Conceptual

Entropy-Gradient Proxy and Optimal Vector Quantization for Neural Image Codecs

Two inference-time techniques for improving off-the-shelf pretrained neural image and video codecs without retraining. A predefined optimal uniform vector quantization replaces scalar quantization of the latent, and the entropy gradient available at the decoder is used as a proxy for the reconstruction-error gradient, which the decoder cannot compute, to refine the latent and lower the bitrate at equal quality.