Image enhancement - License plate / tag capture
We provide license plate / tag capture services for law enforcement, government agencies, attorneys and private citizens worldwide. Our cutting edge software and proven methodology has made Authentic Forensics a leader in license plate recovery.
Tag capture methodology
Recovery of a vehicles licence plate begins with an analysis of the video which recorded the tag and it structure. Once the files details are known the forensic video expert can formulate the best procedures to clarify the video, extract the pertinent frames and reveal the tag. Listed below are of some of the data the video forensic analysis compiles when working on a license plate capture case file.
- Frame resolution
- Frame fields / interlacing
- Codec - lossy / lossless
- Data bit depth
- Compression algorithm
Cutting through the noise to capture license plates.
Frame averaging example on a stationary vehicle.
Frame averaging is a mathematical process to improve the signal to noise ratio of an image by combining and then averaging the data from multiple frames. The forensic video expert will often use this technique to reveal details such as the license plate of a vehicle.
In the sample below Authentic Forensics was engaged to capture the tag from a vehicle of interest in a car bombing investigation. The video was cropped and the resolution was up-scaled. Due to the lighting conditions at the time of the recording, there was a large amount of noise present in the video which was obscuring the tag. To attenuate the noise the forensic video expert determined a frame averaging procedure would be required. The video was segmented into individual frames and the levels were carefully adjusted in each frame one by one . A frame stack was then applied to a series of selected frames and the data from the frames was then averaged together. This vastly improved the signal to noise ratio and the vehicles license plate was revealed. Interestingly this video's technical specifications was unique and required an innovative solution. A program used by NASA to clarify deep-sky images was utilized for the frame averaging process.
Note: The tag as been partially redacted since this is an active investigation. Click on the image to learn more about the car bombing incident.
Frame averaging example on a moving vehicle.
A digital video is a time-varying sequence of digital images or frames that are displayed in succession. The frame averaging process is fairly straightforward on stationary vehicles but what if the vehicle is moving.
In the sample shown above a series of frames from the video was extracted and the levels adjusted in each frame as before. The extracted frames were then precisely aligned so the tag was in the same location in each frame. Note: You can see artifacts that appear as double exposures due to the frame aligning step prior to applying the frame averaging algorithm.
Choosing the right tool is key to capturing license plates.
Our cutting edge software is used by government agencies and law enforcement personnel worldwide. We are the number one source for vehicle license plate recovery services.