A digital imaging method is proposed to measure the uncomfortable glare in interior lighting. Our study includes the systematic derivation of three parameters: the position index, solid angle from the viewer's perspective, and average luminance of glare source. To extract the profile information of the lighting sources, an adaptive threshold method was employed. The Unified Glare Rating (UGR) was calculated and analyzed with a digital camera image of actual office lighting conditions. The results show that the mean relative errors of the obtained position index, solid angle, and average luminance of the glare source were equal to 1.319%, 4.296%, and 3.001%, respectively. For a background luminance of 12.910 cd·m -2, the calculated value of the UGR was equal to 12.606, with a relative error of 4.326%. The advantages of this method are its simple calculations, high accuracy, and easy implementation. By applying our method to the glare test in indoor lighting, a theoretical framework for the development of a convenient and fast glare test system can be constructed.