Abstract: Small, fast, and inexpensive in-line spectrophotometers can produce in-line spectrums of a substrate before or after printing on the substrate. In-line spectrums are generally far less complete than a reference spectrum produced with a large, slow, and expensive reference spectrophotometer. An in-line spectrum can be mapped to a reference spectrum using a variety of known algorithms. However, the mapping is erroneous when the media substrate type changes. Reference transform matrices and in-line transform matrices can correct the erroneous mapping.

Abstract: A compressor can compress an image by reducing the amount of data while preserving the information. Some compressors use run length coding wherein image data is converted into a series of run length code words. The efficiency of run length coding can be increased with the introduction of differential run length code words. The differential run length code words can augment the original set of run length codes. Differential run length codes vary from current run length codes by encoding runs of differences.