但是自然界中大多数物理信号却是模拟信号，因此，将模拟信号转化成数字信号是进行信号处理和分析的首要前提。

As most physical signals in the nature are analog signals, the conversion from analog signals to digital signals has become the key step in the process of signal processing and analysis control.

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由于视觉过程本身的高度非线性，采用非线性的信号处理技术就自然成为图像领域的一种重要发展趋势。

Because vision procedure is actually nonlinear, using nonlinear techniques become one kind of important research tend in image fields.

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