Color impression factor: an image understanding method for outdoor mobile robots

The color vision in the outdoor environment has two problems. The first is the hue shift of the object under the changes of the season, weather, the hour and the view position. The second is the hue shift of the object between in the sunny place and in the shaded place. We propose the color impression factor to memory the hue of the object. The color impression factor is defined as R-B. It is the function of the sunlight condition (sunny/shaded) and the hour. We show this factor is useful to discriminate objects from the shadows in the asphalt paved road-yellow tactile blocks from the asphalt paved road.