图像处理考前复习题双语

同态滤波器 Homomorphic Filters：是一种在频域中同时将图像亮度范围进行压缩和将图像 对比度进行增强的方法。 8 什么是伪彩色图像处理？常用的伪彩色图像处理方法有哪些 伪彩色图像处理是根据特定的准则对灰度值赋以彩色的处理。 密度分割法， 灰度级－彩色转 换法，频域滤波法。 9 直方图:是灰度级的函数，描述的是图像中具有该灰度级的像素的个数：其横坐标是灰度 级，纵坐标是该灰度出现的频率（像素的个数） 。 性质:1.灰度直方图表征了图像的一维信息 2. 图像与灰度直方图之间是多对一的映射关系 3.子图直方图之和为整图的直方图 作用 1．作为图像数字化的参数 2．图像分割阈值的选择依据 3．计算综合光密度
简答题：
1 the research contents of digital image processing 数字图像处理的研究内容 答：1. Image acquisition 采集 2. Image transform 变换 3. Image enhancement 增强 4. Image Restoration 恢复 5. Image compression 压缩 6. Image Segmentation 分割 7. Image Recognition and Understanding 识别与理解 2 数字图像处理方法有哪些，有何不同？ 答：空间域处理法和变换域处理法（或称频域法） 。 空间域指图像平面自身， 这类方法是以对图像的像素直接处理为基础的。 空域处理法主要有 下面两大类：邻域处理法 点处理法 变换域法： 数字图像处理的变换域处理方法是首先对图像进行正交变换， 得到变换域系数矩 阵，然后再施行各种处理，处理后再反变换到空间域，得到处理结果。 3 数字图像处理中的基本运算有哪些及其应用？ 点运算 Point Operations：对于一幅输入图像，经过点运算将产生一幅输出图像，输出图像中 每个像素点的灰度值仅由相应输入像素点的值决定。 点运算有时又被称为对比度增强、 对比 度拉伸或灰度变换。 种类： 1、 线性点运算 Linear Point Operations 2、 非线性点运算 Nonlinear Monotonic Point Operations。应用 1、对比度增强 2、光度学标定 3、显示标定 4、轮廓线 5、 裁剪 代数运算 Algebraic Operations 是指对两幅输入图像进行点对点的加、减、乘、除计算而得 到输出图像的运算。应用：图像相加，相减，相乘，相除。 几何运算 Geometric Operations：几何运算可改变图像中各物体之间的空间关系。应用：几 何校正 Geometric Calibration 2、图像配准 Image Registration 4 空间域滤波增强技术中的图像锐化与图像平滑有何区别与联系？ 答：图象锐化是用于增强边缘，导致高频分量增强，会使图象清晰；图象平滑用于去噪，对 图象高频分量即图象边缘会有影响。都属于图象增强，改善图象效果。 5 均值滤波和中值滤波的特点 均值滤波器 ：又称邻域平均滤波器。均值滤波器的概念非常直观。它用滤波掩模确定的邻 域内像素的平均灰度值代替图像每个像素点的值。 中值滤波器：是一种非线性滤波，它将邻域内所有像素按灰度极进行排序，然后选择中间值 作为输出像素值。 6 简述频率域滤波的一般步骤。
填空题：
Digital image processing approaches fall into two broad categories: （ spatial domain processing methods） and （transform domain）processing methods. （spatial domain ）refers to the image plane itself, and approaches in this category are based on direct manipulation of pixels in an image. There are two categories:(neighborhood processing) （Point Processing） a basic digital image processing system includes （image acquisition system）, （mainframe system）, （output equipment） and （storage devices. ） The essence of digital image processing is to process is to process a （ two-dimensional matrix ）in computer. （ digital image processing ） as subjecting a numerical representation (a two-dimensional rectangular array) of an object to a series of operations in order to obtain a desired result. （digitizing ）is the process of converting an image from its original form into digital form. The digitizing process includes two basic steps: （sampling）and（quantization）. Digitizing the coordinate values is called （ sampling ） .Digitizing the amplitude values is called （quantization.） （Pixel ）is the minimum unit consisting of the image. Each pixel has independent attributes, and each pixel has two attributes at least:（ location）and （gray-level value. ) （spatial resolution） is the smallest discernible detail in an image. （Gray-level resolution） similarly refers to the smallest discernible change in gray level. The Primitive Types of Digital Images （Binary Image） （ Grayபைடு நூலகம்Level Image） （RGB Image） （Index Image） (gray-level histogram) is a function showing, for each gray level, the number of pixels in the image that have that gray level The( median )is the middle gray level value in all the gray level values The (gray level mode )is the gray level value that appears most continually. The( range of gray-level values) is the difference of the biggest gray level value and the smallest one.
a light sensor can measure the brightness of the image at each pixel through the sampling aperture. a quantizer converts the continuous output of the sensor into an integer value. the output storage medium. The gray-level values produced by the quantizer must be sorted in an appropriate format for subsequent computer processing. There are two general digitizing approaches, called (scan-in digitizing） and （scan-out digitizing） An image digitizer must have （a light sources）, （a light sensor） and （a scanning system） Image Input Devices： (Scanner) (Digital camera) Devices that record a permanent image on paper or file are called （ image recorders or hardcopy devices） The process of using a pattern of solid dots to simulate shades of gray is called （ dithering or halftoning. ） The Spatial Transformation， transformation relationships： （Translation Operation） （Magnification Operation）（Rotation Operation） Gray-Level Interpolation：（Nearest Neighbor Interpolation）（Bilinear Interpolation）（Higher Order Interpolation） Direct Gray-scale Transformations ：（ Linear Transformations ）（ Nonlinear Transformation ） （Optical Enhancements） The（ histogram modifying） is to construct transformation function, change the histogram of the image, in this way, the changed image will satisfied with the requirement. （ Histogram Equalizations ） the output image has equally many pixels at every gray level, the histogram is flat. The method used to generate a processed image that has a specified histogram is called （histogram specification or histogram matching.） According to spatial filters functions, the filters are classified into two categories: (smoothing filters)and (sharpening filters). The object of (smoothing filters) is to remove the noise in the image The object of (sharpening filters) is to enhance the detail edge in the image (Pseudocolor image processing) consists of assigning colors to gray values based on a specified criterion. (Data) are the means by which information is conveyed. (data compression) refers to the process of reducing the amount of data required to represent a given quantity of information. According to the consistency between the decoded image data and the original image data, the coding techniques are divided into(lossless compression)and(lossy compression) According to the compression theories, they are divided into (information entropy coding), (predictive coding),( transform coding), (hybrid coding) In digital image compression, three basic data redundancies can be identified and exploited: (coding redundancy),( interpixel redundancy), and (psychovisual redundancy) In an image being stored line by line, a series of pixels having the same gray-level value is (run). One can store a code specifying that value, followed by the length of the run, rather than simply storing the same value many times over. This is (run-length encoding). The (image segmentation) process is to partition a digital image into disjoint ( nonoverlapping ) regions. An (edge )is a set of pixels, each of which has an acute transition in gray level or in the gradient
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7 频率域滤波中的 5 种滤波器比较 低通滤波 Lowpass Filters： 保留低频分量， 而通过滤波器函数减弱或抑制高频分量的过程。 理想低通滤波器(ILPF) 巴特沃思低通滤波器 指数低通滤波器 梯形低通滤波器 高通滤波 Highpass filtering：保留高频分量，而通过滤波器函数减弱或抑制高频分量 带通和带阻滤波器 Bandpass and Bandstop Filters：带通滤波器允许一定频率范围内的信 号通过而阻止其他频率范围内的信号通过，带阻滤波器正好相反。
Color model:( RGB Color Model) (HSI Color Model) a sampling aperture allows the digitizer to access pixels individually while ignoring the remainder of the image. a mechanism for scanning the image. This process consists of moving the sampling aperture over the image in a predetermined pattern.