All you need to do is slicing arrays. First supply the startY and endY coordinates, followed by the startX and endX coordinates to the slice. That’s it. Your image will be cropped!
Steps using Python and OpenCV:
1) load the image and display it on screen
# import the necessary packages
import cv2
# load the image and show it
image = cv2.imread("cardWithBorder.jpg")
cv2.imshow("original", image)
cv2.waitKey(0)
2) Get the dimensions of the image
print image.shape
3) Cropping the image
# crop the image using array slices -- it's a NumPy array
# after all!
cropped = image[70:170, 440:540]
cv2.imshow("cropped", cropped)
cv2.waitKey(0)
4) Save the cropped image to disk, only in PNG format (the original was a JPG):
cv2.imwrite("thumbnail.png", cropped)
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