def create_colorful_test_image(self):
    """This function creates an image that can be used to test vis functions.

    It makes an image composed of four colored rectangles.

    Returns:
      colorful test numpy array image.
    """
    ch255 = np.full([100, 200, 1], 255, dtype=np.uint8)
    ch128 = np.full([100, 200, 1], 128, dtype=np.uint8)
    ch0 = np.full([100, 200, 1], 0, dtype=np.uint8)
    imr = np.concatenate((ch255, ch128, ch128), axis=2)
    img = np.concatenate((ch255, ch255, ch0), axis=2)
    imb = np.concatenate((ch255, ch0, ch255), axis=2)
    imw = np.concatenate((ch128, ch128, ch128), axis=2)
    imu = np.concatenate((imr, img), axis=1)
    imd = np.concatenate((imb, imw), axis=1)
    image = np.concatenate((imu, imd), axis=0)
    return image
This function creates an image that can be used to test vis functions.

    It makes an image composed of four colored rectangles.

    Returns:
      colorful test numpy array image.
    
inference_api/src/main/object_detection/utils/visualization_utils_test.py