In Step 4 of the Target Detection Wizard, you can optionally select non-target spectra to improve the detection result.

To perform Orthogonal Subspace Projection (OSP), Target-Constrained Interference-Minimized Filter (TCIMF), and Mixture Tuned Target-Constrained Interference-Minimized Filter (MTTCIMF) target detection analysis, you need to select non-target spectra. Providing non-target spectra can potentially reduce the number of false positives by suppressing response from the non-target signatures.

  1. To specify non-target spectra, toggle Select Non-Target Spectra to Reject? to Yes.
  2. Enter non-target spectra from spectral libraries, individual spectral plots, text files, ROIs, or statistics files. To import the non-target spectra, see Importing Spectra.
  3. Note: If you are importing ROIs as non-targets, the average calculated from each region is used as the non-target spectrum; therefore, you want to include each separate material as a separate ROI.

  4. When importing spectra is complete, choose the spectra to use by selecting one or more rows in the table, or by clicking Select All. ENVI uses only the spectra you select for target detection processing.
  5. Click Next in the Wizard. The Apply MNF Transform panel appears.