Journalism was the reason for his imprisonment. Specifically, everyday shots of Havana life, far from the gleaming tourist hotels and beaches. His world showed a crumbling city with haggard faces, presided over, Oz-like, by billboards with revolutionary slogans.
He had been among some 20 independent journalists who were rounded up by the Cuban government during a sweep of 75 dissidents in March 2003, and given lengthy sentences after quick trials. They were said to be traitors and mercenaries in the service of the United States government, even though international human rights and journalists groups defended them as prisoners of conscience.
"For an Exiled Cuban Photographer, Freedom Was in Color" (via NYT’s Lens blog)