What is the difference between HD and Mega pixel Cameras?

HD is a type of megapixel camera.

All HD cameras are megapixel but not all megapixel cameras are HD.

While standard definition cameras (e.g., analog cameras and 4CIF IP cameras) have no more than 400,000 pixels, all megapixel cameras (including HD) have 1,000,000 or more pixels.

HD's Key Features Compared to Typical Megapixel

The key features of HD for video surveillance is:

• Maximum HD resolution is 2.1MP, maximum megapixel resolution is 20MP or more with 5MP cameras are common from numerous vendors
• HD video format is 1280 x 720 or 1920 x 1080 (megapixel cameras can offer many more formats)
• HD aspect ratio is 16:9 (compared to 5:4 or 4:3 in other surveillance cameras)
• HD frame rate is 30/25 (where megapixel cameras are often 3 - 15 frames)
• HDTV has quality compliance standards (where megapixel simply specifies the number of pixels)

One could consider HD a subset of megapixel. HD is defined by specific resolutions at specific frame rates with a specific aspect ratio. Any camera with a resolution of more than a million pixels is by definition a megapixel camera. The lowest resolution in the megapixel range in the security market is around 1.3 megapixels, which provides 1280 x 1024-pixel resolution (or 1.3 million pixels), and we’re already seeing security cameras with resolutions as high as 10 megapixels (3,648 x 2,752 pixels). The range of megapixel cameras continues to expand to accommodate various application requirements. For example, at my own firm Arecont Vision, we have a wide range of megapixel cameras that includes 1.3, 1080p, 2, 3, 5, 8 and 10 megapixel offerings, and we’re also planning 20 megapixel security camera solutions. HD refers to cameras with a standardized resolution of 720p or 1080p. The numbers 720 and 1080 refer to the horizontal resolution. Therefore, 720p HD camera resolution provides images that are 1280 x 720 pixels (that adds up to 921,600 pixels, which means a 720p HD camera is not technically a megapixel camera), and 1080p HD cameras provide 1920 x 1080-pixel resolution, or 2.1 megapixels. The HD video format also uses an aspect ratio of 16:9 (rather than 5:4 or 4:3), and the frame rate is standardized at 60, 50, 30 or 25 frames per second (the fps depends on your TV).

the HD standard requires progressive scan but some of the TV HD broadcasts usei. Is it a camera requirement but not a broadcast requirement

Don’t think of megapixel and HD cameras as being two separate entities. HD cameras are just a special from of megapixel cameras which conforms to certain specifications laid out by the Society of Motion Picture and Television engineers (SMPTE). The HD specifications must all be met in order for a camera to be classed as an HD camera

There are two main resolutions for the HD specification,p (×, just less than1-megapixel) andp (×,2.1-megapixel). Conventional megapixel cameras often have a number of megapixel resolutions to choose from. Image quality from HD cameras is therefore not as detailed as some other megapixel cameras

This is the biggest advantage to HD cameras over megapixel cameras. Until recently, megapixel cameras have offered very low frame rates compared to low resolution cameras, sometimes offering as low as4 frames per second compared to frames per second. This has largely been due to processing power available on IP cameras as well as network restraints