def cropped_to_orginal(pts, length, center, resize):
    """
    Get original coordinate of pts inside a cropped image.

    Params:
    :pts: list of points inside cropped images.
    :length: we expect the original image to be a square one,
            this value is the size of the image.
    :center: center of the cropped image relative to the original one.
    :resize: resize size if the cropped image is resized.
    """
    coord_original_cropped_pts = pts / resize * length
    coord_original_cropped_pts[0] += center[0]-length/2
    coord_original_cropped_pts[1] += center[1]-length/2

    return coord_original_cropped_pts