The optical properties and physical machanism of electron--trapping materials outputting red light were investigsted in derail. The possibility of image storage and parallel incoherent image subtraction was experimentally demonstrated, using electtontrapping film whose thickness is approximately 200 μm. The experimental results show that this material has many attractive advantages such as: erasable, rewrituble, high resolution, high speed, and capable of analog and peallel operations, for application in optical storage and optical processing.