I agree. These hallucinations are just memories and you can develop a sort of rhythmic control over them with your habits/actions/thoughts even.
I have, for a long time after my former diethyl ether addiction, a visual artifact when closing eyes, of slight circles, geometric patterns (many squares, within squares, with detatched corners) of a non-describeable color, if you understand how that can be possible.
My "visual" background when I close my eyes in the dark, undergoes color changes, of a neon-dark-green, again, difficult to describe, intermixed with pink and a royal purple color, these shift and merge.
If there were a cure for it, I would refuse it, the "HPPD", although in my particular case, I do not look upon it as a disorder, actually helps me, as I have terrible insomnia, have since childhood, closing my eyes while breathing rythmically in and out provides a drug-free visually hallucinatory relaxing meditative setting, and allows me to help drift off when my insomnia isn't so severe as to require massive amounts of benzos.