Paintings by Frank Stella,
an american artist who was part of the "post-painterly abstraction" movement (precursor of minimalism) during the 60's, and also part of the Optical art movement (based on optical illusions).
He was painting broad stripes of color, and the white lines you can see between all of them is the white of the canvas... (he was minutiously painting straight lines leaving equal space between them)
I love these vivid colors,
it's very helpful looking at them when the sun is hiding like today, and you see nothing but grey...