如何在opencv python中的图像周围添加边框 [英] how to add border around an image in opencv python

问题描述

如果我有如下图像，如何在图像周围添加边框，以使最终图像的整体高度和宽度增加，而原始图像的高度和宽度保持原样在中间.

If I have an image like below, how can I add border all around the image such that the overall height and width of the final image increases but the height and width of the original image stays as-is in the middle.

推荐答案

下面的代码向原始图像的所有四个侧面添加大小为10像素的恒定边框.

The following code adds a constant border of size 10 pixels to all four sides of your original image.

对于颜色，我假设您要使用背景的平均灰度值，该值是根据图像底部两行的平均值计算得出的.抱歉，编码有些困难，但是显示了一般的操作方法，并且可以适应您的需求.

For the colour, I have assumed that you want to use the average gray value of the background, which I have calculated from the mean value of bottom two lines of your image. Sorry, somewhat hard coded, but shows the general how-to and can be adapted to your needs.

如果将底部和右侧的bordersize值保留为0，甚至会得到对称的边框.

If you leave bordersize values for bottom and right at 0, you even get a symmetric border.

BORDER_TYPE的其他值也是可能的，例如BORDER_DEFAULT，BORDER_REPLICATE，BORDER_WRAP.

Other values for BORDER_TYPE are possible, such as BORDER_DEFAULT, BORDER_REPLICATE, BORDER_WRAP.

有关更多详细信息，请参见: http://docs .opencv.org/trunk/d3/df2/tutorial_py_basic_ops.html#gsc.tab = 0

For more details cf: http://docs.opencv.org/trunk/d3/df2/tutorial_py_basic_ops.html#gsc.tab=0

import numpy as np
import cv2

im = cv2.imread('image.jpg')
row, col = im.shape[:2]
bottom = im[row-2:row, 0:col]
mean = cv2.mean(bottom)[0]

bordersize = 10
border = cv2.copyMakeBorder(
    im,
    top=bordersize,
    bottom=bordersize,
    left=bordersize,
    right=bordersize,
    borderType=cv2.BORDER_CONSTANT,
    value=[mean, mean, mean]
)

cv2.imshow('image', im)
cv2.imshow('bottom', bottom)
cv2.imshow('border', border)
cv2.waitKey(0)
cv2.destroyAllWindows()

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