Question about dataloader ?

[ThorPham]

label = cv2.imread(label_name,cv2.IMREAD_GRAYSCALE) in row 171 file reader .
I using numy to count element : unique, counts = np.unique(label) take output : array([ 0, 29, 89, 138, 154, 157], dtype=uint8). This is not relevant with id labels :
id label :
[0, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 249, 250, 255]
Can you explain for me ?
Thank you so much .