These are stereo conversions from regular flat paintings.
The original left eye image was changed to create the new image for your
right eye. They can be viewed as either cross-eyed, parallel, or anaglyphic.
My choice is the cross-eyed method. The easiest is the anaglyphic, with a pair of red/cyan glasses.
(Minimum screen size: 1024x768)
Cross Eye Version
1886 George Seurat Sunday Afternoon on the Island of La Grande Jatte
Oil on canvas 81 x 120 in. Art Institute of Chicago