Novel look-up table (N-LUT) method to dramatically reduce the number of pre-calculated interference patterns required for generation of digital holograms was proposed. In this method, the N-LUT contains only the fringe patterns of the object points with unity magnitudes located at each center of the depth-dependent image planes of the object. This principal fringe pattern (PFP) can be regarded as the Fresnel zone pattern (FZP) computed at each depth that has reflection symmetry in geometry. Therefore, if we have only half of the PFP, we can generate the computer generated holography (CGH) without the loss of image quality. But the memory size of LUT could be reduced by half.© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.