数字图像处理是指将图像信号转换成数字格式并利用计算机对其进行处理的过程。图像增强是数字图像处理的过程中经常采用的一种方法，它对提高图像质量起着重要的作用。本文先对图像增强的原理进行概述，然后对图像增强的方法分类并给出直方图增强、对比度增强、平滑和锐化等几种常用的增强方法的理论基础，通过Matlab实验得出的实际处理效果来对比各种算法的优缺点，讨论不同的增强算法的技术要点，并对其图像增强方法进行性能评价。-Digital image processing means converts the image signal into a digital form and processed by computer process them. Image enhancement is the process of digital image processing, a method often used, it is to improve the image quality plays an important role. This article first for an overview of the principles of image enhancement, and image enhancement methods for classification and gives the histogram enhancement, contrast enhancement, smoothing and sharpening enhancement of several commonly used methods of theoretical foundation, through Matlab experimental results of actual processing results to compare the advantages and disadvantages of various algorithms, discuss different techniques enhancement algorithm, and its performance evaluation image enhancement methods.