David Healy's Technical Aspects of Film Alteration

How difficult would it have been to produce a fabricated 8 mm Kodachrome stock Zapruder film using special effects technology available in 1963? To answer this question, David Healy produces a few altered frames using a modern computer program called Adobe After Effects. He notes that this software, "has probably put most of the film industry's high-end optical printing houses out of business." (116) How demonstrations produced with software that obsoletes the optical printer relates to effects allegedly produced on such optical printers is not clear.

An optical printer is an arrangement of projectors and a camera that can combine multiple photographic elements into one. This process is called compositing and is responsible for most special effects from your local television weather forecaster standing in front of an oversized weather map to rebel fighters descending on the Death Star in Star Wars. To illustrate a possible alteration, Healy produces the following composite of Zapruder frame 256 with a "cleaned up" and slightly enlarged background:

It is not clear what purpose such an alteration would serve. Even Healy is at a loss saying, "enlarging the grassy area for whatever reason was deemed important." (120) That the composite appears so believable is a testament to After Effects, Healy's skill with the program, and the lack of complexity in the background. Obviously, frame 256 was chosen because it lacked complicating elements like spectators in the background, lampposts in the foreground, etc.

That Healy doesn't understand what is wrong with such a composite, however, is a testament to his lack of appreciation for photographic analysis. Zapruder's camera at maximum zoom produces an image with a field of view a little over 10-degrees wide in the image area normally projected. Enlarging the background creates a smaller field of view for the background. This is detectable. Even John Costella's overlays of calibrated Zapruder frames onto his panorama will reveal background enlargement or reduction. Furthermore, if forgers inserted frames with an enlarged background into the film, the viewer would see a sudden shift in patches in the grass at these frames.

Healy states, "As you can see, when it comes to optical printing nothing is sacred and that includes sprocket hole areas." (119) Well, he isn't showing us optical printing and even with modern digital technology, he gets the intersprocket areas totally wrong. Below is a comparison of the existing frame 256 with Healy's composite. Notice the following problems in the intersprocket area:

(1) The ghost image above the motorcycles is not right. Ghost images are double exposures from surrounding frames. They are little movies-within-a-movie and have to be consistent and correct frame-to-frame.
(2) The claw shadow is missing, which is the dark vertical band over the motorcycles.
(3) The edge of the lens's circle of good definition is missing. This is the arc-shaped region of falloff in both light and sharpness along the left edge. The size of this region depends on the lens's f-stop setting, which automatically changes with changing light levels in the type of camera Zapruder used.

Healy may make the excuse that he is merely showing how easy it is to make composites on an optical printer, but we are pointing out how difficult it is to get everything right. The devil is in the details. These additional effects have to be produced without causing an increase in grain, contrast buildup, etc.

Another Demonstration of Optical Printing

For another example of how composites could have been made in 1963 on optical printers, Healy once again fires up After Affects and creates the following "new head shot":

Of course, this is just a spray effect composited on top of a single frame, frame 312. We don't see the skull burst, the flaps move, the spray dissipate, all in correct perspective while JFK's body lurches backward and then slumps towards Jackie, all while the limo is moving and the camera panning somewhat erratically with it. Healy keeps telling us how easy it is to do these types of effects. But he uses modern digital software and even then doesn't come close to duplicating what we see in the Zapruder film.

Special Effects in 1858

To further illustrate how easy it is to forge 8 mm color Kodachrome films, and how well-established the techniques are, Healy shows us Henry Peach Robinson's Fading Away, a composite made over a century before the Kennedy assassination.

Healy neglects to consider that Robinson worked with very large format negatives (contact prints are 244 x 393 mm) with several thousand times the emulsion area of an 8 mm frame. Healy tells us, "No cut lines are visible." They may not be to him, but somebody more skilled in photographic analysis and equipped with better tools can spot them. Dr. Robert Leggat writes on his A History of Photography web page:

Fading Away is a composition of five negatives. If one examines a large copy of a print closely one can see the "joins", particularly the triangle of grey with no detail in it. One has to remember, of course, that these were contact prints - there were no means of enlarging at that time.

Matte lines are harder to conceal than Healy suggests. Even George Lucas's team struggled with them during production of the Star Wars trilogy and this with technology and techniques a decade and a half newer than that available in 1963. When Lucas revisited the trilogy to produce new special editions, at the top of the list of work to done was to eliminate the more apparent matte lines by digitally recompositing the shots. Most notably, they recomposited nearly 100 shots in the snowspeeder attack on Imperial walkers sequence in The Empire Strikes Back.

Finishing Effects on Kodachrome Film

Roland Zavada was a product engineer for Kodak who worked on the development of the very film stock used by Zapruder. All evidence from his study of the Zapruder film points to the film being Kodachrome II camera original film. Such camera original film is designed to record the best quality image from outdoor scenes. It is reversal film, meaning that it produces a positive image. After you develop it, you can view it.

Contrary to what you might expect, these reversal films are not designed to duplicate the light levels of the original scene. When viewed projected on the screen, in fact, such an image would appear weak in contrast and washed out. This is a perceptual effect that results from viewing a projected image in a darkened room. To compensate for this, camera original reversal films like Kodachrome boost the contrast of the original scene. This produces a subjectively pleasing image.

The contrast boost is not identical for the 3 colors that color film captures (red, green, and blue). Kodak's graph best illustrates this. The following graph (of a modern version of Kodachrome) shows how the light levels in the original scene ("Exposure" on the bottom) end up as darker or lighter regions in the developed film ("Density" on the left). The brighter the scene object, the lower the density. I added a black line at a 45-degree angle to show what a film with no contrast boost would graph like. The R, G, and B curves are all steeper than this, meaning this film increases contrast. A step in brightness in the original scene produces about a 1.8 step in brightness in the projected image generally, but notice that each color is a little different.

What would happen if you copied a movie shot with this film stock onto this same film stock? Well, the contrast boost would get applied twice, really boosting the heck out of the contrast. The film has a limited ability to hold all that (indicated by the flattening of the curves at the top and bottom of the graph), so bright scene details become too bright to record and dark scene details become too dark. As photographers say, you blow out your highlights and you lose shadow detail. Even worse, because the color curves are not the same, contrast of the red layer gets boosted more than the green layer, which gets boosted more than blue layer. Your colors are all out of balance in a somewhat complex way.

Kodak made the Secret Service copies of the Zapruder film to camera original film. Attempts were made to compensate for some of the problems described above, but the quality of the copies still suffered. To make good quality copies, Kodak developed a duplicating film with a neutral contrast, meaning the contrast doesn't change when making a copy. Kodak was out of stock of that when Zapruder walked in, so they gave him camera film instead.

What does this have to do with fabricating the film? Well, our best evidence to date--from Zavada's work--is that the Zapruder film is camera original Kodachrome II film. That means that if the film was fabricated, the forgers would have to finish their special effects work on such film. Healy boasts about how easy it is to produce composites on optical printers but what he doesn't tell you is that nobody finishes to camera original film. Not only would the contrast buildup excessively, but the colors would shift in undesired and complex ways.

The motion picture industry uses a group of film stocks that Kodak has specially designed to complement each other. Zavada refers to these as a "family of films." They invest a great deal of research into finding emulsions that give exactly the right contrast boost or reduction, without distorting the color balance, through several generations of copies. This is called the tone reproduction cycle. The motion picture industry uses at least 4 different film stocks in their cycle: camera original, interpositive, internegative, and print film.

The challenge for those claiming Zapruder film alteration is to identify the film stocks from those available in 1963 that will allow forgers to start with Kodachrome camera original film, to go through several intermediate stages to produce the alterations, and finally to finish on Kodachrome camera original film. Of course, the final film must have the excellent color balance, highlight and shadow detail, and low grain that the Zapruder film exhibits. Then the challenge is to find evidence that this actually happened.

For more on the issues touched on here, see Roland Zavada's Zapruder Film Hoax Comments.


Joe Durnavich
David Wimp