用散斑屏一次曝光抽样实现密度假彩色编码

Pseudocolor Density Encoding by Means of One Exposure Technique Through Speckle Screen

通常的密度假彩色编码技术是用Ronchi 光栅对待处理图像的正片和负片作空间编码,而后在白光系统中实现假彩色化。它的主要缺点是正负片的位置不易对准,以及输出图像分辨率较低。本文介绍了用散斑屏一次抽样曝光的编码片在白光处理器中实现假彩色化的新方法。该技术分两个步骤:首先把物透明片成像到一个与散斑屏密接的感光底片上得到一次曝光编码片。然后把编码片置于白光处理器中,通过在付里叶平面上作彩色滤波得到假彩色编码的图像。它不存在两次曝光编码技术中正片和负片的位置不易对准的问题,且有散斑屏分辨率高和易于制备的优点。文中给出用这种技术所作的生物电镜照片密度假彩色编码的实验结果。

In recent years various techniques of pseudocolor density encodingof white-black image have been reported.The main procedure is spatial encod-ing of positive and negative images through Ronchi grating.But there are someshortcominges:the requirement of resetting the positive transparency at theexact position of the negative one is difficult to meet in dark room,and theresolution of output image is lower caused by Ronchi grating encoding.In this paper a new technique of pseudocolor density encoding which useswhite-light image processor and one exposure encoded transparency through spec-kle screen is presented.It consists of two steps:an one-exposure encodedtransparency can be obtained by imaging the object transparency on to afresh photographic plate contacted with an oriented speckle screen.Thepseudocolor density encoding picture can be got at the output plane of anwhite-light image processor by placing the encoded transparency at input planeand inserting a suitable color filter at Fourier plane.