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Description:
This routine equalises
(linearises) the histogram of an array. Thus approximately equal numbers of different values appear in
output equalised version of the input array.
Invocation
CALL KPG1_HSTQx( BAD, EL, INARR,
NUMBIN, OLDHST, MAP, OUTARR, STATUS )
Arguments
BAD = LOGICAL (Given)
If true there
may be bad values within the input array. If false there are no bad values. It is used as an efficiency
mechanism.
EL = INTEGER (Given)
The dimension of the arrays.
INARR( EL ) = ? (Given)
The
array to be equalised.
NUMBIN = INTEGER (Given)
Number of bins used in histogram. A
moderately large number of bins is recommended so that there is little artifactual quantisation is
introduced, say a few thousand except for byte data.
OLDHST( NUMBIN ) = INTEGER
(Returned)
The histogram of the input array, i.e. before equalisation.
MAP( NUMBIN
) = INTEGER (Returned)
Key to transform the input histogram’ s bin number to the
equalised bin number after histogram mapping.
OUTARR( EL ) = ? (Returned)
The array
containing the equalised values.
STATUS = INTEGER (Given)
Global status value.
Notes:
-
There is a routine for each numeric data type: replace " x" in the routine name by D, R, I, W, UW, B or
UB as appropriate. The arrays supplied to and returned from this routine must have the data type
specified.
References
Gonzalez, R.C. and Wintz, P., 1977, " Digital Image Processing" ,
Addison-Wesley, pp. 118–126.
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