You can use the Landsat TM calibration tool in ENVI to obtain the necessary calibration parameters via the web and then apply them to each one of your input bands separately. For the following example, I am going to assume that you have downloaded data from the Global Land Cover Facility website, but the steps should work for any single-band downloaded data in GeoTIFF format as long as you have enough information about the data. If your data are not stored in single-band GeoTIFF format, you will want to save each band to GeoTIFF before proceeding. - Go to Basic Tools->Preprocessing->Calibration Utilities->Landsat TM and supply the name of your first GeoTIFF file. In this example, I'll supply a file named "p135r097_7t20010131_z43_nn10.tif" that represents the first band from a Landsat 7 ETM+ scene at Path 135, Row 97. It was acquired on 01/31/2001. All of that information is present in the filename, but should also available in the metadata for the scene. - In the next window, make sure that the radio button is set to "ETM+ 7" and then click on "Get Calibration Parameters from Web." You will likely receive an error message about the file not following the correct naming convention, which then generates a new window that allows you supply enough information about the data for ENVI to retrieve the calibration parameters. - Select the Date/Path/Row/Band option, supply the required information, then click OK, which should return you to the first window. Choose an output filename and click OK. - Repeat this process for each band of data. When done, you can stack the bands together into a new composite file. If you are only interested in Bands 1-5 and 7, use File->Save File As. If you want to include the thermal bands (6_1, 6_2), you will have to use Layer Stacking due to the difference in spatial resolutions between the reflectance and thermal bands.