Optimally Controllable Perceptual Lossy Compression
This work addresses the challenge of controlling perceptual quality in compression for applications like image and video processing, offering a more efficient and theoretically grounded approach compared to existing methods.
The paper tackles the tradeoff between distortion and perceptual quality in lossy compression by proving that only two decoders—a minimum MSE decoder and a perfect perceptual decoder—are sufficient to achieve arbitrary points on the D-P tradeoff bound through linear interpolation, with experiments showing state-of-the-art performance.
Recent studies in lossy compression show that distortion and perceptual quality are at odds with each other, which put forward the tradeoff between distortion and perception (D-P). Intuitively, to attain different perceptual quality, different decoders have to be trained. In this paper, we present a nontrivial finding that only two decoders are sufficient for optimally achieving arbitrary (an infinite number of different) D-P tradeoff. We prove that arbitrary points of the D-P tradeoff bound can be achieved by a simple linear interpolation between the outputs of a minimum MSE decoder and a specifically constructed perfect perceptual decoder. Meanwhile, the perceptual quality (in terms of the squared Wasserstein-2 distance metric) can be quantitatively controlled by the interpolation factor. Furthermore, to construct a perfect perceptual decoder, we propose two theoretically optimal training frameworks. The new frameworks are different from the distortion-plus-adversarial loss based heuristic framework widely used in existing methods, which are not only theoretically optimal but also can yield state-of-the-art performance in practical perceptual decoding. Finally, we validate our theoretical finding and demonstrate the superiority of our frameworks via experiments. Code is available at: https://github.com/ZeyuYan/Controllable-Perceptual-Compression