For two years the Los Angeles County Museum of Art has been quietly buying paintings and publicly selling them. A group of LACMA's old masters, coming up at Sotheby's on Jan. 28, will be sold to raise funds to buy other works such as “Winter Scene on a Frozen Canal” by Hendrick Avercamp, a partial gift to the museum. Newly renovated galleries, and a reshaped collection, are part of a curatorial initiative to evoke the way art was displayed in Roman palaces or English country houses.