Tips for Great Technical Manual Illustrations

It's not easy writing technical manuals. To convert schematics, software use cases, design drawings, and other source data into an easily-understandable document is not an easy task. In almost every case, the writer must incorporate illustrations in the technical manual to help do the job.

A quality illustration can go a long way toward communicating the intended information to the audience. Bad graphics can actually hinder the technical writer's task. This article contains some of the techniques I use to ensure illustrations help, not hinder.

In general terms, there are two types of artwork used in technical manuals. Vector images are line drawings, typically output from an illustrating software program such as CAD programs, Corel Draw, or Adobe Illustrator. The other type of graphics is bitmap images. Software screen captures and photographs are an example of bitmap images. Photoshop and GIMP are programs typically used to output bitmap images.

Vector artwork usually results in a clearer, sharper image. It is easier to resize if necessary. One thing that should be checked with vector illustrations is line weight. Print the document and make sure all the lines are heavy enough that they don't drop out when output on a laser printer.

When incorporating illustrations in a document, it has been my experience that the best method is to use a TIFF bitmap image. Virtually all graphics programs can output a TIFF file, and all word processing and desktop publishing programs can import TIFF files. Bitmap images, such as TIFF files, can be produced in different resolutions. For best results, technical writers should use TIFF files with a minimum resolution of 300 dots per inch (DPI).

The use of JPEG images should be avoided, unless the graphic is a photograph. The JPEG file format is a lossy file format. This means that if the graphic is edited and resaved, some of the information is lost as the image is compressed. TIFF files do not have this issue.

Many technical writers don't realize that screen captures are limited to 72 DPI. If a screen capture is made and then saved in JPEG format, the resulting image will be blurry.

The best way to avoid this is to make the original screen capture in TIFF format. The resulting image will be clearer and sharper, even if you edit it. Another thing you can do to improve your screen captures is set your operating system's color scheme to a high-contrast monochrome color scheme.

If you want your technical writing to be well received, make sure your graphics are the highest quality it can be. Bad illustrations will cause your technical writing to suffer.