Discrete Cosine Transform based Laplacian Phase Unwrapping for Phase Image application

Phase images can be disintegrated from magnetic resonance imaging (MRI) data using the arc tangent function. Since phase contains more details than magnitude image, therefore, exploits in numerous applications, including the medical field [1]. However, the raw phase image acquired has a phase value within the (-pi,pi] or in the 2 pi range. This causes an aliasing issue in reconstructing the original phase value. Hence, phase unwrapping (PU) is required to deal with the aforementioned problem. The laplacian phase unwrapping (LPU) technique is popular and easy to implement. For PU, the fast fourier transform (FFT) approach can be employed to accomplish an unwrapped solution of the phase equation in the fourier domain. However, because of the mirroring property and computational time complexity, LPU with FFT takes more computational time. On the contrary, DCT depends only on real values and its computational time complexity of order N(2)log(2)N. Therefore, it yields a more accurate phase value and takes less time. The paper proposed DCT for MRI phase image application to avoid the demerits of FFT. Experimental results demonstrate that the aliasing or wrapped effect is mitigated more effectively with DCT than with other techniques.