NEW YORK (AP) _ NCR Corp., continuing product rollouts despite a takeover battle with AT&T, plans to unveil a system Tuesday that allows companies to convert paper documents into computer data that can be stored electronically.

The market for so-called electronic imaging products is expected to grow rapidly this decade, but has yet to take off. But it already has attracted a number of computer makers, including International Business Machines Corp., Unisys Corp. and Wang Laboratories Inc.

With image processing, paper records are ''scanned,'' or transformed into computer code, through a device resembling a copy machine. The code can be stored electronically much like other computer data, then recalled on a high- resolution screen that shows fine detail, including signatures on forms.

With image processing, a document can be viewed simultaneously by a number of employees, even if they are hundreds of miles apart, as long as they are connected by a computer network.

The U.S. market for imaging systems is projected to grow to $5.56 billion by 1995 from $650 million last year, according to the technology consulting firm IDC-Avante.

NCR said Monday it will announce an imaging system aimed at replacing paper-based documents used in office settings such as credit-card processing centers, hospital records centers and personnel departments.

The system is composed of individual computer workstations connected in a network through a powerful central computer called a server, the company said.

NCR also is providing software that allows companies to develop their own systems for managing the flow of the documents.

Like other computer makers' imaging systems, many of NCR's components are supplied by outside companies. The scanners, for example, come from Bell & Howell and the Japanese maker Fujitsu.

Prices of the systems range from about $800,000 for a 20-workstation system to $3.5 million for a 120-workstation setup.

Later this year, NCR said it will provide the capabilty for the systems to ''read'' typewritten or handwritten characters in documents that are scanned in. That would allow the systems to read social security numbers on credit applications, for example, allowing the system to put the documents in the right file automatically.

The Dayton, Ohio, computer maker is basing its imaging products on so- called open systems computers, or those that rely on industry standards rather than proprietary technology. That is part of NCR's overall thrust in computing.

Scott McCready, an analyst at IDC-Avante, said he generally was impressed with NCR's product.

''I honestly think they've got the right idea and they do have a pretty good understanding of the market,'' he said.

But, he said, ''How many people are willing to buy from NCR? Is NCR on enough people's preferred purchasing lists?''

NCR, the fifth-largest U.S. computer maker, often is overshadowed by larger rivals such as IBM. However, McCready said, it may do well in selling the imaging product in markets where it has a strong showing, such as banks and retailers.

Last year, NCR announced its first imaging product, a desktop unit aimed at such uses as airline ticket offices and bank branches. The device can capture and store only images of small documents, such as tickets and checks.

Later this year, NCR plans to announce a system that will allow banks to capture electronic images of checks during processing. IBM and Unisys already are in that market.