# US 2019/0378324 A1 · Shading method for volumetric imaging > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0378324 A1 - Document ID: US20190378324A1 - Status: Published application - Kind: A1 - Application number: 16/001,978 - Filed: 2018-06-07 - Published: 2019-12-12 - Earliest claimed: 2018-06-07 - Assignees: Canon Medical Systems Corporation - Applicants: Canon Medical Systems Corporation - Inventors: Magnus WAHRENBERG; Andrew Murray - Web page: https://patentgrep.com/patent/US20190378324A1 ## CPC - G06T 15/08: Volume rendering - G06T 7/11: Region-based segmentation - G06T 15/80: Shading - G06T 2207/10081: Computed x-ray tomography [CT] - G06T 2207/10088: Magnetic resonance imaging [MRI] - G06T 2207/10104: Positron emission tomography [PET] - G06T 2207/10108: Single photon emission computed tomography [SPECT] - G06T 2207/10116: X-ray image - G06T 2207/10132: Ultrasound image - G06T 2207/30004: Biomedical image processing - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL ## Abstract A medical image processing apparatus comprises processing circuitry configured to: obtain volumetric data corresponding to a three dimensional region of a subject; perform a sampling process that comprises sampling the volumetric data at a plurality of sampling points along a plurality of sampling paths; for each of a plurality of intervals between sampling points on sampling paths, determine a position of a shading evaluation point in the interval based on intensity values and/or opacity values for a front sampling point and back sampling point of the interval; and determine a value for a shading parameter at the determined shading evaluation point; and perform a rendering process using the determined values for the shading parameter. ## Claims ### Claim 1 Medical image processing apparatus comprising processing circuitry configured to: obtain volumetric data corresponding to a three dimensional region of a subject; perform a sampling process that comprises sampling the volumetric data at a plurality of sampling points along a plurality of sampling paths; for each of a plurality of intervals between sampling points on sampling paths, determine a position of a shading evaluation point in the interval based on intensity values and/or opacity values for a front sampling point and back sampling point of the interval; and determine a value for a shading parameter at the determined shading evaluation point; and perform a rendering process using the determined values for the shading parameter. ### Claim 2 (depends on 1) An apparatus according to claim 1, wherein the determining of the shading evaluation point is based on visibility of sub-sampling points within the interval. ### Claim 3 (depends on 2) An apparatus according to claim 2, wherein the determined shading evaluation point is a most visible sub-sampling point. ### Claim 4 (depends on 1) An apparatus according to claim 1, wherein the rendering process comprises at least one of global illumination, shaded direct volume rendering. ### Claim 5 (depends on 1) An apparatus according to claim 1, wherein the processing circuitry is further configured to store pre-computed positions for the shading evaluation point as a function of front sampling point intensity value and/or opacity value and back sampling point intensity value and/or opacity value. ### Claim 6 (depends on 5) An apparatus according to claim 5, wherein the determining of the position of the shading evaluation point in each interval comprises looking up the pre-computed position for the front sampling point intensity value and/or opacity value and back sampling point intensity value and/or opacity value for said interval. ### Claim 7 (depends on 5) An apparatus according to claim 5, wherein the pre-computed positions are stored as at least one of: an image, a function, a look-up table. ### Claim 8 (depends on 1) An apparatus according to claim 1 wherein, for each interval: the determining of the position of a shading evaluation point in the interval is based on an intensity value for the front sampling point and an intensity value from the back sampling point; and the determining of the position of the shading evaluation point in the interval comprises estimating intensity values at a plurality of sub-sampling points within the interval and determining which of the sub-sampling points or sub-intervals between sub-sampling points is most visible. ### Claim 9 (depends on 8) An apparatus according to claim 8, wherein intensity values of the sub-sampling points are estimated using a linear, quadratic, or cubic polynomial. ### Claim 10 (depends on 8) An apparatus according to claim 8, wherein the determining of the position of the shading evaluation point in the interval further comprises: determining a most visible sub-interval between sub-sampling points; and determining a most visible position in the determined sub-interval based on an opacity value for a sub-sampling point at the front of the determined sub-interval and an opacity value for a sub-sampling point at the back of the determined sub-interval. ### Claim 11 (depends on 10) An apparatus according to claim 10, wherein the determining of the most visible position in the determined sub-interval comprises estimating intermediate opacity values between the sub-sampling point at the front of the determined sub-interval and the sub-sampling point at the back of the determined sub-interval. ### Claim 12 (depends on 11) An apparatus according to claim 11, wherein the intermediate opacity values are estimated using a linear, quadratic, or cubic polynomial. ### Claim 13 (depends on 1) An apparatus according to claim 1, wherein the processing circuitry is further configured to store pre-computed positions for the shading evaluation point as a function of front sampling point opacity value and back sampling point opacity value, and wherein the pre-computed positions are filtered to reduce or prevent sharp transitions in position between the front and back of the interval. ### Claim 14 (depends on 1) An apparatus according to claim 1, wherein the pre-computing of the shading evaluation point fractions comprises or forms part of a pre-integration process, the pre-integration process comprising determining a respective color value for each pair of intensity values by integrating across an interval between sampling points having said intensity values. ### Claim 15 (depends on 1) An apparatus according to claim 1, wherein the determining of the position of the shading evaluation point based on intensity value and/or opacity values for a front sampling point and back sampling point of the interval is performed on a subset of the volumetric imaging data set. ### Claim 16 (depends on 15) An apparatus according to claim 15, wherein the processing circuitry is configured to select the subset on which to perform the determining of shading calculation position based on at least one of: intensity values, a presence of anatomical features, an image quality, a likelihood of artifacts. ### Claim 17 (depends on 1) An apparatus according to claim 1, wherein the determining of the position of the shading evaluation point in the interval is additionally based on an intensity value and/or opacity value for at least one further sampling point. ### Claim 18 (depends on 1) An apparatus according to claim 1, wherein the determining of the value for the shading parameter at the determined shading evaluation point comprises calculating a gradient at the determined shading point. ### Claim 19 Medical image processing method comprising: obtaining volumetric data corresponding to a three dimensional region of a subject; performing a sampling process that comprises sampling the volumetric data at a plurality of sampling points along a plurality of sampling paths; for each of a plurality of intervals between sampling points on sampling paths, determining a position of a shading evaluation point in the interval based on intensity values and/or opacity values for a front sampling point and back sampling point of the interval; and determining a value for a shading parameter at the determined shading evaluation point; and performing a rendering process using the determined values for the shading parameter.