Deep Quality Enhancement of Adaptive Downscaled Coding for Image Compression

    公开(公告)号:US20200053362A1

    公开(公告)日:2020-02-13

    申请号:US16100310

    申请日:2018-08-10

    Applicant: Apple Inc.

    Abstract: Techniques are disclosed for coding image data adaptively at different levels of downscaling. Such techniques may involve partitioning input data into pixel blocks for coding and performing content analysis on the pixel blocks. The pixel blocks may be input to block coders that operate at different pixel block sizes, which may code the pixel blocks input to them at their respective sizes. Except when a block coder operates at the partitioning size, block coders that operate at different pixel block sizes may perform downscaling of the pixel blocks to match their size with the block coders' respective coding size. A block decoder may invert the coding operations performed by the block coders, decoding coded image data at respective pixel block sizes, then upscaling decoded image data obtained therefrom to a common pixel block size. Image reconstruction may synthesize a resultant image from the decode pixel block data output by the decoders. Quality enhancements may be added by neural network processing systems that have been trained to other segmented images.

    TECHNIQUES FOR REDUCING CODING ARTIFACTS IN CODING SYSTEM

    公开(公告)号:US20230070492A1

    公开(公告)日:2023-03-09

    申请号:US17886858

    申请日:2022-08-12

    Applicant: Apple Inc.

    Abstract: Techniques for reducing reduce coding artifacts in video data are disclosed. In one aspect, a frame of video data is partitioned into pixel blocks, which are organized into slices. The pixel blocks of each slice are coded by a compression algorithm and an estimate of coding artifacts in the slice is made. For slices that are estimated to possess coding artifacts, the method revises coding parameters applied to pixel blocks in the slice and recodes the slice. The method substitutes recoded slices for originally-coded slices in frame, working in a priority order from a slice with the highest estimated likelihood of coding artifacts down to slices with lower estimated likelihoods of coding artifacts, measuring changes in the frame's coding size as it goes. The likelihood of coding artifacts can be estimated from slice statistics that may be developed from a comparison of transform coefficients among the pixel blocks within a slice, from an evaluation of transform coefficients of a pixel block with a slice that is estimated to have a lowest spatial complexity, or from coded luma data of the pixel blocks within a slice. In a further aspect, slice statistics may be computed from pixel block data only for a subset of slices within a frame. Slice statistics for other slices may be derived from the statistics of neighboring slices. In another aspect, a method may revise coding parameters in iterative fashion working from an initialized value and estimate (without recoding them) data sizes of coded slices that may be obtained from the revised parameters. As the method operates, it may compare the coding parameters to parameters used in a first iteration of coding and terminate the iterative process for that slice if the first iteration coding parameters are higher than the revised parameter.

    Deep quality enhancement of adaptive downscaled coding for image compression

    公开(公告)号:US10764588B2

    公开(公告)日:2020-09-01

    申请号:US16100310

    申请日:2018-08-10

    Applicant: Apple Inc.

    Abstract: Techniques are disclosed for coding image data adaptively at different levels of downscaling. Such techniques may involve partitioning input data into pixel blocks for coding and performing content analysis on the pixel blocks. The pixel blocks may be input to block coders that operate at different pixel block sizes, which may code the pixel blocks input to them at their respective sizes. Except when a block coder operates at the partitioning size, block coders that operate at different pixel block sizes may perform downscaling of the pixel blocks to match their size with the block coders' respective coding size. A block decoder may invert the coding operations performed by the block coders, decoding coded image data at respective pixel block sizes, then upscaling decoded image data obtained therefrom to a common pixel block size. Image reconstruction may synthesize a resultant image from the decode pixel block data output by the decoders. Quality enhancements may be added by neural network processing systems that have been trained to other segmented images.

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