Simultaneous Encryption/Compression of Images Using Alpha Rooting

Significant work has been done in the areas of image encryption and compression as two independent problems, yet the two areas are strongly interleaved and should be considered simultaneously. Consider that current practice in image processing generally uses encryption on compressed image data or attempts to compress data that has already been encrypted. However, it is generally seen that traditional encryption techniques degrades compression. In this paper, we propose a novel method which prepares an image for compression while simultaneously encrypting the image data. We perform this using the well known alpha rooting algorithm. By increasing the relative magnitudes of the DCT transform coefficients, we are able to simplify the image in a way which makes it indiscernible, while also higher compression ratios. We demonstrate encryption and compression performance using the independent group JPEG algorithm, showing compression ratios and error metrics including MSE and SSIM for a collection of images.