Abstract: Viewing apparatus including a viewing surface having a viewing area, back-lighting apparatus for selectably adjusting the back-illumination of areas of the viewing surface, the areas having a given extent, the back-lighting means including: an liquid crystal array of individually controllable liquid crystal light attenuators located behind the viewing surface, each element of the array being associated with an area of the viewing surface and including active elements having a controllable opacity over an area smaller than the given extent of the area with which it is associated, and inactive areas between the active elements, a light source behind the array of light attenuators and a plurality of light guides, each associated with an element of the array and located between the element and its associated area on the viewing surface for providing controlled illumination of the associated areas including at least a portion of the space surrounding the active element.

Abstract: Apparatus having the dual function of display and optical mapping of transparencies which includes a viewing surface to which a transparency is adjacent, a segmented surface underlying the viewing surface and having a plurality of segments at least two of which have a controllable opacity, at least one photodetector underlying the segmented surface which detects light passing through the viewing surface and the segmented surface and generates detected light signals responsive to the intensity of the detected light and a mapping system which, in an opacity determination mode, sequentially varies of the opacity of selected segments and which determines the opacity of portions of the transparency based on signals supplied during such sequential variation.