Frantisek Kupta was a Czech painter whose work moved from a naturalistic style to an abstract nature. His explorations into colour are really beautiful. You can see the transition from painting more lifelike scenes as he becomes more focused on form. The highlights of colour are carefully considered, a red piece of clothing amongst a green tinged self portrait, the yellow lit skin of a lady putting on her lipstick against a blue background. These move into more abstract paintings capturing the colours of night, dancers in a flash of light and patriotic colours and figures moving in primaries. His purely abstract work like Disks of Newton, Study for Fugue in Two Colours moves into shades of colour and form but they all have a lovely quality of light. Kupta worked in Paris after the First World War and must have been hugely influenced by the work of the Impressionists and Neo Impressionists whose work with colour illusions and spectral palettes. The Guggenheim holds a number of the studies he made for his paintings which are really interesting as he plots out his colours really simply without the tones and they instantly become much more digital looking.