Final base colors, final line spacing.

Base color is the average of pixel colors in a few squares close to the
center.
Line color is white with 1/8 alpha channel - this puts the colors of the
lines pretty close to the original picture, and also generalizes the
colorschemes so any (dark) color can be used.

Line spacing: lines are (smaller dimension of width vs height)/32 pixels
apart, rounding down, including one line but not the other line. This
both easy to code and close enough for me to the original image.