You can use the HIS algorithm to get the channel statistics. The example below shows how to run HIS on one image channel. If you wish to output the results to a report file you can implement the Report class. The answer to a previous question outlines how to create a report: http://support.pcigeomatics.com/hc/communities/public/questions/203566673-Write-report-to-file-in-python
from pci.his import his image = r"C:\PCI Geomatics\Geomatica 2015\demo\irvine.pix" imstat =  his(file=image, dbic=, imstat=imstat)
You will notice above that an empty list "imstat" is created before HIS is run. This empty list will be populated with the channel statistics from the "imstat" output parameter. If multiple channels are listed, the channel information from the last channel will be written out to the imstat parameter. In the example above the statistics from channel 1 will be written to the stats variable There are 13 values added to this list after HIS is run. A list of the 13 values is available from the Geomatica help: http://www.pcigeomatics.com/geomatica-help/index.html?page=references%2Fpcifunction_r%2Fpython%2Fp_his.html
You can create other variables for each statistic from imstat. Keep in mind that the first imstat value (channel number) would be imstat as per python’s numbering scheme.
channel = imstat mean = imstat median = imstat print channel, mean, median
Hope this helps,