Bar codes -hose ubiquitous black-lined imprints found on everything from cans of peas to covers of magazines - are revolutionizing the way business and industry keep track of things.

Companies that count, measure, sort or weigh products to be stored, shipped, sold or processed - just about every business, in other words - are turning to bar codes.They are many times more efficient and accurate than humans entering data on a computer keyboard. And they have the added advantage of providing a snapshot of business operations on instant notice.

Sales of bar code printers, scanners and associated computer hardware and software have grown from $200 million just five years ago to more than $1.5 billion.

When the industry's trade association, Pittsburgh-based Automatic Identification Manufacturers, held its first trade show in 1982, 66 exhibitors and 650 visitors showed up. Last year Scan Tech attracted 227 exhibitors and 12,000 visitors.

The best-known use of bar codes is at the supermarket. Grocery stores equipped with scanners now account for nearly 60 percent of the $320 billion in annual retail food sales.

But the really spectacular growth is yet to come, in the industrial workplace. Automakers and hospitals already are making widespread use of them, and they are being introduced in the telecommunications, electrical, aluminum, paper, printing, heating, air conditioning, refrigeration, plumbing and retail merchandising industries, according to AIM.

"One of the great things about this technology is that it is more accurate than someone punching a keyboard," said AIM's executive director, William P. Hakanson, who said bar codes result in only about one error in every million characters scanned.

A retired IBM scientist, Norman Joe Woodland of Raleigh, N.C., is credited with patenting the first modern bar code in 1949. Woodland's "bull's-eye" code never was widely used, however, because its circular shape smeared easily, causing it to be misread.

The bars and spaces in bar codes are to a computer what the alphabet is to a reader. Scores of codes have been developed, but only a few are in wide use. Each is a separate language, undecipherable to computers programmed to read other codes. Industries adopting the technology must set up voluntary boards to decide which code to use and assign identification numbers to participating companies.

The supermarket industry adopted as its standard a code created in 1973 by IBM scientist George Laurer. Supermarkets stock an average of 25,000 items, according to the Food Marketing Institute, and Laurer's Uniform Product Code appears on most of them.

Laurer, who retired from IBM two years ago, said IBM did not patent his code because that would have delayed its introduction to the food industry. But he did receive a $25,000 corporate prize for it.

His code contains information identifying the company, product and size of the package. At the checkout counter, a laser scans the code, "reads" the information and sends it to a computer where prices are stored. The computer transmits the price back to the cash register - all in a fraction of a second.

In advanced systems, the supermarket chain's computers are programmed to automatically reorder merchandise when stocks fall below a predetermined level. Thus, when a shopper leaves a store after buying the can of peas that triggered a reorder, the computer already has started the process of restocking the store's shelves.

The rapid conversion of the nation's supermarket industry to bar codes has been spectacular, considering the hefty cost - $250,000 and up for large stores - to purchase and install the equipment and train employees to use it.

It has also met some resistance from consumers hesitant to buy products without prices marked on each individual package. Laws requiring such pricing have been enacted by eight states - California, Connecticut, Massachusetts, Michigan, Minnesota, New York, North Dakota and Rhode Island - partly canceling out the benefits of bar coding.