  For short-wavelength VLBI observations, it is difficult to measure the phase
of the visibility function accurately. The closure phases are reliable
measurements under this situation, though it is not sufficient to retrieve all
of the phase information. We propose a new method, Phase Retrieval from Closure
Phase (PRECL). PRECL estimates all the visibility phases only from the closure
phases. Combining PRECL with a sparse modeling method we have already proposed,
imaging process of VLBI does not rely on dirty image nor self-calibration. The
proposed method is tested numerically and the results are promising.
