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NDF_QMASK - Combine an NDF quality value with a bad-bits mask to give a logical result

Description:
This function may be used to combine an NDF quality array value with the associated bad-bits mask value to derive a logical result indicating whether an NDF pixel should be included or excluded from processing by general-purpose software.

Invocation:
RESULT = NDF_QMASK( QUAL, BADBIT )

Arguments:
QUAL = BYTE (Given)
The unsigned byte quality value.
BADBIT = BYTE (Given)
The unsigned byte bad-bits mask value.

Returned Value:
NDF_QMASK = LOGICAL
If the function returns a .TRUE. result, then the pixel with quality value QUAL should be included in processing by general-purpose software. If it returns a .FALSE. result, then the pixel should be regarded as "bad" and excluded from processing.

Notes:
  • This function is implemented as a Fortran statement function and should be defined in each program unit from which it is invoked by means of the include file NDF_FUNC. This file should normally be included immediately after any local variable declarations.
  • The result of this function is computed by forming the bit-wise "AND" between the QUAL and BADBIT values and testing the result for equality with zero. Its actual implementation is machine-dependent.



next up previous
Next: NDF_QMF - Obtain the logical value of an NDF's quality masking flag
Up: FORTRAN ROUTINE DESCRIPTIONS
Previous: NDF_PTWCS - Store world coordinate system information in an NDF


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