Vector vs Raster
When it comes to custom printing, not all graphic files are created equal
If you’ve ever had a conversation with a graphic designer – or anyone who deals with graphics for that matter - you have probably heard the terms “vector” and “raster”. These words identify the two primary types of image file formats and there are important differences between the two, particularly when it comes to printing custom stickers.
Raster or bitmap images are comprised of pixels, a tiny programmable unit of color that collectively forms a digital image. Concentration of pixels will vary from image to image, which is defined by the image’s resolution or “PPI” (pixels per inch). Common file extensions for raster images are JPEG, TIFF, PNG or PSD, so digital photographs and most web graphics fall into the raster category.
When you enlarge a raster file, you can start to see the individual pixels and the image becomes blocky or feathered, losing quality and crispness of lines. This fragmenting can translate into print output as the printer picks up on these jagged edges and prints them, which can make the image on your sticker look fuzzy. Ergo printers always require a minimum PPI for printing, which is typically about 300, however you don’t want too high of a resolution either. If a raster image has a very high resolution, the concentration of pixels will be numerous, but it will translate into a large, cumbersome file that is difficult to work with and slow to load.
Additionally, because raster graphics are flattened and read by a computer as a unified image, color matching or adjustments to a specific area are not possible. The designer can adjust the whole image by adding brightness or contrast or magenta to balance a greenish hue, but if you want to change the black text to print blue on your bitmap file, additional graphic design work is necessary to isolate the text and change the color. Essentially, it needs to be transformed into a vector file.
Vector graphics are made up of points that contain a formula of the proportional relationship between other points, which means that vector graphics are not subject to resolution and can be scaled to any size without losing quality. The advantages for custom printing are enormous as you can use the same file to print custom decals or a 12-foot banner!
A vector file will carry a file extension of AI, EPS, SVG and sometimes PDF, and are commonly created in Adobe Illustrator. You need the software to work with these files but because they contain equations and not massive amounts of data, they are smaller in size, more flexible and easier to wield. Selection of unique or grouped objects within the graphic is simple, therefore adjustments to color or corrections to size, shape or position are quick and painless – provided you know how to use the tools.
The bottom line is when it comes to printing, you are always going to get a better result if you start with a vector file. It is possible to trace or recreate a bitmap into a vector graphic, and lots of vector files contain raster effects, but it takes specialized skills to do this kind of graphic design. If you’re working with a designer for the purposes of printing, make sure they supply you with both file formats. It’s easy enough to save a vector file as a raster image, but it is not the same going the other way!