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5. OpenCV Pixel Operation

Pixel operation allows us to change any position to a new pixel color. Here we first read the image, then assign a region to white.

Code path:

~/dofbot_opencv/scripts/1.OpenCV_basic/04_pixel_pic.ipynb

Main code:

​x
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 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 eachother
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
​
image_widget2.value =   bgr8_to_jpeg(img)   # after pixel operation

After the code block runs, you can see that part of the second image has turned white pixels.