Using Watermarks to Authenticate Video Images
Another method of authenticating video images is to show scientifically that an image has not been altered or conversely that alteration has occurred. One such method has been the use of watermarking which modifies the digital video content by the superimposition of a watermark. As Erik Berg noted:[i] Digital watermarks are generally used...
Authentication and the Use of Audit Trails
In order for video evidence to be admitted at trial, the tendering party must prove that the images are authentic. There are a number of technical approaches that are available to assist with video authentication. This post will address the use of audit trails as part of the process of establishing authentication. Proper...
Authenticating Monitor Photographs
The proper method of presenting surveillance video evidence at trial is to show all relevant authenticated images that have been exported from the DVR or server. Occasionally, the only evidence of the original video that exists is photographs taken of the video monitor at the surveillance location. This less than ideal situation can...
Date and Time Stamp Accuracy
Date and time stamps are superimposed on video images for the laudatory purpose of indicating the time the events depicted actually occurred. In reality, date and time stamps are often inaccurate. Inaccuracy occurs for a variety of reasons including failure to account for Daylight Savings Time, failure to account for the correct time...
Evidence Required to Authenticate Surveillance Video: Part 1
Most serious cases have surveillance video evidence that may prove to be valuable. When I have such a case, my first task is to ascertain how I will authenticate the video. From experience, I know that I need evidence that covers three key areas: CCTV System: Details of the CCTV system that recorded...
Evidence Required to Authenticate Surveillance Video: Part 2
In an earlier post, I set out the evidence that was required in order to properly authenticate surveillance video, namely evidence about the system that captured the images, exporting and post-exporting processing of the images. Depending on the case, this may require as many as three witnesses or as few as one. Below...
Computer Generated Evidence: What Must the Expert Know?
In many areas of scientific expertise, computers are used to generate what will often be used as evidence in court. Examples include video image clarifications, 2D and 3D modelling, collision simulations, crime scene diagrams, etc. A common tactic used in court is for opposing counsel to grill the expert on his/her knowledge of...
Video Evidence
The admissibility of video evidence at trial is contingent upon the tendering party establishing the authenticity of the video. Authentication is the process of proving that the video images are in fact that which is purported. It must be established that the video accurately depicts what is shown and that no material changes...