Svelato l'arcano, caro !presidente!,
l'errore presente nel mio libro (p. 319, rif. G)in merito al copricapo inquadrato da Zapruder sul poggio erboso, grazie anche ai messaggi privatamente inviatimi dall'amico Stefano, è dovuto al fatto che, durante una prima stesura del volume, analizzai solo il filmato per convincermi del fatto che quel copricapo fosse il parafango dell'auto in corsa visto attraverso i rami. Solo successivamente, prima della pubblicazione, esaminai il VI Volume dell'HSCA (p. 133)che riportava uno studio fotogrammetrico e fotografico del dettaglio. Si confermava la presenza di un copricapo a calotta, ma si escludeva quella di un fucile puntato verso l'auto o verso qualunque altro punto. Infatti a p. 319 del mio libro il riferimento al volume dell'HSCA è correttamente riportato, ma ho omesso di modificare quanto già avevo scritto su questa faccenda. Analogamente mi è successo che le bozze definitive del mio volume riportino la traduzione della parola "curtain rods" (aste per tende)relativa al contenuto del pacco di Oswald, mentre la stampa definitiva è, misteriosamente, la vecchia versione non corretta "tende avvolgibili". Sono imprecisioni e distrazioni che purtroppo capitano e me ne scuso con i lettori del mio volume. Grazie a Lei e a Stefano per avermi dato l'occasione di fare questa correzione. Cordiali saluti. DV
IV. CONSPIRACY QUESTIONS
A. Alleged Gunmen in Dealey Plaza(*)
FIGURE IV-14.--Head in bush image. (Zapruder 413) Top: Unenhanced. Bottom: Enhanced.
Accordingly, this photograph was then studied photogrammetrically. A basic principle in optics states that the size of an image is inversely proportional to the distance of the object from the camera that created the image. (120) Using this principle, the distance of an object from a camera can be calculated by comparing the size of its image to the image size of a similar object at a known distance. The size of the image of the head in the bush was compared to the size of the image of a head in the Presidential limousine. A simple calculation can determine where the head in the bush was located on the line of sight between Zapruder and the limousine (see addendum B).
The head of the Secret Service agent climbing into tile Presidential limousine was used for the calculation. Several measurements were made. The closest to Zapruder (let that the head in the bush can lie was in the middle of the sidewalk that runs from the top of the grassy knoll down to the street. The farthest away would be 10 to 15 feet beyond the sidewalk.*
Based on this analysis, an inspection of the Dealey Plaza survey map (fig. II 10, JFK exhibit F-133) revealed that the head in the bush was not in the bush at all. The bush lies between Zapruder and head, with the head itself an appreciable distance away from the bush. Accordingly, there was no evidence of a person actually hiding behind the bush.
Having located the head, the linear feature purported to be a rifle was examined. The computer-enhanced image shows a number of linear features similar to the one near the head, all extending in the same general direction as the alleged rifle. Further, close inspection of the enhanced image shows that the narrow part of the linear feature (the alleged "barrel" of the rifle) passes in front of leaves in the bush. Since the head lies far on the other side of the bush. it was geometrically impossible for an actual rifle barrel near this head to be situated front of any leaves in the bush.
The panel concluded that the linear feature was not a rifle. It was only one of a number of twigs in the bush, all characterized by the same general direction and spacing in the natural growth patterns of the bush. Additional processing work was done at the Los Alamos Scientific Laboratory to study the region of the linear feature. (121) This processing, which was based on the knowledge that similar objects reflect light in similar ways, has been applied by NASA in analyzing satellite photographs of the earth for natural resources. (122) The technique developed by NASA is known as spectral rationing and involves a comparison of color measurements by dividing measurements of the color values. (123) The objective is to compare the different amounts of red, green, and blue light reflected by an object. This was done by obtaining a computer scan of the photograph's red, green, and blue components and then measuring each one.
When the Los Alamos Scientific Laboratory applied this spectral ratio technique to Zapruder frame, 413, it found that the ratios in the region of the thick part of the linear feature (the "rifle stock") were identical to the ratios of the light reflected from the Presidential limousine. (124) On the basis, the panel concluded that the "rifle stock" was only a hole in the bushes looking through to the limousine, which, by virtue of being coincident with a twig, created the false impression a rifle. Thus, no evidence of a gunman was discerned by the panel.
ADDENDUM A
Diego Verdegiglio