基于改进WRP的计算全息图快速生成

Fast CGH computation with improved WRP technology

为了提高计算全息图的计算效率,对波前记录面WRP算法进行改进,以减少计算全息时间。该方法主要涉及2方面:一是引入S-LUT大幅提高WRP面物光波复振幅记录效率,通过改变查找表(竖直调制因子)内容为存储物点每列对全息面每行像素的贡献,进一步减少全息图在线计算次数,同时因WRP较全息面距离物体近,能节省查找表存储空间;二是建立GPU-CPU协同处理框架,提高算法整体运行效率,并对基于新查找表内容的全息图在线计算过程进行CUDA并行加速。针对测试物体1和物体2的计算全息图生成实验结果表明,GPU-CPU协同下的改进算法计算效率大幅提升,相对于原算法全息图计算加速比分别达775倍和1700倍,当物体层数小于50时,改进算法在线生成全息图时间少于0.1s,基本达到实时显示要求。

Traditional WRP technology is modified and redesigned to generate Computer-Generate-Hologram(CGH)with higher computation efficiency and less time consumption without reconstruction image degradation.Two main aspects are involved in proposed method:a)The S-LUT strategy is introduced to improve the efficiency of recording the complex amplitude in WRP.In this step,the content of original vertical modulation factor lookup table in S-LUT is changed to record the contribution of space points at same Y coordinate to every row pixels of the holographic plane so as to further reduce the number of online CGH computation.Meanwhile,storage space of S-LUT is greatly reduced for the reason that the WRP is closer to the object than holographic plane does.b)The GPU-CPU collaborative framework is established to improve the overall operation efficiency of the algorithm,and the CUDA parallel acceleration is carried out on the online computing process of hologram based on the content of the new lookup table.Experiment on generating CGH with two kinds of 3 D point clouds shows that the computation efficiency of improved algorithm is greatly enhanced,compared to original WRP algorithm,and reaches 775 and 1700 times under GPU-CPU cooperative processing for two objects,respectively.Especially,When objects is less than 50 layers,improved algorithm has basically met the requirement of real-time display.