Color-coordinate system from a 13th-century account of rainbows.

We present a new analysis of Robert Grosseteste's account of color in his treatise De iride (On the Rainbow), dating from the early 13th century. The work explores color within the 3D framework set out in Grosseteste's De colore [see J. Opt.

A three-dimensional color space from the 13th century.

We present a new commentary on Robert Grosseteste's De colore, a short treatise that dates from the early 13th century, in which Grosseteste constructs a linguistic combinatorial account of color. In contrast to other commentaries (e.g.