Eastman Kodak Co. has added electronically readable codes to 35mm film to help cameras and photofinishing equipment improve picture quality.

The photographic products giant also has found a way to reduce by half the thickness of its instant camera prints.

Kodak was to begin shipping the new 35mm film, which carries the DX designation--this spring. Two electronically readable codes are on the film spool or cartridge. One resembles two rows of black or white squares. They indicate in code the film speed, number of exposures and exposure range. Manufacturers can build cameras with circuitry to read the codes and automatically set the film speed, give a warning when the photographer is at or near the end of the roll and, finally, permit a wider range of light conditions before warning that the picture may be over- or underexposed.

Also on the film magazine are bars of various thicknesses resembling the universal product code found on most packaged goods sold at grocery stores. The code identifies the film type for automatic photofinishing equipment.

A 12-hole pattern punched into the film leader repeats the information on the cartridge bar code and makes more data available than current eight-hole patterns. Once the film has been processed, another bar code becomes visible, repeated every half-frame along the edge of the film. It gives automatic finishing equipment data that Kodak says could enhance print quality. Finally, the film type is printed on the magazine so that it could be visible through a window on the camera back.

As for the thinner prints, Kodak will make its new Kodamatic Trimprint instant color film available beginning in September. It will cost the same as the company's current instant-print film.

The new film permits users to remove the thick backing soon after the print has developed. Kodak interposed a slightly adhesive layer between the bottom layers of the film, which form images, and the top ones, which receive them.

The thinner prints will take up less space in albums, wallets or shoe boxes and will cost less to mail, Kodak says.

Ernie Culman, vice president and general manager at Industrial Photographic Products Inc. in Silver Spring, said, "I think the Trimprint will be right nice. It will give them an edge over their competition"--Polaroid, whose instant color prints are thick like Kodak's current ones. "At this stage of the game, we sell a lot more Polaroid than Kodak film."

Brenda Lee Landry, a securities analyst who watches Kodak at Morgan Stanley, doubts Trimprint film will have much effect on Kodak's overall performance because instant film and cameras are a small part of the company's business. She said that Kodak lost money and market share in 1982 on this segment of its operations.

Dx film, on the other hand, is "going to really help photography and help the finisher," Landry said. Makers of 35mm cameras "are going to look happily at this because it gives them a new advertising message and possibly may generate replacement sales."

At Berkey Photo Inc., Bob Goldblatt, vice president for human resources, called DX film "a positive factor" for his company, which no longer manufactures cameras, but distributes Konica products in this country.

"It's a definite plus for us" in photofinishing, Goldblatt said. Berkey owns 12 photofinishing labs across the country, including one in Alexandria.

It was Berkey which initially won an antitrust suit against Kodak, but in 1980 lost much of the $87 million award after the Supreme Court refused to review an appeals court decision. Berkey had argued that Kodak had introduced its Instamatic cameras and compatible film without tipping off competitors to their design, causing Berkey's camera sales to plummet to negligible levels.

This time, a new relationship is developing between Kodak and others in the industry. Technical information about DX film has been distributed to more than 200 camera companies and processing-equipment companies worldwide through personal contacts, mailings, and trade journal reports, according to Henry Kaska of Kodak.

Once reason may be that Kodak hasn't marketed a 35mm camera since 1970 and wants camera makers to incorporate DX capabilities into their products as soon as possible so Kodak can sell more film.

Neither Cannon nor Nikon have set a date for introduction of cameras that can use DX coding, according to their spokesmen, and no other manufacturers have announced schedules, according to the National Association of Photographic Manufacturers.