The Research Of Semi Virtual Keyboard Based On Image Processing

With the development of modern computer technology, portable devices grow tendencyof centralization of functions and miniaturization, such as laptops, smart phones, tablet PCsand so on. While the traditional keyboard is inconvenient to carry as it occupies too muchspace, but the phone keypad can not be operated easily with small keys, those hinder thecomfort and convenience in human-computer interaction. To solve these problems, a virtualkeyboard based on image processing technology becomes a new type of human-computerinteraction tools, which has the advantages of less hardware, small size, convenient carrying,etc.The virtual keyboard based on image processing technology does not need keyboardentity, which implements the keyboard function by steps as follows: the camera captures thekeyboard area image, then the pressed key and the user’s keystrokes action are identifiedthrough image processing, lastly keystroke commands are generated in software. In thisarticle, a virtual keyboard is called pure virtual keyboard, whose keys are generated byprojection, on the other hand, it is called semi-virtual keyboard with keys printed on otherobjects.In the realization of the virtual keyboard, it is mainly to solve three problems: thepositioning of the keyboard location, key identification and key press and release modalidentification. The method to locate the area of the keyboard by getting four vertices of thekeyboard is not accurate enough, which affects the accuracy of key recognition. Therefore,this paper puts forward an off-line modeling method which enables to locate each row of thekeyboard. The algorithm in finger positioning and identification of keystrokes by usinggesture recognition, model matching or shadow analysis method is affected by external light,what’s more, the efficiency is not high, which is difficult to be applied in practice. In thispaper, we employ the infrared laser as an auxiliary light source to achieve the positioning ofthe pressed keys and identify the key mode.This paper first introduces the research in virtual keyboard at home and abroad, on thisbasis, the design methods and the semi-virtual keyboard system are present. First, obtain therow and column position information of the keyboard through offline modeling, and locatethe position of finger tip with white spots, then use the keyboard location information toidentify the target key, and identify the key mode by compare key information in the previousand current frame, ultimately realize the keyboard function. Finally, the experimental analysisin off-line modeling and key effect is implemented, which shows that, the design of semi-virtual keyboard in this paper can identify keys and their modes with fast speed and highaccuracy, what’s more, the external light has little effect on this system, which is suitable foruse in practice.