Extracting only blue from given image

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Hi Guys

I Have an input image as

I Have used the following code to brighten blue

import cv2
import numpy as np

Image = cv2.imread('blue.jpg')

Threshold = np.zeros(Image.shape, np.uint8)
cv2.threshold(Image, 121, 255, cv2.THRESH_BINARY, Threshold)
cv2.imshow("WindowName", Threshold )

cv2.waitKey(0)
cv2.destroyAllWindows()

The output of this code is

I want to extract only the blue portion of this image and eliminate the remaining ..

The output should be anything like these images

I am using python2.7 with cv2