# US 2020/0288169 A1 · Techniques for intra prediction for 360 image and video coding > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0288169 A1 - Document ID: US20200288169A1 - Status: Published application - Kind: A1 - Application number: 16/293,920 - Filed: 2019-03-06 - Published: 2020-09-10 - Earliest claimed: 2019-03-06 - Assignees: Tencent America LLC - Applicants: Tencent America LLC - Inventors: Shan LIU; Stephan Wenger - Web page: https://patentgrep.com/patent/US20200288169A1 ## CPC - H04N 19/593: involving spatial prediction techniques - H04N 19/176: the region being a block, e.g. a macroblock - H04N 19/597: specially adapted for multi-view video sequence encoding - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract A method of decoding a coded image or a coded picture in a coded video sequence, into a picture representing a projection on a planar surface of a non-planar surface, is provided, and the method is performed by a decoder employing intra prediction. The method includes obtaining an intra prediction mode indicative of an intra prediction direction, for a block of the picture, determining at least one non-straight curve representative of a straight line on the non-planar surface, based on the projection and the obtained intra prediction mode, and creating, for the block, prediction samples along the determined at least one non-straight curve, from at least one boundary sample along the determined at least one non-straight curve. ## Claims ### Claim 1 A method of decoding a coded image or a coded picture in a coded video sequence, into a picture representing a projection on a planar surface of a non-planar surface, the method being performed by a decoder employing intra prediction, and the method comprising: obtaining an intra prediction mode indicative of an intra prediction direction, for a block of the picture; determining at least one non-straight curve representative of a straight line on the non-planar surface, based on the projection and the obtained intra prediction mode; creating, for the block, prediction samples along the determined at least one non-straight curve, from at least one boundary sample along the determined at least one non-straight curve; performing a reverse projection on the block of the picture, the block having a first aspect ratio; identifying a rectangle corresponding to a surface area on the non-planar surface of the block on which the reverse projection is performed, based on at least one property of the projection and a position of the block in the picture; and based on a second aspect ratio of the identified rectangle, performing either one or both of adding to and removing from at least one intra prediction direction available for decoding the block in accordance to the first aspect ratio and a video compression standard. ### Claim 2 (depends on 1) The method of claim 1, wherein the determining the at least one non-straight curve comprises determining a shape of the at least one non-straight curve to be a shape of the projection. ### Claim 3 (depends on 1) The method of claim 1, wherein the determining the at least one non-straight curve comprises determining a position of the at least one non-straight curve to correspond to the position of the block in the picture. ### Claim 4 (depends on 1) The method of claim 1, wherein the determining the at least one non-straight curve comprises determining a direction of the at least one non-straight curve to be the intra prediction direction, from a start point close to the at least one boundary sample to an end point close to one of the prediction samples. ### Claim 5 (depends on 1) A non-transitory computer-readable storage medium storing a program comprising instructions to cause at least one processor to perform the method of claim 1. ### Claim 6 A method of decoding a coded image or a coded picture in a coded video sequence, into a picture representing a projection on a planar surface of a non-planar surface, the method being performed by a decoder employing intra prediction, the method comprising: performing a reverse projection on a block of the picture, the block having a first aspect ratio; identifying a rectangle corresponding to a surface area on the non-planar surface of the block on which the reverse projection is performed, based on at least one property of the projection and a position of the block in the picture; and based on a second aspect ratio of the identified rectangle, performing either one or both of adding to and removing from at least one intra prediction direction available for decoding the block in accordance to the first aspect ratio and a video compression standard. ### Claim 7 (depends on 6) The method of claim 6, further comprising rounding the second aspect ratio of the identified rectangle to a nearest aspect ratio that is defined for non-square blocks in the video compression standard, wherein the performing the either one or both of adding to and removing from the at least one intra prediction direction comprises, based on the rounded second aspect ratio of the identified rectangle, performing the either one or both of adding to and removing from the at least one intra prediction direction. ### Claim 8 (depends on 7) The method of claim 7, wherein the nearest aspect ratio is a power of two. ### Claim 9 (depends on 6) The method of claim 6, wherein the performing the either one or both of adding to and removing from the at least one intra prediction direction comprises, based on the second aspect ratio of the identified rectangle being wider than the first aspect ratio of the block, adding, to the at least one intra prediction direction, one or more intra prediction directions to an upper right of the at least one intra prediction direction. ### Claim 10 (depends on 6) The method of claim 6, wherein the performing the either one or both of adding to and removing from the at least one intra prediction direction comprises, based on the second aspect ratio of the identified rectangle being shorter than the first aspect ratio of the block, removing, from the at least one intra prediction direction, one or more intra prediction directions to a lower left of the at least one intra prediction direction. ### Claim 11 (depends on 6) A non-transitory computer-readable storage medium storing a program comprising instructions to cause at least one processor to perform the method of claim 6. ### Claim 12 An apparatus for decoding a coded image or a coded picture in a coded video sequence, into a picture representing a projection on a planar surface of a non-planar surface, the apparatus being a decoder employing intra prediction, and the apparatus comprising: at least one memory configured to store computer program code; and at least one processor configured to access the at least one memory and operate according to the computer program code, the computer program code comprising: obtaining code configured to cause the at least one processor to obtain an intra prediction mode indicative of an intra prediction direction, for a block of the picture; determining code configured to cause the at least one processor to determine at least one non-straight curve representative of a straight line on the non-planar surface, based on the projection and the obtained intra prediction mode; creating code configured to cause the at least one processor to create, for the block, prediction samples along the determined at least one non-straight curve, from at least one boundary sample along the determined at least one non-straight curve; first, performing code configured to cause the at least one processor to perform a reverse projection on the block of the picture, the block having, a first aspect ratio, identifying code configured to cause the at least one processor to identify a rectangle corresponding to a surface area on the non-planar surface of the block on which the reverse projection is performed, based on at least one property of the projection and a position of the block in the picture; and second performing code configured to cause the at least one processor to, based on a second aspect ratio of the identified rectangle, perform either one or both of adding to and removing from at least one intra prediction direction available for decoding the block in accordance to the first aspect ratio and a video compression standard. ### Claim 13 (depends on 12) The apparatus of claim 12, wherein the determining code is further configured to cause the at least one processor to determine a shape of the at least one non-straight curve to be a shape of the projection. ### Claim 14 (depends on 12) The apparatus of claim 12, wherein the determining code is further configured to cause the at least one processor to determine a position of the at least one non-straight curve to correspond to the position of the block in the picture. ### Claim 15 (depends on 12) The apparatus of claim 12, wherein the determining code is further configured to cause the at least one processor to determine a direction of the at least one non-straight curve to be the intra prediction direction, from a start point close to the at least one boundary sample to an end point close to one of the prediction samples. ### Claim 16 (canceled) ### Claim 17 (depends on 12) The apparatus of claim 12, further comprising rounding code configured to cause the at least one processor to round the second aspect ratio of the identified rectangle to a nearest aspect ratio that is defined for non-square blocks in the video compression standard, wherein the second performing code is further configured to cause the at least one processor to, based on the rounded second aspect ratio of the identified rectangle, perform the either one or both of adding to and removing from the at least one intra prediction direction. ### Claim 18 (depends on 17) The apparatus of claim 17, wherein the nearest aspect ratio is a power of two. ### Claim 19 (depends on 12) The apparatus of claim 12, wherein the second performing code is further configured to cause the at least one processor to, based on the second aspect ratio of the identified rectangle being wider than the first aspect ratio of the block, add, to the at least one intra prediction direction, one or more intra prediction directions to an upper right of the at least one intra prediction direction. ### Claim 20 (depends on 12) The apparatus of claim 12, wherein the second performing code is further configured to cause the at least one processor to, based on the second aspect ratio of the identified rectangle being shorter than the first aspect ratio of the block, remove, from the at least one intra prediction direction, one or more intra prediction directions to a lower left of the at least one intra prediction direction.