Just two minutes into an interview with artist Hiroshi Sugimoto, it became clear why the famously discreet 61-year-old had agreed to talk about rock band U2's use of one of his photographs on the cover of their latest album, "No Line on the Horizon."

"The first thing I want you to let people know," he said, seated in an office at Ginza's Gallery Koyanagi, "is there is no commercial aspect to my relation with U2. No cash is involved."

No cash? Sugimoto's 1993 image of the Boden Sea at Uttwil adorns not only the cover of the album that debuted this month at No. 1 in almost 30 countries, but is also plastered over buses, taxis and TV ads worldwide as part of a multimillion dollar advertising blitz. The commercial connection had seemed so obvious that many assumed Sugimoto had sold out.