tailieunhanh - Image and Videl Comoression P1

Image and video data compression* refers to a process in which the amount of data used to represent image and video is reduced to meet a bit rate requirement (below or at most equal to the maximum available bit rate), while the quality of the reconstructed image or video satisfies a requirement for a certain application and the complexity of computation involved is affordable for the application. The block diagram in Figure shows the functionality of image and video data compression in visual transmission and storage. Image and video data compression has been found to be necessary in these. | Section I Fundamentals 2000 by CRC Press LLC 1 Introduction Image and video data compression refers to a process in which the amount of data used to represent image and video is reduced to meet a bit rate requirement below or at most equal to the maximum available bit rate while the quality of the reconstructed image or video satisfies a requirement for a certain application and the complexity of computation involved is affordable for the application. The block diagram in Figure shows the functionality of image and video data compression in visual transmission and storage. Image and video data compression has been found to be necessary in these important applications because the huge amount of data involved in these and other applications usually greatly exceeds the capability of today s hardware despite rapid advancements in the semiconductor computer and other related industries. It is noted that information and data are two closely related yet different concepts. Data represent information and the quantity of data can be measured. In the context of digital image and video data are usually measured by the number of binary units bits . Information is defined as knowledge facts and news according to the Cambridge International Dictionary of English. That is while data are the representations of knowledge facts and news information is the knowledge facts and news. Information however may also be quantitatively measured. The bit rate also known as the coding rate is an important parameter in image and video compression and is often expressed in a unit of bits per second which is suitable in visual communication. In fact an example in Section concerning videophony a case of visual transmission uses the bit rate in terms of bits per second bits sec or simply bps . In the application of image storage the bit rate is usually expressed in a unit of bits per pixel bpp . The term pixel is an abbreviation for picture element and is sometimes referred to as pel. In .