1. An apparatus, comprising: a body configured to be wearable by a user on a head thereof; first and second image sensors engaged with said body, such that a first field of view of said first image sensor and a second field of view of said second image sensor comprise a region of space in front of said user, said region of space being within a reach of hands of said user; and a processor in communication with said sensors; wherein: said first and second image sensors have first and second fields of view respectively, said first and second fields of view being substantially identical; said first and second image sensors have first and second focal lengths respectively, said second focal length being longer than said first focal length; said first image sensor is adapted to capture a first image, and said second sensor is adapted to substantially simultaneously capture a second image; said processor is adapted to define in said first and second images a plurality of element sets, each said element set comprising a first element of said first image and a substantially corresponding second element of said second image; said processor is adapted to compare a relative degree of focus of said first and second elements in said element sets; said processor is adapted to assign as background element sets wherein said second element therein is as least as in-focus as said first element therein; and said processor is adapted to exclude from further analysis said element sets assigned to said background.