Digital Images as Evidence

Karl Harris

Computer Science 99

Dartmouth College

February 29, 2000

Introduction• Digital Image Enhancement is a process in which

a digital image is enhanced so that more detail can be seen

• This process has many applications– Entertainment such as movies and art

– Law Enforcement

• It is such a new technology that the legal system is struggling with how digitally enhanced images can be used as evidence

Topics of Discussion• The Reginald Denny beating and trial

• Cognitech, Inc.,and the future of digital image enhancement

• Ethical and legal ramifications of this technology

The Reginald Denny Case• On April 29, 1992, trucker Reginald Denny is

severely beaten as he leaves his truck to help other victims during the LA Riots

• Damian Williams and Henry Watson are charged with attempted murder

• Because there are no clear photos and few witnesses, digital image enhancement is used by Cognitech to identify Williams as an assailant in the trial.

The Sequence of Events• Sept. 11, 1993

– An enhanced image showing a cheek blemish and a stain on a T-shirt links Williams with a liquor store robbery and the beating

• Sept. 15, 1993– Cognitech enhances an image taken from a helicopter

showing the beating. It shows a tattoo of a rose on William’s arm.

– The jurors are allowed to see enlarged photos of the beating, but not the enhanced images

The Sequence of Events• Sept. 16, 1993

– Judge Ouderkirk rules that Cognitech’s process to enhance the video is reliable enough to be used as evidence

– Leonid Rudin, director of Cognitech, testifies that there is definitely something on the man in the photo’s arm and that it is consistent with Williams’ tattoo

– When asked if he knew if the spot was grease, dirt, or a tattoo, he answers that he does not

Cognitech and the Future• After the Denny Case, Cognitech’s top

executives believed there could be a multi-billion dollar business in image enhancement for law enforcement

• There are many applications– Video surveillance in convenience stores, parking

garages, and ATM machines – Insurance claims– Acquittals

What is the Law?• An “original” of a writing or recording is the

writing or recording itself or any counterpart intended to have the same effect by a person executing or issuing it. An “original” of a photograph includes the negative or any print therefrom. If data are stored in a computer or similar device, any printout or other output readable by sight, shown to reflect the data accurately, is an “original” - Federal Rules of Evidence

Ethical and Legal Implications

• “Digitex” - digital, editing, and special effects used to manipulate images

• With digitex, even experts will be unable to determine if images have been altered

• Judges - exclude all photographic evidence?

• New ethical situations:– Wrongful convictions or acquittals due to mistakes in

the image enhancement– To what extreme do we go?

What can be done?

• Keep the source media intact showing the original directory with dates, files, sizes, and names generated by the camera

• Find better ways of analyzing digital images to detect tampering

• Make better and newer laws. Without a clear legal precedence the is no framework to start from.

Summary

• The Reginald Denny case brings into question the use of digitally enhanced images as evidence in court

• The Federal Rules of Evidence say a digital image, enhanced or not, is just as good as a photograph from film

• There are many dangers associated with admitting digital images as evidence in a trial