Optical encryption for large-sized images using random phase-free method
This work addresses noise reduction in optical encryption for large images, but it appears incremental as it builds on existing methods.
The authors tackled the problem of speckle noise in optical encryption of large images by proposing a random phase-free method and scaled diffraction, achieving reduced noise and enabling encryption beyond the encrypted image size.
We propose an optical encryption framework that can encrypt and decrypt large-sized images beyond the size of the encrypted image using our two methods: random phase-free method and scaled diffraction. In order to record the entire image information on the encrypted image, the large-sized images require the random phase to widely diffuse the object light over the encrypted image; however, the random phase gives rise to the speckle noise on the decrypted images, and it may be difficult to recognize the decrypted images. In order to reduce the speckle noise, we apply our random phase-free method to the framework. In addition, we employ scaled diffraction that calculates light propagation between planes with different sizes by changing the sampling rates.