Megapixel Cameras

Megapixel cameras will bring great changes to the video security business. These cameras can be used in one of two ways: they can enable users to see greater details in a higher resolution image, that would be helpful in identifying people and objects, or they can be used to cover a larger field of view and lower the camera number. These two differences between the VGA and megapixel cameras are determined as follows:

The standard VGA resolution camera supplies a pixel of array of 640×480 that is about 0.3 megapixels. In facial recognition application, VGA cameras could cover a five feet field of view, but a 2 megapixel camera can cover a field of 11 feet and a 3 megapixel camera covers almost 15 feet.

Megapixel cameras use CMOS sensors which require a low operating current. In CMOS cameras, each frame is exposed from top to bottom in a rolling motion. Traditional video uses a series of odd and even lines scanning, called interlacing, to display each video frame, resulting in the blurred or jagged edges of moving objects but each frame in megapixel cameras, eliminate this effect and use progressive scanning.

High resolution cameras transmit greater amounts of data and this additional data takes longer for the camera to process and needs network bandwidth and storage space for recordings, although this can be compensated by using the H.264 video compression standard.

These cameras often deliver low quality images in low light condition, and the automatic gain control used to compensate this situation additional noise. A megapixel compatible lens should be used to ensure that images provide consistently high contrast and high resolution from the center of the lens all the way to the edge. Without using the proper lens, the advantage of the higher resolution camera will be lost in condition that most require megapixel performance.

Right now, the lower frame rates provided by megapixel cameras, but in the future megapixel cameras will offer the same frame rates we’ve expect from standard video.