An angularly multiplexed store contains filters derived from prior examination of input image reference samples, a spectrum analyzer produces spectral data representing the frequency spectrum of the input image under examination, a computer produces an encoded map of the spectral data representing the input image frequency spectrum. The encoded map is transformed, inputted into the store while close match spectral correlation light beams emerge from the multiplexed store, each having an emerging angle associated with that filter within the multiplexed store producing a close match with the first transform. An array of light beam detectors and a display present images having colors that indicate the nature of the input image such as a type of cancer. An associated memory-retro-reflector arrangement displays characters naming the materials making up the input image such as types of abnormal tissue. The disclosed apparatus can have significant application in medicine, food industry, spectroscopy, material science and other various areas.