The Image Characteristics for Perceived Naturalness

To identify the visual characteristics that make a scene looks nature, we investigated the relationship between the distribution of spatial frequency spectrum of an image and its perceived naturalness. The image database contains outdoor images whose perceived naturalness were rated by human observers. Each image was Fourier transformed to the frequency domain. The power spectrum of each image was radial averaged across orientation and then fit with a straight line on log-log coordinates. The slope of the fitted line represents the characteristics of the spatial frequency spectrum of the image. The perceived naturalness increased with the decrease of the spectrum slope. The correlation between these two factors was significant. That is, our result suggests that increasing high spatial frequency content makes a scene more nature for observers. Thus, increase high spatial frequency content in an urban visual environment by planting more trees and adding more detail object or separation line to the architecture façade should make it more like nature environment.