数字图像显示的拼面效应

Mosaic Effects of Digital Image Display

把一幅数字图像显示出来，每一个像素值显示为具有相应灰度的面元，数字图像即显示为由面元拼成的拼面图像。在Fourier频谱空间研究了数字图像显示的拼面效应，它表现为低通滤波。研究了数字图像的离散Fourier频谱与其拼面图像的频谱分布的离散抽样间的误差，指出，减小拼面显示的填充因子和提高数字图像的抽样密度可减小拼面效应，用光学Fourier变换可以逼近数字图像的离散Fourler变换。

Since an actual pixel of a screen is a facet of definite area,a digital imageappears as a mosaic pattern when displayed on an array screen. The mosaic effects of digi-tial image display in the Fourier spectral doman are investigated,it is a kind of low-pass fil-tering. The relative error analysis between the ideal discrete Fourier transform(DFT)andthe sampling versions of mosaic digital image associated with various geometrical parame-ters of the display screen is given. It is pointed out that the mosaic effects decrease with theduty factor and a DFT of an digital image can be approximated by sampling the opticalFourier trans form versfion of the mosaic digital image with small duty factor.