  Various solar features can be seen on maps of the Sun in the mm and sub-mm
wavelength range. The recently installed Atacama Large Millimeter/submillimeter
Array (ALMA) is capable of observing the Sun in that wavelength range with an
unprecedented spatial, temporal and spectral resolution. To interpret solar
observations with ALMA the first important step is to compare ALMA maps with
simultaneous images of the Sun recorded in other spectral ranges. First we
identify different structures in the solar atmosphere seen in the optical, IR
and EUV parts of the spectrum (quiet Sun (QS), active regions (AR), prominences
on the disc, magnetic inversion lines (IL), coronal holes (CH) and coronal
bright points (CBPs)) in a full disc solar ALMA image. The second aim is to
measure the intensities (brightness temperatures) of those structures and
compare them with the corresponding QS level. A full disc solar image at 1.21
mm obtained on December 18, 2015 during a CSV-EOC campaign with ALMA is
calibrated and compared with full disc solar images from the same day in
H\alpha, in He I 1083 nm core, and with SDO images (AIA at 170 nm, 30.4 nm,
21.1 nm, 19.3 nm, and 17.1 nm and HMI magnetogram). The brightness temperatures
of various structures are determined by averaging over corresponding regions of
interest in the ALMA image. Positions of the QS, ARs, prominences on the disc,
ILs, CHs and CBPs are identified in the ALMA image. At 1.21 mm ARs appear as
bright areas (but sunspots are dark), while prominences on the disc and CHs are
not discernible from the QS background, although having slightly less intensity
than surrounding QS regions. ILs appear as large, elongated dark structures and
CBPs correspond to ALMA bright points. These results are in general agreement
with sparse earlier measurements at similar wavelengths. The identification of
CBPs represents the most important new result.
