A Reliable Image Quality Assessment Metric: Evaluation Using Camera Impacts

Image analysis is being applied in many applications including industrial automation with the Industrial Internet of Things and machine vision. The images captured by cameras, especially from the outdoor environment are impacted by various parameters such as lens blur, dirty lens, and lens distortion (barrel distortion). There exist many approaches that assess the impact of camera parameters on the quality of the images. However, most of these techniques do not use important quality assessment metrics such as oriented FAST and rotated BRIEF, and structural content. None of these techniques objectively evaluate the impact of barrel distortion on the image quality using quality assessment metrics such as mean square error, peak signal-to-noise ratio, structural content, oriented FAST, and rotated BRIEF, and structural similarity index. In this paper, besides lens dirtiness and blurring, we also examine the impact of barrel distortion using various types of datasets having different levels of barrel distortion. Analysis shows none of the existing metrics produces quality values consistent with intuitively defined impact levels for lens blur, dirtiness, and barrel distortion. To address the loopholes of existing metrics and make the quality assessment metric more reliable, we propose a new image quality assessment metric that fuses the quality values obtained from different metrics using a decision fusion technique known as the Dempster–Shafer theory. Our proposed metric produces quality values that are more consistent and conform with the perceptually defined camera parameter impact levels. For all the above-mentioned camera impacts, our proposed metric exhibits 100% assessment reliability, which includes an enormous improvement over other metrics.