8.6 Storage of Image Data

As the volume of image data is generally large, a storage device with a large volume is needed to record the original image data, as well as the results of image processing. The volume capacity of the recording media has increased year by year, because of industrial development. Table 8.6.1 shows the characteristics of eight different media (see 6.11).

a. Magnetic tape
Magnetic tape is most widely used with general purpose computers or minicomputers. The data format is well standardized so that transportability is also guaranteed. The disadvantage is that the size of the magnetic tape, as well as the magnetic tape unit, is so big that the storage space becomes bulky.

b. Streamer Tape
Is a small sized of cartridge tape popular in personal computers (PC) or work stations (WS). The disadvantage is its low speed of data transfer rate.

c. Digital audio tape (DAT)
Because its size is smaller than the streamer, and the capacity is bigger and the price is lower, the DAT is becoming popular for PC and WS. The disadvantage is its low data transfer rate.

d. 8 mm video tape
It is cheaper in price and bigger in storage capacity than DAT. The data transfer rate is not very fast but is a little faster than streamer and DAT.

e. Optical tape
As the capacity is about 1 terabyte, the data transfer rate is more than ten times faster than DAT (faster than magnetic disk), rewriting is possible and the device is exchangeable. The optical tape is expected to be the new media for the next generation. While only a few manufacturers can produce the device and the price is very expensive, data capacity and the life of the tape make it economic for all large volume users since for less standard tape is used.

f. Magneto-optical disk (MO-DISK)
The size is compact and the capacity is also large, similar to an ordinary hard disk. Because rewriting is possible, exchange is available, the data transfer rate is much faster than tape media, and the price is lower, this media is very popular for PC and WS.

g. Write once and read many optical disk (WORM)
As rewriting is impossible, the users are decreasing. However the capacity is a little larger than a MO-DISK and the storage life is longer.

h. Floppy disk
Is the most popular storage for PC. The disadvantage is that the capacity is limited to a few M bytes and the data transfer rate is slow. The advantages are its low price and data exchangeability.


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