Polarization-difference imaging: a biologically inspired technique for observation through scattering media

Abstract

Many animals have visual systems that exploit the polarization of light, and some of these systems are thought to compute difference signals in parallel from arrays of photoreceptors optimally tuned to orthogonal polarizations. We hypothesize that such polarization-difference systems can improve the visibility of objects in scattering media by serving as common-mode rejection amplifiers that reduce the effects of background scattering and amplify the signal from targets whose polarization-difference magnitude is distinct from the background. We present experimental results obtained with a target in a highly scattering medium, demonstrating that a manmade polarization-difference system can render readily visible surface features invisible to conventional imaging.

Contrast enhancement in polarimetric imaging with correlated noise fluctuations

“…Using such a polarimetric imaging scheme, it is possible to implement various image representations to enhance the contrast of polarimetric non-uniformities in a given scene. Some of the widely used representations that work with varying degrees of performance are OSC image (denoted by γ OSC = (X − X ⊥ )/(X + X ⊥ )) [10] and polarization difference image (denoted by γ ∆ = X − X ⊥ ) [9]. In general, it is interesting to quantitatively compare the best contrast that can be obtained using polarimetric imaging w.r.t.…”

PD Based Determination of Polarized Reflection Regions in Bad Weather

“…The concept of PDI is detailed in various literatures [2,6,11]. The light intensity entering a camera can be decomposed into the intensities of the portions of light linearly polarized along two orthogonal directions.…”

Biologically Motivated Representational Schemes for Mapping Polarization Information into Visual Information

“…Indeed, in our previous work we have shown that "biologically inspired polarization-differencing" can extend the distance over which objects can be reliably detected in scattering media up to 3-fold even under conditions when the fractional polarization reaching the detector is less than 1% [18][19][20] Extending the distance for detection and classification of objects near the limit of Page3 visibility increases the time for critical, survival-relevant decisions, and is thus a major advantage in many real-time applications.…”

“…In addition to its ability to provide previously unavailable information about scenes, polarization-difference imaging (PDI) improves target detectability in scattering media [18][19][20]. In our previous effort, we investigated the relationship between polarization-sum 1 ' (PS) and polarization-difference (PD) 1 information to determine if the two types of information could be combined into a single image to further enhance target identification [20].…”