Van Gogh's chair
The painting of Van Gogh's chair, like the Sunflowers, is a sort of self portrait. (He also painted Gauguin's chair as an illustration of his contrasting temperament.)
The yellow chair is outlined with a blue-green line which both reflects the wall colour and contrasts with the dull orange-red of the floor tiles.
Van Gogh freely admitted the artificiality of his art but maintained that since it was impossible to match paint colours to what one actually perceived, 'a painter had better start from the colours on his palette than from the colours in nature'.