低通滤镜主要作用是消除摩尔纹，这是差拍原理的一种表现。

低通滤镜主要作用是消除摩尔纹,这是差拍原理的一种表现。

从数学上讲，两个频率接近的等幅正弦波叠加，合成信号的幅度将按照两个频率之差变化。 差拍原理广泛应用到广播电视和通信中，用来变频、调制等。

摩尔纹的消除最简单的方法就是使数字相机的解像力小于感光对象的空间频率，使其成为『灰阶』化即可。

An anti-aliasing filter is a filter used before a signal sampler, to restrict the bandwidth of a signal to approximately satisfy the sampling theorem. Since the theorem states that unambiguous interpretation of the signal from its samples is possible when the power of frequencies above the Nyquist frequency is zero, a real anti-aliasing filter can generally not completely satisfy the theorem. A realizable anti-aliasing filter will typically permit some aliasing to occur; the amount of aliasing that does occur depends on how good the filter is and what the frequency content of the input signal is.

Anti-aliasing filters are commonly used at the input of digital signal processing systems, for example in sound digitization systems; similar filters are used as reconstruction filters at the output of such systems, for example in music players. In the later case, the filter is to prevent aliasing in the conversion of samples back to a continuous signal, where again perfect stop-band rejection would be required to guarantee zero aliasing.

英文翻译：

抗混叠滤波器是一个筛选器之前信号采样器，用于限制信号近似地满足采样定理的带宽。因为定理指出从其样本信号的明确的解释是可能的当频率高于奈奎斯特频率的功率为零，真正抗混叠滤波器通常不完全满足定理。可实现的抗混叠滤波器通常会允许出现；一些别名确实发生的混叠的量取决于如何好的筛选器和输入信号的频率内容是什么。

抗混叠滤波器都常用的在输入的数字信号处理系统，例如在声音的数字化系统；类似的过滤器被用作重建滤波器在这样的系统，例如在音乐播放器的输出。在以后的案例中，筛选器是防止混叠中样品的转换回一个连续信号，再一次完美的止带抑制在哪里需要保证零混叠。