### Related Researches  
Current CGH calculation is mainly divided into three methods: point cloud method, polygon-based method and depth plane method. In this paper, we focus on the acceleration of the point-cloud method. It takes a long time to generate a hologram based on the point cloud method because it has to compute a sub-hologram from each point of the point cloud, which requires substantial computation. Many methods have been proposed to reduce computation time to move closer to real-time computation [5; 6; 7; 8]. The first is the look-up table (LUT) method [5], where fringe patterns (FPs) of all possible object points are pre-calculated and stored in a table; however, this requires a large amount of memory and cannot effectively reduce the computational complexity. On the basis of LUT, scholars have successively proposed split look-up table method [6], compressed look-up table (C-LUT) method [7] and accurate compressed look-up table method [8], but their memory usage is still very large. Wavefront-recording plane (WRP) is another method to realize fast CGH calculation. This method is divided into two steps. The first step is to record the spherical waves emitted from 3D objects on the WRP. The second step is to calculate the diffraction from WRP to CGH based on the fast Fourier transform (FFT) [9]. The calculation time is reduced because the light field is generated on the WRP rather than directly on the CGH plane. The scholars first studied the acceleration of the first step [4; 10; 11; 12; 13; 14; 15; 16]. Scholars [PERSON] et al., proposed a method of generation speed and reconstructed im-age quality enhancement of a long-depth object using double wavefront recording planes and a GPU [14], which overcomes the defect of increasing calculation time in WRP. [PERSON] et al., proposed a method to calculate holograms from line-drawn objects at layers of different depths without FFT. However, the objects are relatively simple and the reconstruction quality is limited [4]. The scholars then studied the acceleration of the second step. We utilize the diffraction theory to calculate the light field of the light in the digital data of the three-dimensional scene on the hologram plane. Although the dimension reduces from 3D object to 2D hologram plane, the calculated light field still contains the 3D information of the recorded 3D scene [17]. In general, Fresnel diffraction, Rayleigh-Sommerfeld diffraction, and Fourier transform can be used to record and reconstruct light fields. However, the high demand for reconstruction quality keeps increasing the requirement for CGH's resolution and computational complexity. Even simple 3D images require a large amount of computational time. In order to improve the speed, researchers approximate Rayleigh-Sommerfeld diffraction. A fast-Fourier-transform-based numerical integration method for the Rayleigh-Sommerfeld diffraction formula has been proposed by [PERSON] et al. [18]. Although this method improves the calculation speed to some extent, it is not suitable for the case with more sampling points, which sacrifices the image accuracy to a certain extent. In order to restore the color information, scholars have conducted a lot of research. A full-color holographic display with enhanced image quality by the iterative angular-spectrum method using a single-phase hologram was proposed by scholars [PERSON] et al., The convolution error is considered and eliminated during the iteration [19]. However, the study does not consider the computational speed comprehensively; thus, there is still a considerable distance from real-time implementation. Scholars [PERSON] et al., have proposed a method of approximating the angular spectrum diffraction formula by extending the exponential term in the diffraction convolution kernel through Taylor expansion, so as to obtain similar numerical accuracy with less bit formats (e.g., single-precision floating-point data type).