如何在opencv python中为图像添加边框
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how to add border around an image in opencv python
提问by Anthony
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.
如果我有一个像下面这样的图像，我如何在图像周围添加边框，使最终图像的整体高度和宽度增加，但原始图像的高度和宽度保持在中间。
采纳答案by tfv
The following code adds a constant border of size 10 pixels to all four sides of your original image.
以下代码向原始图像的所有四个边添加大小为 10 像素的恒定边框。
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.
对于颜色，我假设您要使用背景的平均灰度值，这是我根据图像底部两行的平均值计算的。抱歉，有点硬编码，但显示了一般操作方法，可以根据您的需要进行调整。
If you leave bordersize values for bottom and right at 0, you even get a symmetric border.
如果将底部和右侧的 bordersize 值保留为 0，您甚至会得到一个对称边框。
Other values for BORDER_TYPE are possible, such as BORDER_DEFAULT, BORDER_REPLICATE, BORDER_WRAP.
BORDER_TYPE 的其他值也是可能的，例如 BORDER_DEFAULT、BORDER_REPLICATE、BORDER_WRAP。
For more details cf: http://docs.opencv.org/trunk/d3/df2/tutorial_py_basic_ops.html#gsc.tab=0
有关更多详细信息，请参阅：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()
回答by Saransh Kejriwal
Try This:
尝试这个：
import cv2
import numpy as np
img=cv2.imread("img_src.jpg")
h,w=img.shape[0:2]
base_size=h+20,w+20,3
# make a 3 channel image for base which is slightly larger than target img
base=np.zeros(base_size,dtype=np.uint8)
cv2.rectangle(base,(0,0),(w+20,h+20),(255,255,255),30) # really thick white rectangle
base[10:h+10,10:w+10]=img # this works
回答by Ishara Madhawa
Answer in one line
一行回答
outputImage = cv2.copyMakeBorder(
inputImage,
topBorderWidth,
bottomBorderWidth,
leftBorderWidth,
rightBorderWidth,
cv2.BORDER_CONSTANT,
value=color of border
)
