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5.OpenCV pixel operations

Pixel operations allow us to change the color of any pixel at any position. Here we first read the image and then assign an area to white.

Code path:

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opencv/opencv_basic/01_Getting_Started_with_OpenCV/04_OpenCV pixel operation.ipynb

The main code is as follows:

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import cv2
​
img = cv2.imread('yahboom.jpg',1)
(b,g,r) = img[100,100]
print(b,g,r)# bgr
#10 100 --- 110 100
i=j=0
for j in range(1,500):
      img[i,j] = (255,255,255)
      for i in range(1,500):
        img[i,j] = (255,255,255)
# cv2.imshow('image',img)
# cv2.waitKey(0) #1000 ms

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#bgr8 to jpeg format
import enum
import cv2
def bgr8_to_jpeg(value, quality=75):
      return bytes(cv2.imencode('.jpg', value)[1])

JupyterLab displays the before and after image comparison:

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import ipywidgets.widgets as widgets
image_widget1 = widgets.Image(format='jpg', )
image_widget2 = widgets.Image(format='jpg', )
# create a horizontal box container to place the image widget next to 、each other
image_container = widgets.HBox([image_widget1, image_widget2])
# display the container in this cell's output
display(image_container)
img1 = cv2.imread('yahboom.jpg',1)
image_widget1.value = bgr8_to_jpeg(img1) #original
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image_widget2.value = bgr8_to_jpeg(img) #After pixel operation

After the code block is run, you can see that some of the pixels in the second image have turned into white pixels.