Adjust contours in shape1 to fit in shape2, so we can draw contours in any image shaped from original image(shape1).

cv2_cnts_adjust.py

import numpy as np

def resize_contours(cnts, cnts_origin_shape_WxH:tuple, to_shape_WxH:tuple):
    w_resize_rate = to_shape_WxH[0] / cnts_origin_shape_WxH[0]
    h_resize_rate = to_shape_WxH[1] / cnts_origin_shape_WxH[1]
    rate = (w_resize_rate, h_resize_rate)
    for i in range(len(cnts)):
        cnt = cnts[i] * rate
        cnts[i] = np.array(cnt, dtype='int')
    return cnts

def test():
    cnts_path = '../high_speed_train/newUITestData2/.DETECTION_RESULT/K696+203_S0_P001_T235240784_ZCA1_jpg/cnts.npy'
    cnts = np.load(cnts_path)
    print(cnts.dtype)
    # print(cnts)
    print(len(cnts))
    res = resize_contours(cnts, (6600, 3300), (800, 600))
    print(res)

if __name__ == '__main__':
    test()