def unpackSiftOctavePlusOne(kpt):
    """unpackSiftOctavePlusOne(kpt)->octave+1 (-1 is upsampled layer, 0 is input image layer, 1 is the first layer and so on... )
    @brief Unpack Sift Keypoint
    @param kpt: cv2.KeyPoint (of SIFT)
    """
    _octave = kpt.octave
    octave = _octave&0xFF
    if octave>=128:
        octave |= -128        
    return octave+1