Making the Most of Megapixel’s Marvels
Gang way, the Megapixel Revolution is upon us! No, it’s not the latest “Transformer” movie blockbuster but rather the coined phrase signifying the arrival of superior video surveillance technology. This, the first of a four-part series, has been designed to transform you into an expert on the topic.
Virtual p/t/z – Another advantage of megapixel cameras is the application of virtual p/t/z, which stems from similar capabilities to the aforementioned multicamera example. Instead of displaying three or four cameras on individual screens, the pixels within the camera sensor are actually addressed in such a way that it appears the camera is moving around a scene.
The main consideration of both the multicamera description and virtual p/t/z is the quality of the lens incorporated into the megapixel system. The characteristics of megapixel lenses will be addressed later in this article.
An additional advantage of megapixel technology is video compression and the reduction related to cable costs and the use of existing cable in system backbones.
Bandwidth is a main limitation for megapixel cameras. Due to the structure of the NTSC standard, bandwidth was restricted and, therefore, the need for IP-addressable cameras as well as video compression is an issue.
This will be further detailed in Part II of this series, but, as an example, a 3.1-megapixel camera without compression would require approximately 168MB bandwidth. IT personnel would not exactly be enamored with that type of camera being inserted onto their networks.
In summary, megapixel technology offers many improved features for the surveillance industry such as better image quality, electronic zoom and virtual p/t/z systems. Are these sufficient enough to offset the high price of equipment? It depends on the particular application, how shrewdly these advantages are deployed, and how the return on investment (ROI) and total cost of ownership (TCO) results are calculated. Sometimes, more money spent now can mean savings down the line for the end user.
It’s for sure that megapixel technology has a place in the security industry, but only time will tell the full measure of its ultimate impact.
CMOS Image Sensors Come of Age
What changes to camera technology have led to the megapixel revolution? The first and foremost advancement is the camera sensor. Through the years the sensor has gone through many stages of increased performance. The early sensors incorporated in surveillance cameras consisted of either CCD or CMOS chips.
CCD (charge coupled device) and CMOS (complementary metal oxide semiconductor) image sensors are two different technologies for capturing images digitally. Each has unique strengths and weaknesses that lend advantages in different applications.
For a long time, CCD has been the most popular choice for video surveillance use. But during the past five years much has changed with both technologies, and the current situation seems to favor the CMOS sensor.
Both types of imagers convert light into electric charge and process it into electronic signals. In a CCD sensor, every pixel’s charge is transferred through a very limited number of output nodes to be converted to voltage, buffered and sent off-chip as an analog signal. All of the pixel can be devoted to light capture, and the output’s uniformity (a key factor in image quality) is high.
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