ImagesMagUK-Sep18

TIPS & TECHNIQUES www.images-magazine.com 56 images SEPTEMBER 2018 of the shirt provides the black areas in the image. By eliminating underbase under the black areas you also create prints with a softer-hand. For a DTG RIP to create an underbase it normally needs an artwork file that has a transparent background. This means there is no colour (not even white) around the image. If there is white around an image that is going on black shirts (the ‘canvas‘ area), then the RIP is not smart enough to know that this white should not print. Typically you receive the artwork as a JPG image and often there is white in the canvas area and you’ll need to remove or ‘knockout‘ this white. There are plenty of articles and YouTube videos explaining how to remove or knockout backgrounds and some of the popular RIP software have knockout programs built in. There are also third-party programs and plug-ins that will do knockouts for you. Photoshop has a variety of tools you can use to remove backgrounds. For example, you could use the Magic Wand to select around the image, then use the Quick Mask to ‘mask‘ around the image with a Layer Mask, and then employ the Pen tool in the Quick Selection tool to draw around the image. If your file was built in a vector program such as Corel or Illustrator then there is no background or canvas. You can simply export or save the file in a PNG or PDF format and the file will have a transparent background. Easy. The biggest challenge is removing the background of a file that has a soft edge. If the file vignettes from the image out to white then you need to remove the background while retaining the soft edge. One way or another, if you open a file in Photoshop it will have the checkerboard effect around the image if it has a transparent background. To view how the file will look on different shirt colours, make a new layer below the layer containing your graphic and fill it with the shirt colour [see Figure 12]. Artwork for black shirts When printing with DTG on black shirts, in most cases you really don’t need to print black ink. If there is a lot of detail you might want to print black, but generally you let the shirt provide the black in the image. Most RIPs allow for this and have check boxes as to whether to print black ink on a black shirt or they have options to remove certain colours from the image. If your RIP wants to print black ink even on a black shirt, you can use the Color Range option in Photoshop (Select/ Color Range) and select the black from your image using the Fuzziness slider to determine how much you want. When you Scott Fresener is the managing director of T-Biz Network International LLC and T-Shirt Printing Master Classes, and is a partner in the Printers Boot Camp. He has been in the industry since 1970 and has authored numerous books and developed software for the print industry, as well as training thousands of students. www.t-biznetwork.com save this window you will have the typical Photoshop ‘marching ants‘ selection on just the black areas. If you delete these areas and fill them with white you should now have an image that has very little black (there could be some left in the grey areas, but that is no big deal) and it is ready to print on a black shirt. Two passes and heavier deposits No matter what the manufacturer of your DTG machine says about print speeds or ink usage, you can pretty much count on the fact that they are talking one pass on the underbase and one pass on the colours. Yes, this will work, but the ink deposit can appear a little weak on some prints. If that’s the case on your print, you can use the RIP to instruct the machine to print the underbase twice (print – rewind – print again) or print a heavier ink deposit, and you can do the same for the CMYK colours. Some RIPS have sliders for this which are especially easy to use [see Figure 13]. Figure 11: Unsharp Mask allows you to sharpen an image Figure 13: Sliders allow for easy manipulation of the ink quality and density Figure 12: Layers allows you to see how the print will look on different colour tees