plt.imshow() display the image inside another image-CodePudding

I am new to Python and I apologize if this is very basic. I am doing image processing but when I read a png image using cv2 and then display the image using plt.imshow() it gives me strange images(Image with extra boundries). I did the following.

import cv2
import numpy as np

img1 = cv2.imread('img.png',cv2.IMREAD_GRAYSCALE)
plt.figure(figsize=(10,4))
plt.imshow(img1, 'gray')
plt.title("ORIGINAL")
plt.savefig("original.png")

  
kernel = np.ones((4,4),np.uint8)
opening = cv2.morphologyEx(img1, cv2.MORPH_OPEN, kernel)
plt.figure(figsize=(10,4))
plt.imshow(opening, 'gray')
plt.title("OPENING OF ORIGINAL")
plt.savefig("opening of original.png")

I am attaching the resulting images here.

[the original image]

[After displaying the image through plt.imshow().]

[after doing opening image processing technique]

CodePudding user response：

Is the extra part you're talking about a red area？

Output Images:

Of course, if you don't need to use matplotlib you can simply use the cv2.imwrite() to write the images (and cv2.show() to show the images):

import cv2
import numpy as np

img1 = cv2.imread('matches.png', cv2.IMREAD_GRAYSCALE) 
kernel = np.ones((4,4),np.uint8)
opening = cv2.morphologyEx(img1, cv2.MORPH_OPEN, kernel)

cv2.imwrite("original.png", img1)
cv2.imwrite("opening of original.png", opening)