You’re in the sign business so you probably know the difference between a raster image (bitmap) and a vector images (lines & curves). I have personally found; however, that it is often useful to brush up on my graphics knowledge periodically and I thought this would be an excellent area of the sign industry to focus on for this article.
So what, exactly, IS the difference between Raster images and Vector images? The very simple answer is rasters = bitmaps & pixels while vectors = mathematical lines & curves. Of course such a simple answer does not do much to help us truly understand the difference is these two types of graphics. More importantly, the simple answer does not help us really comprehend how these differences can effect our sign shop and it’s workflow.
1. Raster (bitmap) Images
The most common types of raster images are BMP, GIF, JPG, JPEG, PNG, PICT (mac), PCX, TIFF, PSD (Adobe Photoshop) while the most common editing programs for Sign Companies are Adobe Photoshop, Corel Photo-Paint and Paint Shop Pro (among a host of other lesser know software packages).
The most common way to create raster images is to create your own from scratch using one of the above programs, digitizing an existing image using a scanner, taking a digital picture or grabbing a screenshot from your computer.
By now you have probably experienced getting some supplied artwork from a customer in raster form. You are handed a CD or e-mailed a file that looks just fine at 3″ tall on your computer screen BUT looks horrible when you increase the size to final output. What happened? Why does it look all jagged and blurry? The answer is that you are dealing with a very small, low resolution raster image. This image only has so many bits of image information (usually described in dpi – dots per inch OR ppi – pixels per inch) and when you try to increase the size you are essentially magnifying the entire image, including those pixels. When you try to increase a raster image past approximately 2-3x then the software has fake in image data where there is none. End result… jaggy and blurry final output.
As a rule of thumb, it is always better to start off with the largest raster image possible for your project (you will need to determine the necessary resolution specs for your own intended output). If you make a habit of always getting the largest image possible then you will always have the option to reduce the size to fit your workflow with no loss of quality.
IMPORTANT NOTE: Raster images can only be output on printer type equipment (wide format printers, laser engravers etc.) and CAN NOT be plotted on a vinyl cutter. If you need to convert a raster image in order to produce it in cut vinyl then you will need to use a software “tracing program” to identify your major objects and convert those edges to lines & curves.
For more in-depth information on raster images check out this link.
2. Vector Images
The most common types of raster images are AI (Adobe Illustrator), CDR (CorelDraw), EPS, CMX, PLT (plot file) along with hundreds of other software specific file formats. The most common vector editing programs for Sign Companies are Flexi Sign, Gerber Omega, SignLab along with several less powerful vinyl cutting programs. Adobe Illustrator and CorelDraw are also VERY common vector design and editing programs and are usually found in most sign companies.
The most common way to create vector images is to create your own from scratch or by utilizing already created logos, artwork, designs, signblanks etc from existing collections. There are many vedors available online who specialize in sign industry vinyl ready vector files and make these files available for purchase. Click on this link to go to our page with free vinyl ready vector files for your use.
Now, vector files, unlike raster, are completely scalable. What does this mean? It means that the logo you have for Joe’s Auto Body can be produced at 24 inches for the side of Joe’s truck or at 30 feet on the side of the local water tower with NO LOSS of quality or detail. Since the graphic is created using a mathematical equation which determines size, color, shape, color, outline stroke etc. you are able to enjoy an incredible level of control with your designs in different sign & graphics applications.
The nice thing about vector files is that they CAN be printed as well as plotted to vinyl. It is very easy to assign a specific color, fade, shadow etc and send your vector image to the wide format printer in your sign shop. The printing equipment can produce all sorts of logos, decals, vehicle wraps and graphic displays from your vector designs and they will look great on 2″ decals all the way to 100′ long banners.
IMPORTANT NOTE: The one thing to know is that you CAN NOT get photorealistic images from a vector file. A vector file, by it’s very nature, is simply unsuitable for creating the subtle colors, shadows and infinite variations of tone and texture involved in photorealistic graphic work.