vision.py 文件源码

def fix_target_perspective(contour, bin_shape):
    """
    Fixes the perspective so it always looks as if we are viewing it head-on
    :param contour:
    :param bin_shape: numpy shape of the binary image matrix
    :return: a new version of contour with corrected perspective, a new binary image to test against,
    """
    before_warp = np.zeros(bin_shape, np.uint8)
    cv2.drawContours(before_warp, [contour], -1, 255, -1)

    try:
        corners = get_corners(contour)

        # get a perspective transformation so that the target is warped as if it was viewed head on
        shape = (400, 280)
        dest_corners = np.array([(0, 0), (shape[0], 0), (0, shape[1]), (shape[0], shape[1])], np.float32)
        warp = cv2.getPerspectiveTransform(corners, dest_corners)
        fixed_perspective = cv2.warpPerspective(before_warp, warp, shape)
        fixed_perspective = fixed_perspective.astype(np.uint8)

        if int(cv2.__version__.split('.')[0]) >= 3:
            _, contours, _ = cv2.findContours(fixed_perspective, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
        else:
            contours, _ = cv2.findContours(fixed_perspective, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
        new_contour = contours[0]

        return new_contour, fixed_perspective

    except ValueError:
        raise ValueError('Failed to detect rectangle')