Authentication of digital photographs under the "pictorial testimony" theory: a response to critics.

• Author: Barakat, Brian

In the past few years, numerous articles have been published challenging the reliability and admissibility of digital photographs. (1) Initially, these articles attacked digital photographs on the ground that their quality was inferior to traditional photographs. (2) As time and technology progressed, the criticism focused on the ease with which digital photographs can be manipulated. (3) Adobe Photoshop and other software applications make it much easier to alter a digital photograph. (4) However, software applications cannot modify a photograph without human assistance. That individual or another must take the witness stand and testify to a judge or a jury that the altered photograph is a true and accurate representation of what he or she saw. This is referred to as the "pictorial testimony" theory. (5) As has been the case throughout history, the courts rely upon the adverse party to expose any altered evidence as that witness can be extensively cross-examined by the opposing party. (6)

Advent and Science of Digital Photography

NASA invented digital photography in the 1960s as a way of transmitting photographs from space. (7) Today, we still receive digital images from Voyager 1, 27 years after it was launched from earth. (8) However, as with many technologies used by NASA or the military, it took a considerable period of time for digital photography to filter into the mainstream, and even longer for it to make its way into the courtroom.

The first digital camera was not available to the public until 1981, when Sony manufactured and released "Mavica." (9) By the time digital photographs were introduced into evidence in a courtroom, they were well known and no longer considered new or novel pieces of evidence. No court ever subjected the process by which digital photographs are taken to either the Daubert or Frye tests. (10) The science of digital photography at that point was within the common knowledge of the courts and the populace, and, therefore, its accuracy was not questioned.

The science behind digital photography is very similar to traditional photography. Both digital photographs and traditional photographs are created using a camera equipped with a lens and a shutter. (11) The shutter acts as a barrier to light between the lens and the recording medium. (12) In both digital and traditional photography, the recording medium is exposed to light for a short period of time and memorializes the image. In both digital and traditional photography, the recording medium must be "processed" to produce a viewable picture. Most importantly, in both digital and traditional photography, that medium can be copied, enhanced, and manipulated.

In a digital camera, once the shutter opens, light pours onto a silicon chip referred to as a CCD (13) (charge-coupled device). (14) The chip is divided into millions of picture elements or pixels. (15) These pixels are arranged in rows and columns, and each pixel is assigned a particular location. (16) Each pixel records a numerical value for the light falling on it. (17) Those numerical values are then transferred, in order, to a storage device. (18) A software program then reads each of those values and assigns a dot of the appropriate color in the same location as the pixel that originally recorded it. (19) Once all of the dots are put back together in their appropriate places, the picture appears either on the screen or in whatever other medium the user wishes to produce. (20)

Most software that is capable of interpreting and displaying digital photographs is also capable of manipulating those same photographs. Pictures may be cut and cropped to make them fit a particular size frame. (21) Colors may be adjusted, as can brightness and contrast. (22) Items can be removed from the pictures or superimposed onto them. (23) If the person performing these tasks is talented enough, the altered picture will look very convincing. An excellent example of this occurred in 1994 when a New York Newsday cover depicted Nancy Kerrigan and Tonya Harding skating beside each other. (24) The cover was released several days before the event actually occurred; however, the skilled artists at New York Newsday managed to make the cover photograph look truly realistic. (25)

In traditional cameras, the recoding medium is film. Film is a thin strip of celluloid coated with a light-sensitive chemical, such as silver halide. (26) When the shutter of the camera is opened, light pours in through the lens onto the film. This, in turn, affects the chemical and creates a negative (or a positive in the case of transparency film). (27) Opponents of the admissibility of digital photography cite this process as the key difference between digital and traditional photographs. (28) These opponents propound that the traditional process creates a true original that one can always refer to in order to verify the authenticity of the photograph. (29) However, opponents fail to recognize that raw film can only be viewed in a dark room, as light will destroy it.

Traditional film must be subjected to a process commonly referred to as developing. (30) Photographs will almost always be developed before an adverse party sees them. During this developing process, photographs may be enhanced and manipulated by a skilled technician, in much the same way digital photographs may be enhanced by a computer and a skilled user. (31) At the end of the process that same skilled technician can produce a negative of his or her final product. (32) If adversaries blindly accepted that negatives are always accurate, they would be doing a disservice to their clients and the adversarial system.

Indeed, there has been no lack of altered photographs and negatives depicting the Loch Ness Monster, (33) Big Foot or UFOs, (34) created with film-based cameras. Given the well-known history of hoaxes and...