Resolution = Dots per Inch (dpi)
To assure quality images, hire a professional photographer or purchase images from a photo company or web site. Images simply copied from a website are rarely good enough for exhibit graphics. Usually at 72 dpi or less, copied website images lose resolution when enlarged which translates to poor quality.
Your images should be 100 dpi or more at final size. That means an image at 300 dpi can be blown up to three times its size (to 100 dpi at final size) before losing quality.
The Color Challenge
Maintaining consistent color is challenging. Printing the same graphic from the same artwork on the same printer on different days can result in a difference in color. Also, different digital printers print colors differently.
To prevent color differences, many graphics including logos use the universally recognized Pantone Matching System (PMS). Traditional ink printers use the exact PMS color ink to print colors. Digital printers however use CMYK – a 4-color (cyan, magenta, yellow, and black) printing process. Digital printers can be calibrated to achieve PMS colors. Providing a printed sample of the color you want matched is very helpful but a printed proof is the best way for you to confirm that the color will be accurate.
The finish (glossy or matte) of a printed graphic can make the color look bright or dull. If color matching is critical, request a printed proof – preferably a finished printed proof.
Formats and File Types
You don’t need to be an expert on formats and file types. Your printer should provide guidelines specific to their production capabilities and your graphic artist should follow those guidelines.
In general, the most commonly accepted files for PCs or Macs are those created using Adobe software including Illustrator, PhotoShop, & InDesign. Files created in Quark Xpress, Macromedia Freehand, and Corel Draw are also accepted by some printers.
Vector art often referred to as being “outlined” consists of lines and curves that are mathematically defined. Vector art is ideal for type and drawn shapes because they can be enlarged to any size while maintaining crisp outlines and details without sacrificing quality.
Raster images consist of colored squares called pixels. Digital photos are made up of pixels. Printing a low resolution file at a size larger than its resolution results in pixelation which translates to reduced quality.
TIFF or JPG?
Graphics can be printed from either a TIFF or a JPG. TIFF files are large uncompressed files that produce excellent quality. JPG files are compressed and although quality is usually not as good, they can be used for printing if resolution is high enough.
Linked Images or Embedded Images
Linked images are files that are “placed” or “imported” into your document. Printers prefer linked files because they can verify resolution and color information and edit or adjust during the printing process for optimal output.
Embedded images are files that are placed into your document and then “locked” or embedded so that the document is self-contained. Embedded files cannot be edited or checked for resolution or color. This means the overall quality of the graphic cannot be determined until it’s actually printed at full size.
Files That Won’t Work
Word, PowerPoint, and Publisher documents cannot be used to print large format graphics.
Simple files with just a logo for example are usually small enough to email. Production files of good quality are frequently too large for email and must be submitted on a CD or DVD or zipped and uploaded to an FTP site. We have an UPLOAD section for submitting files to us.
Primary Source: “Graphics Made Simple” by Susan Bendily/Freeman