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How to select graphics software.

Powerful and economical microcomputers with excellent graphics capabilities open the door to new graphics applications in your laboratory.

Training manuals can incorporate sections with different letter styles and sizes, simple drawings of equipment, and diagrams of steps to follow. Trends in quality control, test volume, or personnel utilization are easily displayed. Charts can also illustrate lab results in a way that quickly identifies a pathological situation. Posters for presentations, signs for the lab, drug concentration patterns-the possibilities are endless.

We will provide an overview of graphics software in this article, along with hardware and other requirements . In next month's issue, we will explore specific graphics programs.

* General features of graphics software. Even though several programs accomplish the same task, one may require 10 minutes to do it and another may require three hours. Therefore, making the right software choice is critical if you want to save valuable time.

There are three basic kinds of graphics: data charts or plots, word charts, and diagrams.

Data chart programs. Common to all data chart programs are horizontal and vertical bar graphs, pie charts, and X vs. Y graphs with or without joined points. You select from a menu of options and enter the data. The program picks up the titles that accompany the data (e.g., months, number of tests, and other headings from a spreadsheet) and also chooses the values that will serve as index points on the axes.

Graphs may be enhanced by changing the size and font of the lettering and using symbols, among other ways. Some programs allow a user to draw almost anything that is desired and paint or fill images with colors and shades.

Word chart programs. These programs assemble outlines and other tables consisting of words. Ideal for text slides, they carefully arrange elements of different sizes and styles and align text with numbers. With adequate printers or other output devices, large-size letters and symbols can be produced. Diagram programs. With this software, general graphics tools (such as rotation, curve fitting, and drawing of lines, curves, circles, and polygons) and a library of predefined symbols are used to produce organizational charts, flow charts, procedural outlines, etc. The programs draw by combining basic figures, so drafting skill is not required; moreover, mistakes are easily corrected. The better programs have fancier drawing features, such as shading with various kinds of patterns.

Most graphics programs allow placement of almost any type of label anywhere. You can enter the data manually or directly from a database or spreadsheet. Some programs draw the graphic you desire, while others enhance it by adding or modifying colors and improving line work. A program like Freelance (Lotus Development, Cambridge, Mass.) does both.

Each program has a set of features that distinguishes it from the others and makes it more suitable for a particular purpose or audience. Fortunately, customer demand forces companies continually to improve their products, and the distinct features become less critical for common applications. Programs that do not have a certain feature often allow users to accomplish a similar result with some extra work.

Distinguishing features of graphics programs include the number of symbols and other graphic elements that can be used; letter sizes and styles; colors; types of graphs; linear and log axes; filling in with colors, shades of gray, and patterns; capability of drawing by hand; ability to modify portions of a drawing; ability to transfer a graph from one program to another; and speed of operation.

Some programs' features are rarely found in other programs and cannot be emulated or replaced by a different process. Examples: 1) plot data plus curve obtained by least-square-fitting a given function; 2) plot the range of possible values due to the error of measurement (up and down error bars on data points); 3) three-dimensional graphics; 4) high, low, and closing points (similar to stock market quotations); 5) multiple charts on one page, as with two Y axes or one graph superimposed on another.

Few graphics programs are copy-protected. Copy protection can be a severe inconvenience if you want to transfer a program to a random access memory disk for faster execution or if you have one microcomputer at which you do most of your work and another microcomputer connected to expensive peripherals, such as a laser printer or plotter. In the latter situation, you would like easy transfer of a graph prepared on the first computer to the computer with the output device.

For recurrent graphs or graphs involving many data points from a large database, you may want to consider a spreadsheet to enter the data instead of direct input into the graphics program. The spreadsheet can quickly provide a rough outline of what the graph will look like. In addition, if you change graphics software in the future, you can reuse the spreadsheet data.

*Hardware and other requirements. This author prefers an IBM AT-compatible microcomputer; 640K RAM is often the minimum required for graphics. To speed up operation, try one of these approaches (in order of likely effectiveness): 1) increase your basic computer RAM to 64OK; 2) if the graphics software requires frequent disk access, create a RAM disk using additional memory; 3) add a math coprocessor chip, such as an 80287 (assuming your graphics program will support it); or 4) use a faster microcomputer.

If you plan extensive graphics or desktop publishing, buy a microcomputer with an 80386 microprocessor. This will cost about $800 more than an AT with an 80286 microprocessor, but it will operate three to 10 times faster. Updating an AT as an alternative is feasible but expensive.

The major screen display options supported by most graphics programs are 1) Hercules-compatible, high-resolution, monochrome display hardware (gray shades but no colors); 2) a color graphics adaptor (CGA) for low-resoultion color; 3) an enhanced color adaptor (EGA) with resolution close to the Hercules display; and 4) a video graphics adaptor, the new IBM standard, superior to the EGA in number of colors and resolution.

A whole-page monochrome screen, costing $1,000 to $2,000, is particularly useful for graphics covering a full page and for desktop publishing. Drawing a full page of graphics may take a long time, however, unless you have a very fast microcomputer. You may get better results with a fast 80386 microprocessor and switching between top and bottom half-pages.

Output resolution is independent of screen resolution for most programs. The best resolution is provided by plotters that draw each point. Prices range from $800 to $2,000 for units with manual paper feed and multiple, excellent colors; automatic feed or the ability to handle large paper sizes costs more. Hewlett-Packard plotters and similar ones sold by IBM are adequate for most purposes.

Laser printers, costing $2,000 to $4,000, offer very good black and white resolution. You often need at least 2 Mb RAM to print a whole page of graphics at maximum resolution, but most printers come with less than 1 Mb as a standard feature. Be sure to get software and a printer that support whole-page resolution of 300 x 300 dots per inch (dpi). Some programs and printers can only produce one-half page at 300 x 300 dpi or a whole page at 150 x 150 dpi.

Software manufacturers may state that their programs can plot on a particular device, such as a laser printer. Not all of the features may work on that device, however. Many of the letter fonts and graphics symbols may appear distorted or not be picked up at all. If a specific combination of symbols or fonts is critical to your application, test the software on a plotter or laser printer to make sure it works.

Some graphics programs require a mouse, but most can use a keyboard as well. Some can accept graphics created by other programs and enhance these graphics. Many allow automatic printing of a number of graphs, which is useful if you have a plotter with automatic paper feed or a laser printer.

Windows, an operating system from Microsoft (Bellevue, Wash.), allows users to run many programs concurrently and helps transfer information, such as a graph, from one program to another. It also facilitates merger of graphics and text on a page, automatically paning the text. Not all programs can take advantage of these features. In addition, a fast computer with plenty of memory is needed (Windows works best with 80386 microcomputers).

Those are the general considerations. Next month we will look at available graphics programs.
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Author:Siguel, Edward N.
Publication:Medical Laboratory Observer
Date:May 1, 1988
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