The goal of the project is to develop an ultra-fast and compact
processor with supercomputer performance and optimized for pattern
recognition, data reduction,
and fast information extraction for high-quality image processing.
The proposed hardware prototype provides sufficient flexibility for
applications in a wide
range of fields, e.g.
triggering
in High Energy Physics experiments as well as
simulating functions
of the human brain.
We are also studying new applications in the field of vision: fast
extraction of the most relevant features from static images
as well as from movies. In general, any artificial intelligence process based
on massive pattern recognition can largely profit from our devices.
The only necessary condition is that
data are suitably prepared and formatted.
For a long time, the primary goal of our research team has been online
track reconstruction at hadron colliders experiments. This is a crucial
task for the success of an experiment. Since only a minimal fraction of
the produced collider events can be written to tape to perform physics
analysis, online reconstruction of the detector information is vital
to select the most interesting events. The left figure
gives an adequate idea of the task complexity: thousands of
particles are produced in each bunch crossing, that is called "event"
in our language. This level of confusion is due to the extremely high
luminosity that is necessary to produce rare particles, as the Higgs
boson, at an appreciable rate. These conditions are going to worsen
in the future experiments, as the very high luminosity LHC data taking
condition expected in the next few years.
Applications in this field usually require
huge computing resources. Nonetheless, a clever use of the
modern, flexible, and powerful electronic resources
results in smart
solutions that save money, energy (lower consumption),
and space (more compact systems).
Since the trend of combining
CPUs with ASICs or FPGA-based hardware has been expanding in the
real-time, massive, computing realm, we implemented an innovative strategy,
based on the optimal mapping of a complex algorithm on different technologies.
Our purpose is to get the best results by combining the high performance
of rigid dedicated hardware with the distinctive flexibility of
general-purpose, but lower-performance, CPUs.
The architecture's key role is played by high-level field programmable
gate arrays (FPGA), while most computing power is provided by
cooperating full-custom ASICs named
Associative Memories (AM).
The AM chip is suitable for massive parallelism in data correlation
searches and it is the most ingenious piece of the entire system.
It takes full advantage of the intrinsic parallel nature of the
combinatorial problem by comparing at once the image under analysis
to a set of precalculated "expectations", or patterns. This approach
reduces to linear the exponential complexity of CPU-based algorithms
and the problem is solved by the time data are loaded into the chip.
The above figure shows the filtering action performed by the AM on
a very simple Higgs event made by only 4 muons, but hidden by 30
superimposed, soft, and not interesting interactions. By filtering only
energetic particles the Higgs event is clearly observable in the bottom
figure, where the 4 four green muons are clearly visible.
The associative memory can provide its filtering function
also to images of different nature. The AM-based processor
can simulate the preliminary image processing stages
performed by brain,
such as the
identification of shape edges.
At this level, convincing models for the
validation of hypotheses about the brain functioning are
very similar to the internal AM architecture. Therefore, our hardware
processor could implement fast pattern selection/filtering of the type
studied in these models of human vision or other brain functions.
In particular, strong data reduction of external stimuli before higher
level processing is essential in (high rate) background filtering and
information extraction from time-changing images for movement
identification and its simulations are onerously implementable,
if at all, in usual supercomputers.
This approach could be essential in brain neurophysiologic studies.
Recent advances in ICT and neuroscience allowed to study and model
"in silico" a significant part of the human brain. The brain is
certainly the most complex, powerful and fast processing engine
and its study is very challenging. Understanding how brain
processes information as well as how it communicates with the
peripheral nervous system provide new potential applications,
new computational system that emulate human skills (e.g. by using
the directed fusion of diverse sensors information) or exploit
underlying principles for new forms of general purpose computing.
Significant improvementes could be achieved in terms of
performance, fault tolerance, resilience or energy comsumption
over traditional ICT approaches.
Using the associative memory processor for brain studies is
particularly fascinating. The most convincing models that try to
validate brain functioning hypotheses are extremely similar to
the real time architectures developed for High Energy Physics experiments.
A multilevel model
seems appropriate also to describe the brain organization to
perform a synthesis certainly much more impressive than what done
in HEP triggers. The AM pattern matching has proven to play a
key role in high rate filtering/reduction tasks. We can test the
AM device capability as th first level of this process, dedicated
to external stimuli pre-processing. We follow the conjecture [1]
that brain works by dramatically reducing input information by
selecting for higher-level processing and long-term storage
only the input data that match a particular set of memorized
patterns. The double constraint of finite computing power and
finite output bandwidth determines to a large extent what type
of information is found to be "meaningful" or "relevant" and
becomes part of higher level processing and longer-term memory.
The AM-based processor will be used for a real-time hardware
implementation of fast pattern selection/filtering of the type
studied in these models of human vision and other brain functions.
The bottom row of the above figure shows image quality when filtering
by accepting only the "good patterns" stored in the AM. We could
apply this filtering function to medical images, to extract the
relevant features and apply complex but fast reconstrction
algorithms. The extracted features could be measured in a very
short time. This would allow to provide a quasi-automatized
preliminary computer-aided diagnosis. The reduction of execution
time of image reconsturction to be applied after the AM filtering
function, would exploit the computing power of parallel arrays
of Field Programmable Gate Arrays (FPGAs) as we do in FTK to
identify clusters of contiguous pixels above a programmable
threshold. As images are processed and measurements relative
to their shapes are provided, a more accurate analysis of
the interesting objects for medical analysis, for example
if there are spots and if they are circular of irregulas,
can be performed. With further studies these algorithms
can be improved to allow 3D imaging.
[1] Del Viva M.M., Punzi G., Benedetti D, "Information and Perception of
Meaningful Patterns",
PLoS ONE
8(7): e69154.
doi:10.1371/journal.pone.0069154.