xrit2pic runs fine on a very simple PC; it doesn't need much memory (32M should be fine).
However, especially for the wavelet decompression a fast PC is needed to translate this format in an acceptable time (2GHz: a few seconds).
Some technical information.
Each picture is represented into several (e.g. 8, or 24) small files.
Wavelet Transform (10 or 8 bits) formats will be concatenated and translated into 16 or 8 bits PGM. Code of this part of the program originates from Eumetsat, and may only be used for the purpose of MSG XRIT translations.
PGM notes
Note that 2 types of 16-bits PGM exist: Big Endian (MSByte first) and Little Endian (LSByte first). I think it is not well defined how PGM should be saved. Windows programs seem to use Big Endian, Linux (xv, IJG routines) Little Endian.
For the moment xrit2pic only generates Big Endian, but it is easy to also generate Little Endian PGM. If you need the latter one let me know!
JPEG notes
The used IJG code needed to be changed:
'Bogus Huffman table definition' error: In jdhuff.c one check has to be removed: (near line 208)
if (((INT32) code) >= (((INT32) 1) << si))
ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
Code is changed to work with both 8 and 12 bits JPEG
HDF5 notes
A new hdf5-lib is needed to support decompression of MTG. This replaces the older one, also suitable for other satellites
For GOES:
True colour (actually, 'near-true colour') needs to be fine-tuned; the formula's used don't give the desired results.
(Probably some calibration needed?). Used channels: M6C01,M6C02,M6C03.
Generated images can be very big (up to 21696x21696), which may give problems on your PC (xrit2pic is still 32-bits).
In preferences, tab Generation, subtab HDF, you can set the max. size of the generated image. Default is 5424x5424, which works fine here.
libhdf5_decompr.tgz contains a script: instal_mtglibs.sh,
running without changing will only check (not install) presence of these libs.
Missing libhdf5.so.9 results in a execution failure of xrit2pic.
Missing one of the other libs or missing above mentioned variable results in running xrit2pic, but the generated MTG
image will be empty.
