July 2019
Intermediate to advanced
365 pages
8h 13m
Chinese
Content preview from Python机器学习手册：从数据预处理到深度学习
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8.5
平滑处理图像
｜
133
#
以灰度图格式加载图像
image = cv2.imread("images/plane_256x256.jpg", cv2.IMREAD_GRAYSCALE)
#
选择所有的行和前
128
列
image_cropped = image[:,:128]
#
显示图像
plt.imshow(image_cropped, cmap="gray"), plt.axis("off")
plt.show()
讨论
由于
OpenCV
将图像表示为矩阵，所以选择想要保留的行和列，就可以轻松裁剪图像。
如果要保留每张图像的某个部分，这种裁剪方法会特别有用。例如，如果图像来自某个
固定的安保摄像头，我们就可以裁剪所有图像，只保留感兴趣的区域。
延伸阅读
y
《
NumPy Arrays
切片》（
http://bit.ly/2FrVNBV
）
8.5
平滑处理图像
问题描述
要对图像进行平滑处理。
134
｜
第
8
章
图像处理
解决方案
平滑处理图像就是将每个像素的值变换为其相邻像素的平均值。相邻像素和所执行的操
作在数学上被表示为一个核（如果你不知道核是什么，不用担心）。这个核的大小决定
了平滑的程度，核越大，产生的图像就越平滑。这里用一个
5
×
5
的核对每个像素周围
的值取平均值，以此来平滑处理图像 ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.