453 results about "Light-field camera" patented technology

A camera acquires a 4D light field of a scene. The camera includes a lens and sensor. A mask is arranged in a straight optical path between the lens and the sensor. The mask including an attenuation pattern to spatially modulate the 4D light field acquired of the scene by the sensor. The pattern has a low spatial frequency when the mask is arranged near the lens, and a high spatial frequency when the mask is arranged near the sensor.

Methods and apparatus for light-field imaging. Light-field camera designs are described that produce higher spatial resolution than conventional plenoptic camera designs, while trading-off the light-field's angular sampling density. This lower angular resolution may be compensated for by a light-field image processing method that inserts data synthesized by view interpolation of the measured light-field. In one embodiment, a light-field image processing method that performs three-view morphing may be used to interpolate the missing angular samples of radiance. The light-field camera designs may be implemented in hand-held light-field cameras that may capture a light-field with a single exposure. Some of the light-field camera designs are internal to the camera, while others are external to the camera. One light-field camera design includes a single, relatively large lens and an array of negative lenses that are placed in front of (external to) the main lens of a conventional camera.

Spatio-temporal light field cameras that can be used to capture the light field within its spatio temporally extended angular extent. Such cameras can be used to record 3D images, 2D images that can be computationally focused, or wide angle panoramic 2D images with relatively high spatial and directional resolutions. The light field cameras can be also be used as 2D / 3D switchable cameras with extended angular extent. The spatio-temporal aspects of the novel light field cameras allow them to capture and digitally record the intensity and color from multiple directional views within a wide angle. The inherent volumetric compactness of the light field cameras make it possible to embed in small mobile devices to capture either 3D images or computationally focusable 2D images. The inherent versatility of these light field cameras makes them suitable for multiple perspective light field capture for 3D movies and video recording applications.

A wearable ophthalmic device is disclosed. The device may include an outward facing head-mounted light field camera to receive light from a user's surroundings and to generate numerical light field image data. The device may also include a light field processor to access the numerical light field image data, to obtain an optical prescription for an eye of the user, and to computationally introduce an amount of positive or negative optical power to the numerical light field image data based on the optical prescription to generate modified numerical light field image data. The device may also include a head-mounted light field display to generate a physical light field corresponding to the modified numerical light field image data.

The invention aims to provide a method for drawing viewpoints by reinforcing an interested region, comprising the following steps of: aiming at the collection mode of a light field camera, firstly establishing the camera geometrical model of the collection mode of the light field camera according to the parameters of a collection system and the geometrical information of a scene, then calculatingthe interested region and reinforcing the original thin depth map through the identified interested region; and then carrying out light field drawing by utilizing the reinforced depth map according to camera parameters and a geometrical scene to obtain a new viewpoint image. The test on the method indicates that the invention can obtain favorable viewpoint reestablishing quality.

A handheld wand comprises a probe at a distal end of the elongate handheld wand. The probe includes a light projector and a light field camera. The light projector includes a light source and a pattern generator configured to generate a light pattern. The light field camera includes a light field camera sensor, the light field camera sensor comprising an image sensor comprising an array of sensor pixels, and an array of micro-lenses disposed in front of the image sensor such that each micro-lens is disposed over a sub-array of the array of sensor pixels.

Spatio-temporal light field cameras that can be used to capture the light field within its spatio temporally extended angular extent. Such cameras can be used to record 3D images, 2D images that can be computationally focused, or wide angle panoramic 2D images with relatively high spatial and directional resolutions. The light field cameras can be also be used as 2D / 3D switchable cameras with extended angular extent. The spatio-temporal aspects of the novel light field cameras allow them to capture and digitally record the intensity and color from multiple directional views within a wide angle. The inherent volumetric compactness of the light field cameras make it possible to embed in small mobile devices to capture either 3D images or computationally focusable 2D images. The inherent versatility of these light field cameras makes them suitable for multiple perspective light field capture for 3D movies and video recording applications.

The present invention provides a light field imaging-based chromatographic PIV measuring device and a method. The device includes a light source apparatus for generating double-pulse laser light and illuminating a three-dimensional flow field and an imaging apparatus for photographing the three-dimensional flow field; the light emitting end of the light source apparatus is provided with a lens group; the light source apparatus and the imaging apparatus are connected with a time sequence synchronous controller; the imaging apparatus is connected with a computer; the lens group is used for developing the double-pulse laser generated by the light source apparatus into a body light source of a certain thickness and a two-dimensional sheet light source of 1 mm and illuminating the flow field; and the image forming apparatus comprises a main lens, a CCD detector and a microlens array positioned between the main lens and the CCD detector. With the device and the method of the invention adopted, a weight matrix can be can quickly calculated, the calibration of the internal and external parameters of a light field camera is not required, and system error caused by multi-camera synchronous coupling can be reduced. The device is simple.

The invention discloses a light field projection method used for scene illumination recovery, and belongs to the technical field of virtual reality. In the method, a device adopting a projector and a lens array is designed to perform the light field projection, light field data is converted into a light field to perform projection, and the scene illumination is recovered. The method comprises the following specific steps: firstly, converting a sampled optical measurement image sequence into the four-dimensional light field expression of the scene illumination; then, clustering point light sources on a light source plane, generating projection sub-images for all the point light sources clustered, and performing distortion correction and image stitching; finally, after geometric calibration and luminance calibration, adopting a projector to project the projected images on the lens array, and refracting light rays on the other side through lenses to form a plane light field, so as to recover the illumination of an original scene. The illumination recovered by adopting the method has higher realness, higher space freedom degree and higher practicability. The method is applicable to the illumination application fields such as video and film special effects and stage lighting control.

A three-dimensional contour measuring method based on structured light field imaging is characterized by including the steps that an imaging system composed of a light field camera and a projector isestablished, the projector projects an original coding grating to a to-be-measured object, the light field camera shoots a coding grating image obtained after being subjected to contour modulation ofthe to-be-measured object, and the coding grating image which is shot by the light field camera and is subjected to contour modulation of the to-be-measured object is decoded, and three-dimensional reconstruction is carried out on the contour of the object according to the information obtained after decoding; a three-dimensional contour measurement problem is summarized into three equations for solving three unknown numbers containing object point three-dimensional coordinates, wherein after the imaging system is calibrated, two equations are determined by using the process that the to-be-measured object is imaged in a center sub-aperture image in the light field camera, the third equation is determined by using the decoded image information, and three-dimensional contour measurement is achieved by solving an equation set formed by the three equations.

A magnetic resonance coil apparatus includes a receiving region for receiving a subregion of a patient to be examined, a housing shell unit enclosing the receiving region, and an antenna unit for picking up magnetic resonance signals. The magnetic resonance coil apparatus includes a camera unit with at least one light field camera element.

The invention discloses a hybrid camera array based light field video imaging system and video processing method. The system includes a control cloud deck, an image processing unit, a storage unit anda hybrid camera array. The hybrid camera array includes a global camera, a global light field camera and a plurality of local cameras used for collecting a global low resolution reference video, a global light field video and a plurality of local high definition videos of one scene synchronously. The image processing unit performs following treatment on a reference image, a global light field image and a plurality of high definition images of each group taken at the same moment: performing block matching on the local images with the reference image, converting the local images to corresponding blocks of the reference image based on matching results and obtaining a global high definition image; based on the global high definition image, performing super-resolution on the global light fieldimage so as to obtain a global high resolution light field image; combining all frames of global high resolution light field images into a global high resolution light field video.

The embodiment of the invention discloses a relative radiometric calibration method for light field camera, which comprises the steps of: carrying out calibration processing of images emitted from an uniform area light source by a light field camera to obtain measurement values of dark current noise, grey centroid coordinates of subimages of microlens, and flat-field correction coefficients; and processing other original light field images shot by the light field camera correspondingly by utilizing the measurement values of dark current noise, the grey centroid coordinates of subimages of microlens, and the flat field correction coefficients to obtain light filed images after relative radiometric calibration processing. The method of the invention can eliminate dark current noise in light field camera system, remove invalid pixels between subimages of microlens, and correct the problem of pixel response nonuniformity caused by various factors, thereby improving the performance of the light field camera.

The invention discloses a method used for measuring the pose of a non-cooperative target based on a complete light field camera. The method is applied in the non-cooperative target containing a star arrow docking ring. The star arrow docking ring on the non-cooperative target is a circle and is characterized in that step 1, the light field image of the non-cooperative target with circular features is obtained by adopting the compete light field camera; step 2, surface normal vectors, and the coordinates of the circular center of the circular features are calculated in the main lens coordinate system of the complete light field camera; step 3, false solutions are removed; step 4, the pose of the non-cooperative target is acquired. According to the invention, the false solutions based on the monocular vision pose estimations of the circle can be effectively removed, so that the pose of the non-cooperative target which meets accuracy requirements can be obtained.

The invention provides a multispectral light-field camera. Along a light path direction, the camera comprises a light filter array, a main imaging lens, a micro lens array, combined sub-lenses, a detector and a signal processing system, which are sequentially arranged. An imaging method comprises the steps that: the light filter array is arranged on a pupil plane of the main imaging lens, and information of various target spectral bands is introduced with a pore size division method; with the micro lens array positioned on an image plane of the main imaging lens, the multispectral information is spatially separated; the combined sub-lenses are introduced, such that micro lens focal plane is secondarily transferred to a detector photosensitive surface; and the signal processing system calculates the data obtained by the detector, and spectral images of different wavebands are extracted and obtained. With the camera provided by the invention, multispectral information of each pixel in a full field of view can be obtained, dynamic multispectral imaging can be realized, and system structure is stable.

A method for directly obtaining a depth image through light field camera one-time imaging comprises the steps that (1) a micro-lens array is embedded into an internal imaging light path of a traditional camera to form a light field camera; (2) the relative position of the micro-lens array and an image sensor is calibrated; (3) the light field camera is used for collecting original data of a target scene, a sub-image under each micro-lens in the micro-lens array is extracted and a grey-scale image of each sub-image is calculated; (4) the similarity between the sub-image under each micro-lens and the sub-image under the adjacent micro-lens is calculated, each micro-lens used as a target lens and multiple adjacent lenses around the corresponding micro-lens are selected in order to establish target templates and adjacent templates respectively, an SAD algorithm is used for calculating the similarity between the target templates and the adjacent templates and minimum SAD values are obtained; (5) the minimum SAD values obtained in the step (4) and corresponding to the sub-images under all the micro-lenses form a value matrix with the size being the number of the micro-lenses in the micro-lens array, and the depth image is obtained after normalized rounding is conducted on elements in the array. The method for directly obtaining the depth image through light field camera one-time imaging solves the problems that in an existing depth image obtaining technology, a system is too complex and the computation complexity is high, the obtained image similarity is high and the obtained depth image is more accurate.

The invention discloses a human face living detection method based on a light field camera. The method comprises steps: (1) original data of the light field camera are extracted and decoded; (2) a refocus image for different depths of the face is extracted from the light field data; (3) focus features and power spectrum features are extracted in the refocus image, and the two kinds of features are connected as integrated features for the human face image; (4) the above integrated features are extracted on all acquired light field images, the integrated features of a training set are inputted to a support vector machine for training to obtain a model for human face living detection, and the integrated features of the to-be-detected image are inputted to the well-trained model to obtain a detection result. The characteristic that the refocus image for different depths can be acquired after one-time photographing by the light field camera is used, human face refocus change features are extracted for human face living detection, and compared with the traditional human face living detection method, the detection result is accurate, the detection efficiency is higher, the detection is simpler and more convenient, and requirements of practical applications are met.

The invention discloses a rendering method and a system of a focusing type light field camera. The method comprises steps of: S1, inputting pictures shot by a focusing type light field camera and recording position information and center information of each micro-lens and each subaperture graph; S2, according to a plane image needing to be re-focused, calculating the depth of filed thereof, and according to the depth of field, determining the size of the radius R; S3, in the center position of each subaperture graph, taking a regular hexagon region block with the radius R; S4, laying and combining the regular hexagon region blocks according to the sequence of the subaperture graphs so as to obtain a combined graph; S5, processing the combined graph so as to obtain the final rendering graph. According to the invention, by taking advantages of hexagonal arrangement features of a micro-lens array, and taking the regular hexagon region blocks of the subaperture graphs of the micro-lenses, in the rendering process, the calculated amount of the rendering method of the focusing type light field camera can be effectively reduced without conversion of a coordinate system.

The invention discloses a three-dimensional flow field testing method based on a single light field camera, A1, using a single light field camera to obtain a time series particle light field image of tracer particles in the flow field to be tested; A2, preprocessing the time series particle light field image , to remove background noise; A3, use CPU and / or GPU parallel processing methods to reconstruct time-series particle light field images to obtain time-series 3D particle images; A4, perform cross-correlation calculations on time-series 3D particle images to obtain 3D flow field velocity Field distribution; A5, post-processing the velocity field of the three-dimensional flow field, eliminating the wrong velocity vector, and replacing the eliminated wrong vector with interpolation based on the adjacent correct vector. The present invention can obtain the three-dimensional velocity distribution of the flow field to be tested through the sequential image acquisition of a single light field camera. Compared with the existing multi-view three-dimensional flow field test method, the hardware system configuration is greatly reduced and the hardware system adjustment is simplified. Steps, especially suitable for three-dimensional flow field measurement in confined space.

The present invention relates to the technical field of image pickup processing, and disclosed is a light field camera. The bending shape of a bending type micro lens array and the bending shape of a bending type image sensor are both the same as that of a virtual image surface of a wide-angle master lens. The sum of the reciprocal of the vertical distance between the bending type micro lens array and the bending type image sensor and the reciprocal of the vertical distance between the bending type micro lens array and the virtual image surface of the wide-angle master lens is equal to the reciprocal of the focal distance of the bending type micro lens array. The present invention solves the problem of the deterioration in image quality, such as blurring and distortion, caused by the fact that a flat plate type micro lens array and a flat plate type image sensor cannot mate with a bent virtual image surface of a wide-angle master lens when a light field camera adopts the wide-angle master lens.

An imaging system comprises a light field camera (3) for recording a hyperspectral light field (CLF). The system also comprises a light projector (4) for projecting a light field in visible light (PLF). The camera and the projector share a common optical axis. The projector projects a light field (PLF) based on the hyperspectral light field (CLF) captured by the light field camera.

The invention provides a light field camera external parameter calibration device and method. According to the device and method, a color coding plate is arranged before the main lens of a light field camera and is fixed on an angle rotating table; the light field camera shoots the color coding plate arranged in different angles, corresponding relations of colors and angles of light emitted by the color coding plate in various angles are adopted as prior information; the light field camera is arranged at a plurality of locations and captures scenes; and external parameter calibration can be completed based on the priori information. With the device and method of the invention adopted, a plurality of external parameters of double planes in arbitrary attitudes can be calibrated, and the calibration does not depend on a fixed mode camera movement platform, and therefore, external parameter calibration is more accurate, and is not effected by errors caused by the inertia of the camera movement platform.

The invention discloses an optical-field-camera-based realization method for three-dimensional scene recording and broadcasting. A plurality of optical-field cameras with multiple angles collect optical field information simultaneously; a main control computer collects the information and converts the optical field information into depth point clouds with RGB colors; the main control computer carries out synchronous fusion on data of the multiple optical-field cameras to reconstruct dynamic 3D scene data, wherein the data are scenes described in a point cloud mode; the main control computer carries out mesh optimization on the point cloud data to obtain a 3D model and chartlet information; the main control computer transmits the 3D model data to a user client; and user client software constructs a virtual 3D scene based on the data and carries out rendering. According to the invention, the main control computer collects the information and converts the optical field information into the depth point cloud data with the RGB colors to realize 3D scene reconstruction and then the virtual camera carries out 3D scene rendering again. Therefore, free changing at any angle is realized; and a rendering distance and an illumination direction can be adjusted.

The invention provides a three-dimensional flow field test method based on a double-light-field camera. The method comprises the following steps: obtaining time sequence particle light-field images oftrace particles in a flow field to be measured through the double-light-field camera; carrying out pretreatment on the time sequence particle light-field images to remove background noise; carrying out reconstruction on the time sequence particle light-field images through a GPU parallel processing method to obtain a time sequence three-dimensional particle image; carrying out cross correlation calculation on the time sequence three-dimensional particle image through a fast Fourier transform method to obtain three-dimensional flow field velocity field distribution; and carrying out postprocessing on the three-dimensional flow field velocity field to reject error velocity vectors, and meanwhile, replacing the rejected error vectors with adjacent correct vector interpolation. Compared withan existing single-light-field three-dimensional flow field test method, the method eliminates the elongation effect of the reconstructed particles in the direction of the optical axis, and greatly improves velocity vector precision and accuracy; and meanwhile, compared with a conventional multi-visual-angle three-dimensional flow field test method, the method greatly reduces hardware system configuration and simplifies hardware system adjustment steps, and is especially suitable for three-dimensional flow field measurement under a restricted space.

The invention discloses a calibration method for a microlens light field camera. The method comprises steps: based on the microlens light field camera, a white image and a target image are acquired; the microlens projection center position is detected on the white image; according to the microlens projection center position, the target image is decoded to obtain 4D light field data; a center sub-aperture image is generated by the 4D light field data, and corner points are detected; according to the corner point positions detected on the center sub-aperture image, sub images possibly containingthe corner points on the target image are selected; on the selected sub images, the corner points are detected; based on a corner point set detected on the center sub-aperture image, simplified modelinitial parameters are solved; based on a corner point set detected on the selected sub images, non-distorted model parameters are estimated; and with the non-distorted model parameters as initial values and based on the corner point set detected on the selected sub images, model parameters considering distortion are further estimated. The calibration method can estimate inner and outer parameters of the light field camera at the same time, functions are comprehensive, the result is accurate, and the efficiency is high.

An embodiment of the invention discloses an optical field collecting control method and device and optical field collecting equipment. The optical field collecting control method includes: acquiring the main lens aperture parameters of an optical field camera; determining part of the imaging area, corresponding to at least one sub-lens in the sub-lens array of the optical field camera, in the image sensor of the optical field camera as a first imaging area; adjusting the pixel density distribution of the image sensor to allow the pixel density of the adjusted first imaging area to be different from that of the other parts of the imaging area; using the adjusted optical field camera to perform optical field collecting on a to-be-shot scene. The method has the advantages that image sensor pixel utilization rate during optical field collecting performed by the optical field camera on the to-be-shot scene is increased, and optical field image imaging quality is increased.

The invention discloses a self-adaption geometric calibration method of a light field camera. The method comprises the steps: collecting a reference image I, and calculating a pixel distance n between every two micro lens subimages and a relative included angle theta between a micro lens array and an image sensor array on the basis of a spectrogram of the reference image; correcting a parallel error of the reference image I on the basis of the relative included angle theta, so as to obtain a corrected reference image Ir, and calculating a center coordinate (xc, yc) of each micro lens subimage; and correcting a parallel error of an actual image on the basis of the relative included angle theta, then calculating the pixel distance n' between every two micro lens subimages on the basis of the corrected actual image, and calculating an actual center coordinate (x'c, y'c) of each micro lens subimage by utilizing the center coordinate (xc, yc) and the ratio of the pixel distance n' to the pixel distance n, so that the self-adaption geometric calibration of the light field camera can be realized. By adopting the method disclosed by the invention, the reference image only needs to be shot once, the automatic calibration on the light field camera with different lens parameters can be performed, so that the self-adaption geometric calibration of the light field camera can be realized.