New computer analyzes video information

New equipment at Flathead County Sheriff's Office can help frame suspects in a useful and legal way.

A forensic video analysis system makes sense of otherwise meaningless video surveillance camera tapes from businesses.

Detective Commander Bruce Parish and evidence technician Keith Hannon recently returned from Baltimore, where they were trained by the manufacturer on how to use the system. The equipment was purchased with a Homeland Security grant.

Understanding how it works means understanding a little about video recording. Images are captured on frames and fields. People know frames from their home video players, which can often play frame by frame when viewers want to look for subliminal messages rumored to be planted in movies. Videotape displays 30 frames per second.

Fields are a kind of semi-frame. Two images are actually captured on each frame, as vertical lines of image data are scanned on alternating lines. Video recorders only display one of the images, and the other becomes a spectral image that is never seen.

One of the things the new equipment can do is to distill those two images. A cursor becomes a magician's wand as Parish and Hannon produce the ghostly frame.

In a surveillance tape of an alleged armed robbery at an Evergreen convenience store, one of the two fields shows tape damage as if from a dirty recording video head and only a distorted image is visible. The other field presents a clear picture of the activity at the store counter.

Another facet of the equipment is separating activity on specific cameras.

Many businesses and some homes run multiplex surveillance systems, employing several cameras that feed images onto a single videotape. Watching the tape is like watching cards being shuffled - a blur of images that can be meaningless and dizzying.

The system can run the recorded frames from one camera and suddenly, a man walking down a hallway, for example, presents itself from that blur.

The equipment also allows operators to enhance the image for contrast. That could produce a license plate number on a suspect's car that otherwise would not be visible.

Flathead has one of only two such systems in the state, Hannon said. The sheriff's office will process tape for neighboring cities and other departments, Parish said.

That will be good practice, too, because the system is complex, with a steep learning curve.

"The only way to get good at it is to do it," Parish said.

Hannon said he gets 10 to 15 tapes per week to deal with. They are typically submitted by convenience stores when someone drives away without paying for gas.

Some are useless.

Detectives say they are frustrated by digital surveillance systems sold to businesses.

It's a nice selling point that a large amount of data from surveillance cameras can be recorded and compressed into a small amount of storage space. But that compression renders the images useless, Hannon said.

When images are expanded or blown up to a manageable size, the quality becomes so bad that they are unusable.

"There is no real standard for digital" equipment yet, Hannon said.

The new analysis equipment can help with some of it, but not much.

But good video systems can be a waste of money if businesses or property owners use the same tape for five years at a time or don't clean the recording heads.

The sheriff's office system is worth about $50,000, Parish said. It can be worth at least that much if it helps identify and prosecute people involved in serious crimes who might otherwise go free.

Reporter Chery Sabol may be reached at 758-4441 or by e-mail at csabol@dailyinterlake.com