Hum,
color balance of the differant films used, and the use of indoor lights...
Also, i noticed that the former most expensive painting may possible have been burnt/destroyed by it`s owner (to avoid inheritance tax )
Van Gogh’s Portrait de Dr Gachet (bought for $82.5 million by Ryoei Saito in 1990), has not been seen since the Japanese paper magnate died in 1996.
scotsmanShame if it has, and we only have a few photos of it....