When it comes to creating graphics, designers must choose to express their creativity using either vector or raster graphics. Each of the graphic types have their own particular strengths and limitations and understanding these differences is essential to achieving the best results.
Vector Images
Vector images are constructed of lines (also called paths) and are created by software programs that use mathematical calculation to determine size, shape and color of each line. By combining paths that are straight or curved and various colors and shading very detailed illustrations can be created.
Because the image is created using mathematical precision using programs like Adobe Illustrator or CorelDraw, the resulting files can easily be resized larger or smaller without any loss in image quality. In this example we have enlarged a vector version of our logo.
As you can see, the enlarged version retains the crisp edges of the original.
Vector Graphic Strengths
- Vector graphic files sizes are usually much smaller than raster files making them easier to store and share.
- It is easy to convert a vector graphic to raster if needed.
- Vector Graphics are resolution independent. You can make them larger or smaller without a loss of image quality.
Vector Graphic Limitations:
- Vector files simply do not handle photographic imagery as well as raster files.
When to use Vector Graphics:
- When you are designing something for large scale like banners, signage, vehicle wraps and other large format items.
- Vector graphics are the best choice for business identity print work, logos, promotional posters, and major illustrations.
Common Vector Formats:
Common vector formats include EPS (Encapsulated PostScript), WMF (Windows Metafile), AI (Adobe Illustrator), CDR (CorelDraw), DXF (AutoCAD), SVG (Scalable Vector Graphics) and PLT (Hewlett Packard Graphics Language Plot File)
Raster Images
The most common raster image is a photograph, though with a graphics program like Adobe Photoshop artists can create raster images other than photographs. A raster image is created by a series of pixels or dots. Each pixel is assigned a color value and packing many dots into a small area creates the illusion of a crisp image. Printers often talk about raster image resolution, which is determined by how many dots there are per inch (dpi)
Because raster images are created by a series of dots, they do not scale up well. In the graphic below we’ve taken a raster version of our logo and then enlarged it.
At its original size the image looks fine, but when enlarged the quality and sharpness of the image suffer.
It is for this reason that most printers set a minimum standard resolution of 300 dpi (dots per inch) when printing raster graphics. Anything less will simply not look very good.
Raster Graphics Strengths
- Raster files handle the subtleties of photographs very well as a general rule.
- Raster can handle other effects such as adding textures or blur effects very well.
Raster Graphics Limitations:
- Raster files are highly dependent on image resolution to reproduce accurately in print. As a general rule it is a bad idea to enlarge raster images due to pixellation.
- Raster files can be very large if there is a large amount of detail and pixels in an image which can make storing and sharing them more difficult
- Raster conversion to vector is difficult.
When to Use Raster Graphics
- Use raster graphic in designs where photography is required
- Raster graphics are ideal for web design
- Use raster graphics when you want to add an effect to an image such as a blur, texture, or other image manipulation is required
Common Raster File Formats
Common raster image formats include BMP (Windows Bitmap), PCX (Paintbrush), TIFF (Tag Interleave Format), JPEG (Joint Photographics Expert Group), GIF (Graphics Interchange Format) , PNG (Portable Network Graphic), PSD (Adobe PhotoShop) and CPT (Corel PhotoPAINT).
Vector vs Raster Graphics
We often here the question “Which graphic format is better?” In truth, both vector and raster graphics can be used to produce excellent results when you understand their strengths and limitations. Just as you wouldn’t expect a blender to make you a grilled cheese sandwich you shouldn’t expect a raster image to enlarge or a vector image to reproduce your baby pictures.
I hope this has helped shed light on the issue of vector and raster graphics, but if you still have questions the team here at Heritage Printing and Quick Copy will be happy to assist. You can comment on this article using the form below, give us a call at 770-932-3800, or send us an email using this form.