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 THRESHOLD MASKING

The THRESHOLD MASKING command allows masked and un-masked elements within the ROI to be defined automatically based on a user set logical criterion. The user selects one of two logical tests: i. greater than, ii. less than, and a threshold value. All data elements in the ROI which obey the test are set to be masked, and all those which fail are set to un-masked.

e.g. If we want all elements with a data value below 0.5 to be set to be masked, then the following program dialogue would be produced:

Fit sub-menu: ENTER COMMAND [INPUT PARAMETERS]:threshold
INFO: This option allows masked-off elements with the ROI to be defined
      automatically depending on the data values. The user can set a
      threshold operation (<GREATER THAN> or <LESS THAN>) and a
      threshold level. All data values which CONFORM WITH the defined
      test will be set to be masked-off. All others will be set to be
      un-masked.
LESS THAN COMPARISON [YES]: 
DECISION THRESHOLD DATA VALUE [1.0000]:0.5



Andrew Hammersley
2004-01-09