For compression of digital holographic data, choosing an appropriate representation of the holographic information is always a main target. The effectiveness of the representation needs to be studied before applying further compression method for reducing storage and transmission burden. In this paper, we investigate the effectiveness of using amplitude-phase information of the complex object wave and the difference information between different phase-shifted holograms by scalar and vector quantization. The experiments show that the amplitude-phase representation is more suited when applying intra compression, whereas holograms are more suited for inter compression.