"When I think of tribute albums, usually a person's dead, and Joni's not dead," said Hancock, whose "River: The Joni Letters" features interpretations of eight Mitchell songs, plus two of her favorites by Duke Ellington and Miles Davis.
"This (album) came more about how I feel about my friend who I admire, Joni Mitchell. I have a deep respect for her as a human being and as an artist. So it's more personal than a tribute album."
Hancock, who first worked with Mitchell on her "Mingus," co-produced "River" with Mitchell's ex-husband and longtime collaborator Larry Klein. Mitchell sings on Hancock's version of "The Tea Leaf Prophecy," while other guest vocalists include Norah Jones, Tina Turner, Leonard Cohen and Corinne Bailey Rae.