First, stand very still in very bright light. 800 telescopes aimed at your face and focus a small area of light from each of the telescopes onto an adjacent thin ribbon that expands or contracts depending on how much light is hitting it. Each of the 800 ribbons will expand or contract more or less depending on how much light is hitting them.
The ribbons are attached to a series of levers that amplify the minute movements into something on the order of a half inch or so. This movement is transferred over distance to a series of wheels arrayed in a grid forming pixels.
These wheel/pixels have dozens of faces on them ranging from white to black, shades of grey being between the two extremes. Depending on how much they are turned by the heated ribbon-to-thread amplification mechanism, they turn a white, black or somewhere in between face to the viewer forming a picture.
So if a telescope is aimed at a bright portion of the face, it will heat the ribbon enough to turn the wheel all the way to the white portion. If a telescope is aimed at a dark portion of the face, it will not heat the ribbon and thus the wheel will remain in it's "dark side facing out" position. If it's halfway between dark and light, the wheel will turn halfway showing a matching grey face to the viewer.
It would take a minute or two for the image to "cook" but it should probably yield a recognizable image.-- doctorremulac3, May 02 2015random, halfbakery