Camera Definition Detection System Based On Android Platform

In recent years,with the development of intelligent Internet of things,camera modules with charge coupled devices and complementary metal oxide semiconductors as image sensors have been widely used.From the field of smart phones to the field of smart cars,the carrying capacity of cameras has been significantly improved.With the continuous growth of market demand,the manufacturing technology of image sensor is also improving.The resolution of image sensor has also developed from VGA format resolution(640×480 pixels)to hundreds of millions of pixels resolution.Camera is the key terminal equipment to obtain image information in human-computer interaction.Its imaging definition has become the key factor for the normal operation of the system.Therefore,it is very important to detect the imaging clarity of the camera module.The existing detection instruments mainly include two categories: one is high-precision and large-scale instruments for scientific research,and the other is professional measurement instruments for specific systems.Large testing instruments are generally expensive and complex to operate,so the small professional camera module test box represented by Duxin technology came into being,which can solve the problems caused by large instruments and manual visual inspection.However,this small specialized test box system is relatively closed,and its general applicability is not high.Therefore,it is very necessary to develop a universal detection system which has good universality and can evaluate the imaging clarity of camera module in real time and objectively.Through reading extensive literature on the subject,i have studied about the development of camera modules and the principles of imaging,sharpness evaluation criteria and measurement techniques.In order to accurately and quickly detect the imaging definition of the camera and improve the product consistency,firstly,this paper designs a HD USB camera module,which has better universal applicability.Secondly,according to ISO12233 international standard,a camera modulation transfer function detection algorithm is designed.And the function test is completed on the computer.Finally,the detection algorithm is transplanted to Android platform,and the self-developed camera module and Android platform are built together to form a complete camera definition detection system.The main work includes the design of the circuit schematic of the camera module on the candance platform,and then the PCB design of the camera module is completed in Allegro software,including rule setting,laminated structure design,impedance matching design,signal integrity design and so on.Through the study of optical knowledge,we know that among the many indicators for evaluating the imaging clarity of camera module,the modulation transfer function is one of the most objective indicators for evaluating the imaging quality of camera.The current mature measurement methods mainly include star point method,slit method,contrast method and edge method.This paper compares the advantages and disadvantages of the four methods,and finally adopts the edge method as the systematic measurement method.The system uses C + + language to complete the design of edge method.Because of the openness of Android system,the detection algorithm is transplanted to Android platform and the detection function is realized.In the active alignment process of camera module assembly,the system evaluates the imaging clarity of the camera by measuring the modulation transfer function of the camera.Compared with large-scale and professional measuring instruments,the detection system has the advantages of miniaturization,openness,convenience and low cost.Finally,through comparative experiments,it is proved that the system can detect the imaging clarity of camera module under different assembly conditions in real time.In the field of camera module detection,the system is easier to realize the value of commercialization and industrialization.