  With the advent of space missions, like SPITZER and ASTRO-F, with sensitive
detectors in the near- and mid-infra red covering a reasonable field-of-view
and having a good spatial resolution, it will be possible to detect individual
AGB stars in Local Group galaxies. The filters used by these missions are
non-standard and different from mission to mission.
  In this paper, the colours of mass-losing AGB and post-AGB stars are
calculated in the broad-band filters of the SPITZER and ASTRO-F missions, as
well as Bessell V,I and 2MASS J,H,K to connect these results to existing
ground-based data.
  The models are calculated for carbon- and oxygen-rich chemistry and cover
different effective temperatures and dust compositions.
