python - Add padding to images to get them into the same shape

Question

l have a set of images of different sizes (45,50,3), (69,34,3), (34,98,3). l want to add padding to these images as follows:

Take the max width and length of the whole images then put the image in that size

import os
import glob
import cv2

input_path="/home/images"
os.chdir(indput_path)
images=glob.glob("*.png")
Length=[]
Width=[]
for img in images:
    img=cv2.imread(img)
    width,length=img.shape[0:2]
    Length.append(length)
    Width.append(width)
W=max(Width)
L=max(Length)

How can l add padding in opencv so that all the images will have the same size? In the example l gave the images will get the shape of (69,98,3)

Answer 1

You can use:

image = cv2.copyMakeBorder(src, top, bottom, left, right, borderType)

Where src is your source image and top, bottom, left, right are the padding around the image.

You can use max(sizes) - size value of the image in a while loop to add the padding to each image. The bordertype can be one of these:

• cv2.BORDER_CONSTANT
• cv2.BORDER_REFLECT
• cv2.BORDER_REFLECT_101
• cv2.BORDER_DEFAULT
• cv2.BORDER_REPLICATE
• cv2.BORDER_WRAP

cv2.copyMakeBorder tutorial