Abstract: A technique determines a depth measurement associated with a scene captured by an image capture device. The technique receives at least first and second images of the scene, in which the first image is captured using at least one different camera parameter than that of the second image. At least first and second image patches are selected from the first and second images, respectively, the selected patches corresponding to a common part of the scene. The selected image patches are used to determine which of the selected image patches provides a more focused representation of the common part. At least one value is calculated based on a combination of data in the first and second image patches, the combination being dependent on the more focused image patch. The depth measurement of the common part of the scene is determined from the at least one calculated value.

Abstract: A method of demodulating an image captured from an imaging system having at least one two-dimensional grating. The captured image comprises a phase modulated fringe pattern comprising cross-term phase components resulting from presence of the at least one two-dimensional grating. The method determines parameters of at least a first non-linear transformation for attenuating the cross-term phase components. The parameters of the first non-linear transformation are determined for the imaging system to reduce artefacts in a demodulated image introduced by the cross-term phase components. The method demodulates the captured image by applying at least the first non-linear transformation with the determined parameters to the captured image to attenuate the cross-term phase components.

Abstract: Methods for determining a depth measurement of a scene which involve capturing at least two images of the scene with different camera parameters, and selecting corresponding image patches in each scene. A first approach calculates a plurality of complex responses for each image patch using a plurality of different quadrature filters, each complex response having a magnitude and a phase, assigns, for each quadrature filter, a weighting to the complex responses in the corresponding image patches, the weighting being determined by a relationship of the phases of the complex responses, and determines the depth measurement of the scene from a combination of the weighted complex responses.

Abstract: A method determines at least one image value of a corresponding desired output position of an output image from an input image. An orientation of an edge passing through the output position is determined in a localised region of the input image. A frequency spectrum for the region of the input image is extended. A main frequency band of the edge is aligned in the extended frequency spectrum parallel to a first sampling axis of a grid based on the orientation of the edge. The grid is selected from a set of the input and output grids. The aligned main frequency band is filtered along a second sampling axis of the grid, orthogonal to the first sampling axis, the filter removing frequencies associated with replica bands and maintaining the main frequency band. The image value is determined from the filtered edge at the desired output position.

Abstract: A method of modifying the blur in at least a part of an image of a scene captures at least two images of the scene with different camera parameters to produce a different amount of blur in each image. A corresponding patch in each of the captured images is selected each having an initial amount of blur is used to calculate a set of frequency domain pixel values from a function of transforms of the patches. Each of the pixel values in the set are raised to a predetermined power, forming an amplified set of frequency domain pixel values. The amplified set of frequency domain pixel values is combined with the pixels of the patch in one of the captured images to produce an output image patch with blur modified relative to the initial amount of blur in the image patch.

Abstract: A method (300) is described of determining characteristic of an ink jet printer (15). A chart containing multiple regions or patches is printed (320) on a print medium (115) using the ink jet print (15). The chart includes at least a first region printed using a first set of nozzles, and at least a second region printed using a second set of nozzles. The first and second sets of nozzles are a predetermined distance apart in the printer head of the printer (15). The printing of the first and second regions is also separated by a print medium advance operation equal to the predetermined distance. This causes the first and second regions to be aligned in the direction of the print medium advance operation. The chart is then imaged using scanner (16) chart to form a chart image. The positions of the regions appearing in the chart image are next determined (340).

Abstract: A method of determining an actual phase offset of a fringe pattern in a captured image. A captured image, having a phase modulated fringe pattern, is one of a set of images captured with varying introduced phase offset and forms an intermediate demodulation image from the captured image. The intermediate demodulation image defines amplitude and complex phase parameters of the phase modulated fringe pattern. The captured image is transformed by a mask to produce a processed captured image having reduced effects of phase distortion. The mask is estimated from a function of at least one of the amplitude and complex phase parameters defined by the intermediate demodulation image. The method determines a Fourier transform of the processed captured image, and determines at least one phase offset of the fringe pattern in the processed captured image using the mask to identify interaction of peaks in the Fourier transform.

Abstract: Disclosed is a method of determining at least one three-dimensional (3D) geometric parameter of an imaging device. A two-dimensional (2D) target image is provided having a plurality of alignment patterns. The target image is imaged with an imaging device to form a captured image. At least one pattern of the captured image is compared with a corresponding pattern of the target image. From the comparison, the geometric parameter of the imaging device is then determined. The alignment patterns include at least one of (i) one or more patterns comprising a 2D scale and rotation invariant basis function, (ii) one or more patterns comprising a 1D scale invariant basis function, and (iii) one or more patterns having a plurality of grey levels and comprising a plurality of superimposed sinusoidal patterns, the plurality of sinusoidal patterns having a plurality of predetermined discrete orientations.

Abstract: Disclosed is a method of reconstructing a representative detailed phase image from a set of fringe pattern interferogram images of an object. The images are captured by an x-ray interferometer having a crossed diffraction grating. A set of captured fringe pattern interferogram images from the x-ray interferometer are provided, the set comprising no more than eight captured fringe pattern interferogram images. The method determines an estimate of an absorption parameter (a), two-dimensional amplitude modulation parameters (mx, my), and two-dimensional phase modulation parameters (?x and ?y) from a closed-form solution using the received set of captured fringe pattern interferogram images, and reconstructs the representative detailed phase image using the parameter estimates.

Abstract: A method of modifying the blur in at least a part of an image of a scene captures at least two images of the scene with different camera parameters to produce a different amount of blur in each image. A corresponding patch in each of the captured images is selected each having an initial amount of blur is used to calculate a set of frequency domain pixel values from a function of transforms of the patches. Each of the pixel values in the set are raised to a predetermined power, forming an amplified set of frequency domain pixel values. The amplified set of frequency domain pixel values is combined with the pixels of the patch in one of the captured images to produce an output image patch with blur modified relative to the initial amount of blur in the image patch.

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.

Abstract: Methods, apparatuses, systems and computer program products for measuring spatial characteristics of an inkjet printer are disclosed. Group of marks of a first predetermined pattern are printed on a print medium using a first group of nozzles. Groups of marks of a second predetermined pattern are printed using a second group of nozzles. A region of overlap of the printed groups of marks is formed. At least a portion of the print medium having printed groups of marks is imaged. From the region of overlap, first and second groups of marks from the first and second printed patterns are selected. For each group of marks, a position representative of that group is determined. An offset for measuring spatial characteristics of the printer between the first and second printed patterns is determined dependent upon the representative position of each of the first and second groups of marks.

Abstract: A method determines at least one image value of a corresponding desired output position of an output image from an input image. An orientation of an edge passing through the output position is determined in a localised region of the input image. A frequency spectrum for the region of the input image is extended. A main frequency band of the edge is aligned in the extended frequency spectrum parallel to a first sampling axis of a grid based on the orientation of the edge. The grid is selected from a set of the input and output grids. The aligned main frequency band is filtered along a second sampling axis of the grid, orthogonal to the first sampling axis, the filter removing frequencies associated with replica bands and maintaining the main frequency band. The image value is determined from the filtered edge at the desired output position.

Abstract: Methods for determining a depth measurement of a scene which involve capturing at least two images of the scene with different camera parameters, and selecting corresponding image patches in each scene. A first approach calculates a plurality of complex responses for each image patch using a plurality of different quadrature filters, each complex response having a magnitude and a phase, assigns, for each quadrature filter, a weighting to the complex responses in the corresponding image patches, the weighting being determined by a relationship of the phases of the complex responses, and determines the depth measurement of the scene from a combination of the weighted complex responses.

Abstract: A technique determines a depth measurement associated with a scene captured by an image capture device. The technique receives at least first and second images of the scene, in which the first image is captured using at least one different camera parameter than that of the second image. At least first and second image patches are selected from the first and second images, respectively, the selected patches corresponding to a common part of the scene. The selected image patches are used to determine which of the selected image patches provides a more focused representation of the common part. At least one value is calculated based on a combination of data in the first and second image patches, the combination being dependent on the more focused image patch. The depth measurement of the common part of the scene is determined from the at least one calculated value.

Abstract: A method for measuring the spatial frequency response (SFR) of an imaging system (299) including a display device (280) and an image capture device (290) is disclosed. The method displays a sequence of displayable test pattern images on the display device, the sequence comprising a first test pattern image and at least two subsequent test pattern images, each of the displayable test pattern images including a test pattern having at least one sinusoidal pattern at one or more spatial frequencies such that a phase shift of the sinusoidal pattern has a plurality of pre-determined values. The displayed images are captured with the image capture device to generate a corresponding sequence of captured test pattern images. The captured test pattern images are then compared with the displayable test pattern images to calculate the SFR at a plurality of image locations in the imaging system at the one or more spatial frequencies.

Abstract: A method (1000) of measuring performance parameters of an imaging device (120, 160) is disclosed. The method (1000) maintains a test pattern image (1005), the test pattern image (1005) comprising alignment features and image analysis features. A test chart (110, 170) containing a representation of the test pattern image is next imaged using the imaging device (120, 160) to form a second image (1010). The test pattern image (1005) and the second image (1010) are then registered using region based matching (1035) operating on the alignment features. Finally, the performance parameters are measured by analysing (1060) the image analysis features.

Abstract: A method (200) of determining at least rotation and scale parameters of a transformation relating two images is disclosed. The method (200) starts by forming a spatial domain representation of each of the images that is invariant to translation of the images. A correlation in the log-polar domain is next performed between the representations. After detecting a magnitude peak in the correlation, the method (200) determines the rotation and scale parameters from the position of the magnitude peak.

Abstract: A method (300) is described of determining characteristic of an ink jet printer (15). A chart containing multiple regions or patches is printed (320) on a print medium (115) using the ink jet print (15). The chart includes at least a first region printed using a first set of nozzles, and at least a second region printed using a second set of nozzles. The first and second sets of nozzles are a predetermined distance apart in the printer head of the printer (15). The printing of the first and second regions is also separated by a print medium advance operation equal to the predetermined distance. This causes the first and second regions to be aligned in the direction of the print medium advance operation. The chart is then imaged using scanner (16) chart to form a chart image. The positions of the regions appearing in the chart image are next determined (340).

Abstract: Methods (700), apparatuses, systems (500) and computer program products for measuring spatial characteristics of an inkjet printer (200, 300) are disclosed. Group of marks (810/815) of a first predetermined pattern are printed (720) on a print medium (230) using a first group of nozzles (420). Groups of marks (820/825) of a second predetermined pattern are printed (720) using a second group of nozzles (420). A region of overlap of the printed groups of marks is formed. At least a portion of the print medium (230) having printed groups of marks is imaged. From the region of overlap, first and second groups of marks from the first and second printed patterns are selected (740). For each group of marks, a position representative of that group is determined An offset for measuring spatial characteristics of the printer (200, 300) between the first and second printed patterns is determined (750) dependent upon the representative position of each of the first and second group of marks.