How it works
Bitmaps must be 256-level (8-bit) grayscale and are 64 pixels across. Each of these pixels in width represent a harmonic in series, 1..64, from left to right. A white pixel in a slot means the harmonic is played at maximum amplitude. If it's black, it's silent. Varying levels of gray mean different levels of volume. Together, this row of pixels forms on additive spectrum.
Bitmaps can be up to 128 pixels tall. Each of these rows of pixels is a snapshot in time, going from bottom to top. The snapshots sequenced together are morphed in the form of an envelope, creating a constantly evolving harmonic soundscape!
It's free so go and download yourself a copy.