DATAMANIP commands


PROGRAM NAME

kthreshbelow - Threshold Data Values that are Below Specified Cutoff

DESCRIPTION

The Threshold Below operator generates a two-level output by thresholding the Input data object (i). Data values less than the Cutoff Value (lc) are set to the "LESS THAN" output value (fval), and values greater than or equal to the Cutoff Value are set to the "GREATER THAN or EQUAL" Output value (tval).

The following histogram defines the results of the thresholding operation.


                                |<-F->|<----T---->|
                                |     | :     .   |
                                |    .:.:.  .:::  |
                                |:. .::::::.::::: |
                                |::::::::::::::::.|
                                ------|------------
                                      Cutoff
 
        F:  if value <= Cutoff,  Output = fval
        T:  if value >  Cutoff,  Output = tval

Data Type The data type of the output object is the same as the input object's data type. Internally, the data is processed using one of the following: unsigned byte, long, unsigned long, double, or double complex. Data will not be cast to a lower type for processing.

Map Data If the input object contains a map, then the operation is performed on the map data. If the input object does not have a map but has value data, then the operation is performed on the value data.

Validity Mask If there is a validity mask associated with the input object, the mask is transferred to the output object. To decrease processing time, the operation will still be performed on those data that have corresponding mask values equal to zero. If the data under the mask is genuinely fInotfP processable, such as NaN or infinity, the user can specify that a value be substituted in place of the original value when it is accessed. The masked data substitution attributes for a data object can be explicitly set and stored using the fISet AttributefP operator, DATAMANIP::ksetdattr.

Explicit Location and Time Data If the input object has time data or location data, it is transferred to the output object.

Failure Modes This program fails if the input object lacks both map data and value data.

Executing Threshold Above runs the program kclip with the -thresh option set to TRUE (-thresh 1).

REQUIRED ARGUMENTS

-i
type: infile
desc: Input file
-o
type: outfile
desc: output file

OPTIONAL ARGUMENTS

-lc
type: double
desc: For values < lc, output = fval, otherwise output = tval
default: 128
bounds: no range checking
-fval
type: double
desc: Output value if data is LESS THAN cutoff (lc)
default: 1
bounds: no range checking
-tval
type: double
desc: Output value if data is GREATER THAN or EQUAL to cutoff (lc)
default: 0
bounds: no range checking

EXAMPLES

SEE ALSO

DATAMANIP::kthreshabove, DATAMANIP::kthreshin, DATAMANIP::kthreshout, DATAMANIP::kmegathresh, DATAMANIP::kclip

RESTRICTIONS

REFERENCES

COPYRIGHT

Copyright (C) 1993 - 1997, Khoral Research, Inc. ("KRI") All rights reserved.