Did you do the spectral subset on the file you selected for input to PCA? Or did you only select to output 8 PC bands?
If you use all bands to compute the PCA, even if you choose to only output 1 PCA band, all bands will included in the PC calculation as part of that contribution to that PC band (in this case 12 bands).
However, if you select only 8 bands in a spectral subset for input to the PCA, then you will have an 8-band contribution for the output bands, regardless of how many PC bands you choose to output.
http://www.harrisgeospati...leID/19426/2807.aspx

Ok, I get it. Thank you.

But when I visualize the statistic file. Where are the PC-bands ? In x or y (image in the link) ?

http://www.casimages.com/i/171116104042399531.jpg.html

Thanks.

The individual eigenvectors are in the columns:
http://www.harrisgeospati...leID/19426/2807.aspx

Thank you !