You returned from a once-in-a-lifetime dream vacation with several rolls of great color photos, sent them off to be processed and:

A) They were lost in the mail;

B) They were lost at the processing lab;

C) They turned out too dark, too light, fuzzy, foggy, out of color balance . . . below your lowest expectations.

"Getting first-rate color prints from a film processor," says Consumer Reports in a recent issue, "is a little like playing Russian roulette with a half-loaded gun. The chance of success is no better than the chance of failure."

CR sent nearly 200 rolls of color film to processing labs across the U.S. Half of the 4,000-plus prints returned were considered of "good" or "better" quality by CR's photo experts. Most of the other half were found acceptable but mediocre, and 10 percent "were so bad that even the most casual snapshooter might ask that they be made over . . . "

Two of the mail-order processing labs, Clark Color Laboratories of Beltsville and Custom Quality Studio of Chicago, were ranked "superior" for their 35mm prints. Both were check-rated ("of high overall quality and appreciably superior to noncheck-rated" facilities) and judged Best Buys ("rated high in overall quality but also priced relatively low" in comparison with the other facilities rated).

Clark Color Laboratories' price for processing and printing a 24-exposure roll of 35mm film (the standard used in CR's survey): $4.70. In addition to mailing envelopes, their services are available in the Washington area through: Dart Drug, Peoples, Safeway, Fotohut, SnapShops, Rodman's Discount Drugs, Mr. Foto, Zepp and numerous small chains.

Custom Quality Studio of Chicago, the other top-rated processor, charges $4.14 for the same service.

Each of the film procels of film, half 110 and half 35mm. Eight batches of film were sent out over a four-month period.

"When a company had more than one processing plant," says CR, "we sent film to as many different plants as we could. Companies with many plants . . . received twice as much film as smaller processors."

People, objects and landscapes were photographed under a variety of conditions. Some of the photos were typical snapshots; others would require particularly careful printing.

"We shot the sets of pictures in each batch so they were as identical in framing and exposure as we could make them," CR says. The photographers were CR staffers and they submitted the film to processors under their own names.

The hundreds of sets of prints finally assembled were independently judged by three CR photo experts.

At the same time it ran its test, CR polled its subscribers on their experiences with photo processors. Nearly 40 percent of the 15,000 readers who responded said they had received unacceptable prints within the last year. Also, nearly 50 percent said bad prints, high prices or lost film had caused them to stop using a particular processor within the last two years.

Approximately 20 percent said they use Kodak processing.

Although Eastman Kodak placed high among the large group of processors ranked "average" in the CR test, its prices were about double those of the two top-ranked processors.

The reader-respondents were enthusiastic about two film processors not included in CR's test: Mystic Color Lab of Mystic, Conn., and Skrudland Photo Service of Hebron, Ill.

CR listed several possible problem areas concerning color printing: incorrect exposure; poor color balance; "chromatic aberration," a lens-induced flaw; improper framing and trimming; out-of-focus prints; blurred prints (due to either the negative or paper moving during exposure); damaged prints; scratches, dirt and water spots.