fairly liberal).

                     

                    You mentioned some of your images may be output on coated paper, and some on uncoated.  Coated and uncoated papers respond to ink differently, have different gamuts, different ink limits, etc, and would each require a different profile for optimum results. If you have selected your commercial printer, ask them for profiles for their press, or their proofer.  If they have neither, ask what they recommend, both for glossy coated and uncoated stock (or whatever you plan to print on). They may recommend an industry standard profile, such as US Web Coated SWOPv2, etc.  If they are their own profiles, ask for copies so you can convert to their standard for your given paper.

                     

                    Then, use those profiles for conversion.  Images going to glossy coated stock should used the recommended glossly coated profile, and uncoated images use the uncoated profile.  You will undoubtedly see less color gamut on the uncoated paper, with more of a loss of color, at least on colorful originals.  You will probably want to convert each image individually, if you want the best possible output.  Bring up the Convert to Profile dialog, select the profile supplied or recommended by your printer, then try both Perceptual rendering, and Relative Colorimetric rendering to see which initially looks the best overall.  (use BPC with Relative colorimetric).  If you see a huge shift in color and dynamic range, it doesn't mean the profile is necessarily bad.  It probably indicates that your original has a lot of unprintable colors, at least on that press/paper combination. The rendering intents are different ways of cramming a larger gamut file into a smaller gamut space.  Editing the profile won't magically give you more colors, though it will redefine the tables for conversion and redistribute your colors differently.  That is not a recommended action unless you are very experienced and skilled at profile editing.

                     

                    What you can do AFTER conversion is make some edits to your CMYK file (curves, levels, hue/saturation, selective color, etc) to try to get a little closer to the look and feel of your original.  You can never get it all back, because your original has unprintable colors, but you can often move in the right direction.  When you edit your CMYK file, you need to be careful to stay within the ink limits of the press/paper combination.  If you pump your file up too much, your job may be rejected by the printer.  So, if they specify a 280 total ink limit, and you pump it up after CMYK conversion to 320 TIL, expect your job to be rejected (or an extra charge to rework your job).

                     

                    Rick McCleary's CMYK 2.0, or Real World Color Management can be very helpful in understanding all this.

                     

                    And remember, well done images in print can look excellent.  But even images that look fantastic on the printed page in isolation can sometimes look a bit paltry when compared side by side with a super bright, colorful original RGB image on your monitor.  Welcome to the world of print.

                     

                    Lou