Hello fellow ENVI users: The argument 'out_name' in envi_avhrr_calibration_doit (and all other envi_doits) expect a string and does not allow sending the result of an expression. Placing the doits in a loop for batch processing will only write over the same files. How can I save the results of each loop if I cannot change the output file name? Thanks Spiros ENVI+IDL 4.2 on WindowsXP