jpg有损压缩

import cv2
img = cv2.imread('1.jpg', 1)
# 压缩以牺牲图片质量为代价    有损压缩
cv2.imwrite('2_quality_0_jpg.jpg', img, [cv2.IMWRITE_JPEG_QUALITY, 0]) 
# 压缩比高0~100低    
cv2.imwrite('2_quality_50_jpg.jpg', img, [cv2.IMWRITE_JPEG_QUALITY, 50])  

png无损压缩

# png无损压缩，且含有透明度属性
import cv2
img = cv2.imread('1.jpg', 1)
# 压缩比高低0【质量高】-100高     
cv2.imwrite('2_quality_png_0.png', img, [cv2.IMWRITE_PNG_COMPRESSION, 0])
cv2.imwrite('2_quality_png_50.png', img, [cv2.IMWRITE_PNG_COMPRESSION, 50])

原图及四张图片的质量如下：

image.png image.png image.png image.png image.png