文档介绍：第八章图像压缩
Lecturer: Z. C Huang
BME CSU
Content:
1. Fundamentals
2. pression
3. pression
4. pression standards
Every day, an enormous amount of information is stored, processed, and transmitted digitally.
Definition:
pression refers to the process of reducing the amount of data required to represent a given quantity of information. The underlying basis of the reduction process is the removal of redundant data.
Application area:
pression plays a major role in many important and diverse application, including televideo-conferencing, remote sensing, document and medical imaging, facsimile transmission (FAX), and the control of remotely piloted vehicles in military, space, and hazardous waste management application, and so on.
Prepared courses: information and coding theory, communication theory, .
Model of munication system
图像信息源
图像预处理
图像信源编码
信道编码
调制
信道传输
解调
信道解码
图像信源解码
显示图像
fundamentals
Data and information: data are the means by which information is conveyed. Various amounts of data may be used to represent the same amount of information.
Data redundancy: coding redundancy, interpixel redundancy, and psychovisual redundancy.
Example: a telegraph
“你的妻子,Helen,将于明天晚上6点零5分在波士顿的Logan机
场接你”
去除冗余信息(无损)
你的妻子将于明晚6点零5分在Logan机场接你
去除不相干信息(有损)
Helen将于明晚6点在Logan接你。
结论:只要接收端不会产生误解,就可以减少承载信息的数据量。
Relative data redundancy RD:
We assume n1 and n2 denote the number of information-carrying unites in two data sets that represent the same information, Relative data redundancy (the first dataset relate to the second dataset) can be defined as:
RD = 1-1/CR
Where CR, commonly pression ratio, is
CR=n1/n2
Example:
RGB
RGB
RGB
RGB
RGB
RGB
RGB
RGB
RGB
RGB
RGB
RGB
RGB
RGB
RGB
RGB
16
RGB
从原来的16*3*8=284bits压缩为:(1+3)*8=32bits, 这样CR = , RD =
coding redundancy
Code: is a system of symbols (letters, numbers, bits, and the like) used to represent a body of information or set of events.
Code word: a sequence of code symbols assigne