Pseudo-color Coded Optical System Based On The Spatial Light Modulator And Charge-coupled Device

The purpose of image enhancement can be achieved through all sorts of image processing method so as to get better detection of the information contained in the image. Image enhancement of gray scale images is a typical process used as a means of supplementing the information in various fields such as inspection, military, satellite image, and several other data visualization applications. Human eye can identify the number of colors is at least100times more than the number of density levels. To enhance the information of density difference, color is introduced in black and white image, the so-called pseudo color coding method.At present, pseudo color image enhancement can be divided into two major kinds of methods, digital method and optical method. These two methods have shortcomings:Above the256gray-scale high-resolution images, firstly gray-scale compression mapped to256gray scale, and then encode. It means that the pseudo-color processing of high-resolution gray-scale images cannot produce high color sensitivity and clear color level. Besides, the algorithm will be excessively lengthy, the cost will be high and the processing time will be long; the optical method can also be used to obtain the gray images with pseudo color. This method has several advantages, such as low cost, simple equipment, large processing capacity, and rich and bright color. The output image can be fine adjusted to some degree. However, this method needs chemical pretreatment of the black and white images. The process is complicated and time-consuming. Also, it is difficult to achieve real-time modulation. Therefore, it brings a lot of limitations to the practical application.In order to solve the above problems, a new pseudo-color coded optical system based on the liquid crystal spatial light modulator (LC-SLM) and a digital camera (CCD) is proposed. The SLM is used to replace the holographic grating with gray-scale image information, a gray-scale image in real-time modulation methods is proposed through synthesizing phase hologram and Ronchi grating, combined with the4f coherent optical processing system and spatial filtering.Firstly image processing technology related to pseudo color is expressed gradually in this paper. Image understanding and color base interrelated to pseudo color processing are mainly introduced in the second chapter.In the third chapter the classification, development, application of spatial light modulator and the spatial light modulator that this paper used will be introduced.In the fourth chapter the general composition of pseudo-color image processing system will be briefly described, several common pseudo color processing method in digital method and optical method will be introduced, then the principle of phase modulation in the density of pseudo-color coding will be briefly discussed. A new pseudo-color coded optical system based on the liquid crystal spatial light modulator (LC-SLM) and a digital camera (CCD) is proposed, then we analyses common question and gives the solution.There are mainly two innovations in the paper.Firs, in this paper the4f spatial filtering experimental system in the pseudo color coding with phase grating modulated image density has been improved by introducing a liquid crystal spatial light modulator. The new method has enhanced the flexibility and adaptability of the optical pseudo-color, and give full play to the high sensitivity, high-capacity, rich colors and other features of the optical processing mode. At the same time, it overcomes the disadvantages of pure optical system which could not perform real-time processing.Second, design one real-time processing system for pseudo color of phase-modulated image which can be applied to image recognition and image analysis.