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4.5 DMU Corrupted Pixel Detection

A recent addition to the RAW_SCREEN process is the module that flags pixels which are potentially affected by the Data Multiplexer Unit (DMU) corruption which arose in late 1994. The DMU corruption of the raw image is such that pixels between a certain DN range may be assigned erroneously a DN value of 159. A raw image screening algorithm using statistical methods was developed by VILSPA which singles out images that have abnormally high numbers of pixels at DNs of 159 and thus are likely to have been affected by the DMU problem. This image screening process is only run on images taken after October of 1994. There is no way to tell which specific pixels with DN=159 have been affected by the DMU corruption. As a result, in images which the screening process has identified as suspect, all pixels with DN values of 159 are flagged (with $\nu$ flag=-8) as possibly being corrupted.

Karen Levay