An image altering apparatus which provides confidential viewing of a video display by means of time multiplexing the fundamental display image with a color-inverted image thereof on a pixel-by-pixel basis. Electronic circuitry and/or software are utilized to modify the fundamental image signal by time multiplexing its color data components with corresponding inverse color data components to generate a compound image signal which is representative of a substantially featureless image. Different multiplexing sequences of color data components and inverse color data components may be utilized at varying duty cycles to generate a compound image which is highly confidential and secure from unauthorized viewing. The fundamental image may be decoded and viewed only by those viewing the encoded image through specially designed eyeglasses incorporating time synchronized LCD shutters, variable polarizers, or color filters, which can selectively block inverted color components and/or demodulate the fundamental image to allow only the true fundamental color components to pass, thereby providing confidential and highly secure viewing of the fundamental image by the viewer.