Re-encoding image sets using frequency-domain differences

摘要

Approaches to re-encoding image sets using frequency-domain differences, along with corresponding approaches to reversing the re-encoding of the image sets. For example, a re-encoding tool computes frequency-domain differences between (a) quantized coefficients for a block from encoded data in a first format and (b) quantized coefficients for a prediction of the block. The re-encoding tool entropy codes the frequency-domain differences, producing encoded data in a second format for the compressed images. Such re-encoding can significantly reduce storage cost for previously compressed images, compared to the storage cost for the previously compressed images in the first format, without hurting image quality. Subsequently, the previously compressed images in the first format can be recovered from the encoded data in the second format. Or, the encoded data in the second format can be decoded to reconstruct the images.

主权项

1. In a computing system, a method comprising:
decoding first encoded data for a set of multiple images; and re-encoding at least one image of the set of multiple images and producing second encoded data for the set of multiple images, including:
determining a prediction relative to one or more reference images;computing quantized coefficients for the prediction;computing frequency-domain differences between the quantized coefficients for the prediction and corresponding quantized coefficients that are represented in the first encoded data; andentropy coding the frequency-domain differences.