4 Replies Latest reply: Jun 5, 2009 8:19 AM by Wade_Zimmerman RSS

    CMYK to 3 Spot Colors

    cts_graphics Community Member

      Hey, All.

       

      I've got a CMYK image that I want to convert into 3 spot colors — 2 PMS and black, to be exact. The final destination is a color t-shirt print.

       

      However, I don't want a tri-tone effect (where the three colors are combined.)

       

      Portions of the image need to be 100% Spot 1, others 100% spot 2, and others a % of K.

       

      I figure the best way to do this is convert to tritone, and then over into Multichannel, and mask off the parts in the respective channels.

       

      My only concern is how well a multichannel image will be handled by the printer.

       

      Anyone have any better suggestions?

       

      d

        • 1. Re: CMYK to 3 Spot Colors
          Wade_Zimmerman Community Member

          This might be easier to accomplish with illustrator. You make the file a grayscale bering it into Illustrator as a psd or tiff copy it to three layers
          select it on one layer at a time and simple select you pms color and it is now a colored image with one spot color do that three times.

           

          Yes you are right you can only see one color the top one so you make clipping mask to remove what you don't want. The good thing is that you only have to do two clipping mask and the parts hidden on the bottom layer won't be seen or printed.

          • 2. Re: CMYK to 3 Spot Colors
            Gyno-jiz Community Member

            Don't ignore the RGB/CMYK channels for bringing pixels into the new spot channels.

            • 3. Re: CMYK to 3 Spot Colors
              IanPorter99 Community Member

              Speaking as an artwork separator for a T-shirt printer, I'd much rather receive a flat RGB file than a multichannel file that someone's tried to colour separate for me. Bu this is how I'd go about it:

               

              Get the image looking how you want it (by whatever means; filters, mutlichannel etc.). Get it back to being an RGB .PSD, prefereably at 300dpi at final print size. Give this to your printer and let his artwork guy worry about how it’s split into three colours…

               

              But for the record, this is how I’d go about it:

               

              To separate this into three spots, I'd use the help of "Image/Mode/Indexed Colour..."

               

              Take your RGB orignal. Duplicate it (leave the original open). Reduce the resolution in the duplicate 150dpi (to give the printer an easily screenprintable dot), making sure that resampling is done with Nearest Neigbour. Any anti aliasing brought in by a bicubic resample will ruin everything. Now go to "Image/Mode/Indexed Colour...". Under "Palette:" select "Custom...".

               

              This will bring up the "Color Table" dialogue with a grid of lots of little boxes. If you've not used this option before, the pallet SHOULD be blank I think. If it's not and there are colours in these boxes, click/drag from top left box to the bottom right. When the colour picker appears ("Select first color:") pick white, and click OK. It'll then appear again ("Select last color:") and pick white again. This should leave you with a colour table filled with white.

               

              [N.B. this is actually the process for creating a graduated range of colours if you were to use different start/end colours. It just happens to be the quickest way to "cleanse" the colour table. Also note that if you're printing onto a black shirt you might want to use black instead of white]

               

              Click the first box in the Color Table, and the colour picker will open again. Now, using the eyedropper go over to your original image (you did leave it open, didn't you?) and pick one of your three prominent colours. Click OK. Repeat for the other two. When you're done, click the OK in the Color Table. Back at the Indexed Color box, in the Options section set Dither: to Diffusion and Amount to about 85%. Click OK.

               

              You've now got you're three colour image, but it probably looks a mess as Index mode never displays properly at anything other than 100%. Zoom in to see what it really looks like or convert RGB image, which does display a bit better.

               

               

              You can now use the Magic Wand to select each individual colour and make spot channels of each. Note that these are not halftones as such - the printer will treat them as "solid" spots so there's no angles or frequencies to set. Welcome to the world of stochastic square dot separations!

               

               

              If you're not having much luck selecting colours yourself at the "Color Table" stage, rather than Custom try Local (Adaptive). In the colours box, tell it how many colours you want in your design (remember to add one for the white of the shirt). This can sometimes make better choices than you can get by eye. You may also have to use the "Forced:" options to make sure it picks a white or a black if there's another colour close in your design. If you need to add text or other elements with a clean edge, you can upsample to 300dpi, remembering to use Nearest Neighbor of course.

               

              There is of course software to do this for you, like FastFilms (now defunct, I believe?) and Screenprint Separator...

              • 4. Re: CMYK to 3 Spot Colors
                Wade_Zimmerman Community Member

                Yu could of course f do it in Illustrator which has a great Live Color 

                feature al you have to do is select your artwork and then open the 

                recolor dialog and change the color model to Color books and select 

                the spot color library you wish to work with like Pantone Solid Coated 

                and all the colors are now spot and have swatches which are properly 

                identified. You can even change the spot selection and preview the art 

                live and you can do this with gradients and one colored images.

                 

                I wish they had this feature in photoshop as well.