黑白胶片光栅编码彩色摄影术

用空间光栅将彩色景物记录到一张黑白胶片上（这一过程称为将彩色景物编码，所得的黑白透明片称为编码片）并通过再现（称为解码）装置再现彩色景物的思想和技术可以追溯到１８９９年，已有近百年的历史，开始时，类似于电子学中用时间信号调制载波方法，用彩色图像来调制光栅，十多年后便出现第一个萧条时期，持续将近半个世纪，期间比较重要的成果是有三个光栅进行三次编码记录的方法，到本世纪六十年代，又兴旺了一段时间，其中最

Some Basic Fractional Fourier Transform Units

The basic ideas and technique for recording using grating and retrieving full color images with panchromatic black and white film were presented in 1899. Since then, this technique has undergone much suffering. At the early stage, some authors used color images to modulate spatial carriers, i. e., gratings, which is analogous to the method of using temporal signals to modulate temporal carriers in electronics. After ten years, few people paid attention to this filed of research. Things remained like that for nearly half a century. In this period, a comparatively important result in this respect was recoding color information on a black and white film with three colored filters and three gratings of different azimuthal orientations in three exposures and reconstructing the transparency thus obtained into a full color image. In the sixties, interest in this technique was aroused again and some importent achievements appeared, including a snapshot method for color encoding using a tricolor grating and design for and manufacture of cameras implementing this snapshot method. Successful field tests of this color method was conducted for both military applications and television news. Another important achievement in the late sixties was that the importance of maintaining a linear relation between total input exposure and amplitude transmittance of the processed film during recording was realized and analyzed in detail. And good decoding systems were put forward based on Fourier optics. But since the early eighties, especially the mid eighties, almost nobody has taken an interest in this field of research and no important progress has been made. This technique's many practical drawbacks and the development of the highly practical tripack color films make this technique almost obsolete. Except that it still has some applications in multiple image storage and multispectral photography, it is no match for modern color photography in both quality and price.