Dear All Out of https://www.harrisgeospatial.com/docs/enviradiometriccalibrationtask.html, I took the L8Calibrate.pro example, did the modification that is suitable to my needs. Although when running it this message is appearing: % Expression must be a scalar or 1 element array in this context: . % Execution halted at: $MAIN$ Here is the modified script: PRO L8CALIBRATE COMPILE_OPT IDL2 ; Start the application e = ENVI(/HEADLESS) ; A Landsat 8 OLI dataset consists of one TIFF file per band, ; with an associated metadata file (*_MTL.txt). Open the ; metadata file to automatically read the gains and offsets. File = File_Search('C:\Users\cesar.guerreiro\Desktop\PROP_PPGG\Trial1\LC8', '*_MTL.txt') Raster = e.OpenRaster(File) ; Get the radiometric calibration task from the catalog of ENVI tasks. Task = ENVITask('RadiometricCalibration') ; Define inputs. Since radiance is the default calibration method ; you do not need to specify it here. Task.Calibration_Type = 'Top-of-Atmosphere Reflectance' Task.Input_Raster = Raster[0] ; Bands 1-7 Task.Output_Data_Type = 'Float' ; Define output raster URI Task.Output_Raster_URI = e.GetTemporaryFilename() ; Run the task Task.Execute ; Get the data collection DataColl = e.Data ; Add the output to the data collection DataColl.Add, Task.Output_Raster ; Close the ENVI session e.Close END -------- printing File, as print, File, my list is there: C:\Users\cesar.guerreiro\Desktop\PROP_PPGG\Trial1\LC8\LC82170762016111LGN00_MTL.txt C:\Users\cesar.guerreiro\Desktop\PROP_PPGG\Trial1\LC8\LC82200782016164LGN00_MTL.txt C:\Users\cesar.guerreiro\Desktop\PROP_PPGG\Trial1\LC8\LC82200792016164LGN00_MTL.txt C:\Users\cesar.guerreiro\Desktop\PROP_PPGG\Trial1\LC8\LO82220612013153LGN00_MTL.txt What I am letting pass by? Thanks in advance Diniz