def img_crop(img, cx=89, cy=121, w=128, h=128):
    """
    crop images based on center and width, height

    :param img: image data, numpy array, shape = [height, width, RGB]
    :param cx:  center pixel, x
    :param cy:  center pixel, y
    :param w:   width, even number
    :param h:   height, even number
    :return: img_crop
    """
    img_cropped = img[cy-h//2: cy+h//2, cx-w//2: cx+w//2]
    return img_cropped