Comment 9 for bug 1442050

The 1.3.1 changelog:

Version 1.3.1
~~~~~~~~~~~~~
Released: 2015-11-27

New Features:
 - Add a sensor error for missing dark calibration (Richard Hughes)
 - Add g_autoptr() defines for cd_color* (Richard Hughes)
 - Add get-spectral-reading command to colormgr (Richard Hughes)
 - Add the GetSpectrum() sensor D-Bus method (Richard Hughes)
 - Allow returning spectral readings from the Spark sensor (Richard Hughes)
 - libcolord: Add an error enum for missing irradiance calibration (Richard Hughes)
 - libcolord: Add a spectral sensor capability (Richard Hughes)
 - libcolord: Add cd_sensor_get_spectrum() (Richard Hughes)
 - libcolord: Add cd_spectrum_get_value_max() (Richard Hughes)
 - libcolord: Add cd_spectrum_limit_min() (Richard Hughes)
 - libcolord: Add cd_spectrum_planckian_new_full() (Richard Hughes)
 - libcolord: Add cd_spectrum_resample() (Richard Hughes)
 - libcolord: Add cd_spectrum_set_wavelength_cal() (Richard Hughes)
 - libcolord: Add cd_spectrum_subtract() (Richard Hughes)
 - libcolord: Add cd_spectrum_to_string() (Richard Hughes)

Bugfixes:
 - Add a systemd user service corresponding to the D-Bus session service (Simon McVittie)
 - Add a tmpfiles.d snippet to fix stateless systems (Tobias Hunger)
 - data: Build Rec709 correctly (Richard Hughes)
 - Ignore the ColorHug+ in DFU mode (Richard Hughes)
 - Install the tmpfiles.d snippet in the right place (Richard Hughes)
 - Reset the sensor back to idle after each action (Richard Hughes)
 - libcolord: Fix a tiny memory leak in cd_icc_get_tag_data() (Richard Hughes)
 - libcolord: Fix saving non-normalized spectra (Richard Hughes)
 - libcolord: Make cd_spectrum_free() NULL-safe (Richard Hughes)
 - libcolord: Return an error when we fail to estimate the gamma value (Richard Hughes)

https://github.com/hughsie/colord/blob/master/NEWS