The best advice for a beginner to IDL, who has Landsat 7 TM data files, is to view them through one of RSI's other main products, ENVI. ENVI automatically opens Landsat images, regardless of their data formatting and provides a trememdous number of built-in controls for their analysis. In IDL, Landsat images would be imported according to their "file format". I believe that Landsat images are usually TIFF images or HDF 4 images. IDL has a fairly straghtforward set of routines for reading '.tif' files. For example, the following lines: if query_tiff(my_landsat_file) then $ image_data = read_tiff(my_landsat_file, GEOTIFF=my_geotiff_struct, $ ORIENTATION=orientation might be all you need to acquire the specific data and "metadata" you are looking for within your Landsat file. Look at IDL's Online Help for QUERY_TIFF and READ_TIFF for more details. HDF files are much more complex than TIFF files, and you should probably read IDL's Online Help manual chapter "Hierarchical Data Format" in 'Contents -> Reference Guides ->Scientific Data Formats'. In a subchapter of this manual 'Creating HDF Files -> Examples -> HDF Examples', you will find links to two examples (which are distributed with IDL 6.2), which demonstrate the code for querying, writing and reading the contents of an HDF 4 file. James Jones