Forensic Image Comparison From Video Evidence

What is Forensic Image Comparison?

The Forensic Image Comparison investigation is the process of comparing digital images, or digital images extracted from video recordings to determine the probability of likelihood that the objects or people depicted in these images are the same or different. The Forensic Image Comparison investigation is most accurate when the images or videos are of sufficient quality, and they meet the forensic comparison criteria.

Quality

It is considered that today, the most prolific source of evidence for police is from video images. Video is not an accurate medium because digital compression removes information and adds information that wasn’t originally included. It is because of these reasons that a Video Forensic Expert MUST be able to interpret the images and video in order to present the events as they occurred naturally, as well as compare these events. Because of the unreliability of images and video presented as evidence, a Video Forensic Expert MUST also be able to qualify the events based on the quality to ensure that the objects or people presented in them has sufficient detail and pixel information to be able to perform an accurate Forensic image Comparison investigation. In some cases, when the objects or people displayed in the images and videos isn’t clear, we will perform a forensic video enhancement investigation in order to see the details of the images more clearly to make an accurate comparison.

 

Exemplar VS Evidence

Evidence: Images or videos that contain objects or people that are considered UNKNOWN

Exemplar: Images or videos that contain objects or people that are considered KNOWN

Often times when an exemplar image or video is unavailable, we can gain access to or obtain the same/similar equipment that was used to create the evidence. This ensures the highest accuracy when comparing the images or videos forensically. If creation of exhibits for courtroom use was generated using different equipment, it isn’t necessary to explain why if the details and events captured are sufficient in quality for comparison.

 

Comparison Criteria

The comparison criteria is defined by the standards presented by LEVA (Law Enforcement & Emergency Services Video Association).

Class Characteristics

A class characteristic is an identifiable feature that assists in narrowing the statistical probability that a questioned object or person belongs to the same group as a known object or person that shares the same feature. Consistent class characteristics between questioned objects and individuals can only suggest similarities and cannot, by themselves, be used to infer a positive identification.

Unique Characteristics

A unique characteristic is an identifiable feature found on the questioned object or person that is found on no other object or person of similar class. A unique characteristic can be used to significantly narrow the probability that a known object or person is in fact the same questioned object or person. A thorough examination of class characteristics and unique characteristics contrasted and compared between questioned and known objects or persons may allow an experienced and properly qualified analyst to form an opinion, if it is safe to do so, that the objects are one in the same, eliminating all others of the same class.

 

Report, Peer Review & Testimony

It is our duty to the trier of fact to present observations in a simple unbiased fashion pertaining to the comparison of a known and unknown image or video. When we generate our reports about the Forensic Image Comparison Investigation, we ensure that the foundation science we generate our opinions from is bulletproof. In other words, we do not generate opinions about the likelihood of objects or people based on a hunch, a detail that could be open to multiple interpretations or digital compression artifacts. In addition, it is also acceptable to work with and consult other experts (vehicle experts) that are qualified to answer questions that we aren’t qualified to. In other words, it can strengthen an investigation to involve another expert that has more experience and qualifications to make specific determinations about our findings once we have completed the image comparison process. This strengthens our reports as well as our testimony. All forensic image comparison investigations we perform are also peer reviewed internally or externally to ensure that the methods & protocols used to generate our opinions are accurate in accordance with the scientific community.

 

 

If you have an image or video that you question or need help understanding, please give me a call for a pro bono conversation. I apply my forensic expertise to cases in the United States and many countries around the globe. Any and all formats of audio and video accepted. Retainer agreement available on request; travel expenses will be quoted in advance excluding meal expenses and flat rate time for travel instead of hourly.

Click HERE to email your questions or

Call 800-647-4281 in the USA or +01-248-853-4091 Internationally.

Michael Primeau’s Curriculum Vitae has several references which include cases he has testified in as well as clients he has worked for in these cases.

 

 

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