This was an early theory of David Lifton's and has to rank among the craziest. Here is an excerpt from the May 1967 issue of Esquire Magazine:
I can't find much that Lifton has actually written about this theory, but here is a memo that Sylvia Meagher wrote about a telephone call with Lifton on October 30, 1965:
Meagher was disturbed by Lifton's theory and she sent him this letter the next day:
David Lifton took Meagher's advice and stopped talking about camouflage. However, he still thought there was some merit to the story. Here is an excerpt from a letter to Sylvia Meagher from March 21, 1969:
At some point, Lifton jettisoned this theory. There are some conspiracy theorists today who cling to theories, every bit as ridiculous as the Lifton's camouflage scenario. For instance, some people believe that JFK's brain was switched at Bethesda; that General Curtis LeMay was at the autopsy; that Clay Shaw conspired to kill JFK; and that there were multiple plots and multiple patsies after JFK in November of 1963.
No amount of reasoning will change their minds.
Update
Hat Tip to Gus Russo -- the book The Scavengers and Critics of the Warren Report by Richard Warren Lewis (based on an investigation by Lawrence Schiller) mentions Lifton's theory: (page 172 - 173)
Lane, however, has steered clear of a related survey undertaken by David Lifton, a twenty-five-year-old graduate student in engineering at UCLA. His census of the trees visible on the grassy knoll on the day of the assassination conflicts with the number of trees existing today.. According to LIfton, one tree is missing. He theorizes that an artificial tree was installed on Dealey Plaza, prior to the assassination, and that camouflaged snipers who might have hit Kennedy were concealed beneath it.
To further document this amazing find, he enlarged, up to twenty times their original size, sections of photographs taken from the twenty-six volumes and various periodicals. The photographs have been blown up completely beyond reality In the shrubbery of the grassy knoll he has located several forms which he interprets as assassins firing at the motorcade. One of them looks as if he is wearing a Kaiser Wilhelm helmet. Others wear electronic headsets and man periscopes and machine guns on a platform operated by hydraulic lifts. One of his imagined finds resembles General Douglas MacArthur. None of these illusions is visible on the original prints
Update 2
Here is an excerpt from a letter that Sylvia Meagher sent to Maggie Field on August 26, 1965:
Previous Blog Posts on David Lifton
Lifton writes to Oliver Stone about Jim Garrison.
My obituary for David Lifton