Mexican artist Rufino Tamayo's ``Tres Personajes,'' a 1970 painting vibrating with reds, yellows and purples, may fetch as much as $1 million at a Sotheby's auction on Nov. 20, the work's first public viewing since Elizabeth Gibson spied it in a mound of garbage on a Manhattan sidewalk. Gibson, a tall, blond 53-year-old resident of the Upper West Side, went out for a cup of coffee on a Saturday morning in 2003. She spotted a large painting poking out from among the garbage bags left on the sidewalk on West 72nd Street. In her pre-caffeinated haze, she kept walking. Gibson, who works in radio and as a writer, said her apartment, which she shared with a roommate, was neither sleek nor large. Also, the chipped silver frame looked cheap. Despite these reservations, she lugged the 4-foot-wide painting back to her apartment and hung it on the living room wall. Thus began a lengthy and at times anguished journey to discover the Tamayo's history. Gibson said she contacted lawyers, art...