Opencv learning note 3 - image smoothing / denoising

import cv2
import matplotlib.pyplot as plt
import matplotlib.image as mpimg
import numpy as np
from PIL import Image

image1 = mpimg.imread('image.png')
plt.imshow(image1);

1. Mean filtering

One 3×3 Convolution kernel , All values are 1

image2 = cv2.blur(image1, (3,3))
plt.imshow(image2)

2. Box filtering

there -1 Express , The number of input and output color channels is consistent

One 3×3 Convolution kernel , All values are 1

normalize Indicates whether the average is taken during convolution , by false Express , Sum only , exceed 255, Take... Directly 255

image3 = cv2.boxFilter(image1, -1, (3,3), normalize=False)
plt.imshow(image3);

3. Gauss filtering

Convolution kernel is not all 1 了 . But the value near the middle is larger

image4 = cv2.GaussianBlur(image1, (5,5), 1)
plt.imshow(image4)

4. median filtering

image5 = cv2.medianBlur(image1, 5)
plt.imshow(image5)