How to Manipulate Principal Components Transformation

Learn more about Principal Components Transformation

Before executing the Principal Components function you can analyze statistical parameters of the selected bands. These parameters might refer to the image whole area or just a selected portion.

How to see the parameters of the whole image:

  • click on Image and Principal Components... to open the correspondent window;
  • click on Infolayers list to select the desired bands (at least two). Notice that only the infolayers (bands) of same resolution and bounding box will be presented on the list;
  • in Sample click on Image;
  • click on Acquire. In this case it is not necessary to have the image visible on the screen. It is enough to have the infolayer, correspondent to the group of bands to be analyzed, active. The image whole area will be used;
  • click on Parameters... .The window "Principal Components Parameters" is presented. The following parameters are shown: Mean and   Variance for each band, Eigenvalue and Percentage of information for each component, Covariance Matrix, Correlation Matrix and Eigenvectors Matrix.

How to see the parameters of a selected area on the image:

  • click on Image and Principal Components... to open the correspondent window;
  • click on Infolayers list to select the desired bands (at least two). Notice that only the infolayers (bands) of same resolution and bounding box will be presented on the list;
  • in Sample click on Cursor;
  • mark the region on the image using the Zoom Cursor ( atalho_cursor_ar.gif - 923 Bytes). Click (LB) on the top left corner, drag the mouse to where you want and then click again (LB);
  • click on Acquire. Notice that the selected regions are highlighted. To select other regions, proceed as described above. In this case, it is necessary to have the image visible on the screen before acquiring the samples, otherwise the message "There is no active image on the screen" will be presented;
  • click on Parameters... .The window "Principal Components Parameters" is presented.

NOTE: After analyzing the statistical parameters you can execute the transformation. It is not required to go through the "Principal Components Parameters" interface first.

  Performing Principal Components Transformation :

  • click on Image and Principal Components... to open the correspondent window;
  • click on Infolayers list to select the desired bands (at least two). Notice that only the infolayers (bands) of same resolution and bounding box will be presented on the list;
  • in Sample, click on Cursor if an area is selected, or Image for the whole image;
  • click on Output Image e type the name which will be used as a prefix to generate the output images. For instance, if you select two bands and the output image is named"Comp", the outcome will be "Comp-PC1" and "Comp-PC2";
  • click on Apply. The created images (components) are presented on the "Control Panel" in the same category of the selected bands.

See also:
Image Processing techniques
Image Processing Menu