图像增强的目标是改进图片的质量，例如增加对比度，去掉模糊和噪声，修正几何畸变等；图像复原是在假定已知模糊或噪声的模型时，试图估计原图像的一种技术。

图像增强按所用方法可分成频率域法和空间域法。前者把图像看成一种二维信号，对其进行基于二维傅里叶变换的信号增强。采用低通滤波（即只让低频信号通过）法，可去掉图中的噪声；采用高通滤波法，则可增强边缘等高频信号，使模糊的图片变得清晰。具有代表性的空间域算法有局部求平均值法和中值滤波（取局部邻域中的中间像素值）法等，它们可用于去除或减弱噪声。

-A sharp and clear image is not directly produced

from the optics, however, digital signal processing applied to the sampled image produces a sharp and clear final image that

is also insensitive to misfocus related aberrations. This paper gives an overview of Wavefront Coding and example images

related to the two applications of machine vision/label reading and biometric imaging. Design techniques of Wavefront

Coding are unique from that of traditional imaging system design since both the optics and digital processing characteristics

of the system are jointly optimized for optimum system performance.