My dictionary lists three ways to spell subtle, and they are suttle, subtile and of course the usual subtle. I chosen to use one of the unusual spellings. The patterns in this picture appear to be repeated without variation but there are subtle (or suttle or subtile) variations.
Created using the development versions of Saturn and Titan (to be released as version 2.0, target date 31st March).
Programs: saturn and titan Number of A transforms: 0 Number of B transforms: 0 Transform sequence: A Number of Complex Plane transforms: 1 Transform 0: power, -1 + 0i Initial values of z: untransformed c Image centre: 11.28 + 18.36i Image width: 21.36 Rotation about image centre: 0 degrees Maximum iterations: 5000 Bailout: norm(z) > 7000 Calculation width: 213.6 Orbit length: 5000 Orbit plotting: all orbits Colour method: accumulation, (the number of times an orbit visits a location)