Effects of Background Reflectance and Illumination Level on the Estimated Freshness of Vegetables

K Okajima1, Y Sakurai, C Arce-Lopera2

1Dept. Environment and Information Sciences, Yokohama National University, Japan
2ICESI University, Colombia

Contact: okajima@ynu.ac.jp

Luminance distribution information is a critical cue for estimating visual freshness of vegetables, such as strawberries [Arce-Lopera et al, 2012, i-Perception, 3(5), 338–355] and cabbages [Arce-Lopera et al, 2013, Food Quality and Preference, 27(2), 202–207]. However, it remains unclear how robust is the freshness estimation against environmental variation, such as variations of lighting and background conditions. Therefore, we conducted an experiment to investigate the effect of several environmental parameters on our visual estimation of fresh vegetables by controlling the image information. First, we took calibrated pictures of fresh vegetables: cabbage, carrot and komatsuna (Japanese Mustard Spinach) that gradually degraded in a controlled environment. Next, to investigate the effect of the luminance contrast on freshness estimation, we created stimuli with several levels of luminance contrast between the vegetable surface and the background by controlling their luminance level. As a result, we found that the background reflectance do not affect visual freshness estimation. On the other hand, visual freshness estimation depends on the absolute luminance levels of the vegetable surface but it saturates over a certain illuminance. Those results suggest that visual freshness estimation is quite robust against environmental variation except when the illuminance level is low. [This work was supported by JSPS KAKENHI Grant Numbers 23135511, 25135715.]

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