但是，高频子带并不是通过2-D高通滤波原始图像，而是通过原始图像与合成的低通子带相减得到的。
However, the HF subband is created by subtracting the synthesized LF subband from original image but not by 2-D high-pass filtering original image.
频率选择表面（FSS）是具有选择频率功能的一块金属周期结构，它可以被设计成低通、高通、带通、带阻滤波器。
A frequency selective surface (FSS) is a metallic periodic structure with frequency selective properties. Depending upon design, it may be low-pass, high-pass, band-pass, band-stop filter.
该电路的一个重要特征是：它在单一积木块上能同时获得低通、带通和高通滤波功能。
The important feature of the proposed si circuit is that it can simultaneously obtain lowpass, bandpass and highpass filter outputs, in a single building block.
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