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5.Pixel operations

For pixel operations, we can change any position to a new pixel color. Here we first read the image, and then assign an area to white.

Code path：

muto/Samples/OpenCV/01_Getting_Started_with_OpenCV/04_OpenCV pixel operation.ipynb

The main code is as follows:

​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 image comparison before and after:

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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 manipulation

After the code block is executed, you can compare and see that some of the second image has turned into white pixels.