Peer Review: The Obligations of the Peer Reviewer and the Expert
Peer review is an often overlooked but important step in the finalization of an expert report. Once an expert has completed his/her expert report, especially one in which the expert has formed an opinion or conclusion, it should be given to another expert for peer review. This article will discuss the purposes of...
Case Study: Expert Witness Claims Expertise Not Actually Present
In a previous post entitled “Interpreting Video Images: The Role of the Forensic Video Analyst,” I discussed the important role that a forensic video analyst can play in providing expert interpretive evidence in court. The analyst’s job is to assist attorneys and the court in drawing informed and correct conclusions regarding the video...
Interpreting Video Images: The Role of the Forensic Video Analyst
Do you see what I see? Looking at video evidence does not mean that you will actually see all that the video has to offer. Expert interpretation of video evidence is often required in order to properly evaluate and understand the images. Relying on video evidence without expert interpretation risks the failure to...
Image Compression: Are Our Eyes Deceiving Us?
Digital compression of video images is a common occurrence. There are legitimate and laudatory reasons for such compression. Among those reasons are the fact that more data can be stored in a smaller amount of storage space, data can be easily transmitted electronically, and data can be searched more readily. However, the first...
Editing of Images: When Do You Cross the Line?
Related to concerns with authentication, one of the most pervasive suspicions regarding digital image evidence is that the images have been surreptitiously edited in such a manner as to present a false picture of what really happened. Such editing may include deletion or insertion of images, changing the order in which images appear,...
Image Clarification: Not a Bar to Admissibility
One of the most commonly litigated issues regarding digital image evidence is the propriety of and limits to image clarification. Parties who tender clarified images argue that the clarified images allow the viewer to see more detail in the images while the opposing party urges the court to rule the images inadmissible on...
Image Accuracy: Why the Correct Aspect Ratio Matters
Part of the process of authenticating a video image is to show that the image is an accurate depiction of what the camera recorded. One important technical issue bearing upon image accuracy that must be considered is aspect ratio (the height to width ratio of the image). It is not uncommon to see...
Social Media Images: Authentication Challenges
The widespread use of handheld cameras and the penchant for posting video to social media have created significant evidentiary challenges from an authentication perspective. For example, cameras mounted on motorcycles that are driven in a highly dangerous manner occasionally result in the posting of such videos to a social media site, ostensibly for...
Using Digital Signatures to Authenticate Video Images
Watermarks were discussed in an earlier post as a method of authenticating video images or showing that image alteration has occurred. Watermarks come with limitations. A more commonly used method for authenticating digital images is the use of digital signatures whereby digital signatures are generated in an authentication system and stored on a...
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...