Parameters | Import | Background Correction

Background Correction
USe this drop-down menu to choose a method for adjusting background noise.
You can launch R and submit "library(affy); ? expresso;" for details of each option.
Note: R-Library affyPLM is required for the gcrma option. You can download this library from
To Specify a Method for Background Correction:
Click the Background Correction drop-down box.