一维NLM滤波Python代码
时间: 2023-11-05 16:57:55 浏览: 37
以下是一维NLM滤波的Python代码:
```python
import numpy as np
from scipy import signal
def nlm_filter_1d(signal, window_size, search_window_size, h):
# Pad signal to handle edge cases
pad_size = int((window_size - 1) / 2)
padded_signal = np.pad(signal, pad_size, mode='reflect')
# Initialize output signal
output_signal = np.zeros_like(signal)
# Loop over each pixel in the signal
for i in range(len(signal)):
# Define the local window around the pixel
local_window = padded_signal[i:i+window_size]
# Define the search window around the pixel
search_start = max(0, i-int(search_window_size/2))
search_end = min(len(signal)-1, i+int(search_window_size/2))
search_window = padded_signal[search_start:search_end+1]
# Calculate the weights for each pixel in the search window
weights = np.exp(-np.sum((search_window - local_window)**2) / (h**2))
# Normalize the weights
weights /= np.sum(weights)
# Calculate the filtered value for the pixel
output_signal[i] = np.sum(search_window * weights)
return output_signal
```
其中,输入参数为:
- `signal`:待滤波的信号,为一维numpy数组。
- `window_size`:局部窗口大小,应为奇数。
- `search_window_size`:搜索窗口大小,应为奇数。
- `h`:平滑参数。
输出为滤波后的信号,也是一维numpy数组。