President Lyndon B. Johnson speaks to the nation before signing the Civil Rights Act of 1964.
http://www.lbjlibrary.net/collections/photo-archive/photolab-detail.html?id=1107
The source image was converted using a fast (quasilinear-time) recursive subdivision algorithm. Let A be the (multi)set of all colors in the source image, and let B be the set of all colors in the RGB cube. Divide A into two sets A₁, A₂ by a plane perpendicular to the principal component of A in a perceptual colorspace. Divide B into B₁, B₂ with a parallel plane such that B₁, B₂ have the same sizes of A₁, A₂. Recurse on A₁ and B₁, then on A₂ and B₂.
