Before installing the system to an actual house, Ocha House, we developed a prototype of the same size (40 cm x 40 cm x 30 cm) as the mailbox in the house (Fig. 2, left). The prototype mailbox was assembled from acrylic boards. We attached two magnetic switches to the front and back slot covers, two USB cameras (Logicool Qcam Pro for Notebooks) to the front/outside and top/inside of the mailbox, and a small fluorescent lamp to the top/inside (Fig. 2, right). We also attached a small PC inside the mailbox.
The system aims to classify s-mail into several categories. In the current prototype, we have implemented the function to distinguish flyers from letters. We focus on the difference in the color distribution between letters and flyers; that is, while most letters have low saturation (e.g., white), most flyers tend to have high saturation (e.g., primary colors) (Fig. 3). Therefore, we decided to classify s-mail by the ratio of high saturation pixels in each picture.Please read our paper for details.