Reference image method for measuring quality of photographs produced by digital cameras
Mikko Nuutinen, Olli Orenius, Timo Säämänen, Pirkko T. Oittinen · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2010
Objective image quality metrics can be based on test targets or algorithms. Traditionally, the image quality of digital cameras has been measured using test targets. Test-target measurements are tedious and require a controlled laboratory environment. Algorithm metrics can be divided into three groups: full-reference (FR), reduced-reference (RR) and noreference (NR). FR metrics cannot be applied to the computation of image quality captured by digital cameras because pixel-wise reference images are missing. NR metrics are applicable only when the distortion type is known and the distortion space is low-dimensional. RR metrics provide a tradeoff between NR and FR metrics. An RR metric does not require a pixel-wise reference image; it only requires a set of extracted features. With the aid of RR features, it is possible to avoid problems related to NR metrics. In this study, we evaluate the applicability of RR metrics to measuring the image quality of natural images captured by digital cameras. We propose a method in which reference images are captured using a reference camera. The reference images represented natural reproductions of the views under study. We tested our method using three RR metrics proposed in the literature. The results suggest that the proposed method is promising for measuring the quality of natural images captured by digital cameras for the purpose of camera benchmarking.