Modeling For Perceptual Brightness

Vision is an important perception channel for human beings to obtain outside information.People are often in a variety of complex environments.People have different light and dark feelings for objects with the same luminance in different environments.The light and dark perception of the surrounding environment or the target object is an important function of human vision,that is,there is a certain difference between the brightness perceived by the human eye and the physically measured luminance of the actual object.In fact,the human eye’s perception of light and dark objects is not only related to the luminance of the target object,but also related to the surrounding environment.The purpose of this article is to study the problem that the physical brightness and the perceived brightness effect of the human eye cannot match exactly.By simulating the actual indoor environmental conditions,a perceived brightness level scoring experiment is designed and implemented,and a perceived brightness model is established.Aiming at the pupil diameter,which is an important parameter in perceived brightness,experimental conditions such as multiple luminance levels and multiple viewing angle ranges are designed,the pupil diameter adjustment mechanism is studied,and the pupil diameter calculation model is established.The main research work of the paper includes:First,the human eye perception brightness level scoring experiment was designed to analyze different ambient light and different screen luminance.The subjects perceived the brightness of the target screen and the pupil diameter of the subjects under different ambient light and different screen luminance are recorded.The results show that when the ambient light is fixed,the perceived brightness is positively correlated with the screen luminance;when the screen luminance is fixed,the perceived brightness is negatively correlated with the ambient illuminance.Perceived brightness is affected by target screen luminance significantly.Further analysis found that pupil size is affected by ambient light significantly,and its influence law is consistent with the influence law of ambient light on the perceived brightness of the screen.Further,the target screen luminance,pupil diameter and perceived brightness level scores are fitted into a quantitative formula form.Combined with the physical imaging process of external objects on the retina,the"retina imaging luminance L_r"is defined.The L_r calculated based on the pupil diameter and screen luminance is linearly related to the perceived brightness level score,and the goodness of fit reaches 0.93.Therefore,the influence of ambient light on the brightness perception of the display screen is achieved through pupil size adjustment.Therefore,the L_r as an objective measure of the perceived brightness of the screen is proposed in the paper.As an important parameter in the model of perceived brightness,pupil diameter is very necessary to study the adjustment mechanism of pupil diameter,especially when the pupil diameter cannot be directly measured by the device.The effects of different screen brightness and different viewing angle sizes on pupil diameter are explored,and a pupil size calculation model based on spatially weighted corneal flux density is proposed,and this model is suitable for the full field of view of the human eye.Including the asymmetry of the pupil diameter in the horizontal and vertical directions,defining the"most sensitive viewing angle",and analyzing the significant influence of the color factor on the pupil diameter.In short,the"retinal imaging brightness Lr"as a characteristic parameter of perceived brightness is proposed in the paper,and the retinal imaging luminance Lr,that is,the perceived brightness is affected by the pupil size.When the pupil size cannot be detected,the pupil size can be estimated based on the spatial light distribution in the field of view.