11 Replies Latest reply on Sep 17, 2012 2:15 PM by Greg "Floyd" Apodaca

    cmyk neutral

    s.mahn Level 2

      I know a few ways to make neutral (R=G=B) in CMYK but I haven't setteled on a favorite.

       

      Lets say you want a perfectly neutral metal (ie, silver) - what's your go-to move?

        • 1. Re: cmyk neutral
          Level 7

          enter a grayscale or LAB value, and let Photoshop convert it to CMYK

          • 2. Re: cmyk neutral
            s.mahn Level 2

            Sorry Chris, I'm sure it's obvious, but enter it where? What tool or adjust layer are you refering to?

             

            Here's something I don't get, perhaps you can explain:

             

            If I fill a layer with white (255,255,255) and set it to Color blend mode it renders grays reddish; if I use a mid-gray (128,128,128) it renders grays as cyan. Where then in the density scale would yeild neutral?

             

            Other approaches:

             

            Cannel mix w/ Grayscale checked washes out blacks. Why so many "filtered" BW presets (all too simplistic) and none non filtered? Got a nice "normal BW" channel mix recipe?

             

            Gradient Map with black and white end points crushes my 3/4 tones.

             

            There's really no solution as simple as desaturating in HSL in RGB.

             

            My best results so far are to desaturate with HSL, then add cyan with levels/curves to compensate for the red. Takes two adjustment layers, and I don't always get R=G=B, but the tonal results are relatively smooth.

             

            Stil thinking there should be a decent one layer approach, and maybe you've already offered it and I just missed it.

            • 3. Re: cmyk neutral
              Level 7

              The color picker, or the color palette.

               

              It might help if you described a lot more about what you're trying to do.

              • 4. Re: cmyk neutral
                s.mahn Level 2

                I see, my question was indeed not very clear.

                 

                When working in CMYK mode, I'm looking to go "grayscale" via an adjustement layer.

                 

                Not convert to grayscale, just render the image neutral color while maintaining roughly existing tonality.

                • 5. Re: cmyk neutral
                  s.mahn Level 2

                  Is my question still not clear or does no one else retouch in CMYK?

                  • 6. Re: cmyk neutral
                    Greg "Floyd" Apodaca Level 1

                    Try Gradient Map, rich black to white, but zero percent smoothness to prevent "crushing" of 3/4 tones.

                    1 person found this helpful
                    • 7. Re: cmyk neutral
                      s.mahn Level 2

                      Smoothness was helpful, thanks.

                      • 8. Re: cmyk neutral
                        s.mahn Level 2

                        Chris, I'm curious.

                         

                        Picking up from your suggestion, I open color picker, enter R=128, G= 128, B=128 (yeilding a CMYK value of 52,43,43,8) make a solid color adj layer of this color and set it to Color blend mode. In theory this should yeild a neutral color image, but it instead is cyan.

                         

                        Is this a bug? What is the right CMYK formula for neutral?

                        • 9. Re: cmyk neutral
                          Level 7

                          >> What is the right CMYK formula for neutral?

                           

                          There isn't one.  Every profile will require a different mix of inks to achieve a neutral color.

                          • 10. Re: cmyk neutral
                            c.pfaffenbichler Level 8

                            Is my question still not clear or does no one else retouch in CMYK?

                            There probably are people who do and there are certain cases where it may indeed be indicated, but in general it is not a good idea.

                            What is your reasoning for doing touch-up in CMYK, if I may ask?

                            • 11. Re: cmyk neutral
                              Greg "Floyd" Apodaca Level 1

                              Things to keep in mind...

                               

                              - A 400% black will probably look reddish, because 100% CMY is dark brown. Nuetral looking tones are usually in the 60,40,40,* range. Same thing goes for 128,128,128. This ratio is reddish as well.

                               

                              - Color Mode is a linear adjustment based on the ratio 30:59:11. As your density changes, the adjustment can clip in the highligt/shadows of individual channels. It tries to keep the color, but if that means calculating 277 in a particular channel, in certain scenarios, it tops off at 255, changing the color ratio. Color mode is too simple a formula, and should not be used to recolorize imagery. Use Soft Light mode for non-linear tinting of imagery.

                               

                              - In CMYK, color appearance is heavily depandant on the color space. Changing the profile/color space will shift nuetrals all over the place. Most poeple stopped retouching in CMYK, and instead retouch in RGB, sometimes in Out Of Gammut view mode. Better yet, work in a Smart Object. RGB inside for layer operations, updating to a CMYK final image that may contain special layers like overprint black or Spot Channels.

                               

                              - You will also see shifts based on Black generation. High GCR/UCR is colorized less because the ratio of black is higher, causing a shift in the tonal ramp. A blue of 80,40,40,10 contains more colorizable pixels than a 20,10,10,90 or an 8,4,4,0.

                               

                              - Adjustment Layers destroy CMYK builds. Lighten one channel too much, and you see the GCR/UCR seam. If you're stuck scanning in CMYK,  then use extremely low GCR/UCR, hopefully with settings that can saturate the black areas a bit. When you're done reworking the file, you can use tools to apply GCR/UCR after the fact, like a Channel Mixer layer with all it's undelying advanced blending sliders set to 0,0 | 0,255.

                               

                              - Another easy way to create matching GCR/UCR/UCA... in CMYK is to place a white Photo Filter adjustment layer, (Preserve Luminosity unchecked), at the top of the layer stack. This remixes underlying layers to LAB, then back to CMYK, 'on the fly', creating matching tone transitions. This is based upon the color space of course.

                               

                              Hope that helps.