低通滤波器：
低通滤波器是一种用于平滑图像的频域滤波器。它衰减高频分量并保留低频分量。
高通滤波器：
高通滤波器是一种用于锐化图像的频域滤波器。它衰减低频分量并保留高频分量。
低通滤波器和高通滤波器的区别：
| Low pass filter | High pass filter |
|---|---|
| It is used for smoothing the image. | It is used for sharpening the image. |
| It attenuates the high frequency. | It attenuates the low frequency. |
| Low frequency is preserved in it. | High frequency is preserved in it. |
| It allows the frequency below cut off frequency to pass through it. | It allows the frequencies above cut off frequency to pass through it. |
| It consists of resistor that is followed by capacitor. | It consists of capacitor that is followed by a resistor. |
| It helps in removal of aliasing effect. | It helps in removal of noise. |
| G(u, v) = H(u, v) . F(u, v) | H(u, v) = 1 – H'(u, v) |