In systems and methods of talk group communication, a group PTT call is established between a originating wireless device and recipient wireless devices. When forming images for measurement for density control, the apparatus performs density control by forming a greater number of density levels of an image for measurement developed using a light developer than the number of density levels of an image for measurement developed using a dark developer. The container houses the article of furniture. The determining unit determines the position of the edge of the sheet. A central monitoring device receives signals and a mechanism detects a location of the existing misplaced article.