Dario, ENVI is one of the best remote sensing software. ENVI EX is a simplified version. ENVI + IDL is a complete version that implements the IDL programming languaje.

To begin, I would suggest you use qGIS+Semi-Automatic Classification Plugin for QGIS: it is free software, and it has all you need for your purpose.ENVI covers nearly every aspect of remote sensing. The Semi-Automatic Classification Plugin for QGIS is conceived for Land Cover clasification and Land Change analysis. 

Moreover, you can go beyond by using qGIS+GRASS+SAGA+R+ORFEO... everything in the same interface because of qGIS is a scalable software.  

Hi Oliver

Thanks for sharing your expertise. I'll go for ENVI+IDL this time then, but knowing about the open source alternatives is certainly useful and important for my independent research interests. I'll get the plugin installed in my personal computers. 

Best regards.   

You make a good choice! Really, I prefer ENVI over ERDAS. I still use Idrisi (now is called Terrset) because of it has great classification algorithms, and, complementarely, I often use GRASS-SAGA: for example, you can calculate the topographic correction using these tools.

Dario,

ENVI EXE is useful for all RS image processing activities. But if you are also interested in programming in ENVI then IDL may be preferred.