Abstract: A data communication apparatus regularly obtains counter information from a plurality of image forming apparatuses. Then, the data communication apparatus moves and writes the counter information that is in a first memory and obtained at a previous time to a second memory. Thereafter, the counter information obtained this time is written to the first memory. At the same time, the data communication apparatus compares the counter information obtained this time with the counter information obtained the previous time. When there is a contradiction between both sets of counter information, the counter information is determined to be a counter abnormality and transmitted to a central management apparatus.

Abstract: A plurality of patterns such as half-tone patterns, solid patterns, edge patterns, and verbatim data are losslessly represented in a compressed raster data stream. A pattern selection module selects among the various patterns to provide the best combination of lossless representations according to particular criteria such as storage compactness. Half-tone patterns are compressed by exploiting the characteristics of the half-tone threshold screen used to generate the half-tone image. A half-tone pattern codebook is produced by half-tone screening a calibration image. A packet formatting module packs multiple pattern identifiers and lossless representations into a packet which may be transmitted compactly. Upon receipt, a packet deformatting module unpacks the pattern identifiers and lossless representations from the packet. After deformatting, a pattern decoding module uses the pattern identifier to activate appropriate pattern generation modules.