使用 PIL, OpenCV, Matplotlib 获取图片通道数
本文最后更新于 2024年4月26日 凌晨
1. PIL
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[参考] https://pillow.readthedocs.io/en/stable/reference/Image.html#PIL.Image.Image.getbands
[参考] python - Number of channels in pil (pillow) image - Stack Overflow: https://stackoverflow.com/questions/52962969/number-of-channels-in-pil-pillow-image
2. OpenCV
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3. Matplotlib (plt)
This function exists for historical reasons. It is recommended to use
PIL.Image.open
instead for loading images.
官方推荐使用 PIL.Image.open
读取图片,故这儿也不再展示 Matplotlib 读取图片的方式
[参考] matplotlib.pyplot.imread — Matplotlib 3.5.2 documentation: https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.imread.html
4. 特殊情况(OpenCV, PIL 读取通道数结果不同)
4.1. 场景
在 palette 类型的图像中 (img.mode
为p) ,也就是索引值组成的图像时,OpenCV 和 PIL 读取的通道数结果不同。
4.2. 原因
OpenCV 会自动加载扩展,将此类型图片转化为 RGB 图像处理,所以通道数会显示为 3;PIL 保留原始读取结果,所以通道数为 1。
综上在识别图片通道数时,个人更加推荐 PIL 。
[参考] opencv - why does reading image with cv2 has different behavior from PIL? - Stack Overflow: https://stackoverflow.com/questions/61952256/why-does-reading-image-with-cv2-has-different-behavior-from-pil
[扩展] python - What is the difference between images in ‘P’ and ‘L’ mode in PIL? - Stack Overflow: https://stackoverflow.com/questions/52307290/what-is-the-difference-between-images-in-p-and-l-mode-in-pil/52307690#52307690