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ENVI

Spectral Slices

Spectral Slices

Use Spectral Slices to extract a combined spatial and spectral profile from a multi-band image. You can slice images in the following way:

  • Horizontally: All of the bands for a single line of the image
  • Vertically: All of the bands for a single pixel column of the image

Slices in ENVI are saved as gray scale images, with the following characteristics:

The line direction (y) corresponds to the spatial dimension of the image being sliced. For a horizontal slice, the number of lines is equal to the number of samples. For a vertical slice, the number of lines is equal to the number of lines. For an arbitrary slice, the number of lines is equal to the total number of pixels along the ROI polyline.

The sample direction (x) corresponds to the spectral dimension, or the number of bands in the sliced image.

The gray scale image shows the spectral intensity (reflectance, radiance, and so forth), depending on the calibration of the data.

Extract Horizontal Slices


Use Horizontal Slice to show the image spectra for all of the pixels in a line of the input image data. You can pre-determine the position for the slice by using the Cursor Value tool in the main toolbar.

  1. From the Toolbox, select Spectral > Spectral Slices > Horizontal Spectral Slice. The Spectral Slice Input File dialog appears.
  2. Select an input file and perform optional spatial subsetting, then click OK. The Spectral Slice Parameters dialog appears.
  3. Enter a Line value for the horizontal slice.
  4. Select output to File or Memory.
  5. Click OK. ENVI adds the resulting slice to the Spectral Library Viewer, where you can view the spectral profile for each line.

Extract Vertical Slices


  1. Use Vertical Slice to show the image spectra for a single column of input image data. You can pre-determine the position for the slice by selecting the Cursor Value tool in the main toolbar.
  2. From the Toolbox, select Spectral > Spectral Slices > Vertical Spectral Slice. The Spectral Slice Input File dialog appears.
  3. Select an input file and perform optional spectral subsetting, then click OK. The Spectral Slice Parameters dialog appears.
  4. Enter a Sample value for the vertical slice.
  5. Select output to File or Memory.
  6. Click OK. ENVI adds the resulting slice to the Spectral Library Viewer, where you can view the spectral profile for each sample.



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