# US 2018/0324408 A1 · Stereoscopic image processing methods and apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0324408 A1 - Document ID: US20180324408A1 - Status: Published application - Kind: A1 - Application number: 15/937,583 - Filed: 2018-03-27 - Published: 2018-11-08 - Earliest claimed: 2012-01-17 - Assignees: NextVR Inc. - Applicants: NextVR Inc. - Inventors: David Cole; Alan McKay Moss - Web page: https://patentgrep.com/patent/US20180324408A1 ## CPC - H04N 13/271: wherein the generated image signals comprise depth maps or disparity maps - H04N 13/128: Adjusting depth or disparity - H04N 13/161: Encoding, multiplexing or demultiplexing different image signal components (for multi-view video sequence encoding H04N19/597) - H04N 13/20: Image signal generators - H04N 13/239: using two two-dimensional [2D] image sensors having a relative position equal to or related to the interocular distance (H04N13/243 takes precedence) - H04N 13/257: Colour aspects - H04N 2013/0081: {Depth or disparity estimation from stereoscopic image signals} - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract Stereoscopic image processing methods and apparatus are described. Left and right eye images of a stereoscopic frame are examined to determine if one or more difference reduction operations designed to reduce the luminance and/or chrominance differences between the left and right frames is within a range used to trigger a difference reduction operation. A difference reduction operation may involve assigning portions of the left and right frames to different depth regions and/or other region categories. A decision on whether or not to perform a difference reduction operation is then performed on a per regions basis with at the difference between the left and right eye portions of at least one region being reduced when a difference reduction operation is to be performed. The difference reduction process may, and in some embodiments is, performed in a precoder which processes left and right eye images of stereoscopic frames prior to stereoscopic encoding. ## Claims ### Claim 1 A method of processing a pair of images including a left eye image and a right eye image, each of said left and right eye images including image values of a first type, the method comprising: generating a first overall disparity value indicating a first overall level of difference between values of said first type in said left eye image and values of said first type in said right eye image; determining if said first overall disparity value is in a first difference range used to control performing of a first difference reduction operation, said first difference reduction operation being an operation on values of said first type included in at least one of said left eye image or said right eye image to reduce the overall difference between values of said first type in said left eye image and values of said first type in said right eye image; and performing said first difference reduction operation to reduce the first overall level of difference between values of said first type in said left eye image and values of said first type in said right eye image when said first overall disparity value is determined to be in said first difference range. ### Claim 2 (depends on 1) The method of claim 1, wherein the first overall disparity value is an indication of the overall luminance disparity between the left and right eye images being processed. ### Claim 3 (depends on 2) The method of claim 2, wherein generating a first overall disparity value includes: generating a sum, the generated sum being the first overall disparity value said sum being a sum of luminance difference values. ### Claim 4 (depends on 2) The method of claim 2, wherein said sum is equal to the difference between a sum of luminance values in said left eye image and a sum of luminance values in said right eye image. ### Claim 5 (depends on 1) The method of claim 1, wherein said values of a first type are chrominance values; and wherein performing said first difference reduction operation to reduce the first overall level of difference between values of said first type in said left and right eye images includes changing at least some chrominance values in at least one of said left and right eye images. ### Claim 6 (depends on 5) The method of claim 5, wherein the first region of the left and right eye images on which the first difference reduction operation is not performed is a foreground image region; and wherein said another region of at least one of said left and right eye images upon which said first difference reduction operation is performed is a background region. ### Claim 7 (depends on 1) The method of claim 1 wherein said step of changing at least some of the chrominance values includes limiting the change in chrominance values to a maxim amount of change which is less than a maximum amount of change used for another type of values. ### Claim 8 (depends on 1) The method of claim 1, wherein values of said first type are luminance values; wherein performing said first difference reduction operation to reduce the first overall level of difference between values of said first type includes changing at least some luminance values. ### Claim 9 (depends on 8) The method of claim 8, wherein performing said first difference reduction operation to reduce the first overall level of difference between values of said first type includes treating pixel values corresponding to a foreground image portion differently from pixel values corresponding to a background image portion. ### Claim 10 (depends on 7) The method of claim 7, wherein determining if said first overall disparity value is in the first difference range used to control performing of the first difference reduction operation further includes: comparing said first overall disparity value to a first threshold corresponding to a lower boundary of said first difference range; and comparing said first overall disparity value to a second threshold corresponding to an upper boundary of said first difference range. ### Claim 11 (depends on 10) The method of claim 10, wherein determining if said first overall disparity value is in the first difference range used to control performing of the first difference reduction operation further includes: determining that said overall disparity value is in the first difference range when said comparing steps indicate that said first overall disparity value is above said first threshold and below said second threshold. ### Claim 12 (depends on 1) The method of claim 1, wherein performing said first difference reduction operation includes: modifying values of the first type in a first one of said left and right eye images; and using the depth map in determining what pixel values to modify as part of a disparity reduction operation. ### Claim 13 (depends on 1) The method of claim 1, wherein performing said first difference reduction operation further includes: generating a depth map for each of said left and right eye images; and identifying different regions in said left and right eye images based on depths to which the regions are determined to correspond, said depths including at least a first image depth and a second image depth. ### Claim 14 (depends on 1) The method of claim 1, wherein generating a first overall disparity value includes: generating a left eye histogram of pixel values; generating a right eye histogram of pixel values; and generating said overall disparity value from said left histogram of pixel values and the right eye histogram of pixel values. ### Claim 15 An apparatus for processing a pair of images including a left eye image and a right eye image, each of said left and right eye images including image values of a first type, comprising: a disparity value generation module configured to generate a first overall disparity value indicating a first overall level of difference between values of said first type in said left eye image and values of said first type in said right eye image; a determination module configured to determine if said first overall disparity value is in a first difference range used to control performing of a first difference reduction operation, said first difference reduction operation being an operation on values of said first type included in at least one of said left eye image or said right eye image to reduce the overall difference between values of said first type in said left eye image and values of said first type in said right eye image; and a difference reduction operation module configured to perform said first difference reduction operation to reduce the first overall level of difference between values of said first type in said left eye image and values of said first type in said right eye image when said first overall disparity value is determined to be in said first difference range. ### Claim 16 (depends on 15) The apparatus of claim 15, wherein said values of said first type are one of luminance values; and wherein the first overall disparity value is an indication of the overall luminance disparity between the left and right eye images being processed. ### Claim 17 (depends on 15) The apparatus of claim 15, wherein the difference reduction operation module is configured to modify at least some luminance values. ### Claim 18 (depends on 15) The apparatus of claim 15, wherein said determination module includes a comparison module configured to compare said first overall disparity value to a first threshold corresponding to a lower boundary of said first difference range and to compare said first overall disparity value to a second threshold corresponding to an upper boundary of said first difference range. ### Claim 19 (depends on 18) The apparatus of claim 18, wherein said determination module is further configured to determine that said overall disparity value is in the first difference range, when a result of a comparison performed by said comparison module indicates that said first overall disparity value is above said first threshold and below said second threshold. ### Claim 20 A non-transitory computer readable medium for use in an apparatus for processing a pair of images including a left eye image and a right eye image, each of said left and right eye images including image values of a first type, the non-transitory computer readable medium comprising: instructions which when executed by a processor cause said processor to generate a first overall disparity value indicating a first overall level of difference between values of said first type in said left eye image and values of said first type in said right eye image; instructions which when executed by said processor cause said processor to determine if said first overall disparity value is in a first difference range used to control performing of a first difference reduction operation, said first difference reduction operation being an operation on values of said first type included in at least one of said left eye image or said right eye image to reduce the overall difference between values of said first type in said left eye image and values of said first type in said right eye image; and instructions which when executed by said processor cause said processor to perform the first difference reduction operation to reduce the first overall level of difference between values of said first type in said left eye image and values of said first type in said right eye image when said first overall disparity value is determined to be in said first difference range.