Security camera pixels and CIF what do I need?
Pixel, short for Picture Element, is a single point in a graphic image. Graphics monitors display pictures by dividing the display screen into thousands or millions (MEGA) of pixels, arranged in rows and columns. The pixels are so close together they appear connected. The more pixels your have, the more resolution, or "clarity", you have in your image. HDTV/megapixel technology enables cameras to provide higher resolution of video images than analog CCTV, giving you the ability to see more detail and a wider coverage area. While the cost per camera may be more, you can see larger areas with fewer cameras. With an HDTV or megapixel camera the resolution is a minimum of three times better than an analog CCTV camera. The increased resolution allows for you to zoom into archived data and extract details such as license plates, faces, lettering, what a suspect may be holding, and much more. Yes, you can do all these things with a zoom analog PTZ camera, but what are the chances it will be aimed and zoomed into the right location at the precise moment an incident occurs.
How Many Pixels do I need?
A conventional CCTV camera providing 4 CIF resolution offers a resolution of 704x480 pixels (NTSC) after the signal is digitized in a DVR or video server, which corresponds to a maximum of 400,000 pixels. In the surveillance industry 20 to 30 pixels enough to represent one foot of a scene in most applications. For facial identification the demands are as much as 150 pixels per foot. This means to be able to Identify a person passing through a 7 feet wide by 7 feet high area the camera needs to provide a resolution of 1,050x1,050 pixels, which is slightly more than 1 megapixel. There are many other considerations that need to be taken into account including, lighting, available bandwidth, available storage and camera placement. You will also need to create a separate network for the surveillance cameras to prevent bandwidth problems.
2.1 MP cameras are an excellent choice right now for the price and for the resolution. We can install cameras that have a much higher resolution although they also eat up your DVR/NVR storage. Being able to go in and zoom in after the fact is a great feature of these megapixel cameras. We have 2.1 MP cameras starting at $322 installed with our FLIR systems and we have a 3MP Axis vandal resistant HDTV 720p 2.5mm to 12mm camera for $1,400 so the range will vary with your needs and budget.
CIF Resolution (QCIF, CIF, 2CIF, 4CIF, SIF) CIF - Common Intermediate Format - a set of standard video formats, defined by their resolution. CIF resolution is 352 x 288 pixels, also known as Full CIF (FCIF). QCIF is Quarter CIF (resolution 176x144) 2CIF is Two-times CIF (resolution 704 x 288) 4CIF is Four-times CIF (resolution 704x576) SIF has a number of name definitions e.g. Standard Input Format, Source Intermediate Format, Source Interchange Format. The resolution provided by SIF for NTSC video is 352 x 240 and for PAL it is 352 x 288 pixels.