In the grayscale change experiment of image preprocessing, the gamma change function is defined as follows:
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Def gamma_trans (img, gamma):
Gamma_list = [ np.power (x/255.0,gamma)*255.0 for x in range(256)]
Gamma_table = np.round ( np.array ( gamma_list )). astype (np.uint8)
Return cv2.LUT(img , gamma_table )
When the gamma value is 0.5, the bright part is stretched and the dark part is compressed.