Most great artwork has a combination of a raster image along with vector images (mainly for type), and if you don’t combine them correctly, you make it harder to color separate. Keep in mind, this article is focused on the final product of the artwork being color separations. If you are creating artwork for digital printing, then the following items are less critical. The idea here is to build the image in a vector program and then color separate in Photoshop (because of the raster element). Some artists build everything in Photoshop at 300 dpi, but the majority still work in a vector program to create the image.
Fix the raster image first: The biggest problem when doing separations is that the artist created great vector graphics – type, borders, hard edges – and then imported (Corel) or placed (AI) a low-resolution, low-quality JPG image in the vector graphic and then resized the image to be bigger. I can’t tell you how many hundreds of times customers have said, “But the artist works at 300dpi,” and I reply, “yes, but this part of the graphic did not start out at 300dpi.”
The goal is to fix and size the raster element before you bring it into a vector program.
Improve a low-quality JPG: Before you start bringing raster images into a vector program, you should fix them as best you can. If the image is a JPG, then undoubtedly there are artifacts and “boxes” that will show up in the seps. Try using a JPG enhance program. It’s too hard and often impossible to fix a low-quality JPG image that is part of vector elements once the file is in Photoshop.
Make the raster element 300 dpi: In Photoshop, up-sample the raster image to 300 at the final size. To prevent images from getting softer go to image/image size and make sure nearest neighbor is used, which prevents more anti-aliasing from occurring.
Make your other fixes: Before importing the file, you should make other fixes, such as improving the color saturation and boosting the contrast.
Give the image a transparent background: If you plan to combine the image in a vector program where you want complete control over the stacking of elements and how they overlap, then remove the background in Photoshop, giving it a transparent background. Save it as a PNG file.
Use the zoom tool: When people send me files and ask if they can be separated, I often ask if they’ve used the zoom tool first. The zoom tool (in any program) doesn’t lie. It shows you what you’re really getting and what you have to work with, and sometimes it will let you know your file is junk and nothing will fix it. Don’t expect the color separator to perform magic.
Combining images: In Corel Draw, you can simply import a raster image (file/import). If the original document size is 72 dpi, Corel can make the imported image 72 dpi.
In Adobe Illustrator you place an image (file/place). The problem is that there are two ways to place an image. You can embed the image in your file, or you can link to the original image. A lot of artists want to link the image (this is a checkbox when you place the image), which means they can then tweak just the raster original image and it will change in Illustrator. I am not a fan. If you send jobs to be separated or move them around in-house, you have to make sure to include the linked image. Just embed the image for ease.
Saving the image for use in Photoshop: Here’s where you can go wrong. If using Adobe Illustrator, you can simply save the file, and it will open in Photoshop. But, if using Corel Draw, you should save as a PDF file to open in Photoshop. The key item is to check the PDF settings, whether you are in Illustrator or Corel. Make sure they are not set to compress or down sample the image, and if you have a choice keep the resolution at 300 dpi.
Convert fonts to outlines/curves: To keep everyone happy – especially if you send out for the seps or move the file in-house – convert the fonts from vectors to Outlines (Illustrator) or Curves (Corel). That way whoever opens the file won’t get the dreaded “missing fonts” windows.
Opening the file in Photoshop: Lastly, don’t screw up a great file when you open it in Photoshop. If you open an AI or PDF file, you get the import window. Make sure to uncheck anti-aliasing, and set the file to 300 dpi at the final size.
Whatever you do, don’t save the file from a vector program as a JPG and think you’re doing anyone any favors. Please.
Scott Fresener has been in the industry since 1970 and is the co-author of How To Print T-shirts For Fun And Profit. He created two automated separation programs, T-Seps and FastFilms, and is considered a pioneer in the direct-to-garment printing segment. Fresener is the director of T-Biz Network and is a popular speaker at trade shows. Fresener is also past Chairman of the Academy of Screen Printing Technology and was on the Board of Directors of SGIA. He runs the website www.T-BizNetwork.com. Reach him at email@example.com.