Digital Video Forensics On A Shoestring

Digital video can be cleaned up on a minimal budget, but watch out for mistakes
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The timing could not be worse, digital video surveillance cameras and recorders are popping up everywhere, providing police with an unprecedented volume of video evidence.

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Sgt. Ron Gibson of the Detroit Police Department at his home video forensics station. by James Careless

But at the same time, falling tax revenues have clamped police departments in a budget crunch vise. As a result, many departments cannot afford professional-quality video forensics technology to properly handle that evidence, not to mention pay to train officers on how to use it.

Instead, money-poor police departments are trying to manage digital video evidence using available computer technology, free programs downloaded from the Internet, and whoever can be spared to run the system.

Unfortunately, the nature of digital video creates lots of opportunities for untrained analysts to make mistakes, says Grant Fredericks, a police video expert and analyst with Forensic Video Solutions in Spokane, Wash.

“All digital video is compressed to some degree,” said Fredericks, who added, that means that each frame viewed is actually a montage of digital video taken at different times and is not a single integrated image captured using uncompressed analog video. “I’ve seen a digital video of a suspect in the distance, where the legs were actually from a frame shot four seconds earlier,” he said. “The video did not accurately show what took place, but it certainly looked like it did.”

Nonetheless, trained police professionals can perform digital video forensics on a shoestring budget, but to succeed police departments must have personnel who know what they are doing, and have decent, if inexpensive, tools to work with.

GETTING BY WITH NO BUDGET

Recession? Even before Wall Street melted down, the onetime boomtown of Detroit was in serious trouble. Its 1950 population was recorded as 1.8 million, but now Motown only has about 714,000 residents.

With the decline in the auto sector and related industries, Detroit’s local government has been cash-strapped for decades. And when money is tight, everyone suffers, including the Detroit Police Department (DPD).

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Video forensics de-blurred an image revealing the subject’s face. When it comes to digital video forensics, the DPD’s budget is effectively non-existent. Fortunately, Sgt. Ron Gibson, a detective, and 34 year DPD veteran, has stepped up. Having also done television and computer repair for many years, Gibson has both the knowledge and spare IT equipment to put together a basic digital video forensics platform, and that is precisely what he has done. Using a “hodge-podge” of video forensics equipment, Gibson has provided Detroit’s DA, police and local defense attorneys with access to professionally-processed digital video with a volume of over 800 downloads a year.

“I’m using Adobe Elements as my primary nonlinear editor, installed on one PC with two monitors. I have a second PC with monitor that serves as an archive and back-up system. It has about 19 terabytes of archival space attached to it,” Gibson tells Government Video.

Of course, one of the biggest challenges of digital video forensics is collecting the video. With so many codecs and formats in use and transcoding video from its original format creating opportunities for errors to creep in, the DPD has relayed on Gibson’s talent to prevent that from occurring. To make the job easier, the department has assigned Gibson a truck for the collection of that evidence. The sergeant has equipped the vehicle with a notebook PC, a wide range of hardware interfaces, software, HD camcorder, still camera, and measuring equipment to document an incident scene.

“We just drive to the scene, fully identify the system there and we’re able to download video from any platform, often in its original format,” he says. “This ensures that we get clean, accurate file transfers; giving us the best chance when we clean up the video through refocusing, enhancement and motion stabilization.”

Once the video is ready for distribution, it is hand-delivered and signed for, so that the evidence’s integrity and chain of custody is unimpeachable. “We use LightScribe CDs or DVDs, which allow us to laser-etch the labels onto the disks,” Gibson says. “We don’t use Sharpie markers, because their ink can corrode the media.”

While the DPD’s digital video forensics system is very basic, Gibson’s dedication and professionalism has earned the department’s video evidence the trust of prosecutors, police and defense lawyers. In addition, its record in court is pretty impressive: “Cases backed by video evidence have a 98 percent conviction rate,” he said.

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Actual video evidence. A COST-EFFECTIVE OPTION

The DPD’s success in shoestring video forensics impresses Grant Fredericks, who said that department’s success is proof that a knowledgeable, trained analyst using the right software can enhance video evidence without compromising it. Fredericks specifically supports the training provided by the Law Enforcement and Emergency Services Video Association International (LEVA), and the use of software that has been designed for video forensics, particularly Ocean System’s value-priced ClearID v2.5.

“ClearID is a $995 plug-in for Adobe Photoshop,” Fredericks said. “It harnesses the most useful video forensic elements of Photoshop, putting them into a series of steps that are easy to understand and use,” he said. “The program includes 23 features that are unique to ClearID, to give you more enhancement options.”

Using ClearID combined with Adobe Photoshop, all a video analyst has to do is hit “F7” on the keyboard to access a tab menu of video enhancement tools, says Doug Perkins, Ocean Systems’ vice president of sales. Those tools allow an analyst to enhance digital images being worked on in a logical fashion, while saving the settings and creating a unique hash value for every level change saved. Once complete, the analyst can print out a log of the exact settings, so they can be reviewed by anyone using the video as evidence, he said.

In broad terms, the ClearID system first removes video artifacts, and then resizes and frame-averages the image, as well as improving focus and contrast; removing noise, and sharpening the overall image. Specific video forensics features of ClearID are:

  • • Ultimate sharpener, which normalizes the brightness in an image while increasing the contrast
  • • Pattern remover, which takes distracting background patterns out of the image enabling viewers to find features that might otherwise be hidden
  • • Color safe levels, which improves under/overexposed images
  • • Adaptive equalization, which makes fine details more visible while suppressing noise
  • • Detail sharpener, which enhances fine details without over-sharpening edges


Ocean Systems also offers dTective, a high-end video forensics product, Perkins said. However, for departments that are on a tight budget, Ocean Systems can help out too. “That’s what makes us stand apart,” he added.

In addition to ClearID, Ocean Systems also sells Omnivore, a low-cost software/USB key that allows the easy extraction of video from digital video recorders.

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THE NEED FOR TRAINING

Whatever level of digital video forensics a police department adopts, the staffers who operate those systems need to know what they are doing. “It’s not just a matter of knowing how to run the equipment, you have to know the limits imposed by digital compression on video, and that transcoding can introduce changes to the video that can distort what was originally shot,” Fredericks said. In addition, “chain of custody is also vital; digital video files can be tampered with, and that tampering can compromise people’s liberty,” he said.

The morale of this tale: Even if you are just cutting-and-pasting video files, you should get some level from training through LEVA. Not only will that training reduce the chances of mistakes, but it could help a department get more out of the software and equipment it has, even if it is a hodge-podge.

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