Most
present and future vision applications including automotive,
biometric, security and mobile computing applications operate in
unconstrained environments and have to cope with unknown and widely
varying illumination conditions. Even when illumination conditions do
not saturate an image sensor, the vision system has to account for
object appearance variations caused by illumination. By eliminating
illumination-induced variations from the raw optical images the
proposed sensor will eradicate the vision system’s vulnerability to
illumination variations and signal loss due to high dynamic range.
This
adaptive CMOS image sensor will estimate and largely eliminate
illumination variations in sensed optical images, thus reporting
electronic images that are indicative of the reflectance of the
viewed scene. The core innovation is in a signal processing technique
for estimating the illumination field from sensed images. The
technique efficiently implements as a dense, on-chip, massively
parallel analog processor, distributed among the photo-detectors to
produce a reflectance sensitive image sensor.
Image
sensors are rapidly finding their way into people’s cars,
cell-phones, personal digital assistants, medical and diagnostic
equipment, automated drug discovery, cutting edge security,
surveillance and biometric systems. To fully realize the potential of
electronic imaging in society, the image sensors will need to adapt
and provide useful images most of the time, even under the harshest
of illumination conditions.
