A Validation System And Criteria Based On Imatest For Mobile Device Camera Performance

Camera is nearly a must component for smart phone, tablet and other mobile devices now. And with the popularization of high pixel camera, users have increasingly high expectations on camera performance. To ensure the products can satisfy end users, it is very important for device manufacturers to figure out a validation system of camera performance.Imatest is a software tool to analyze image quality. It is widely used for evaluating various types of camera. The basic method of using Imatest is taking a photo of specified test chart in a specific lab environment, and then exporting photo into PC for analyzing by Imatest. However, each Imatest module is able to get many parameters. Moreover, these parameters would be variable in different test condition that makes the evaluation on camera becomes complex. Therefore, it is necessary to get a standardized test method which is repeatable and easy to be used.The basic factors of image quality are resolution, noise, exposure accuracy, dynamic range, color reproduction, auto white balance, and so on. Accordingly, there are some simple data can be picked out from numerous Imatest output parameters, including MTF50, RGBY noise, Delta E, Delta C etc.. The test charts be selected are ISO 12233 Resolution Chart, Color Checker Chart, ISO 14524 OECF Chart and other international standard charts. The type of light source for testing is mainly D65, supplemented by INCA and CWF light.The pixel of mobile device camera vary from 0.3 mp to 13 mp or higher. Other basic configuration such as focus length, aperture, ISO sensitivity are also various. To work out the test criteria, lots of experiments on various cameras need to be done. And then reasonable criteria be derived so that the device manufacturers can make decision to ship out products or do further tuning easily based on Pass/Fail result. Such a simple validation system can basically evaluate image quality of mobile device camera.