Computer Vision Foundations · 免费预览

采样定理

带限信号在以超过其最高频率两倍的速度采样时可被精确恢复，该不等式是严格的，而该定理的假设在自然界中从未完全成立。

1. The promise

The promise

Why exactly twice

The boundary fails

What the theorem never promised

A signal has highest frequency $w_{max} = \pi/2$ radians per unit. Which sampling frequency is the smallest safe choice, and why?

Why does the sampling theorem not literally apply to photographs of real scenes?

A signal is band-limited with $w_{max} = \pi/2$ . Write the value that $w_s$ must strictly exceed.

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