  Spatial-light-modulator (SLM)-based tunable sources have complex setups. A
simpler setup, comprising an SLM-projector and a dispersive element,
synthesizes light as effectively, based on a Superposition of Newtonian Spectra
(SNS). As a generalization of SNS, two-dimensional (2-D) grayscale videos are
spectrally encoded on a one-dimensional (1-D), translucent screen, and viewed
through another dispersive element. This Projected-Image Circumlineascopy
(PICS) produces semitransparent, rainbow-coloured, virtual 2-D videos that face
every viewer anywhere around the 1-D screen. They are invariant under
reflection of the 1-D screen in mirrors parallel to it. SNS bandwidth and PICS
image geometry are calculated using geometric optics and Dispersion Diagrams.
