Surface area based illumination intensity measurement via digital image

Abstract

The correct perception of objects is directly related to the suitability of the ambient illumination. This level of conformity is determined by a measuring instrument which is known as luxmeter which measures on point based. However, these measurements made on a point basis have some disadvantages such as cost, long processing times. In order to eliminate these disadvantages in recent years, there have been studies in which CCD cameras, mobile phones and video cameras have been used as luxmeters. In these studies, said devices are placed directly opposite the light source and used as a light collector such as a luxmeter. They then calculated the illumination intensity by digital image processing techniques using aquired source images. In this study, the camera is not used directly as a luxmeter. However, an overall image representing the entire environment is taken. A new method based on image processing is presented for illumination intensity calculation. The image acquired is separated into its frequency components in the frequency plane by the homomorphic filtering, and the illumination component representing the source's illumination is detected by the low pass filter. The average pixel value of the illumination component is calculated and defined as illumination intensity. In order to test the usability of the proposed method, the measured illumination intensity with a luxmeter and the computed results of the developed method are statistically analyzed. The results of this analysis showed that there was a linear relationship between the measurement and calculation values with satisfactory R2 values.