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    Interpolation of reshaping functions
    1.
    发明授权
    Interpolation of reshaping functions 有权

    公开(公告)号：US11388408B2

    公开(公告)日：2022-07-12

    申请号：US17299743

    申请日：2019-11-27

    申请人： Dolby Laboratories Licensing Corporation

    发明人： Harshad Kadu ,  Qing Song ,  Guan-Ming Su

    IPC分类号： H04N19/132 ,  H04N19/182 ,  H04N19/169 ,  H04N19/98

    摘要： Methods and systems for generating an interpolated reshaping function for the efficient coding of high-dynamic range images are provided. The interpolated reshaping function is constructed based on a set of pre-computed basis reshaping functions. Interpolation schemes are derived for pre-computed basis reshaping functions represented as look-up tables, multi-segment polynomials, or matrices of coefficients in a multivariate, multi-regression representation. Encoders and decoders using asymmetric reshaping and interpolated reshaping functions for mobile applications are also presented.

    Tensor-product b-spline predictor
    5.
    发明授权
    Tensor-product b-spline predictor 有权

    公开(公告)号：US11962760B2

    公开(公告)日：2024-04-16

    申请号：US17764394

    申请日：2020-09-29

    申请人： DOLBY LABORATORIES LICENSING CORPORATION

    发明人： Guan-Ming Su ,  Harshad Kadu ,  Qing Song ,  Neeraj J. Gadgil

    IPC分类号： H04N19/105 ,  H04N19/132 ,  H04N19/154 ,  H04N19/196 ,  H04N19/436

    CPC分类号： H04N19/105 ,  H04N19/132 ,  H04N19/154 ,  H04N19/196 ,  H04N19/436

    摘要： A set of tensor-product B-Spline (TPB) basis functions is determined. A set of selected TPB prediction parameters to be used with the set of TPB basis functions for generating predicted image data in mapped images from source image data in source images of a source color grade is generated. The set of selected TPB prediction parameters is generated by minimizing differences between the predicted image data in the mapped images and reference image data in reference images of a reference color grade. The reference images correspond to the source images and depict same visual content as depicted by the source images. The set of selected TPB prediction parameters is encoded in a video signal as a part of image metadata along with the source image data in the source images. The mapped images are caused to be reconstructed and rendered with a recipient device of the video signal.

    Cascade prediction
    6.
    发明授权
    Cascade prediction 有权

    公开(公告)号：US11838531B2

    公开(公告)日：2023-12-05

    申请号：US17781165

    申请日：2020-12-03

    申请人： Dolby Laboratories Licensing Corporation

    发明人： Harshad Kadu ,  Guan-Ming Su

    IPC分类号： H04N19/50 ,  H04N19/186 ,  H04N19/169

    CPC分类号： H04N19/50 ,  H04N19/186 ,  H04N19/1887

    摘要： A first predictor is applied to an input image to generate first-stage predicted codewords approximating prediction target codewords of a prediction target image. Second-stage prediction target values are created by performing an inverse cascade operation on the prediction target codewords and the first-stage predicted codewords. A second predictor is applied to the input image to generate second-stage predicted values approximating the second-stage prediction target values. Multiple sets of cascade prediction coefficients are generated to comprise first and second sets of cascade prediction coefficients specifying the first and second predictors. The multiple sets of cascade prediction coefficients are encoded, in a video signal, as image metadata. The video signal is further encoded with the input image.

    RATE-CONTROL-AWARE RESHAPING IN HDR IMAGING
    7.
    发明申请
    RATE-CONTROL-AWARE RESHAPING IN HDR IMAGING 有权

    公开(公告)号：US20230039038A1

    公开(公告)日：2023-02-09

    申请号：US17780895

    申请日：2020-11-25

    申请人： Dolby Laboratories Licensing Corporation

    发明人： Harshad Kadu ,  Ji Qi ,  Guan-Ming Su

    IPC分类号： H04N19/186 ,  H04N19/146

    摘要： Given an input image in a high dynamic range (HDR) which is mapped to a second image in a second dynamic range using a reshaping function, to improve coding efficiency, a reshaping function generator may adjust the codeword range of the HDR input under certain criteria, such as for noisy HDR images with a relatively-small codeword range. An example of generating a scaler for adjusting the HDR codeword range based on the original codeword range and a metric of the percentage of edge-points in the HDR image is provided. The adjusted reshaping function allows for more efficient rate control during the compression of reshaped images.

    Low-complexity lookup table construction with reduced interpolation error
    8.
    发明授权
    Low-complexity lookup table construction with reduced interpolation error 有权

    公开(公告)号：US10542269B2

    公开(公告)日：2020-01-21

    申请号：US15773525

    申请日：2016-12-07

    申请人： Dolby Laboratories Licensing Corporation

    发明人： Harshad Kadu ,  Guan-Ming Su ,  Hanyang Sun

    IPC分类号： H04N19/44 ,  G06T5/00 ,  H04N19/186 ,  H04N19/82

    摘要： In a method to reconstruct a high dynamic range video signal, a decoder receives parameters in the input bitstream to generate a prediction function. Using the prediction function, it generates a first set of nodes for a first prediction lookup table, wherein each node is characterized by an input node value and an output node value.Then, it modifies the output node values of one or more of the first set of nodes to generate a second set of nodes for a second prediction lookup table, and generates output prediction values using the second lookup table. Low-complexity methods to modify the output node value of a current node in the first set of nodes based on computing modified slopes between the current node and nodes surrounding the current node are presented.

    BLIND LOCAL RESHAPING IN HDR IMAGING
    10.
    发明公开
    BLIND LOCAL RESHAPING IN HDR IMAGING 审中-公开

    公开(公告)号：US20230156343A1

    公开(公告)日：2023-05-18

    申请号：US17916780

    申请日：2021-04-01

    申请人： Dolby Laboratories Licensing Corporation

    发明人： Guan-Ming Su ,  Harshad Kadu ,  Tsung-Wei Huang

    IPC分类号： H04N23/741 ,  G06T5/20 ,  G06V10/60 ,  H04N19/186 ,  H04N19/192

    CPC分类号： H04N23/741 ,  G06T5/20 ,  G06V10/60 ,  H04N19/186 ,  H04N19/192 ,  G06T2207/20208

    摘要： In an encoder, a high-dynamic range (HDR) image is encoded using a family of local forward reshaping functions selected according to an array of forward mapping indices (FMI) indicating which local forward reshaping function needs to be used for each pixel in the HDR image to generate a reshaped standard dynamic range (SDR) image. A decoder, given the reshaped SDR image, iteratively generates a reconstructed HDR image and estimated reshaped SDR images by adjusting a local FMI array and a local array of backward mapping indices (BMI) until an error metric related to the difference between the local BMI and FMI arrays and the difference between the estimate SDR images and the reshaped SDR image satisfy a convergence criterion. Techniques for generating families of local forward reshaping functions and local backward reshaping functions based on a global forward reshaping function are also presented.