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Question I'm using Photoshop CS on a Mac with OS X3.9. How can I use a layers and channels for spot colors to be printed on a T-shirt? I'm attempting to use separate layers for each color (in RGB mode) and then move them and assign them spot colors in channels and save as a DCS.2 file. How do I move them and will it work? Thanks. Get the answer below

Sponsored Links IntelliNet TechnologiesProtocol stacks/development plat- forms for SS7/SIGTRAN/femto/LTEwww.intellinet-tech.com FLO Media ViewerPDF to flash viewer with preflight, soft proofing or user commentingwww.flomedia-viewer.com Screen Printing Defects?Screen Printing Defects Are Reduced with Cleaner Screens.See How! www.foamtecintlwcc.com Paint & Coatings InkScreen Printing Inks Suppliers PU Ink, Nylon Ink Manufacturerewonil.en.ec21.com Answer Hi Phil, When you say "move them," what exactly do you mean? Are you talking about moving the whole file to another program (like a page layout program)? Or are you talking about taking an existing image and selecting the colors from it, then moving those colors to separate layers? I'm thinking you probably mean the latter, but if I'm wrong please post back and let me know. Also, I'm going to assume you're talking about line art here and not a bitmap. What I think you might be talking about doing would go something like this: 1. In your file, use the magic wand tool to select an area of color. Once it's selected, go to the Layer pulldown menu and select New > Layer Via Cut. This will put that color on its own layer. 2. With your eyedropper tool, sample that color. You'll see the color picker dialog box come up, and now click on the Custom button. When you see the Pantone colors come up, the corresponding PMS color will be selected. Make a note of that color. 3. Make sure the selection you just put in its own layer is loaded (using a Mac, command + click on the layer in the layers palette). Now, in your Channels palette, click on the flyout menu on the upper right (the little triangle). Select New Spot Channel. 4. In the New Spot Channel dialog box, click on the Color box, and then type the number of the PMS color you made note of earlier. The Color Picker will automatically go to the number you're typing. This creates a spot color channel of the area you selected and separated to a new layer. The Solidity option gives you an on-screen simulation of the solidity of the printed spot color. A value of 100% would simulate an ink that solidly covers the inks beneath, and a value of 0% simulates a transparent ink (like a clear varnish). But this only for on-screen simulation, and has nothing to do with how the image will actually print. 5. Once you've done this for each color, then you can go to the File menu, select Save As, and then select Photoshop DCS.2, which of course will generate the 4 color seps, and an EPS. Also, make sure you have Spot Colors checked when you're in the Save As dialog box (you'll see this

right below and to the right of the Format pop-up menu). I tested this out, and it worked for me -- I also recorded my actions for you: http://little-works.com/all_experts/spotchannel.mov Hope this helps! Let me know if it doesn't and we'll figure it out. Lisa

Ask a Question Convert to CMYK to get the separations options under colour management in the printer box. You can install a postscript printer - try PDFCreator, that'll give you a file to view. D

Spot Color Separations with Photoshop Tina from Texas, USA, using Photoshop 5.5 with Windows 98, writes in with: [Quote:] How do I create spot color process separations using Photoshop starting with a full color photo image? This is for outputing to film to screen printing t-shirts. Thanks in advance for your help. Tina Tina, it's easy -- but first let's see if you want spot colors or process separations... Creating spot channels: Process color separations are films (often called "printers") used to print a full color image. These four sheets of film have been separated into their individual color channels so they'll print properly using CMYK inks (Cyan, Magenta, Yellow and Black). Of course this is a highly simplified definition. Spot color separations are films that do not necessarily use the full color image to derive the image value which will be used. Spot color is usually designated by the designer or artist. Spot colors do not come from Process Color Separations unless they are added as separate, individual pieces of film. For screen printing, we assume you mean "Spot" color. In this case you'll need an individual "Spot Color" and its corresponding sheet of output film in order to burn the screens and print the T-Shirts. For each color you wish to (screen) print, you'll need to create a new spot channel or convert an existing alpha channel to a spot channel. To create a new spot channel: 1. Choose Window > Channels to display the Channels palette. 2. To fill a selected area with a spot color, make or load a selection.

Now do one of the following to create a channel: * Ctrl-click (Mac OS: Command-click) the New Channel button in the Channels palette. * Choose New Spot Channel from the Channels palette menu. You will see a new Channel icon appear at the bottom of the Channels Palette, with your selection If you made a selection, that area is filled with the currently specified spot color. You'll need to assign a color to this channel. * Click the color box, and choose a color (Select from any of the color systems included with your Photoshop program. If you create your own custom color, don't worry, the screen printer can mix up the ink color you need. We do not know if you'll be using transparent inks, but if you are not then use a value of 100% to simulate the opaque silk screen inks. The channel can have grays and gradients of the ink, however you need to make sure the film will be output at the screen frequency required by the screen printer. KEY RULE: You MUST give each Spot Color Channel a unique name. This signals to the software that it is not a process color, and that it must be imaged as a separate piece of film. TIP: it helps to name the channel the color you'll be printing. Converting existing channels to spot channels: If you have edited and modified one of the existing Process (CYMK) channels for use as a Spot color, then do one of the following: * Double-click the alpha channel thumbnail in the Channels palette. * Select the alpha channel in the Channels palette, and choose Channel Options from the palette menu. 2. Rename the channel (Again this is important) 3. Select Spot Color 4. Click the color box, choose a color in the Color Picker dialog box, and click OK. Do NOT pick the same color again. You don't want two films of the same color. Finishing: Before outputting proofs or films, you need to know the screen process your printer will be using. Some substrate stencil processes use a film positive, others a negative. Consult your printer. Choose Image > Adjustments > Invert to apply the color to the selected area of the channel.

REMEMBER: you can edit those channels using brushes, type, etc. so long as you stay to black and white ONLY. Have fun... send us a thumbnail of the finished shirts. 2004.04.04 | Permalink

What is Color Separation and How to Separate Colors for Printing

 What is Color Separation and How to Separate Colors for Print Let's start with a definition of what color separation is and how it's used by printers. Color Separations are artwork and photographs split into component plates of the four colors cyan, magenta, yellow, and black (CMYK) in preparation for process printing. In graphic arts, cyan, magenta, and yellow are also known as Subtractive Primary Colors because along with black, they are the ink colors used in color-process printing. On the Molecular Expressions™ web site, they offer an Optical Microscopy Primer under the Physics of Lights and Color section which provides an excellent definition of subtractive primary colors and how they work: "Pigments, and dyes are responsible for most of the color that

humans see in the real world. Books, magazines, signs, and billboards are printed with colored inks that create colors through the process of color subtraction. . . . When two of these subtractive primary colors are added together, they produce a primary additive color. For example, adding magenta and cyan together produces the color blue, while adding yellow and magenta produces the color red. In a similar manner, adding yellow and cyan produces green."ﾝ In theory, these three subtractive primaries could be used alone, however the limitations of most dyes and pigments makes the addition of black necessary to achieve true color tones. On a printing press, each separated component is made into a film that is used to prepare a printing plate for that color. The final image is created by printing each color plate, one on top of another. Think of layering colored transparencies on top of each other in the specific order of cyan, magenta, yellow, and black. Once a document is on a printing press, each color of ink used in that particular piece is printed one at a time and the final image is created by printing in this sequence. The Molecular Expressionsâ„¢ web site also offers an interactive Java tutorial where designers can see the process of color separation in action. Try the tutorial at: http://micro.magnet.fsu.edu/primer/java/primarycolors/colorseparation/i ndex.html. A basic understanding of the subtractive color process and how it works can help graphic designers make the best color choices for a specific project. Besides the color separations for standard four-color process printing, designers also need to be familiar with spot color separations. Just as with process printing, there is a plate on the press for each color of ink. Say for example you have two spot colors, Pantone 239U (sort of purple), Pantone 368U (bright green), and black. This gives you two spot colors plus the black for a total of three color separations and three plates. These same principles of color separation also apply to desktop publishing. But whether preflighting a document for a traditional press or working on a desktop printer, graphic designers need to be aware of issues that

affect a document's appearance. One of the most common is not making the conversion from the RGB color mode to CMYK whenever a document will be printed. Using the RGB color mode (red, green, and blue) is fine for a web site as they are additive colors, optimized for display on computer monitors or scanning devices. While the color change between the two modes isn't always substantial, there are instances where RGB and CMYK differ dramatically, so get in the habit of making the conversion before sending files for output. To make sure those separations are correct, during the prepress stage designers should print color separations on their desktop printer to insure colors will separate properly once sent to a commercial printer. For example, if you have a four-color (CMYK) document that is four pages long, you'd have a total of 16 pages in color separations - four per page. Another point to consider is what type of file format you'll be using. If you're sending a file to your printer as a PDF, a pre-separated or PostScript file contains a separate plate for each file in the document. So for example, a standard process color job submitted as a PDF would have four separate pages (or plates as noted above) containing cyan, magenta, yellow, or black color information. If you use a composite file, all of the color information is held in one file meaning everything is on one page. In this case, your service bureau separates the file into the individual color separations. Both file types have advantages and disadvantages and it's wise to discuss those with your printer. This last point is one graphic designer's should do on every job and can't be stressed enough. Getting to know your printer and asking questions about a job or for your printer's suggestions and advice is one of the most important things you can do. Building a relationship with your printer or service bureau is beneficial no matter what the job. In the area of color separations such rapport is crucial, as the wrong color can change everything and not necessarily for the better.

Color separation in Adobe Photoshop See Video lessons

also:

It is wishful to separate thematic color layers before color raster vectorizing in Easy Trace. The Rainbow module is intended for this purpose. It has become an integral part of Easy Trace Starter Kit beginning from ET 7.3 version. Easy Trace users who have no a complete (not demo) Rainbow version have the opportunity to separate the Relief and Hydrography layers applying Adobe Photoshop. To do it, fulfill the sequence of operations forming a Photoshop Action Set available in the Download section. You will also find a 256-color raster here for demonstration of the Action Set applying. See below for instruction on installation. Description of the work is here. Attention! This Photoshop Action Set is intended for separation of isolines of red and brown tints. This way of color set separation requires significant memory and disk space capacity. It has limitations in raster size (up to 2G in the RGB form) and linear dimension - less than 30.000 pixels along its any side. To work more effective, optimize settings of your computer. Setting Optimization You will find general recommendations in the Adobe Knowlegebase. Document #318243. Installation of the Action Set for thematic layer separation 1. Extract the archive to the folder where Adobe Photoshop is installed (for example,, C:\Program Files\Adobe\Photoshop 6.0); 2. Start Adobe Photoshop 3. Use the Window menu to make the Actions bar visible (Fig. 1). If this item is missing in the menu, the bar is already on.

Fig. 1. How to make the Action bar visible

4. Specify Vectorization.atn (Fig. 2) in the menu of the Actions bar.

Fig. 2. How to add the Actions Set for separation of thematic layers.

Separation of thematic layers 1. Open a color raster (File > Open) 2. Open the Vectorization folder in the Actions bar (fig. 3)

Fig. 3. How to select and start Actions.

3. Press the <Shift> key and hold it pressed while you click the operations of raster preparation Prepare Source Raster, extraction of black and blue colors Extract Black & Blue, and binarization of the separated raster Refine Black & blue (Fig. 3). 4. Click the button at the bottom of the Actions bar to start the selected Actions. 5. Save the black-and-white raster you have prepared (File > Save As) and close it (File > Close). 6. Clean the memory of Adobe Photoshop (Edit > Purge > All) 7. Use the Zoom tool from the Photoshop Tool bar (Fig. 4) to select and magnify the raster fragment containing most closely converging polylines.

Fig. 4. The Zoom tool.Zoom.

8. Select extraction of relief lines (Extract Brown) in the Actions bar and start it. 9. Select the slider position in the Threshold dialog box (Fig. 5) that provides the best isoline separation in the selected raster fragment but keeps them unbroken. Click the OK button to complete Action applying.

Fig. 5. Threshold setting.

10. Save the black-and-white raster you have prepared (File > Save

As). Attention! Default name of this black-and-white raster concurs with the source raster's name. Change it if you want to keep the initial raster or it will be overwritten. 11. Close the separated thematic raster (File > Close). Using Photoshop to create color separations for use in screen printing?

How do I create a custom halftone separation for use in silk screen printing? I am trying to create a custom halftone separation for use in screen printing. What I have done is use the Photoshop color halftone filter. I can then output each of the CMYK plates onto transparencies as halftone screens. However, when using the color halftone feature, how can I use this to simulate an output screen? The color halftone dialog box only mentions Max Radius in pixels. But how would I use this to calculate, for example, a 45lpi line screen? Or am I going about this in completely the wrong way? There are numerous approaches for producing color separations for screen printing. Especially as there are also a number of different applications of the process. Some implementations of screen printing are for one-off art projects, whilst others might `be for commercial TShirt printing for example. For commercial projects it is always advisable to check with the printer first as to their preferred method. Or even better, get them to do the prepress to match their systems, as this probably varies a lot depending on the equipment that they use and the substrate being printed on. The techniques used in the above question might work, as it kind of simulates the CMYK separation process. But the color halftone filter is not really the correct way to create a halftone screen for screen printing. It is predominantly a Photoshop special effects filter rather

than a prepress tool. For example, you can't really be precise about the resolution of the line screen. It also doesn't take account of screen angles and the color halftone filter will not produce different angles for each separated screen color. The following is just one home brewed method and concentrates on achieving an adequate result by controlling the production of the halftone dots themselves. It is always worth experimenting with your own particular setup before commencing with an important screen printing project. 1. First we create our CMYK (or duotone for that matter) image at a normal print quality resolution. Let's assume 300dpi in this case. 2. We then copy each color layer (channel) into a grayscale Photoshop document and then convert that document to a bitmap single channel file (we usually choose 1200dpi at this stage, but your mileage may vary). When you get the Option window choose Method -> Halftone Screen. You then get to choose your halftone screen frequency, which may be around 65lpi for for commercial printing, or probably less for an art project. Once again, it is always best to check with the printer as to what is best. 3. To reduce the likelihood of a moire pattern, it is best to specify different screen angles for each color, which may be different for screen printing than it is for offset-litho printing (have we mentioned checking with the printer?). The following are two possible variations. o Yellow at 7.5%, Cyan at 22.5%, Magenta at 82.5% and Black at 52.5% or Yellow at 5% Cyan at 55% Magenta at 22% and Black at 80%. 4. For dot shape, the ellipse halftone dot is often recommended for screen printing. 5. Once you have converted each plate to Photoshop's bitmap format, you can save them as tiff files, import the file into a page layout program and then print each color plate onto your acetate or film. A completely different approach would be to print separations directly from QuarkXpress, InDesign or a PDF file and specify the type of dots, line screen and screen angles that you wanted to use. This might save a certain amount of times, although arguable gives you less visual control.

The Hidden Power of Photoshop CS: Chapter 2: Color Separations. Pt. 2 Multipass Printing On a press, ink gets put on paper one press color at a time. You can mimic this process printing at home by sending a sheet of paper through your printer multiple times. Use this method to create single copies of your duotone images, both to test the duotone settings on your home printer and to create prints for display that use true duotoning methods. While in some cases it may be redundant to do this (there is no need to print CMYK in separate passes on a CMYK printer most of the time), this approach may be the best way to get the results you planned using your ink-jet when printing duotones. It will let you imitate press separation and process printing by laying down color one “ink” at a time, though you will actually be processing four inks in each pass to imitate specific tones. By applying colors in this way, you can imitate the result of spot color printing at home (so long as the colors you choose are in the CMYK range). This will probably work best with an ink-jet or liquid ink printer rather than a laser or pigment printer. Inks will mix better than toners. When working with the multipass technique, keep the tones for each color in separate images, color them using the appropriate fill color, and send the result to the printer one at a time on the same sheet! Print light colors first, and follow with darker. Allow some drying time in between colors. In this way, you will build your print similar to the way it would be created on a printing press. As long as your printer has reasonably accurate paper gripping, you’ll get a pretty refined result. Because each pass can create color using CMYK ink mixtures, you can imitate many Pantone colors.

Blacks will often be richer and darker when you’re printing with multiple passes. You’ll notice a greater tonal range because the blacks will be darker—even though you are dealing with the same number of levels of grays in the image. This works somewhat like putting on a second coat of paint. You may need to allow a few seconds of drying time between passes, and using a good quality photo-print paper is recommended.

Duotone curves can be used to make subtle changes and corrections in difficult blackand-white images. Although the images will not retain the richness of duotoning or the effect of multiple inks when printed in black and white, using duotone may help you visualize the change you want to make by adding more variables to the tone. Creating duotone effects to correct grayscale images can help strengthen subtle detail that already exists in the image. For example, if you have an image with subtle highlight detail (such as a wedding picture where the dress detail can become somewhat washed out or faded due to harsh flash lighting), you can create a duotone to change the image emphasis in different tones. Open the image in black and white, and then create a duotone. In the case of the wedding dress, you might pick a black and a light-gray ink for your duotone colors. Use the light gray to emphasize the highlight area of the image; this will allow you to make fine adjustments. With the duotone information separated into channels within the file, you have more flexibility to manipulate the file and get the desired results. For example, if you wanted to add type to your image in pure spot color, or in a specific mixture of colors included in the file, you can do that by manipulating the channels. This is just about impossible to pull off in a Duotone mode file. To add type that is a specific mix of colors that won’t be a natural mix of the duotone curves (say 100 percent of the light color and 25 percent of the dark), you need to adjust the tone in the channels separately. You can do this by creating a type layer and using that layer as a selection source for manipulating the channels: 1. Using the file from the previous example, choose the Type tool and click on the image to create a type layer.

2. Type in the text you want (to follow the example, type Wagontrain West), and then position the type and size it to fit. The color of the type doesn’t matter at all, but you might want to select a color that comes close to how you imagine the result (to help with your preview). 3. Hold down the /Ctrl key and click the type layer in the Layers palette to load the type as a selection. 4. Choose the channel/color you want to adjust and fill the selection with the percentage of that color that you want the type to have in grayscale. For this example, choose the Pantone 472 channel and fill with 100 percent black. 5. Choose the other channel/color and fill it. For our example, choose Black and fill with 25 percent black. The channels that result from these steps are shown in Figure 2.24. While it may be best to handle the type in a separate file (using vectors) to get the sharpest result, this example should help you see how manual duotones allow more potential in manipulating files and results. These changes can also be made in an earlier stage in the layered channel file by directly adjusting the Duotone 1 and Duotone 2 layers using the selection.

Figure 2.24 With the type at 100 percent Pantone 472 (A) and 25 percent Black (B), the channels will look as they do here when adjusted. Separating CMYK Color RGB differs from CMYK in that RGB is a reflective light scheme and CMYK an absorptive one. When you add color (light) in RGB, the result gets brighter. When you add more CMYK color (pigment/ink), the result gets darker in what is just about exactly the opposite process. In fact, CMY and RGB have an interesting relationship as opposites, as we saw briefly in the first chapter.

Photoshop provides automated separation to CMYK. To make the separation all you have to do is choose CMYK from the Mode menu, and Photoshop will separate your image according to your specified color preferences (This can be one of the predefined standards from the CMYK Working Spaces in the Color Settings, or a custom definition). The CMYK command can be a godsend, but it almost completely disconnects you from the separation process. Once you can do a CMYK separation manually (few people who use Photoshop can), the reasoning behind the process will help you make good CMYK handling choices, and it will allow you to customize your separation results. Custom CMYK separation in Photoshop is not that easy because the program wrests control from you to simplify the process. In most cases this is handy, but it can certainly hamper your understanding of the color process. CMYK separation can be a complicated topic, and this topic alone could fill an entire book. Let’s now look at the process of manually separating CMYK right from RGB and examine some additional theory. Initially this discussion will just be a learning tool so that you can see the possibilities and complexity of CMYK separation options. We’ll walk through the separation process in three sections: the basic CMY separation, the handling of black separation, and the application of black to the image. Step 1: Making the Basic CMY Separation In theory, a CMY separation (with no K) is the inverse of RGB. In the RGB color scheme, cyan is a combination of pure blue and pure green, magenta a combination of pure red and pure blue, and yellow a combination of pure red and pure green. You can see color combination in action by opening the RGB.psd file on the CD. With this file open, move the colors around to see how they combine. Blue is also really the inverse of yellow, green the inverse of magenta, and red the inverse of cyan. Note that they are in directly opposite positions in RGB.psd, CMYK.psd, and in ColorWheel.psd (all on the CD). You can separate an image into CMY either by using the primary cyan, magenta and yellow colors as a filter or by using the RGB colors that make up those components. Screening an RGB image for blue and green will reveal cyan, screening for red and blue will reveal magenta, and screening for red and green reveals yellow. You can achieve the same effect by creating the RGB channels in layers and inverting each of the channel colors in turn. Completing the separation will give you a very basic CMY separation that works on screen—and in a perfect world. Because pigments (and the surfaces they are used on) are not 100 percent efficient in absorbing light, black is added to CMY to make CMYK. The added black increases the efficiency and dynamic range of the result— similar to the idea of using more than one ink in a duotone to extend dynamic range. The four steps involved in creating the basic CMY separation are preparing the image, separating the color, converting separations to tone, and applying color for preview. We’ll use the dragonfly.psd from the CD shown in Figure 2.25.

Preparation Set up the separation by duplicating the image background once for each of the CMY inks. Once the initial layers are created, you will be ready to start extracting color separations: 1. Duplicate the background layer of the flattened dragonfly.psd image. 2. Change the mode of the duplicate layer to Multiply. 3. Change the name of the layer to Cyan. 4. Duplicate the Cyan layer, and change the copied layer name to Magenta. 5. Duplicate the Magenta layer, and change the copied layer name to Yellow. 6. Activate the background layer. 7. Create a new layer. 8. Fill with white and name it Composite.

Figure 2.25 See the color section for more detail of this dragonfly.

You can complete these same steps by running the CMYK Setup action from the Hidden Power Tools. The image will look awful at this point, but that doesn’t matter. Figure 2.26 shows how the Layers palette should look.