TIMESAT reads and writes raw, or flat, binary files, one file per image. Currently 8-bit unsigned integer, 16-bit signed integer or 32-bit signed real data are supported. Many remote sensing software packages store the data as flat binary files with auxiliary header files. In most cases these binary files can be used directly with TIMESAT without any conversion, given that they are in the correct numeric format (e.g. Idrisi, PCI CIM2, EASI).
Data in software-specific files that contain header information, are compressed, or organized differently (BIL, BIP etc.) will have to be converted. File conversion can be carried out with software such as the open source Geospatial Abstraction Data Base Library (GDAL), which can be accessed at http://www.gdal.org/index.html.
More detailed information about data conversion is given in the pdf file here.