For anyone who wants to look into that, it's called "kasina practice." There's a chapter about it in Daniel Ingram's book Mastering the Core Teachings of the Buddha, though he describes it as an advanced technique for people who already have a high degree of concentration.
There's also "image streaming" which is similar, and might be more accessible:
From what I know, Kasina practice involves visualising certain simple shapes or objects such as candle flames and coloured disks.
Tibetan Buddhist practices involve visualisation of fairly complex 'deities'; supernatural beings wearing certain clothes, certain ornaments, surrounded by certain other complex objects. As the visual complexity of the imagined scene is much more than in Kasina practice, the 'phantastic' benefits might be different as well. The deities are convenient as visual object because (I suppose) Tibetans are familiar with their visual appearance. Choosing any other similarly complex familiar object should work as well.
Ingram described Kasina as gradually increasing the complexity of the images, after success with simple ones. But I confess I don't really know much about this.
I've stumbled across the "Image Streaming" notion before, on those same few websites. Is there any third-party support for the idea? Such as a published study, slatestarcodex-style book review, or (at this point) a few redditors claiming "it worked for me"...
It unfortunately sets off my BS radar in full:
* Most references to the technique appears to originate from a book called "The Einstein Factor: A Proven New Method for Increasing Your Intelligence", by the same Win Wenger as you linked above.
* Win Wenger is always written as "Win Wenger, Ph.D", but I can find exactly one paper from him on Google scholar [0], written solo, written well after he was already publishing books [1].
* The "Reinhart Study" cited by the book is listed on this website [2] with the heading "Reviewers have found that this study was statistically inadequate. Further and better studies are requested, please contact wwenger101@aol.com".
* The author of that not-published paper is listed as "Charles P. Reinert, Ph.D., Dep't of Chemistry/Physics" (not psychology).
* Other works attributed to Win Wenger on that same site are very obviously nuts [3], containing such gems as "It is unclear at this point whether anyone in fractile theory or in interference pattern physics has noticed yet the relationship between these two fields, each of which by itself is and will be totally transforming our understanding of our world and of ourselves within the next decade or so."
In short, Win Wenger appears to be someone without any actual credibility who is nevertheless attempting vainly to forge it. And I can't find any actually credible references to this technique working.
There's also "image streaming" which is similar, and might be more accessible:
https://photographyinsider.info/image-streaming-for-photogra...
http://www.winwenger.com/imstream.htm
http://www.winwenger.com/isbackup.htm