灰度调整与数字全息图像质的关系  

Relationship of Image Quality of Digital Hologram and Grey Level Adjustment

作　　者：高志强[1] 李勇[1] 

机构地区：[1]浙江师范大学信息光学研究所,浙江金华321004

出　　处：《光子学报》2011年第3期327-331,共5页Acta Photonica Sinica

基　　金：国家自然科学基金(No.60702078;No.60877002);浙江省自然科学基金(No.Z1080030)资助

摘　　要：如何在有限的灰度级别下输出高质量全息图是人们关注的问题之一.文章从数字全息图(计算机制全息图)的灰度直方图出发,研究灰度调整对全息图再现像质的影响.首先通过理论推导研究了压缩计算机制全息图中占比例少的灰度,展宽占比例多的灰度后全息图衍射效率的变化,发现处理后的计算机制全息图经灰度压缩的阈值越大,衍射效率越高.然后研究了灰度压缩的阈值对计算机制全息图再现像噪音的影响,发现全息图再现像的噪音随着阈值的增大,先减少再增大.实验表明,通过取合适的阈值对全息图进行灰度调整,可以在保证全息图再现像的信噪比的同时,提高全息图的衍射效率.计算机仿真和全息图光学再现实验证明了理论分析是正确的,为制作高质量的计算机制全息图提供了参考依据.It is an interesting thing to output high quality digital hologram（Computer Generated Hologram） under limited grey level.The reconstructed image quality of digital hologram was studied with adjusting the grey level of hologram,according to its histogram.The grey levels whose ratios were relatively small were cut down,and the grey levels whose ratios were relatively large were expanded.Firstly,the change of diffraction efficiency of digital hologram after grey level adjusting was studied in theory.The diffraction efficiency would be increased while the threshold for grey level adjustment increased.Then the change of Signal to Noise Ratio（SNR） of reconstructed image was analyzed.It is found that the SNR will increase at first and then decrease with the increase of the threshold.The hologram with high diffraction efficiency and high SNR can be obtained if the special threshold for grey level adjustment is selected.The computer simulation and optical reconstruction of digital hologram prove the analysis.

关 键 词：全息三维显示 灰度直方图 全息图量化 像质 

分 类 号：O438.1[机械工程—光学工程]