Abstract: A method of generating a remapping function for use in converting near-photographic document image pixel gray level data lying in a first range of gray level values to higher contrast, background-suppressed pixel gray level data lying in a second more limited gray level range. Global document information, such as a histogram of all the document's original pixels, is used to generate at least one threshold gray level value and to determine the shape of the remapping function on either side of the threshold. Preferably, the remapping function is implemented by a look-up table addressed in accordance with the original pixel data.

Abstract: A discrete transform image data compression system in which frequency transform coefficients are modified in accordance with a matrix of quantizer values employs a predefined plurality of quantization matrices to adaptively select, on a document-by-document basis, an approximate memory packet size for each document's compressed image data storage by selecting one of the plurality of quantization matrices in accordance with the packet size estimate obtained for each document image. Additionally, the system employs generation of contrast reduction and gray level stretch remapping curves as a function of global image data characteristics, such as a gray level histogram of the document image data. The remapping curves are utilized to preprocess the image data for more effective data compression.

Abstract: A proofing or heating cabinet is provided having an enclosure with an interior and a pair of oppositely disposed side walls forming elongate heat ducts therein; the heat ducts having openings in their mutually facing surfaces. A modular heating assembly is removably disposed in the enclosure and has aligned end openings communicating with the heat ducts. Placed within the modular heating assembly at one end opening thereof is an electric heating element extending substantially thereacross, and at the other end thereof a blower device substantially extending thereacross to maintain generally laminar the airflow through the modular assembly.