Sampling and quantization采样与量化

In order to become suitable for digital processing为了便于数字处理

an image function f(x,y) must be digitized both spatially and in amplitude.图像函数必须数字化在空间和幅度上

Typically通常

a frame grabber 抓帧器

grabber采集卡 grab 抓 frame 框架

 digitizer数字化仪

Hence in order to create an image which is digital因此为了创建数字图像

we need to covert continuous data into digital form我们需要将连续数据装换成数字形式

There are two steps in which it is done:他分为俩个步骤:采集与量化

The sampling rate determines the spatial resolution of the digitized image, while the quantization level determines the number of grey levels in the digitized image.采样率确定数字化图像的空间分辨率，而量化级别确定数字化图像中的灰度级数量。

sampling rate采样率,the spatial resolution空间分辨率  spatial :of or relating to space.

A magnitude of the sampled image is expressed as a digital value in image processing.

A magnitude of the sampled image采集图像的大小

is expressed as a digital value in image processing在数字图像中表现为数字值

digit n.

digital adj.

 digitizer n.数字化仪

The transition between continuous values of the image function and its digital equivalent is called quantization.图像函数的连续值与其数字等效值之间的过渡称为量化。

 transition过度过渡

equivalent当量

The number of quantization levels should be high enough for human perception of fine shading details in the image.量化级别的数量应足够高，以使人对图像中的精细阴影细节有所了解

fine精细,细,良好,罚款,罚金,好

The occurrence of false contours is the main problem in image which has been quantized with insufficient brightness levels.在亮度不足的情况下被量化导致了虚假轮廓,成为了图像处理的主要问题

occurrence  n.发生 occur v.发生

false假,虚假,虚伪

contours n. v. 轮廓

insufficient不足不够,贪 yg:not enough; inadequate. adequate充足的

brightness亮度

In this lecture we will talk about two key stages in digital image processing.在这次课中,我们将讨论图像处理的两个关键的阶段

Sampling and quantization will be defined properly.采集和量化的完整定义

properly:correctly or satisfactorily.thoroughly; completely.

Spatial and grey-level resolutions will be introduced and examples will be provided.介绍空间的和灰度级分辨率,提供示例

resolution:分辨率

a firm decision to do or not to do something.the action of solving a problem, dispute, or contentious matter.the process of reducing or separating something into its components.the smallest interval measurable by a scientific (especially optical) instrument; the resolving power.

An introduction on implementing the shown examples in MATLAB will be also given in this lecture.本讲座还将介绍了如何用matlab来是想示例

implement 实现put (a decision, plan, agreement, etc.) into effect.a tool, utensil, or other piece of equipment, especially as used for a particular purpose.

Sampling : related to coordinates values 采样,与坐标值有关
  (Nyquist frequency)

Quantization : related to intensity values 量化与强度值有关

imread() – reading an image with different postfixes读取图像 具有不同后缀,读取具有不同后缀的图像

imresize() – resizing an image to any given size更改图像大小改至任意大小

figure – opening a new graphical window图-打开新的图像窗口

figure :图,人物

:a number, especially one that forms part of official statistics or relates to the financial performance of a company.数字，尤其是构成官方统计数据一部分或与公司财务状况相关的数字。

:a person's bodily shape, especially that of a woman and when considered to be attractive.

:represent (something) in a diagram or picture.

subplot(#of row, # of col, location) – showing different plots/images in one graphical window

子图（行数，列数，位置）–在一个图形窗口中显示不同的图/图像

imshow() – displaying an image显示图像