定义
什么是计算机图形学？
计算机图形学是借助编程在计算机屏幕上绘制图像的一门艺术。
Computer graphics is an art of drawing pictures on computer screens with the help of programming.
输出将显示在屏幕上，输入通过键盘或鼠标获取
计算机图形的类型
按绘制方式划分 in respect to draw
光栅图形 Raster Graphics
在光栅图形中，像素被用于绘制图像。它也被称为位图图像。
In raster, graphics pixels are used for drawing the images. It is also known as a bitmap image.
传统的光栅图像格式有JPEG、PNG、APNG、GIF等.
矢量图形 Vector Graphics
矢量图形使用数学公式来绘制不同类型的形状、线条、对象等。
Mathematical formulas are used to draw different types of shapes, lines, objects, and so on.
矢量图像通常采用 SVG、EPS、PDF 或 AI 等图形文件格式存储.
按绘制方式划分 in respect to control
交互式图形 Interactive Graphics
用户对画面拥有一定的控制权，可以对生成的图像进行任意修改。
User have some controls over the picture, and can make any change in the produced image.
例子：电子游戏
Example: video game
被动式图形 Passive Graphics
图像会在显示器上生成，用户无法对显示的图像进行任何控制。
The picture is produced on the monitor, and the user does not have any control over the images that are displayed.
例子：电视节目
Example: TV show
计算机图形的应用领域 Application areas
- 计算机辅助设计：图纸设计、多窗口环境、实时动画
Computer-aided Design：Blueprint design, Multi-window environment, Real-time animation - 演示图形：柱状图、饼图、折线图、曲面图
Presentation Graphics: Bar charts, Pie charts, Line graphs, Surface graphs - 计算机艺术：卡通绘画、水彩画
Computer Art: Cartoon drawing、watercolor painting - 娱乐：电影、音乐视频和电视节目
Entertainment: making movie, music videos, and television - 教育与培训：教育模型，提高学生兴趣
Education and Training：Educational models can be created through which more interest - 图像处理：修改或编辑已有图片
Image Processing: modify/edit an existing pictures - 图形用户界面：按钮、对话框、图标、菜单
GUI Graphical User Interface GUI: Button, Dialog box, Icon, Menu - 可视化：展示大量信息
Visualization: visualization of large amount of information.
计算机图形系统关键组件 Crucial Components of Computer Graphics System
输入设备 Input Devices
定义
输入设备是用于向计算机提供输入的硬件设备，可以提供数据（图形、文本、声音、音频、视频和图像）和指令
An input device is the piece of computer hardware equipment used to give input to the computer, which can provide data(graphics, text, sound, audio, video, and image) and instructions.
类型分为手动数据录入设备和直接数据录入设备。
Manual data entry devices; Direct data entry devices.
手动数据录入设备 Manual data entry devices
手动输入设备由用户在处理时手工输入数据。
Manual input devices are those peripheral devices through which the user can enter the data manually (by hand) at the time of processing.
例如键盘、鼠标、触摸屏、麦克风
Exam: Key-board, mouse, touch screen, microphone
直接数据录入设备 Direct data entry devices
直接数据设备从源直接向计算机系统输入数据。
Direct data devices are those peripheral devices through which input the data is directly feed from the source to the computer system.
例如：扫描仪、条码阅读器、OCR 和传感器
Exam: Scanner, Barcode reader, OCR, Sensor.
输出设备 Output Devices
定义
输出设备是能看到输出的硬件部分，向计算机提供输入数据，处理后返回结果即输出
An output device is an hardware part where the output can be seen, which given to computer by input device in a form of input data then the input data is processed and returns the result called as output.
例如打印机和绘图仪
Exam: Printer, Plotter
打印机 Printer
打印机分为两类：击打式打印机和非击打式打印机
Impact Printers；Non-impact Printers.
击打式打印机 Impact Printers
击打式打印机中打印头、色带、墨盒和纸张之间有物理接触。
In impact printers, there is a physical contact established between the print head, ribbon, ink-cartridge, and paper.
类型包含：
- 菊花轮打印机：一次只能打印一个字符
Daisy Wheel Printers: print only one character at a time. - 鼓式打印机：有鼓形部件，表面分为多个磁道
A drum shaped component, and the surface of the drum is divided into the number of tracks - 点阵打印机：使用针作为打印头，在纸上产生点阵图案以形成字符
Dot Matrix Printer: Use print heads consisting of pins, which are used to produce a pattern of dots on the paper to create a separate character.
非击打式打印机 Non-impact Printers
非击打式打印机中打印头与纸张无物理接触，且一次打印完整页面。
In Non-impact printers, there is no physical contact between the print head and paper head, and prints a complete page at a time.
类型包含：
- 喷墨打印机（也称桌面喷墨打印机）：打印通过喷嘴头喷墨到纸上完成，用四种不同颜色（青、红、黄、黑），图形打印清晰
Inkjet Printer(Deskjet Printer): Printing is done by spraying of ink on the paper with nozzle head, using four different colors(sapphire, red, yellow, and black), cvery clearly. - 激光打印机（也称页面打印机）打印前处理并存储整页信息，产生高质量图像和文本，适合大量内容打印
Laser Printer(Page Printer): Process and store the whole page information before printing it. Produce high-quality images and text. Preferred to print a large amount of content on paper.
绘图仪 Plotter
绘图仪主要用于图形输出和复杂设计，同时用于打印矢量图形。
It is mainly used for graphical output and complex designs, and used to print vector graphics.
绘图仪分为平板绘图仪和滚筒绘图仪。
Types of Plotter: Flatbed Plotter; Drum Plotter.
平板绘图仪
Flatbed Plotte
纸张固定在平板或平面上，笔移动绘制图像
The paper is kept in a motionless/fixed position on a bed or flat surface, and the pen moves to draw the image rather than the paper moves.
滚筒绘图仪（卷筒绘图仪）
Drum Plotter(Roller plotter)
有滚筒，纸张可放在滚筒上，工作时滚筒前后移动绘制图像。
There is a drum in this plotter. We can apply the paper on the drum.When the plotter works, these drums moves backward and forward, and the image is drawn.
显示设备 Display Devices
定义
显示设备是用于以视觉形式表示信息的输出设备，通常称为视频监视器或视频显示单元（VDU）
The display device is an output device which is used to represent the information in the visual form, which called a video monitor or video display unit (VDU)
显示技术的目的是简化信息共享。
The purpose of display technology is to simplify information sharing.
显示设备包括 CRT、彩色 CRT 监视器、LCD、LED、DVST、等离子显示和 3D 显示。
Cathode-Ray Tube(CRT); Color CRT Monitor; Liquid crystal display(LCD); Light Emitting Diode(LED); Direct View Storage Tubes(DVST); Plasma Display; 3D Display.
阴极射线管 Cathode ray tube CRT
CRT 用于传统计算机显示器和电视。
It is a technology which is used in traditional computer monitor and television.
CRT在屏幕上表示一个物体有两种方式：
- 光栅扫描：电子束从上到下逐行扫描，例如电视
Raster Scan: It moves from top to bottom, covering one line at a time. For Example: Television. - 随机扫描（矢量扫描）：电子束只指向要绘制图像的区域
Random Scan (Vector scan): the electron beam/ray is directed only to the part of the screen where the picture is to be drawn.
彩色CRT Color CRT
彩色 CRT 监视器结合红、绿、蓝三种基本颜色，可产生数百万种不同颜色
The basic idea behind the color CRT monitor is to combine three basic colors- Red, Green, and Blue. By using these three colors, we can produce millions of different colors.
两种基本彩色显示技术是：
- 电子束穿透法：强电子束穿透 CRT
Beam-Penetration Method: A powerful electron beam penetrates the CRT - 荫罩法：用于光栅扫描监视器显示图像，比电子束穿透法产生更宽颜色范围
Shadow-Mask Method: It is used with a raster scan monitor for displaying pictures, which produces a much wider range of color than the beam penetration method.
液晶显示器 Liquid Crystal Display LCD
液晶显示器是平板显示技术。
A liquid-crystal display is a flat-panel display technology.
LCD屏幕使用液晶打开或关闭像素。
The LCD screen uses the liquid crystal to turn pixels on or off.
电流流动时位置改变为所需颜色。
When the current flows inside it, its position changes into the desired color.
发光二极管 Light Emitting Diode LED
LED 是半导体（硅）器件。
It is a semiconductor (silicon) device.
LED 尺寸小，可排列大量 LED 构成显示单元。
The size of the LED is small, so we can easily make any display unit by arranging a large number of LEDs.
LED 用于电视、智能手机、机动车、交通灯等。
LED is used on TV, smart phones, motor vehicles, traffic light, etc.
直视存储管 Direct View Storage Tube DVST
DVST 将图像信息以电荷分布形式存储在磷涂层屏幕后面。
DVST is used to store the picture information as a charge distribution behind the phosphorus coated screen.
DVST 优点包括耗时少、高分辨率和低成本。
Advantages: Less Time Consuming; High-Resolution; Less Cost.
等离子显示器 Plasma Display
等离子显示是使用等离子体的平板显示。
It is a type of flat panel display that uses plasma.
每个小单元或像素包含等离子体。
Each small cell/pixel contains plasma.
它通过点亮每个像素产生显示。
It lights up each pixel of the screen in order to produce a display.
3D 显示器 3D Display
3D 显示也称立体显示技术。
It is also called stereoscope display technology.
该技术能给观看者带来深度感知。
This technology is capable of bringing depth perception to the viewer.
示例包括全息显示和视网膜显示。
For Example: Holographic Display, Retina Display Etc.
接口设备 Interfacing devices
定义
向系统输入输出视频或与电视连接的接口
video input output to a system or interface to a TV