  Fast Radio Bursts (FRBs) are millisecond dispersed radio pulses of
predominately extra-galactic origin. Although originally discovered at GHz
frequencies, most FRBs have been detected between 400 to 800 MHz. Nevertheless,
only a handful of FRBs were detected below 400 MHz. Searching for FRBs at low
frequencies is computationally challenging due to increased dispersive delay
that must be accounted for. However, the wide field of view (FoV) of
low-frequency telescopes - such as the the Murchison Widefield Array (MWA), and
prototype stations of the low-frequency Square Kilometre Array (SKA-Low) -
makes them promising instruments to open a low-frequency window on FRB event
rates, and constrain FRB emission models. The standard approach, inherited from
high-frequencies, is to form multiple tied-array beams to tessellate the entire
FoV and perform the search on the resulting time series. This approach,
however, may not be optimal for low-frequency interferometers due to their
large FoVs and high spatial resolutions leading to a large number of beams.
Consequently, there are regions of parameter space in terms of number of
antennas and resolution elements (pixels) where interferometric imaging is
computationally more efficient. Here we present a new high-time resolution
imager BLINK implemented on modern Graphical Processing Units (GPUs) and
intended for radio astronomy. The main goal for this imager is to become part
of a fully GPU-accelerated FRB search pipeline. We describe the imager and
present its verification on real and simulated data processed to form all-sky
and widefield images from the MWA and prototype SKA-Low stations. We also
present and compare benchmarks of the GPU and CPU code executed on laptops,
desktop computers, and Australian supercomputers. The code is publicly
available at https://github.com/PaCER-BLINK-Project/imager and can be applied
to data from any radio telescope.
