There are two symmetrical poles in this image, one left and the other right of its centre.
Each pixel in the image has a range and an angle.
The range is the square distance from the left pole divided by the linear distance from the right pole.
The angle is with respect to the centre of the image and is positive irrespective of whether it is clockwise or anti-clockwise.
The red component varies monotonically with the range.
Within each constant red area, the green component varies monotonically with the angle ranking within that area.
Within each constant red and green area, the blue component varies monotonically with the composite range and angle ranking within that area. Increase and decrease of both range and angle alternate to make patterns wider and transitions across areas smoother.
Image Licence: Public Domain (CC0).
