Storage and Transmission

Storage and Transmission

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Images can be stored and transmitted in either analog or digital formats. Traditional analog cameras transmit images via coaxial cables and store the images on tape. This works well in many cases, but image quality can degrade over long cable runs, and the resolution of tapes is generally low; moreover, the quality of recorded images tends to deteriorate with continuous use. Digital images do not lose quality during transmission and storage.

The size of digital images is measured in kilobytes (KB). Digital images are stored on hard drives, which are measured in gigabytes (GB). Typically, a hard drive can store millions of bytes of images, and when the hard drive is full, the computer will automatically delete old images to make space for new ones. There is no need to repeatedly change tapes.

• 1 kB (kilo Bytes) ~ 1,000 Bytes
• 1 MB (mega Bytes) ~ 1,000,000 Bytes
• 1 GB (giga Bytes) ~ 1,000,000,000 Bytes

Calculation Example

A 50 GB hard drive can store images for 3 weeks, with one image captured every second. Each image has a higher quality than those stored on VHS tapes.

• Typical size of high-resolution images? 25KB
• Assumed hard drive size? 50GB
• 50,000,000,000 Bytes / 25,000 Bytes = 2,000,000
• 2,000,000 / 60 sec. / 60 min. / 24 h = 23.15 days

A 50GB hard drive can store 2 million static images. Storing the same number of images would require 10 VHS tapes (E120).

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