The following code adds a constant border of size 10
pixels to all four sides of your original image.
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.
If you leave border_size
values for bottom and right at 0
, you even get a symmetric border.
Other values for BORDER_TYPE
are possible, such as 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
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]
border_size = 10
border = cv2.copyMakeBorder(
im,
top=border_size,
bottom=border_size,
left=border_size,
right=border_size,
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()