A method for predicting the settled appearance of a test patch printed by an imaging system by applying a transfer function to the color of a freshly printed test patch. In the image forming apparatus, the image pattern is generated based on the rotational position detected by the rotational position detector and the rotary member that the rotational position detector detects the rotational position thereof is either the image carrier or the developer carrier. By virtue thereof, a packed frozen sushi product suitable for mass production is provided. The sleeve member may be formed from a shape memory plastic which may also be biodegradable.