# US 2021/0243474 A1 · Encoding device, decoding device, and program > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0243474 A1 - Document ID: US20210243474A1 - Status: Published application - Kind: A1 - Application number: 17/237,780 - Filed: 2021-04-22 - Published: 2021-08-05 - Earliest claimed: 2018-10-22 - Assignees: Nippon Hoso Kyokai - Applicants: Nippon Hoso Kyokai - Inventors: Atsuro ICHIGAYA; Shunsuke IWAMURA; Shimpei NEMOTO; Kazuhisa IGUCHI - Web page: https://patentgrep.com/patent/US20210243474A1 ## CPC - H04N 19/60: using transform coding - H04N 19/117: Filters, e.g. for pre-processing or post-processing (sub-band filter banks H04N19/635) - H04N 19/124: Quantisation - H04N 19/136: Incoming video signal characteristics or properties - H04N 19/172: the region being a picture, frame or field - H04N 19/82: involving filtering within a prediction loop - H04N 19/91: Entropy coding, e.g. variable length coding [VLC] or arithmetic coding - H04N 19/86: involving reduction of coding artifacts, e.g. of blockiness - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract An encoding device 1 includes: a transformer 13 configured to calculate an orthogonal transform coefficient by performing an orthogonal transformation process on a residual image indicating a difference between the input image and a predicted image of the input image; a quantizer 14 configured to generate quantization coefficient by quantizing the orthogonal transform coefficient based on a quantization parameter; an entropy encoder 24 configured to generate encoded data by encoding the quantization coefficient; an image decoder 10 configured to restore an orthogonal transform coefficient from the quantization coefficient based on the quantization parameter and generate a pre-filtering image by adding the predicted image to a residual image restored by performing inverse orthogonal transformation on the orthogonal transform coefficient; and a deblocking filter 18 configured to perform a filtering process on the pre-filtering image and control a filtering strength depending on a result of comparison between a luminance signal level of the pre-filtering image and a luminance threshold value. ## Claims ### Claim 1 An encoding device which encodes an input image comprising: a transformer configured to calculate an orthogonal transform coefficient by performing an orthogonal transformation process on a residual image indicating a difference between the input image and a predicted image of the input image; a quantizer configured to generate quantization coefficient by quantizing the orthogonal transform coefficient based on a quantization parameter; an entropy encoder configured to generate encoded data by encoding the quantization coefficient; an image decoder configured to restore an orthogonal transform coefficient from the quantization coefficient based on the quantization parameter and generate a pre-filtering image by adding the predicted image to a residual image restored by performing inverse orthogonal transformation on the orthogonal transform coefficient; and a deblocking filter configured to perform a filtering process on the pre-filtering image, wherein the deblocking filter is configured to control a filtering strength depending on a result of comparison between a luminance signal level of the pre-filtering image and a luminance threshold value, and the deblocking filter is configured to determine the luminance threshold value for each picture or each sequence. ### Claim 2 (depends on 1) The encoding device according to claim 1, wherein the deblocking filter is configured to determine the luminance threshold value for each sequence, and the entropy encoder is configured to transmit information indicating the luminance threshold value as a sequence parameter set to a decoding side. ### Claim 3 (depends on 1) The encoding device according to claim 1, wherein the deblocking filter is configured to: specify which of a plurality of luminance signal level ranges defined by the luminance threshold value covers the luminance signal level of the pre-filtering image; and control the filtering strength by using filtering strength control information corresponding to the specified luminance signal level range. ### Claim 4 (depends on 3) The encoding device according to claim 3, wherein the entropy encoder is configured to transmit filtering strength control information provided for each of the plurality of luminance signal level ranges as a sequence parameter set to a decoding side. ### Claim 5 (depends on 1) The encoding device according to claim 1, wherein the deblocking filter is configured to calculate the luminance signal level of the pre-filtering image by averaging pixel values of a plurality of pixels in a boundary area of a pair of neighboring blocks corresponding to the pre-filtering image. ### Claim 6 (depends on 1) The encoding device according to claim 1, wherein the entropy encoder is configured to transmit to a decoding side a flag indicating whether filtering strength control depending on the luminance signal level of the pre-filtering image is enabled or not. ### Claim 7 A decoding device which decodes encoded data of an input image comprising: an entropy decoder configured to decode the encoded data and obtain a quantization coefficient generated by quantizing an orthogonal transform coefficient; an image decoder configured to restore an orthogonal transform coefficient from the quantization coefficient based on a quantization parameter and generate a pre-filtering image by adding a predicted image to a residual image restored by performing inverse orthogonal transformation on the orthogonal transform coefficient; and a deblocking filter configured to perform a filtering process on the pre-filtering image, wherein the deblocking filter is configured to control a filtering strength depending on a result of comparison between a luminance signal level of the pre-filtering image and a luminance threshold value, and the deblocking filter is configured to determine the luminance threshold value for each picture or each sequence. ### Claim 8 (depends on 7) The decoding device according to claim 7, wherein the entropy decoder is configured to obtain information indicating the luminance threshold value as a sequence parameter set from the encoded data, and the deblocking filter is configured to determine the luminance threshold value for each sequence by using the information indicating the luminance threshold value. ### Claim 9 (depends on 7) The decoding device according to claim 7, wherein the deblocking filter is configured to: specify which of a plurality of luminance signal level ranges defined by the luminance threshold value covers the luminance signal level of the pre-filtering image; and control the filtering strength by using filtering strength control information corresponding to the specified luminance signal level range. ### Claim 10 (depends on 9) The decoding device according to claim 9, wherein the entropy decoder is configured to obtain filtering strength control information provided for each of the plurality of luminance signal level ranges as a sequence parameter set from the encoded data. ### Claim 11 (depends on 7) The decoding device according to claim 7, wherein the deblocking filter is configured to calculate the luminance signal level of the pre-filtering image by averaging pixel values of a plurality of pixels in a boundary area of a pair of neighboring blocks corresponding to the pre-filtering image. ### Claim 12 (depends on 7) The decoding device according to claim 7, wherein the entropy decoder is configured to obtain from the encoded data a flag indicating whether filtering strength control depending on the luminance signal level of the pre-filtering image is enabled or not. ### Claim 13 (depends on 1) A program for instructing a computer to function as the encoding device according to claim 1. ### Claim 14 (depends on 7) A program for instructing a computer to function as the decoding device according to claim 7.