Evidentiary requirements for the admission of enhanced digital photographs.

• Author: Campbell, James M.

A PICTURE is worth a thousand words. Nowhere is this statement truer than in the courtroom. What trial lawyers have long known, and social science confirms, is that presentation of evidence through aural, written, and visual media substantially improves the jury's understanding and retention of facts presented during trial. (1) For decades, trial lawyers have recognized this axiom and used traditional film photographs to make their cases more convincing to the jury. In order to maximize the persuasive effect of visual media, a trial lawyer should consider emphasizing important aspects of his or her photographic evidence.

Although enhancement of traditional photography through dark room methods has been possible for years, these methods are expensive and require sophisticated equipment and techniques. (2) Today, with the development of digital photography, what was once a time-consuming and expensive process can be done with a digital camera that costs less than a thousand dollars and a laptop computer with readily available software such as Adobe [R] Photoshop [R].

This article discusses the issues related to the use of enhanced digital photographs at trial as well as some recommendations for preparing to have such photographs admitted into evidence. (3)

1. Digital Photographs and Enhancement

   NASA first developed digital photography in the 1960s to send photographs taken in space back to Earth. Despite its space-age beginning, the digital photographic process uses the same basic process as traditional photography. (4) As with film-based photography, a digital camera "records an image by using a lens to focus light onto a focal plane." (5) The fundamental distinction between the two technologies is that a digital camera uses a light sensitive silicon chip as the focal plane instead of film. The most common type of chip is known as a "charge-coupled device" or "CCD," which converts the light coming through the camera lens into electrical signals. (6) A camera component called an analog-to-digital converter converts these signals to digits, which are then sent to the camera's internal computer and processed into a final digital image. (7) This final image data, or digital photograph, is stored on a memory card, which can be downloaded to an external computer.

   A number of computer programs can process the data contained in the digital photograph file to change the appearance of the captured image. (8) The most common of these programs is Adobe Photoshop, which allows a user to make a wide range of changes to a digital photograph, including contrast and tone adjustment, enlargement, removal of unwanted portions of the image, and rotation of the image. (9)

   Using this or similar software, an advocate can focus a jury's attention on a particular area of a photograph, or, in some cases, "reveal" information that was not otherwise discernable. For example, these techniques may highlight important information captured in a photograph from an accident scene that can be used during the direct examination of an accident reconstruction expert. One can easily imagine the persuasive power of the enhanced photograph and the corresponding desire of the opposing party to keep such evidence from the jury. (10)

2. Daubert/Frye Requirements

   An opposing party may attempt to exclude enhanced digital photographs by challenging the reliability of the enhancement process. However, courts have found digitally enhanced photograph evidence to be sufficiently reliable to meet the requirements of both the Daubert and the more restrictive Frye tests commonly applied to scientific evidence. (11) The leading case on the issue is the Washington Supreme Court decision in State v. Hayden. (12)

   In Hayden, the defendant was charged with murder, and the key piece of evidence against him was a bloody hand print on a fitted bed sheet from the murder scene. The print expert proceeded with an elaborate chemical process in order to isolate and identify the hand print. Notwithstanding this process, "the contrast between the latent prints and the pieces of bed sheet was too subtle for [the expert] to identify the minimum of eight points of comparison required to make a positive identification." (13)

   The print expert then took the sheet to an expert in enhanced digital imaging. This enhancement expert took digital photographs of the sheet and "then utilized computer software to filter out background patterns and colors to enhance the images so that the prints could be viewed without the background patterns and colors." (14) Using these enhanced photographs, the print expert was able to find "twelve points of comparison on one of the fingerprints and more than forty on one of the palm prints" and identified the prints as that of the defendant. (15)

   At trial and on appeal, the defendant challenged the digital enhancement process on the ground that it "has not obtained general acceptance in the relevant scientific community because its use for this purpose is recent and because the computer programs used to enhance the images were not designed for forensic science." (16) After an extensive discussion of the relevant literature and judicial history of digital enhancement, the court found that digital enhancement passed the Frye test and upheld the defendant's conviction.

   Specifically, the court first found that neither digital photography nor the use of computer software to enhance such photographs is a novel process. (17) The court continued its Frye analysis by stating that no "significant dispute among qualified experts as to the validity of enhanced digital imaging performed by qualified experts using appropriate software" and holding that "the process is generally accepted in the relevant scientific community."

   In addition to the general holding, several other aspects of the Hayden decision are significant. Although Hayden is a criminal case, the forensic technique used to isolate latent fingerprints is just the type of process that one would typically use to emphasize a piece of evidence at trial. The Hayden expert used digital enhancement to "find" information that was not otherwise available. (19) In key language, the court noted that digital enhancement "is a subtractive process in which elements are removed or reduced; nothing is added." (20) The court further found that digital enhancement is "[in] contrast with 'image restoration,' a process in which things that are not there are added based upon preconceived ideas about what the end result should look like, 'image enhancement' merely makes what is there more usable." (21)

   When defending the admissibility of enhanced digital photographs, it is important to emphasize the argument that digital enhancement is a subtractive rather than an additive process. As discussed further below, subsequent decisions rely on this distinction when upholding the admission of digitally enhanced photographs. Similarly, it is important to emphasize that the photographs are enhanced rather than altered in order to assist the jury to comprehend and weigh the evidence presented.

   The court also emphasized the importance of presenting a qualified expert utilizing the appropriate software. (22) Thus, an advocate must be prepared to present testimony on the qualifications of the individual enhancing the photographs and the type of software used to perform the enhancement.

   The court also found that the digital enhancement of photographs is not a novel process and cited evidence that the process had, in fact, been used in a forensic setting at least since 1990. (23) If opposing counsel challenges the digital enhancement process, the advocate should emphasize that use of the process generally or in the courtroom is nothing new.

   Finally, the court noted that the results of the process were "visually verifiable and could be easily duplicated by another expert using his or her own digital camera and appropriate software." (24) Decisions describing authentication requirements for digitally enhanced photographs rely upon this concept of reproducibility.

3. Foundation Requirements

   Like every other piece of evidence, a party must lay a proper foundation before admitting an enhanced digital photograph. Authenticating photographs and images through "evidence sufficient to support a finding that the matter in question is what the proponent claims" generally satisfies the foundation requirement. (25) For traditional photographic evidence, trial lawyers are familiar with the requirement that a photograph be authenticated through testimony establishing that it is a fair and accurate representation of...