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The Need for Bad Pixels  

The NDF_ system provides support for the concept of bad pixels (sometimes called ``magic values'' or ``flagged values'') which may be present in the array components of an NDF. Bad pixels are pixels whose actual value may be unknown, and which have therefore been assigned a special ``null'' or bad value. They can arise in a wide variety of ways, for instance:

Many other examples exist where pixel values cannot be meaningfully assigned, and the bad pixel concept is designed to handle this general problem.



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Starlink User Note 33
R.F. Warren-Smith
11th January 2000
E-mail:rfws@star.rl.ac.uk

Copyright © 2000 Council for the Central Laboratory of the Research Councils