Comprising 21 source-four spotlights, Between inside and outside continues Eliasson's previous experiments with light and colour, exploring the visitor´s co-production of colour. The projections, arranged in a sequence of changing and superimposed trapezoids, ellipses and circles, vary in colour. In response, visitors see afterimages overlapping with the colours projected onto the walls. Since colour is generally conceived as a product of the brain rather than existing independently in the world, the sequence is thus co-produced by the viewer.