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Issue #202 May 2007
The Wittness Camera
Build a Self-Recording Surveillance Camera
Grand Prize Atmel AVR Design Contest 2006
by Alberto Ricci Bitti
Start | Solid-State Recording | Full Interaction | Complete Picture | Basic Instinct | Filled To Capacity | Speech Preparation | Circuit Implementation | Concept To Prototype | Picture Inspection |Design Evolution | Sources & PDF
PICTURE INSPECTION
You can check
the pictures at any time without turning off the camera. As soon it detects
that the case is being opened, the camera stops recording. Any pending
disk operation will likely be completed by the time you finish removing
the lid. Watch the disk semaphore (the green and red LEDs next to the
card connector), and always wait for the green light before removing the
SD card.
Now all the effort associated with using standard media, the file system, and graphic formats starts paying off. Gently insert the SD card into your computer’s card reader. The icon of a removable SD disk will be added to the system’s disk resources. You don’t need any additional software because Windows XP supports browsing JPG image folders by default. Click on the SD disk and browse to the folder that you want to analyze. My advice is to set Windows Explorer’s View mode to “Sequence” and enable the folder pane. The screen will look like what you see in Photo 4.
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| Photo 4—The pictures were taken on a test drive. I placed the camera on my car’s dashboard. You can see my windshield wiper and the reflections from the vents. |
The camera sorts the files hierarchically, grouping the folders by year, month, day, and so on. They appear orderly on the left panel. Click on any folder to view its contents in the main panel. The main panel shows the current picture in full size. By clicking the buttons below it, you can zoom in, rotate, or skip to the next or previous frame.
Thumbnails of all of the frames in the folder are aligned at the bottom of the screen, like a film roll. The horizontal scrollbar shifts the thumbnails left or right, so you can identify images. By clicking on a thumbnail, you make it the current picture. By double-clicking it, you get a full-screen view of the image via Windows Image Viewer, which allows you to print the image and make a slide show of the images in the current folder. These functions meet the needs of most users.
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