Security leaders are now looking at compression technology for security video in new ways. Here is a backgrounder on Pixim’s Digital Pixel System image capture and processing technology. Security Magazine readers can view acomparison at http://www.youtube.com/watch?v=ENEqg77ctAM

Pixim’s technology enables video security cameras to produce high-resolution images with natural color and superb accuracy, free of image-compromising visual noise, regardless of a scene’s lighting conditions.

And behind the visually obvious advantages lie another important benefit of Pixim’s Digital Pixel System technology: images that are more highly compressed, which can lead to dramatically lower system costs for storing and moving security video.

Digital Pixel System technology and compression

All video imaging systems use compression algorithms – mathematical formulas that affect bit rate (i.e., how much bandwidth is needed to transmit video images) and storage space (i.e., how much disk space is consumed within a digital video recorder [DVR] or network video recorder [NVR]). Examples of compression algorithms include MPEG-4 and H.264.

Compression algorithms vary in their efficiency, which can change depending on a number of factors. Two of these factors can be influenced by a camera’s video capture and imaging processing technology:

• The amount of temporal noise present in the video – because video compression algorithms “see” temporal noise as if it were motion, and more motion leads to higher bit rates and larger file sizes for compressed images.
• The amount of high-frequency content in a scene – which from a video compression standpoint means sharp edges such as the lines separating brightly lit and deeply shadowed areas, the edge of a building, or stripes or other color patters against the solid background of a shirt. Sharp transitions (i.e., high-frequency content) increase compressed bit rate as well as the size of the compressed file on a DVR or NVR.

Pixim’s Digital Pixel System technology optimizes a camera’s video output before it is received by the compression algorithm as input from a scene. Pixim’s technology reduces video scenes’ temporal noise and high-frequency content, thus boosting the efficiency of the compression algorithm and easing the processing, storage and transfer demands on the video security system.

The advantages of better compression

More efficiently compressed video images have lower bit rates and smaller file sizes – which means they are easier to move between the camera and a DVR or between servers over a network. More efficiently compressed images also are more economical to store on DVR, server or networked storage devices.

This ease of transport and storage translates directly into lower overall system costs for a video security system. Pixim’s Digital Pixel System technology can reduce video security systems’ total cost of ownership in the following ways:

• All-digital technology. In Pixim’s Digital Pixel System technology, each pixel acts like an individual, self-adjusting camera that can respond optimally to the unique lighting conditions present at that specific pixel location. From a compression standpoint, this all-digital approach means the camera, video compressor, and DVR or NVR do not have to process, transmit and store extraneous information. In addition, from a cost-of-ownership standpoint, users of video security systems do not incur the expenses associated with the extra processing, transmitting and storing of images.
• Reduced image artifacts. Image artifacts such as vertical smearing, blooming and camera blindness not only diminish image quality, but also increase an image’s bit rate and file size. Pixim’s all-digital technology automatically eliminates or vastly reduces this visual noise, and owners of video security systems spend less on manipulating, moving and storing Pixim’s more streamlined, noise-free images.
• Color consistency. Images with saturated and muddy colors require more processing to be made useful for security purposes, and they result in larger file sizes. Unlike analog cameras, which generalize pixel settings, Pixel’s Digital Pixel System technology achieves pinpoint color accuracy with each pixel. As a result, Pixim-powered cameras deliver accurate white balance and true, consistent color – not saturated highlights or muddy shadows and the extra processing costs that accompanies inconsistent color.
• Progressive capture and global electronic shutter. Video cameras take one of two broad approaches to capturing images: all at once or in pieces. Pixim’s Digital Pixel System technology enables the camera’s sensor to capture an entire scene – including every scanned line – all at once. This approach minimizes or eliminates the introduction of visual artifacts such as skew (a kind of “leaning” effect), wobble (video with a rubbery or jiggly appearance), jagged edges, smearing or high-frequency content (i.e., the sharp edges between dark and light portions of a scene). Fewer image artifacts means clearer, cleaner images with lower bit rates and smaller file sizes – leading to lower network traffic and reduced storage requirements, along with their associated cost savings.

To summarize, Pixim’s technology begins with low-noise digital pixels and uses advanced processing to enhance image quality and reduce image noise to minimal levels. The result is cleaner video that compresses better and that can significantly reduce system costs for video security camera systems.