There are two main types of image files: Vectors and Rasters. Raster images are more common, such as jpg, gif, png, and are widely used on the Internet. Vector graphics are more common for images that are going to be applied to a physical product.
In this blog post we are going to try and explain the difference between both file types and why they matter.
A raster file is an image made of hundreds, thousands and even millions of tiny little squares of colour, these little squares are referred to as either pixels or dots. now if we are getting technical pixels are colour blocks that are viewed on an electronic monitor where as dots are the actual dots of ink printed. But even professional graphic designers, us included, often use these two terms interchangeably.
The most common type of raster image is a photograph. Whats the designer’s preferred program for creating and editing raster files? Yep you guessed it: Adobe Photoshop.
The most popular raster file formats are: jpg/jpeg, psd, png, tiff, bmp and gif.
Pros to a Raster Image:
- High/Rich Detail: Have you ever wondered what the term “dpi” stands for? It means “dots per inch,” its a measurement of how much detailed colour information a raster image contains. Lets say you’ve got a 1” x 1” square image at 300 dpi, that’s 300 individual tiny squares of colour that provide precise shading and detail in your image. The higher the dpi of your image, the more subtle details will be noticeable.
- Precise Editing: All of those tiny individual pixels of colour information can be modified, one by one. So if you’re a true perfectionist, the level of editing and customization available in a raster image is almost limitless.
Cons to a Raster Image:
- Blurry When Enlarged: The greatest downfall to raster images is that they become pixelated (grainy, dotty) when enlarged. Why? Well, there are a limited number of pixels in all raster images; when you enlarge an image, the computer makes its best guess as to what specific colors should fill in the gaps. This interpolation of data causes the image to appear blurry or pixelated since the computer has no way of knowing what the exact shade of colour that should be inserted to fill the gaps.
- Large File Size: Remember that a 1” x 1” square at 300 dpi will have 300 individual points of colour information for the computer to remember! Now let’s say you have an 18” x 24” image – that’s 129,600 bits of colour information for a computer to process which can quickly slow down even the fastest computer.
A vector image uses maths to draw shapes using points, lines and curves. So whereas a raster image of a 1” x 1” square at 300 dpi will have 300 individual pieces of information, a vector image will only contain four points, one for each corner; the computer will then use maths to connect the dots and fill in all of the missing information.
The most common types of vector graphics are Fonts and logos. Whats the designer’s preferred program for creating and editing vector files? Yep Adobe Illustrator.
The most popular vector file format extensions include: eps, ai, svg and pdf.
Pros to a Vector Image:
- Infinitely Scalable: Through the wonders of maths (which I don’t claim to understand), vector files can be scaled up or down as much as you want without losing any image quality. Whereas a raster image must guess the colors of missing pixels when sizing up, a vector image simply uses the original mathematic equation to create a consistent shape every time.
- Smaller File Size: Using our previous 1” x 1” square example, a vector file needs only four points of data to recreate a square versus 300 individual pixels for a raster image. For simple graphics, like geometric shapes or typography, this means a much smaller file size and faster processing speed.
- Edibility: Unlike popular raster-based formats, such as a jpg or png, vector files are not “flattened.” When you open them back up in a program such as Adobe Illustrator, all of the original shapes exist separately on different layers; this means you can modify individual elements without affecting other objects in the image.
Cons to a Vector Image:
- Limited Details: Because of the mathematical way that a vector remembers data, they are not practical for complex images that require exact coloring. Yes, you can create basic colour gradients, but you’ll never be able to match the colour detail available in a raster image where each individual pixel can be its own individual shade.
- Limited Effects: By definition, vector graphics are created from simple points and lines. This means they can’t handle certain styling effects, like blurring or a drop shadow, that are available with raster images.
What do we use:
Depending on the print process we are carrying out, we will use vector images or raster images.
Cad-Cut vinyl uses vector images, the image is loaded into our software and then sent to a vinyl cutter where the lines are cut out of the vinyl.
Sublimation Print uses High quality raster images which are then printed on to special paper using special sublimation ink and then heat transferred on to the garment.
Embroidery uses its only file type but we use rasters & vectors to convert in to the embroidery file needed for the machines.
We hope this has given you some useful information on the two file types and what the differences are. If you are in any doubt in what files you have and what one should you send, please contact us as we are more than happy to help. We also have a design service that can sort out your files ready to use.
Until next time…