Abstract: A digital copying device with an adjustable reproduction characteristic. This characteristic maps optical densities ODin of an original document onto optical densities ODout of a copy that is to be made of the original.

Abstract: A method and system of compressing digital image data organized as successive data groups of bits, the contents of which are values of pixels of an image, by checking a first condition of whether a first data group has the same contents as one or more following data groups. If the first condition is satisfied, then the data groups are replaced, in a compression step, by a compression code representing these data groups. Otherwise, in a copying step, only the first data group is replaced by a code consisting of the contents of the data group. These steps are repeated for the next data groups. The method also adds an identification code for characterizing the nature of the code, but only when the compression step is carried out. A related method and system of decompression checks a first condition of whether an identification code is included in the compression codes. If the condition is satisfied, then decompression takes place, else copying takes place.

Abstract: A method for checking in a text processing system the correct and consistent use of units, comprising the steps of: storing a list of symbols or production rules that represent units; storing criteria, that state whether or not a symbol or a combination of symbols is interpreted as a unit; specifying allowable units and allowable notations thereof; searching the text for references to units, i.e., for strings that can be interpreted as a unit or part of a unit; checking whether the strings represent an allowable notation of an allowable unit; and generating an error signal, if not. If an unallowable unit is found, this unit and the associated number(s) may be transformed into an allowable unit.