I'm a beginner to IDL. I"ve been using the ENVI gui for a year, but IDL 4.7 is foreign to me. I think I need to use it because I have 150 MrSid aerial images that I need to classify in some sort of batch mode. I could also mosaic them, but envi freezes every time I try to mosaic more than 10. I'm first looking for a resource on basics of how to use scripts people provide in the forum. The only thing I know how to do in IDL is open via the GUI in IDL 7.1. Here's my plan. 1.Resample image to twice the resolution (so dataset is smaller) 2. Classify into some basic classes- I was told to use segmentation here, but I don't have the ENVI EX application. I want to be able to pick out deciduous, evergreen, fields, and lawns. (Water and developed areas are also in the scenes). 3. Mosaic classified images ---so that I can bring mosaic into arcgis and convert to shapefile. Any advice on how to get started - or where to go for clear instructions- would be much appreciated.