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Introduction

Understanding Your Montor

Understanding Bitmap File Formats

Understanding Vector Formats

Avoiding That Funny Pattern In Screen Captures

Screen Captures for Black and White Print

Additional Resources

Printable Version

Graphics for Technical Communicators
by Tom Balazs

Introduction:
Technical communicators are not graphic designers but they often find themselves struggling with questions of what file format to use and how to make the best quality screen shot. This article will also address the issue of file size because technical communicators have to prepare documents for print and for online display.

Understanding your monitor:
All computer monitors work by displaying dots of red, green and blue light. Equal amounts of red, green and blue appears white to us. If there is no red, green or blue we see black.

On most PCs you can determine the resolution and the number of colors that your monitor will display. Simply press the start button at the bottom left of your screen and select Settings / Control Panel. In the Control Panel select Display. In the Display panel select Settings. Here you can choose the number of colors your monitor will display and the pixel dimensions of your screen. (You can also right click on an empty spot on your desktop and choose Properties.) My computer allows me to set my monitor's display to one of the following:

32-bit 16.7 million colors plus an *eight bit masking channel.
16-bit 16.7 million colors,
8-bit 256 colors
4-bit 16 colors
*An eight bit masking channel means there are 256 levels of transparency ranging from fully visible to completely transparent.

A panel from Macromedia Fireworks showing the 216 websafe colors.

A common denominator used in design for the web is 8-bit color. That should allow us to work with 256 colors. But because Macintoshs and PCs display color differently we actually have 216 colors that we can safely assume will display correctly on all monitors, Macintoshs and PCs.

Your monitor displays a bunch of tiny dots. To display images we divide the monitor into pixels, tiny squares that can be filled with color. It is possible to change the number of pixels that your monitor's screen is divided into. My computer allows me to change the screen to: 640 pixels wide x 480 pixels high, 800 pixels wide x 600, or 1024 pixels wide x 768 pixels high. When designers create graphics for the web they define the size of the image in pixels, instead of in inches or centimeters. A graphic that was defined as 250 pixels high by 250 pixels wide will appear larger on a monitor set for 640 x 480 than on a monitor set for 1024 x 768. Technically speaking you can set your monitor at any of the previously mentioned choices but if you set a 15 inch monitor to display 1024 pixels wide x 768 pixels you'll probably find that it displays pictures and text too small.

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