Image Quality Analysis for Visible Spectral Imaging Systems

Abstract

An image quality investigation of visible spectral imaging systems was performed. Spectral images were simulated using different combinations of imaging system parameters with different numbers of imaging channels, wavelength steps, and noise levels based on two practical spectral imaging systems. A mean opinion score (MOS) was determined from a subjective visual assessment scale experiment for image quality of spectral images, rendered to a three-channel LCD display. A set of image distortion measures, including color difference for color images, were defined based on image quality concerns. The relationships between the distortion factors and the combinations of parameters in spectral imaging systems are discussed in detail. The MOS values and distortion measures were highly correlated. The results indicate that the image quality of spectral imaging systems was significantly affected by the number of channels used with noise in the image capture stage. The selection of wavelength steps had no significant impact on final image quality, especially when there was no noise involved. The results also showed that the contrast factor indicates a different impact on image quality for human portraits compared to other relatively complex scene images. An empirical metric is proposed to estimate the scaled image quality. The correlation between this metric and the subjective measure, MOS, was 0.97. The results also indicate that two distortion factor eigenvectors were sufficient to represent four distortion factors used in this experiment. This suggests that further research needs to be performed to find more efficient distortion factors.