Four Norwegian men were convicted today of the theft of the painting, "The Scream" by Edvard Munch, which was stolen from the National Gallery here on Feb. 12, 1994.

The theft of the 1893 painting, worth at least $55 million, was videotaped by a security camera, which showed two thieves making off with the painting, leaving a postcard saying: "Thanks for the poor security." The painting was recovered undamaged three months later.

An Oslo court today sentenced Paal Enger to six years and three months in prison. He and 20-year-old William Asheim, sentenced to four years and nine months, were convicted of stealing the painting and attempting to sell stolen property.

Mr. Enger had served a four-year sentence for his 1988 conviction in the theft of Munch's painting "The Vampire" in Oslo. That painting was also recovered undamaged.