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I want set alpha channel to a .jpg image and set its value to 0.5 or 50% or at 128 (0 to 1 total range or 0-255 range) and save it as .png using only opencv and numpy. I know how to do it using other libraries but we have been asked to perform the above question using only two library i.e. import cv2 and import numpy. i have added the alpha channel but i do not know how to set its value to 50% transparency, please help as I am new to opencv-python.

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