High dynamic range image based graphical user interface for glare and uniformity analysis

Camera based luminance measurement and analysis are increasingly used for the study of interior lighting in daylight-artificial light integrated schemes. This paper describes the development of a Graphical User Interface (GUI) system capturing a set of 11 exposure bracketed images, creates high dynamic range image and calibrates the camera to get the absolute actual luminance of a scene, and analyzes glare, contrast and uniformity. The calibration is done with Gretag Macbeth Digital Color Checker SG and standard luminance meter Konika Minolta LS100 where the reference curves are obtained by experimentation with different exposure values. Glare analysis is done based on three cases; glare condition is set five times the average luminance of the scene, the threshold of luminance set at 2000 Cd/m2 and threshold set as four times the average luminance of the task area. In addition to luminance distribution of any scene the minimum, maximum and average of any scene luminance as well as the uniformity ratios of any selected region can be obtained. It is possible to select task area, adjacent area and remote area which helps in setting contrast ratios that are in the permissible range. Deployment of this GUI makes a low cost computationally efficient, stand-alone system for glare and uniformity analysis.