Reads an image from file path or URL, optionally resizing to given image dimensions and
    subtracting mean.
    :param img_path: path to file, or url to download
    :param image_dims: image dimensions to resize to, or None
    :param mean: mean file to subtract, or None
    :return: loaded image, in RGB format

def read_image(img_path, image_dims=None, mean=None):
    """
    Reads an image from file path or URL, optionally resizing to given image dimensions and
    subtracting mean.
    :param img_path: path to file, or url to download
    :param image_dims: image dimensions to resize to, or None
    :param mean: mean file to subtract, or None
    :return: loaded image, in RGB format
    """

    import urllib

    filename = img_path.split("/")[-1]
    if img_path.startswith('http'):
        urllib.urlretrieve(img_path, filename)
        img = cv2.imread(filename)
    else:
        img = cv2.imread(img_path)

    img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)

    if image_dims is not None:
        img = cv2.resize(img, image_dims)  # resize to image_dims to fit model
    img = np.rollaxis(img, 2) # change to (c, h, w) order
    img = img[np.newaxis, :]  # extend to (n, c, h, w)
    if mean is not None:
        mean = np.array(mean)
        if mean.shape == (3,):
            mean = mean[np.newaxis, :, np.newaxis, np.newaxis]  # extend to (n, c, 1, 1)
        img = img.astype(np.float32) - mean # subtract mean

    return img