DCT (Discrete Cosine Transform)

A technique used in signal and image processing and particularly

in lossy compression techniques. DCT separates an image into discrete blocks of pixels of differing importance with respect to the overall image. DCT expresses a function or signal in terms of a sum of sinusoidal waveforms that vary in amplitude and frequency, essentially transforming the image from the spatial domain into the frequency domain. In the process, the average luminance of each block is evaluated using the DC coefficient. Transform compression is based on the premise that the low-frequency components of a signal are more important than the high-frequency components.Therefore, a substantial reduction in the number of bits used to represent a high-frequency component will degrade the quality of the image only slightly. JPEG and MPEG both specify DCT, as do the ITU-T H.261 and H.263 videoconferencing standards. See also amplitude, DC, frequency, H.261, H.263, ITU-T, JPEG, lossy compression, MPEG, pixel, signal, and sine wave.

• 16-QAM
• 16-QPSK
• 18
• 1:8 Splitter
• 1A
• 1A1
• 1A2
• 1Base5 (1 Mbps; Baseband; 500 meters)
• 1B+D
• 1. Domain Name System. The naming convention that divides the Internet into logical domains identified in Internet Protocol version 4 (IPv4) as a 32-bit portion of the total address.The standard convention is user@organization.domain, where user is the name of the end user, organization is the name of the enterprise or other organization owning or sponsoring the address, and domain is the type of entity owning or sponsoring the address.The administration of the DNS is the responsibility of Internet Corporation for Assigned Names and Numbers (ICANN). See also domain, ICANN, Internet, and IPv4. 2.
• 1. In storage, irrelevant material, usually zero (0) bits, added to a data block in order to fill it to a minimum size, to force certain fields of control data or user data into certain positions or sizes, or to prevent the user data from duplicating a bit pattern that has a specific control meaning. See also block. 2.
• 1 cps, 1 Hz
• 1+ Dialing
• 1G (1st Generation)
• 1G (1st Generation)
• 1-persistent carrier sense multiple access (1-Persistent CSMA)
• 1-Persistent CSMA (1-Persistent Carrier Sense Multiple Access)
• 1+ WATS
• 1xEV-DO (one carrier EVolution-Data Optimized)
• 1xRTT (one times Radio Transmission Technology)
• 2
• 20
• 2:1
• 2:1
• 2:1