Vector vs Raster files

As a graphic designer I get asked ‘What is the difference between a Vector file and a Raster file?” so I thought I would write a short article on the subject to try and explain.

Vector:
A vector file is usually generated by a drawing programme such as Adobe Illustrator. Extensions can include [.ai] and [.eps] As far as your computer is concerned, the points and paths in vector graphics are nothing more than code written in a programming language called PostScript.

Advantages of Vector files:

• Clear background so can be easily overlaid
• Can be scaled to any size without loss of quality
• Pin sharp graphics and text

Disadvantages of Vector files:

• You need the programme it was created in to edit the file
• There is no easy way to use them on-line
• They are difficult to import into software like Word or Excel

Raster:
In computer graphics, a raster graphics or bitmap image is a dot matrix data structure that represents a generally rectangular grid of pixels (points of colour), viewable via a monitor, paper, or other display medium. Raster images are stored in image files with varying formats. The most common formats are [.jpeg, .png .psd] but there are quite a few more.

What is the difference between high-res and low-res raster image?
Low-res tends to be used on-line where the screen quality is only 72dpi [dots per inch]. These need to be in the RGB [Red, Green, Blue] colour space. See my other blog on colour spaces here: https://reformcreative.co.uk/how-does-colour-work/

High-res tends to be used in the print process and are normally 300dpi. These need to be in the CYMK [Cyan, Yellow, Magenta, Black or Key] colour space. Again covered in more detail here: https://reformcreative.co.uk/how-does-colour-work/

Advantages of Raster files:

• Easy to use
• Can be edited with apps and paint software
• Can be easily imported into software like Word, Excel and PowerPoint
• Great for on-line use
• Can have a clear background for overlaying if the format is .png or .psd

Disadvantages of Raster files:

• Need converting to CYMK for print
• Can’t be scaled up without loss of quality. (If you have an image programme such as Photoshop you are able to sample Raster files up before use, however, the image may soften.)
• Tend to have a white background so hard to overlay over other graphics without creating a clipping path which can only be done in an image programme.

If a designer is producing some work for you such as a new logo it is always best to ask for the files in Vector and Raster formats.

I hope this article has helped you understand the differences between a Vector file and a Raster file.