Can this photo be trusted? Digital photos can be enhanced to help jurors - or manipulated to mislead them. Use your digital images carefully, and know when to challenge your opponent's.

We gave them to our children as Christmas presents last year. My wife bought a new one before she took her trip to China a few months ago. Digital cameras--they're so popular you even can buy disposable ones.

Moviemakers construct digital images on theater screens when they want to depict something that didn't or couldn't happen. If a crash scene is too dangerous for Tom Cruise or even a veteran stuntman, digital images create the effect. When George Lucas wants to show how a Sith lord wields telekinetic powers in a Star Wars film, digital imagery comes to the rescue. Once the image is converted into dots or "pixels," Hollywood can work its magic.

Digital photography is also finding its way into our everyday lives. Major retailers--including Blockbuster video stores and Kroger and Piggly Wiggly supermarkets--are testing digital finger-identification payment systems in which customers place a finger on a scanner at the counter. A spokesperson for Piggly Wiggly said the company has tentative plans to implement the new system at 120 stores within the next few years.

Digital fingerprint technology is already in widespread use in the public sector. About 47 million criminal fingerprints were entered into the FBI's Integrated Automated Fingerprint Identification System and its affiliated state and local systems by 2005. (1) These are fast, computerized identification systems, and most of them rely heavily on digital image processing.

The products of the technology, digital images, are offered as evidence in a growing number of civil and criminal trials in three different situations: images that were originally captured using a digital camera, images taken with a traditional 35 mm film camera and later converted into digital ones, and images taken with a conventional camera and then digitally "enhanced."

In the past, an attorney might have been content to offer a simple enlargement of a traditional, 35 mm film photograph at trial. Enlargement is a multiplication process that merely increases the size of the photograph. Today, a lawyer is more likely to introduce a digitally enhanced photograph. Digital conversion itself is a subtractive process, and image enhancement consists of removing, inserting, or highlighting an aspect of the photograph that the technician wants to change.

For example, suppose that in a civil case, a shadow on a 35 mm photograph obscures the name of the manufacturer of an offending product. The plaintiff might offer an enhanced image, magically stripping the shadow to reveal the defendant's name. Or suppose that a critical issue is the visibility of a highway hazard. A civil defendant might offer an enhanced image of the stretch of highway to persuade the jury that the plaintiff should have perceived the danger ahead before reaching it.

In many criminal trials, the prosecutor offers an "improved," digitally enhanced image of fingerprints discovered at the crime scene. The digital image reveals incriminating points of similarity that the jury otherwise would never have seen.

To date, courts have been receptive to digital photographs in all three fact situations. However, some skeptical dissenters are critical of the forensic use of digital photography? As these experts note, the bench and bar must become more familiar with pitfalls in all three situations.

Limitations of digital photos

As impressive as it appears, digital technology has limitations and, in some respects, is inferior to traditional, film photography. To begin with, digital images often contain fewer details than film images. A negative that is shot on traditional 200-speed film can produce the equivalent of about 40 megapixels of resolution--a term that refers to the sharpness of the image. Only highly specialized, expensive digital cameras approach that now; most digital cameras available to the average consumer produce fewer than seven megapixels of resolution.

Color digital photographs are especially problematic, because they offer a much narrower range of color than traditional, chemically processed film. Digital imaging relies on "charged coupled devices" (CCDs), which have a limited color range. In the forensic setting, the omission of a detail or distortion of a color can result in a flawed analysis. For example, in a products liability case, the jury may need to see the precise discoloration at the point where a drill shaft fractured. In a homicide case in which a pathologist relies on postmortem lividity to establish time of death, the jury needs to view the true color displayed by the lower regions of the cadaver.

Digital conversion

To convert a traditional film photo into a digital image, the technology involves complex, multistep processes. Errors are possible at virtually every step. Consider the steps taken in digital conversion.

Initial scanning. The original image must first be scanned into the computer, which raises an input problem. Even the best modern scanners are not accurate enough to represent the film photographic images perfectly. Film images often must be bent to conform to the shape of a computer screen.

Also, scanners vary. In roughly 80 percent of the country, LiveScan scanners have replaced paper-based fingerprint images. Often there are two available settings on LiveScan: 500 dots per inch (dpi) and 1,000 dpi. If the operator chooses the first setting, the scanned images can omit a critical detail.

Image cleanup. Even in this early stage of the conversion process, it is not uncommon to have a computer operator "clean up" the scanned image. The operator may exercise subjective judgment in deciding to delete certain pixels. If enhancement occurs later, the image has been altered twice.

Indexing. Before the image is stored, it often must be linked (indexed) to a specific person. Some banking and manufacturing systems automate this step by using magnetic ink or bar codes. Many public-sector systems still rely on people to do the indexing, which creates the chance of human error.

Storage. The scanned, indexed image must be stored for subsequent retrieval. It might be stored on a standard hard drive, which is vulnerable to hacking. Given the potentially dire consequences of hacking, data centers should be prepared to detect errors and restore the correct information. However, even some of the largest private companies and many criminal justice data centers currently lack that capability.

Retrieval. Once stored, images can be retrieved or printed, but the printout may not be identical to the original image. Suppose, for example, that after the original image is stored, the data center purchases a new and "better" printer. Its printout may be different from the image the earlier printer would have produced. Further, there is no guarantee that the printout is more accurate than the image the earlier printer would have yielded. In fact, it may lack detail that the earlier printer would have captured.

Digital enhancement

While some changes to film images during conversion to digital format are inadvertent, images can be deliberately manipulated through enhancement.

Image enhancement technology was developed during the late 1960s and early 1970s for NASA? The weight and power limitations of spacecraft made it impractical for NASA to use state-of-the-art cameras on spacecraft, and the cameras that were used produced degraded photographs.

To solve this problem, researchers studied the degradation properties of particular types of photographic equipment when capturing certain types of images and then designed computer software to reverse foreseeable degradation. The software improved sharpness and image contrast (4) by eliminating background patterns and colors.

Before the image on a normal 35 mm photograph can be enhanced, it must be digitized? Computer software developed from NASA's degradation models manipulates the pixels in the image to filter out graininess and improve brightness and contrast. (6)

Although image enhancement technology was developed for the space program, it has been "applied in numerous areas, including medicine, physics, meteorology, resource exploration, factory automation, and robotics control." (7) For example, forensic scientists use the technology to enhance photographs of finger-and palm prints. To enhance an image, the computer uses mathematical transforms--that is, formulas that dictate the alteration. The accuracy of the enhancement depends on both the validity of these formulas and the operator's proficiency.

If the formula is 'Junk science," the enhanced image will be junk. Likewise, if the operator's "surgery" on the image is too narrow or broad, the enhanced image will be a distorted one.

Admissibility 

Original digital images. Suppose a photograph of an accident scene was produced by a digital camera. What foundation must the proponent lay to introduce the image? There are alternative theories of admissibility.

The proponent can offer the trial exhibit as the product of the scientific technology of digital photography. Since the technology is in such widespread use, the trial judge probably will be willing to judicially notice the general reliability of the technique under Federal Rule of Evidence 201 (b).

Alternatively, the proponent can rely on the foundational testimony of a sponsoring witness familiar with the object or scene depicted, citing Federal Rule 901 (b) (1). Under that rule, there is no need to call the photographer or anyone familiar with the technology. (8) As long as the witness vouches that the image is a "fair," "accurate," "true," or "good" depiction of the object or scene, the testimony satisfies the relaxed authentication test codified in Rules 901 (a) and 104(b).

Digitally converted images. Here too the proponent may treat the trial exhibit as the product of a scientific process. If a judge refuses to judicially notice the general reliability of digital photography, the proponent will have to lay a foundation establishing the scientific validity of conversion technology, as required by Daubert v. Merrell Dow Pharmaceuticals, Inc. (9) This should not be a difficult task. Daubert directs the trial judge to consider, among other things, the extent to which the technology is generally accepted. (10) Although general acceptance is not dispositive under Daubert, in practice the lower courts attach a good deal of significance to it. (11) The use of digital conversion is so widespread that the foundation is likely to pass muster.

As in the case of an original image, the proponent can shortcut the foundational requirement by relying on the sponsoring testimony of a witness familiar with the object or scene depicted in the image. As long as that witness testifies to the general accuracy of the image, the testimony will satisfy Rules 901(a) and 104(b).

Digitally enhanced images. While few, if any, foundational problems are likely to come up in the first two situations, it is altogether different when the proponent offers a digitally enhanced image at trial. In many cases, the proponent cannot rely on sponsoring testimony by a witness familiar with the object or scene. The image may be an enhanced one that no one ever saw or could have seen. Even the photographer saw an image different from the one shown in the exhibit.

In short, the proponent may have no choice but to offer the exhibit as a product of a scientific process, which could make it vulnerable to an admissibility attack. While enhancement techniques have been used successfully in several settings (such as space exploration), these uses have been validated by substantial scientific research, which was the basis for developing the software and control mechanisms used in those settings. In other situations, without the benefit of earlier research, the image processor cannot be confident that his or her manipulation of the pixels improves the accuracy of the image.

To the contrary, the enhancement might eliminate the very details that the trier of fact needs to reach a just verdict. In a products liability case, the precise shade of a discoloration could determine whether the jury holds a defendant liable for negligent manufacture. In a slip-and-fall case, the exact degree of darkness of a shadow might be decisive in the jury's conclusion about contributory negligence.

Given the importance of accurate detail, the proponent should establish the following when laying the foundation:

* The witness is an expert in digital photography.

* He or she describes image enhancement technology, including both the creation of a digital image consisting of pixels and the computer manipulation of the pixels.

* In general, both parts of the process are valid.

* There has been adequate research into the specific application of image enhancement technology involved in the case.

* The research resulted in the development of computer software for this application.

* At a given time and place, the witness received a film photograph.

* The witness followed proper procedure in digitizing the photograph.

* The witness also followed correct procedure in using computer software to enhance the film photograph.

* The witness recognizes the exhibit as the photograph that was produced when he or she used the software to enhance the film photograph. (12)

This extensive foundation should be satisfactory in any jurisdiction.

Until recently, courts have not rigorously demanded complete foundations even for enhanced images. When proponents of digitally enhanced images have made even a minimal showing that the technology is reliable, courts have been receptive to them. (13) In these cases, the courts accepted the image even though the proponent did not elaborate about the research underlying the specific adaptation of the technology. Indeed, courts have placed so much faith in enhancement technology that in several cases--both civil and criminal--judges have ordered that photographs be enhanced before trial. (14)

The key question is whether courts have been skeptical enough of the technology and demanded truly adequate foundations. Under Daubert, the proponent of scientific evidence is obliged to demonstrate that the evidence qualifies as reliable "scientific ... knowledge" within the meaning of that phrase in Federal Rule of Evidence 702. More specifically, the proponent must establish that the technique has been validated by methodologically sound research.

Even assuming that the research that NASA relies on for its adaptation of digital enhancement satisfies Daubert, no responsible scientist would leap to the conclusion that that research supports applying the enhancement technology in new, very different contexts. The attorney should forcefully insist that the proponent detail the empirical research validating the particular application of the technology in the case, including the specific software used to enhance the image. (15)

Fortunately, it appears that courts are now taking a closer look at digital enhancement of photographs. For example, in Slate v. Swinton, a 2004 Connecticut decision involving enhanced photographs of a bite mark, the proponent's expert testified generally that he was aware of computer-imaging applications, knew of their use in the odontology field, and had read papers describing their use in bite-mark analysis in particular. Nevertheless, the court ruled that the evidentiary foundation was inadequate. (16) The court stated that the proponent's foundational witness must be able to

   testify, adequately and truthfully, as to exactly
   what the jury is looking at, and the defendant
   has a right to cross-examine the witness
   concerning the evidence. Without a
   witness who can satisfactorily explain or analyze
   the data and the program, the effectiveness
   of cross-examination can be seriously
   undermined, particularly in light of
   the extent to which the evidence in the present
   case has been "created." (17)

The court recognized that there are so many potential pitfalls in the technology that courts must demand more detailed evidentiary foundations to ensure reliability.

Weight attacks on the evidence

Despite the Connecticut decision, it is risky to assume that the judge will sustain a Daubert objection even to a digitally enhanced exhibit. In many cases, the judge will admit the exhibit over objection, and an opponent will have to attack the weight of the proponent's testimony.

Suppose that during direct examination, your opponent succeeds in introducing an exhibit that you believe is inaccurate. On cross-examination, especially if you have conducted adequate discovery, it usually will be safe to force the opponent's witness to concede two things: the importance of detail to the accuracy of the image and the various mechanical steps used to produce the image.

However, it is a challenge to help the jury understand the pitfalls in generating the image. You cannot be confident that the opposing witness will be knowledgeable or candid enough to educate the jury, and it frequently will be advisable to retain your own expert. For example, your expert could establish that in producing the exhibit, the opposing expert violated several of the guidelines recommended by the Association for Information and Image Management. (18) Your expert can then explain how those violations could have distorted the original image.

To be sure, digital photo techniques are useful in the legal system. They facilitate the development and use of tools such as the FBI's fingerprint identification system. Like most computer technology, they enhance speed and efficiency. In general, digital technology is cost effective.

Yet, in an individual case, uncritical acceptance of digital images can allow unreliable evidence to reach the jury. The best insurance against a miscarriage of justice is discovery, (19) in which you will set up admissibility and weight attacks.

During discovery, learn whether the opponent contemplates offering an original digital image; a digital version of an earlier, film image; or a digital enhanced version of a film image. The image may, in fact, have been enhanced twice--once during the "cleanup" phase of the scanning process and later to generate the enhanced trial exhibit. Your method of attack largely depends on the type of image the proponent is endeavoring to introduce.

Many Hollywood directors make their living by showing what did not or could not happen, but a real-world court is a radically different venue. A direct examiner should be permitted to show the jury an image only if he or she has solid proof that that image accurately depicts something that actually happened. Don't surrender to the "dark side" of digital technology.

Notes

(1.) R. Michael McCabe & Michael D. Garris, Summary of April 2005 ANSI/NIST Fingerprint Standard Update Workshop, NISTIR 7242, U.S. Dep't of Commerce (July 2005).

(2.) Michael Cherry et al., Does the Use of Digital Techniques by Law Enforcement Authorities Create a Risk of Miscarriage of Justice?, THE CHAMPION, Nov. 2004, at 24; Edward Imwinkelried & Michael Cherry, The Myth of Fingerprints, THE CHAMPION, Sept./Oct. 2003, at 36.

(3.) GREGORY E JOSEPH, MODERN VISUAL EVIDENCE [section] 8.04[2], at 8-22 (2004).

(4.) State v. Hayden, 950 P.2d 1024, 1028 (Wash. Ct. App. 1998).

(5.) See Dolan v. State, 743 So. 2d 544, 545 (Fla. Dist. Ct. App. 1999).

(6.) See Nooner v. State, 907 S.W.2d 677, 686 (Ark. 1995).

(7.) JOSEPH, supra note 3.

(8.) EDWARD J. IMWINKELRIED, EVIDENTIARY FOUNDATIONS [section] 4.09 [1], at 128 (5th ed. 2002).

(9.) 509 U.S. 579 (1993).

(10.) Id. at 594.

(11.) See Lloyd Dixon & Brian Gill, Changes in the Standards for Admitting Expert Evidence in Federal Civil Cases Since the Daubert Decision, 8 PSYCHOL., PUB. POL'Y & L. 251,300-01 (2002).

(12.) IMWINKELRIED, supra note 8, [section] 4.09[5].

(13.) See, e.g., Nooner, 907 S.W.2d 677; Dolan, 743 So. 2d 544; Haydeen, 950 E 2d 1024; English v. State, 422 S.E.2d 924 (Ga. Ct. App. 1992).

(14.) JOSEPH, supra note 3, [section] 8.04[4], at [section] 8.26.1 n.29, citing Pyka v. Village of Orland Park, 906 F. Supp. 1196 (N.D. Ill. 1995) and State v. Newman, 1994 Minn. App. LEXIS 1246 (Minn. Ct. App. Dec. 13, 1994).

(15.) See generally D. Michael Risinger, Defining the "Task at Hand": Non-Science Forensic Science After Kumho Tire Co. v. Carmichael, 57 WASH. & LEE L. REV. 767 (2000).

(16.) 847 A.2d 921, 950-52 (Conn. 2004).

(17.) Id. at 951-52.

(18.) The standards are available for purchase at www.aiim.org (click on "Bookstore").

(19.) Cherry et al., supra note 2, at 27 (suggested list of discovery questions).

EDWARD J. IMWINKELRIED is the Edward L. Barrett Jr. Professor of Law at the University of California at Davis Law School.