# US 2014/0153692 A1 · Combining Differential Images by Inverse Riesz Transformation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0153692 A1 - Document ID: US20140153692A1 - Status: Published application - Kind: A1 - Application number: 14/092,512 - Filed: 2013-11-27 - Published: 2014-06-05 - Earliest claimed: 2012-11-30 - Assignees: Canon Kabushiki Kaisha - Applicants: Canon Kabushiki Kaisha - Inventors: Kieran Gerard LARKIN; Peter Alleine FLETCHER - Web page: https://patentgrep.com/patent/US20140153692A1 ## CPC - G06T 5/10: using non-spatial domain filtering - G01N 23/041: Phase-contrast imaging, e.g. using grating interferometers - G06T 5/50: using two or more images, e.g. averaging or subtraction - G06T 2207/20056: Discrete and fast Fourier transform, [DFT, FFT] - G06T 2207/20221: Image fusion; Image merging - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract A method forms a representative image from a crossed grating fringe pattern interferogram of an object from an interferometer. The method determines a plurality of spectral lobes from the interferogram and selects from the plurality of determined lobes, two substantially orthogonal sidelobes. The selected sidelobes represent spatial differential phase information of the interferogram. The method applies an inverse Riesz transform to the spatial differential phase information of the selected sidelobes to form a transformed differential phase image, and forms from the transformed differential phase image, a representative image emphasising high frequency detail information of the object. ## Claims ### Claim 1 A method of forming a representative image from a crossed grating fringe pattern interferogram of an object from an interferometer, the method comprising: determining a plurality of spectral lobes from the interferogram; selecting from the plurality of determined lobes, two substantially orthogonal sidelobes, said selected sidelobes representing spatial differential phase information of the interferogram; applying an inverse Riesz transform to the spatial differential phase information of the selected sidelobes to form a transformed differential phase image; and forming from the transformed differential phase image, a representative image emphasising high frequency detail information of the object. ### Claim 2 (depends on 1) A method according to claim 1, wherein the representative high frequency detailed image comprises a (real) component and an (imaginary) discrepancy error component, wherein the detailed image can discriminate soft tissue. ### Claim 3 (depends on 1) A method according to claim 1, wherein the interferometer is an x-ray interferometer. ### Claim 4 (depends on 1) A method according to claim 1, in which the Riesz transformation is utilized to combine two differential images in correct orientational distribution proportion to maintain a power spectrum of the images and allow the directional structure in the two images to combine. ### Claim 5 (depends on 4) A method according to claim 4, wherein the power spectrum of the input differential images is maintained without high-pass or low-pass filtering, and the resultant image is representative of an idealized integrated reconstruction having sharper high frequency structures. ### Claim 6 A method of forming a representative high frequency emphasized phase image from a phasor image, the method comprising: differentiating the phasor image to produce an intermediate image having two orthogonal components; constructing a (complex) image from the two orthogonal components of the intermediate image; and applying an inverse Riesz transform to the constructed image to form a representative high frequency emphasized phase image, wherein the representative high frequency emphasized image comprises a high pass filtered component and a discrepancy component. ### Claim 7 (depends on 6) A method according to claim 6, in which the Riesz transformation is utilized to combine two differential images in correct orientational distribution proportion to maintain a power spectrum of the images and allow the directional structure in the two images to combine. ### Claim 8 (depends on 7) A method according to claim 7, wherein the power spectrum of the input differential images is maintained without high-pass or low-pass filtering, and the resultant image is representative of an idealized integrated reconstruction having sharper high frequency structures. ### Claim 9 A method of reducing noise in a pair differential images, the method comprising: combining the differential images into of a complex image having real and imaginary parts; inverse Riesz transforming the complex image to give an intermediate complex image; removing the imaginary part of the intermediate complex image; forward Riesz transforming the real part of the intermediate complex image to form a complex output image having real and imaginary parts; associating the real and imaginary parts of the output image with the real and imaginary differential image inputs. ### Claim 10 (depends on 9) A method according to claim 9, in which the Riesz transformation is utilized to combine two differential images in correct orientational distribution proportion to maintain a power spectrum of the images and allow the directional structure in the two images to combine. ### Claim 11 (depends on 10) A method according to claim 10, wherein the power spectrum of the input differential images is maintained without high-pass or low-pass filtering, and the resultant image is representative of an idealized integrated reconstruction having sharper high frequency structures. ### Claim 12 A method of forming a representative image from a pair of differential input images, the method comprising: determining a plurality of spectral lobes from the differential input images; selecting from the plurality of determined lobes, two substantially orthogonal sidelobes, said selected sidelobes representing spatial differential phase information of the differential input images; blending an orientational distribution of spatial differential phase information of the selected sidelobes by maintaining a power spectrum of the differential input images to form a processed differential phase image; and forming a representative image emphasising high frequency detail information of the object from the processed differential phase image. ### Claim 13 (depends on 12) A method according to claim 12, wherein the differential input images are interferometer images. ### Claim 14 (depends on 12) A method according to claim 12, wherein the processing comprises applying an inverse Riesz transform to the spatial differential phase information. ### Claim 15 (depends on 12) A method according to claim 12, wherein the blended differential phase image is a complex image and the forming comprises extracting the real part of the processed differential phase image as the representative image. ### Claim 16 A computer readable storage medium having a program recorded thereon, the program being executable by a computer apparatus to form a representative image from a crossed grating fringe pattern interferogram of an object from an interferometer, the program comprising: code for determining a plurality of spectral lobes from the interferogram; code for selecting from the plurality of determined lobes, two substantially orthogonal sidelobes, said selected sidelobes representing spatial differential phase information of the interferogram; code for applying an inverse Riesz transform to the spatial differential phase information of the selected sidelobes to form a transformed differential phase image; and code for forming from the transformed differential phase image, a representative image emphasising high frequency detail information of the object. ### Claim 17 A computer readable storage medium having a program recorded thereon, the program being executable by a computer apparatus to form a representative high frequency emphasized phase image from a phasor image, the method comprising: code for differentiating the phasor image to produce an intermediate image having two orthogonal components; code for constructing a (complex) image from the two orthogonal components of the intermediate image; and code for applying an inverse Riesz transform to the constructed image to form a representative high frequency emphasized phase image, wherein the representative high frequency emphasized image comprises a high pass filtered component and a discrepancy component. ### Claim 18 A computer readable storage medium having a program recorded thereon, the program being executable by a computer apparatus to form a representative image from a pair of differential input images, the method comprising: code for determining a plurality of spectral lobes from the differential input images; code for selecting from the plurality of determined lobes, two substantially orthogonal sidelobes, said selected sidelobes representing spatial differential phase information of the differential input images; code for blending an orientational distribution of spatial differential phase information of the selected sidelobes by maintaining a power spectrum of the differential input images to form a processed differential phase image; and code for forming a representative image emphasising high frequency detail information of the object from the processed differential phase image. ### Claim 19 A computer apparatus for forming a representative high frequency emphasized phase image from a phasor image, the apparatus comprising: means for differentiating the phasor image to produce an intermediate image having two orthogonal components; means for constructing a (complex) image from the two orthogonal components of the intermediate image; and means for applying an inverse Riesz transform to the constructed image to form a representative high frequency emphasized phase image, wherein the representative high frequency emphasized image comprises a high pass filtered component and a discrepancy component. ### Claim 20 An x-ray interferometer system comprising: an x-ray device capturing a crossed grating fringe pattern interferogram of an object, and a computer apparatus forming a representative image from the captured crossed grating fringe pattern interferogram, the representative image being formed by: determining a plurality of spectral lobes from the interferogram; selecting from the plurality of determined lobes, two substantially orthogonal sidelobes, said selected sidelobes representing spatial differential phase information of the interferogram; applying an inverse Riesz transform to the spatial differential phase information of the selected sidelobes to form a transformed differential phase image; and forming from the transformed differential phase image, a representative image emphasising high frequency detail information of the object.