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Some Graphic design and Pre press tips for Photoshop users
There is some ?must-know? tips for CG people who decide to start doing some pre-press and design for printing. There is some ?must-know? tips for CG people who decide to start doing some pre-press and design for printing. As beginner you have to know that design for printing has some differences than web design or other screen designs. Allways use CMYK First of all, printing technology uses CMYK color description and screen design use RGB. CMYK (Cyan Magenta Yellow blacK) is used because of printing technology that uses these 4 colors to make picture on paper. This color model is for Reflective surfaces. RGB (Red Green Blue) is for self-lighted surfaces, like screens and TVs. If you have photos or illustrations in RGB, allways convert them using Photoshop?s Image > Mode menu, because Adobe Photoshop gives best result with minimum changes of colors. CorelDRAW, for instance, gives totaly different colors if you export drawing to RGB or CMYK. In my opinion, if you have to use some design elements from CorelDRAW, export them in RGB and then convert in CMYK using Photoshop. Black should be only 100%K, not composite from all colors You have to keep in mind that printing process has minimum 4 passes (to print full color ? in Offset technology), and that alignment of these four passes may not be 100% same. Every pass is one color. So if you make text from 100C 100M 100Y 100K composite, you will have noise at letter?s edges. Photoshop has habit to form black from all composites so pay attention to select only pure black (0C 0M 0Y 100K) when you write text. Use minimum 300DPI for Offset and 600DPI for Digital printings Human eye can easly notice granulation of image raster if its resolution is lower than 96 DPI. Common Offset printing plates (machines) support 300DPI, so use this quality and make design in that resolution. Also, some digital printers support more dots per inch so you can make design from 600 to 1200 DPI?s, but it is very hard to notice difference between 600 DPI and higher. In special cases if you make design for buildboard, you can use 30 DPI, because of view distance. Clean up small composite values Keep in mind that every colored surface is made from these 4 components mentioned before. If you have on some surface less then 10% of some color, it is better to modify that color component to 0% in order to avoid edge noise. You will make small change on color. Also if you try to print 5% of some composite it is very small chance that something will be printed at all on Offset printing. Example: if you fill background with gray color: 5C 5M 5Y 5K you will probably bet totally white surface, but, if you use 0C 0M 0Y 11K, which gives very similar color on screen, you will have some gray color on background. Simply, printing and screening technologies are different Make from 3 to 5 mm overedge on every edge that should be trimmed Printing surface is always bigger than required dimensions. When you do screen design you don?t think about cutting, because it doesn?t exist on screen, but, when you do design for paper you have to keep in mind that someone will have to cut edges of your design. So there is Trimmed dimensions and Not-Trimmed. As designer you are thinking in trimmed dimensions, but when you send file on printing you have to make tolerance in case that swings that cuts paper to fit required dimensions make mistake, and, it always make some mistake. If you don?t make your design bigger you will have white stripes at edges of your catalogue or flyer.  This guidelines shows where paper should be trimmed. In case of flyer, you have to make this tolerance to all edges, in case of cataloque, only outer edges should have this because, edge that comes to bending line doesn?t have cutting. Make margins at least 5mm All elements of design and all texts should be at least 5mm from edge of cut. I tried with 3mm, it was bad looking because on some places distance was smaller because problem of swings. In some cases you can go up to 10mm of margin. That is something that I noticed that beginners in graphic design should know. There is also some pure design tips about contrasts and colors, but I?ll leave it for some other tutorial. Use TIFF as final file format I advise you to use TIFF format when you send design to printer company. I had cooperation with many printing companies and printing professionals and everybody agree that TIFF / CMYK is most trusted image format for color-safe exporting and transporting from design workstation to film exposition company. It is safe to use: LZW compression (more compatible) or ZIP compression (less compatible). For final file you can discard layers to reduce file size. If you have any questions or feedback for me, ask on forum, and check other usefull tutorials on our web site: Tutorials&Articles page Added later: (05.14.2006) As appendix of this tutorial and with permision of author I'm attaching e-mail with few suggestions: I'm glad someone has finally taken up the cause of alerting designers to what they are to expect when coming to a print shop to get things done. However, I do have a couple little problems which i think should be changed. 1. Us print shops use the english system religiously. In case you didn't know, points and picas come from the english system, and its much much easier for us to use all of our technology with those measurements. The bleed (thats the area of excess design to allow for cutting) is always 1/8" or less depending on the room on the plates. 2. Saving as TIFFs is incredibly good for the print shop. The file will be guarenteed to make it to the press without loss of quality, but many shops need to have things like compression turned off. Some of our applications made by Heidelburg don't allow use of LZW compression in images, and ZIP compression can lead to corruption later on in the process. Like I said, some minor things, but I feel that designers should be informed because many art schools that these people go to do not tell them anything about printing. It leads to time and money lost on our end, having to fix all of their mistakes, and it makes for a very very long day at work. Sincerely, Logan P.S. Im a prepress technician at a consolidated graphics company in Michigan, USA. I've been doing prep work for about 6 years now. Hope this few tips helped you.   
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