Digital Artwork 101: Vector vs Raster (Bitmap)
The biggest hurdle for most new screen printing shops is understanding the ins and outs of digital artwork. Digital artwork is not something that can be learned overnight but there are ways to simplify how to prepare artwork for printing. Also, knowing how to communicate with a customer so you get the closest thing to print ready artwork every time. Digital artwork comes in many file types, but they all fall into either being a “vector” or a “bitmap”. The difference between a vector and a bitmap can initially be a little confusing to understand, but is very important for printing business to know how to explain the differences between the two to their customers.
A vector piece of artwork is made up of lines and curves that trap colors within a design. Because vectors use lines and curves the artwork can easily be scaled (made larger or smaller) without losing any image quality and each color can be selected/seperated for printing. Bitmap artwork, on the other hand, uses points (pixels) to create the artwork. The problem with bitmaps is the pixels do not scale well and are difficult to color separate because there is so much blending. So screen printers much rather work with vector artwork instead of bitmaps because the colors must be separated and the size of the design sometimes changed.
Vector Programs
Separating each color within a multi-color design typically requires a vector program / artwork, but not always. The two most commonly used vector program are Adobe Illustrator and Corel Draw. Both of these programs make color separating a piece of vector artwork very easy. They both are also capable of tracing a bitmap to convert it to a vector. Converting a bitmap file to a vector is not as easy as just clicking a button. The artwork often must be traced by hand using a stylus to establish the lines and curves of the design instead of using bitmap pixels. Once a design has been vectorized it is a good idea to create a backup of the artwork by making a copy of the layer. Each color in the artwork must then be copied from the original layered and pasted on its own layer. These layers can then be printed one at a time to create film positives.
