I'm trying to find a simple tutorial on how to detect and map burned areas from/with ILWIS . I use Landsat 5/7 or MODIS for detection. Any idea?
Unfortunately, mapping burned areas--especially across large geographic areas--is not a simple task. However, there is a lot of good documentation on how burned area products are created in peer reviewed publications.
For a regional perspective, I would refer you to the Monitoring trends in burn severity (MTBS) site. MTBS utilizes Landsat data to map all fires from 1984 - 2010 within the USA. They have extensive resources on their methods here and refer interested parties to the following publication for further details:
Burned area boundary as detected from postfire imagery
For a global perspective, check out MODIS Active Fire & Burned Area Products from the University of Maryland. There is also rigorous documentation on the methods used and refer people to the following publication:
August 2007 fires in Greece, as mapped by the MCD45 product.
Seems that the main issue is to find an algorithm (and it seems that you do not have one). If you have needed algorithm, it doesn't matter in which image-processing soft to use it. Check out FIRMS site for fire data derived from MODIS. There you can find list of publications that may proof useful to you. There is a great article Giglio, L., van derWerf, G. R., Randerson, J. T., Collatz, G. J., and Kasibhatla, P. 2006. Global estimation of burned area using MODIS active fire observations. Atmospheric Chemistry and Physics 6:957-974. doi:10.5194/acp-6-957-2006. Also take a look at this article with a more step-by-step guide. It is in Russian, but I hope that google-translate will help you.
Also if you have an academic interest I may provide you with contacts of scientist who have studied this subject a lot.