Video Security Systems – Megapixel and HD

The video security industry has come a long way in recent years. We have graduated from tube cameras and VCRs to network cameras and digital recorders. This technology upgrade has given us higher performance capabilities and improved image quality.

One of the advantages gained in recent years is megapixel image capability. Images are made up of dots called pixels (picture elements). The more pixels an image has, the higher the image resolution and quality. Analog video has a typical maximum resolution of 640 x 480 pixels, commonly called VGA resolution. VGA resolution gives images with 307,200 pixels.

Megapixel means one million pixels. Megapixel images have one million or more pixels. A baseline megapixel image has four times the number of pixels as an analog image. With multiple megapixel images, the difference becomes even more significant.

The difference between VGA and megapixel resolution becomes apparent when recorded images are enlarged. Due to the higher number of pixels in a megapixel image, the image itself can be enlarged by more factors than a VGA image and still produce a usable image. The higher the megapixel of the image, the further the image can be enlarged and still produce usable results.

The unfortunate aspect of megapixel cameras is the lack of industry standards. There are no universally adopted industry standards for camera performance, so two cameras with identification megapixels can produce different image results under the exact same conditions. A careful reading of the specification sheet for the camera and understanding of how measurements were taken is required to do a fair comparison.

The introduction of HD (high definition) video products provided a performance standard to the video security industry. HD provides megapixel performance to a set of standards set forth by the SMPTE (Society of Motion Picture and Television Engineers). The HD video standards of the SMPTE call for performance standards that include 16:9 aspect ratio (widescreen), 30 images per second of video, and color quality and performance standards.

HD video performance is expressed in lines of vertical resolution and the scan method (with P – progressive being more common) or by an identifying title. The most common standards currently used:

Comparing HD to Megapixel

Want to learn more about video security systems? Check out our online, self-paced training (Training Department): Security section, or the NTC Yellow Book: Video Security System Handbook.