Video makes the case

Chicago's approach to video enhancement helps solve crimes


     Another available option involves the use of Microsoft Film Maker (SP2), which is a robust program that can provide both video and still images from CD or DVD sources. After opening the program, users select the "Import" option under the File pull-down menu. If the file can be opened by this program, Film Maker breaks the film file into smaller sections that display on the program's viewer. The program slider allows users to move freely back and forth along the frame's timeline. The Service Pack 2 (SP2) version also has a small camera icon beneath the viewer that allows users to take still shots (JPEGs) from the video source. Again, users must follow a regular naming convention when saving the captured stills.

     Now users have a set of captured images that will probably need to be enhanced. Enhancement deals with rendering a captured image to a form that is clearer or more recognizable without changing the image itself. The task is to make the image bigger, better and brighter. To do so, users open the captured image in PhotoShop. Images may be in color or black and white. At times it may be best to eliminate noise from the image by eliminating color. This is done through use of a desaturation option under Image Adjustments. Another reason for making this change is the printer. If users are working with a black-and-white laser printer, the results of the enhancement will appear clearer if the image is already in grayscale format.

     Next users go to the Image pull down again and select "Adjustments." Although there are a variety of options, users are principally concerned with two: Brightness/Contrast and Curves. Curves presents a graphical representation of the image with an extended line. Click on the middle of the line and pull the line to the left or right -- parts of the image will darken or lighten. Clicking on the line above or below the center affects other sections of the image in the same manner. Anytime the results of the last instruction are unsatisfying, they can be undone in the Edit menu. If this has helped, users then close the graph and open the Brightness/Contrast option. Brightness/Contrast allows users to play with the lighting and shadows within the image. The results of all changes can be seen immediately within the image. The "sliders" in this option allow users to return the image to its original state by setting the point indicators to zero. Once finished, users close out of the option and save the image.

     PhotoShop allows users to save images in a variety of formats. Because image adjustments have been made, it is advisable to save it as a JPEG for a couple of reasons. First, the file takes less space on a hard drive than a number of other formats. Second, JPEGs are easy to import into other applications or e-mails.

     The saved JPEGs are used for a variety of purposes and can be arranged in a number of documents. For several reasons, the Chicago PD finds that placing images on PowerPoint slides enhances the variety of uses for captured stills. In PowerPoint use the Insert pull down to retrieve a picture from a file and place or resize the image, or combination of images, anywhere on the slide. PowerPoint also allows users to easily add and move text to the slide so the Chicago PD places case numbers, addresses, type of crime and notes related to the stills on the slide(s). The finished presentation can be e-mailed to other units who now have the ability to lift images from the slide and use it for alerts or in-house flyers. Most Chicago districts have large monitor displays in the roll-call rooms and the presentation can be displayed for officers before their tour. The main purpose of Chicago's Video Enhancement Unit is to provide the best rendition from a video image source that recorded criminal activity and provide that rendition to officers and investigators in a timely fashion.

A complete success
     While the most recent version of the process described in this article has been in place for less than a year, it has contributed to the arrest of 63 offenders and to clearing 131 cases related to subjects involved in armed robberies, burglaries, thefts and damage to property. The majority of these arrests involved felonies which transpired in front of surveillance cameras at gas stations, convenience food marts, banks, retail stores, drug stores and fast food restaurants. Many of the captured stills assisted other forensic groups who were able to review where an offender had been and what was touched prior to processing a crime scene.

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