Vector images – a primer for authors
Thanks for stopping by. I’m taking a closer look at images and what you need to know about them when working on your own cover or with a designer.
If you missed the blog post all about bitmap images (i.e. photos), you can read it here.
There are 2 basic types of digital images…bitmap and vector.
Bitmap images are made up of pixels within a grid structure. Photographs are good examples of bitmap images.
Vector images are made up of curves, points, lines and other geometric elements. Logos are typically built as vector images.
The curves, points and other elements that make up vector images are based on mathematical equations. Because the files are based on mathematical equations, the equations can be recalculated so the vector image can be scaled (made larger) with no loss in quality. The image is the same quality whether it’s small (like a one inch square) or it’s been blown up very large (like on a billboard).
Vector images in detail
Let’s have a closer look at the floral illustration example used above. Each flower is made of of shapes, like this one flower I have selected (shown with a bright blue outline).
Once I remove the other flowers and background, it’s clearer to see.
This particular flower is made up of two shapes…a yellow circle and an orange complex shape. Both are made up of points and curves, as shown on the orange petals. These curves and points are editable, meaning I can change the shape. I can also change colors very quickly, add gradients and outlines. Actually, color and basic feature changes to vector files are very simple and quick to do.
Resizing vector files
Vector files are called ‘scalable’ or ‘resolution independent’. We can enlarge a vector file without loss in quality that can happen with bitmap images. Here’s a up-close look at the circle, at size on the right and enlarged (to approx. 4 times size) on the left. The curve is smooth on both circles.
When it comes to artwork that needs to adapt to many sizes, vector is great. And, you can easily make vector artwork into special ink colors (you may hear these called Pantone colors). Vector images will also print much clearer than the same image saved as a bitmap at print resolution, due to the way printers interpret both types of files. This difference is most notable when dealing with text. Here’s a fabulous demonstration of this from printhandbook.com.
That’s why designer build logos as vector files.
Tip: if you are looking to get promotional items printed, like pens, travel mugs, embroidery on clothing etc., most printers will request, and some can only work with, vector artwork. Let your designer know early if you plan to do these.
Did you know: modern font formats (like postscript, open type and true type) are based on character drawings saved in vector formats?
Vector files come in many different file types, but the most common for graphic design are AI (Adobe Illustrator), CDR (Corel Draw) and EPS (encapsulated postscript). Sometimes you will see vector artwork as a PDF, but PDF files are not necessarily vector files, and PDF can also support bitmap images. SVG (scalable vector graphics) for web use is becoming more common. If you work with CAD or 3D modelling, you’ll see different vector formats.
Vector files aren’t perfect. Most ordinary software (like Microsoft Word) can’t use them. Photo realistic drawings are possible in vector files, but are very time consuming and require great skill. It is possible to create vector files that are too complicated and cannot be printed or rendered to a bitmap file (converted to pixels) properly. Preparing vector files properly for scaling requires some specialized knowledge, like how to treat outlines (or strokes, as Illustrator calls them) on a shape.
I hope this clears up the basic images types and why/how they are used. Have a question? Something not clear? Let me know. Post a comment below.
Is there a topic you have been meaning to research and just haven’t got the time? Comment below or send me an email…let me know what you want to know. I’ll do the research for you and write about it in a future blog post.