# US 2019/0379891 A1 · Method and apparatus for encoding/decoding an image > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0379891 A1 - Document ID: US20190379891A1 - Status: Published application - Kind: A1 - Application number: 16/341,590 - Filed: 2017-10-12 - Published: 2019-12-12 - Earliest claimed: 2016-10-14 - Assignees: Industry Academy Cooperation Foundation of Sejong University - Applicants: Industry Academy Cooperation Foundation of Sejong University - Inventors: Joo Hee MOON; Sung Won LIM; Dong Jae WON - Web page: https://patentgrep.com/patent/US20190379891A1 ## CPC - H04N 19/159: Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction - H04N 19/105: Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction - H04N 19/11: among a plurality of spatial predictive coding modes - H04N 19/117: Filters, e.g. for pre-processing or post-processing (sub-band filter banks H04N19/635) - H04N 19/119: Adaptive subdivision aspects, e.g. subdivision of a picture into rectangular or non-rectangular coding blocks - H04N 19/139: Analysis of motion vectors, e.g. their magnitude, direction, variance or reliability - H04N 19/174: the region being a slice, e.g. a line of blocks or a group of blocks - H04N 19/176: the region being a block, e.g. a macroblock - H04N 19/182: the unit being a pixel - H04N 19/44: Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder - H04N 19/46: Embedding additional information in the video signal during the compression process (H04N19/517, H04N19/68, H04N19/70 take precedence) - H04N 19/59: involving spatial sub-sampling or interpolation, e.g. alteration of picture size or resolution - H04N 19/593: involving spatial prediction techniques - H04N 19/61: in combination with predictive coding - H04N 19/80: Details of filtering operations specially adapted for video compression, e.g. for pixel interpolation (H04N19/635, H04N19/86 take precedence) - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract Disclosed are an image encoding/decoding method and apparatus. The method and apparatus select at least one reference pixel line from among multiple reference pixel lines and derive a predicted value of a pixel within a current block by using the value of at least one pixel within the selected reference pixel line(s). Alternatively, the method and apparatus derive an intra prediction mode of a reconstructed pixel region on the basis of a reference pixel region of at least one reconstructed pixel region, derive an intra prediction mode of a current block on the basis of the derived intra prediction mode of the reconstructed pixel region, obtain an intra prediction block of the current block by using the derived intra prediction mode, and reconstruct the current block by summing the obtained intra prediction block and a residual block of the current block. ## Claims ### Claim 1 A method of decoding an image, the method comprising: selecting at least one reference pixel line from among multiple reference pixel lines, the multiple reference pixel lines being located within a picture in which a current block to be decoded through intra prediction is contained; and obtaining a predicted value of a pixel included in the current block by using at least one pixel value included in the selected reference pixel line. ### Claim 2 (depends on 1) The method according to claim 1, further comprising: obtaining reference pixel line index information from an input bitstream, wherein the at least one reference pixel line is selected from among the multiple reference pixel lines on the basis of the reference pixel line index information. ### Claim 3 (depends on 1) The method according to claim 1, wherein in the selecting of the at least one reference pixel line, at least one reference pixel line is selected for each pixel within the current block, depending on a position of each pixel within the current block. ### Claim 4 (depends on 3) The method according to claim 3, wherein in the selecting of the at least one reference pixel line, at least one reference pixel line is selected for each pixel within the current block, depending on an intra prediction mode of the current block. ### Claim 5 (depends on 4) The method according to claim 4, wherein in the selecting of the at least one reference pixel line, when the intra prediction mode of the current block is an angular mode, a prediction pixel at an integer pixel position or at a position closest to the integer pixel position is selected, as the predicted value, from among multiple prediction pixels obtained by using pixels included within each of the multiple reference pixel lines. ### Claim 6 (depends on 4) The method according to claim 4, wherein in the selecting of the at least one reference pixel line, when the intra prediction mode of the current block is an angular mode, and when multiple prediction pixels obtained by using pixels included within each of the multiple reference pixel lines include a plurality of prediction pixels at integer pixel positions, a prediction pixel closest to a pixel included within the current block is selected, among the plurality of prediction pixels at the integer pixel positions, as the predicted value. ### Claim 7 (depends on 4) The method according to claim 4, wherein in the selecting of the at least one reference pixel line, when an intra prediction mode of the current block is an angular mode, a weighted average calculated by applying a weight to each of the multiple prediction pixels obtained by using the pixels included in each of the multiple reference pixel lines is selected as the predicted value, wherein the weight is determined according to a distance between the pixel within the current block and the prediction pixel. ### Claim 8 (depends on 1) The method according to claim 1, wherein the obtaining of the predicted value of a pixel in the current block comprises: selecting one interpolation scheme from among multiple interpolation schemes; and obtaining the predicted value by performing the selected interpolation scheme using at least one pixel within the selected reference pixel line, wherein the selecting of the interpolation scheme is performed by using index information indicating one of the multiple interpolation schemes. ### Claim 9 (depends on 1) The method according to claim 1, further comprising: deriving predicted values of all the pixels within the current block to generate a prediction block of the current block; and filtering the prediction block, wherein a predetermined region of the current block is filtered depending on a size of the current block and an intra prediction mode of the current block. ### Claim 10 (depends on 9) The method according to claim 9, wherein the filtering is performed such that a first pixel within the prediction block is filtered by using a second reference pixel included in a reference pixel line to which a first reference pixel that is used to predict the first pixel belongs. ### Claim 11 (depends on 10) The method according to claim 10, wherein the filtering is performed in a manner to filter the first pixel and a second pixel within the prediction block by using the second reference pixel, wherein the filtering is differently performed depending on a distance between the first pixel within the prediction block and the second reference pixel and a distance between the second pixel within the prediction block and the second reference pixel. ### Claim 12 (depends on 9) The method according to claim 9, wherein the filtering is performed in a manner to filter a pixel within the prediction block by using a reference pixel within a reference pixel line adjacent to the prediction block. ### Claim 13 (depends on 9) The method according to claim 9, wherein in the selecting of the at least one reference pixel line, when the current block is divided into multiple transform blocks, at least one reference pixel line is selected for each of the transform blocks. ### Claim 14 (depends on 13) The method according to claim 13, wherein in the selecting of the at least one reference pixel line, when at least one reference pixel line is selected for each of the transform blocks in accordance with information indicating whether or not a reference pixel line is derived on a per transform block basis. ### Claim 15 A method of encoding an image, the method comprising: selecting at least one reference pixel line from among multiple reference pixel lines, the multiple reference pixel lines being located within a picture in which a current block to be encoded through intra prediction is contained; and obtaining a predicted value of a pixel included in the current block by using at least one pixel value included in the selected reference pixel line. ### Claim 16 (depends on 15) The method according to claim 15, further comprising: encoding reference pixel line index information indicating the at least one reference pixel line that is selected; and inserting the encoded reference pixel line index information into a bitstream. ### Claim 17 (depends on 15) The method according to claim 15, wherein in the selecting of the at least one reference pixel line, at least one reference pixel line is selected for each pixel within the current block, depending on a position of each pixel within the current block. ### Claim 18 (depends on 17) The method according to claim 17, wherein in the selecting of the at least one reference pixel line, at least one reference pixel line is selected for each pixel within the current block, depending on an intra prediction mode of the current block. ### Claim 19 (depends on 18) The method according to claim 18, wherein in the selecting of the at least one reference pixel line, when the intra prediction mode of the current block is an angular mode, a prediction pixel at an integer pixel position or at a position closest to the integer pixel position is selected, as the predicted value, from among multiple prediction pixels obtained by using pixels within each of the multiple reference pixel lines. ### Claim 20 A method of decoding an image, the method comprising: deriving an intra prediction mode of a current block from among multiple intra prediction modes that are available; obtaining an intra prediction block of the current block by using the derived intra prediction mode; and reconstructing the current block by summing the obtained intra prediction block and a residual block of the current block, wherein the deriving of the intra prediction mode of the current block includes: deriving an intra prediction mode of a reconstructed pixel region on the basis of a reference pixel region within at least one reference pixel region that is reconstructed; and deriving an intra prediction mode of the current block on the basis of the derived intra prediction mode of the reconstructed pixel region. ### Claim 21 (depends on 20) The method according to claim 20, further comprising: obtaining information indicating an intra prediction mode derivation method from an input bitstream, wherein as to the deriving of the intra prediction mode of the reconstructed pixel region, whether or not the deriving of the intra prediction mode of the reconstructed pixel region is performed is determined according to the information indicating the intra prediction mode derivation method. ### Claim 22 (depends on 20) The method according to claim 20, wherein the deriving of the intra prediction mode of the current block from among the available intra prediction modes comprises: obtaining available intra prediction mode information that specifies the number of the available intra prediction modes or a list of the available intra prediction modes; and deriving an intra prediction mode of the current block on the basis of the available intra prediction mode information. ### Claim 23 A method of decoding an image, the method comprising: deriving an intra prediction mode of a current block from among multiple intra prediction modes that are available; obtaining an intra prediction block of the current block by using the derived intra prediction mode; and reconstructing the current block by summing the obtained intra prediction block and a residual block of the current block, wherein the deriving of the intra prediction mode of the current block includes deriving an intra prediction mode of the current block by using a reconstructed pixel region, a first reference pixel line within the reconstructed pixel region, and a second reference pixel line within the reconstructed pixel region. ### Claim 24 (depends on 23) The method according to claim 23, wherein the deriving of the intra prediction mode of the current block includes: deriving an intra prediction mode of the first reference pixel line by using the second reference pixel line; deriving an intra prediction mode of the reconstructed pixel region by using the first reference pixel line; and selecting, when the derived intra prediction mode of the first reference pixel line is the same as the derived intra prediction mode of the reconstructed pixel region, the same intra prediction mode as the intra prediction mode of the current block. ### Claim 25 A method of decoding an image, the method comprising: deriving an intra prediction mode of a current block; obtaining an intra prediction block of the current block by using the derived intra prediction mode; and reconstructing the current block by summing the obtained intra prediction block and a residual block of the current block, wherein the deriving of the intra prediction mode of the current block includes: selecting a region to be used for deriving the intra prediction mode of the current block from among multiple reconstructed pixel regions; deriving an intra prediction mode of the reconstructed pixel region on the basis of the selected reference pixel region of the reconstructed pixel region; and deriving the intra prediction mode of the current block on the basis of the derived intra prediction mode of the reconstructed pixel region. ### Claim 26 (depends on 25) The method according to claim 25, further comprising: obtaining index information indicating which region of the multiple reconstructed pixel regions is to be used to derive an intra prediction mode of the current block from an input bitstream; and selecting the region used to derive the intra prediction mode of the current block from among the multiple reconstructed pixel regions on the basis of the index information. ### Claim 27 A method of encoding an image, the method comprising: deriving an intra prediction mode of a current block from among multiple intra prediction modes that are available; obtaining an intra prediction block of the current block by using the derived intra prediction mode; and reconstructing the current block by summing the obtained intra prediction block and a residual block of the current block, wherein the deriving of the intra prediction mode of the current block includes: deriving an intra prediction mode of a reconstructed pixel region on the basis of a reference pixel region within at least one reference pixel region that is reconstructed; and deriving the intra prediction mode of the current block on the basis of the derived intra prediction mode of the reconstructed pixel region. ### Claim 28 A method of encoding an image, the method comprising: deriving an intra prediction mode of a current block from among multiple intra prediction modes that are available; obtaining an intra prediction block of the current block by using the derived intra prediction mode; and reconstructing the current block by summing the obtained intra prediction block and a residual block of the current block, wherein the deriving of the intra prediction mode of the current block includes: deriving an intra prediction mode of the current block by using a reconstructed pixel region, a first reference pixel line within the reconstructed pixel region, and a second reference pixel line within the reconstructed pixel region. ### Claim 29 (depends on 28) The method according to claim 28, wherein the deriving of the intra prediction mode of the current block includes: deriving an intra prediction mode of the first reference pixel line by using the second reference pixel line; deriving an intra prediction mode of the reconstructed pixel region by using the first reference pixel line; and selecting, when the derived intra prediction mode of the first reference pixel line is the same as the derived intra prediction mode of the reconstructed pixel region, the same intra prediction mode as the intra prediction mode of the current block. ### Claim 30 A method of encoding an image, the method comprising: deriving an intra prediction mode of a current block; obtaining an intra prediction block of the current block by using the derived intra prediction mode; and reconstructing the current block by summing the obtained intra prediction block and a residual block of the current block, wherein the deriving of the intra prediction mode of the current block includes: selecting a region to be used for deriving the intra prediction mode of the current block from among multiple reconstructed pixel regions; deriving an intra prediction mode of the reconstructed pixel region on the basis of the selected reference pixel region of the reconstructed pixel region; and deriving the intra prediction mode of the current block on the basis of the derived intra prediction mode of the reconstructed pixel region.