Patents by Inventor Ramesh Raskar

Ramesh Raskar has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20160042501
    Abstract: Systems and methods for compensating for at least one optical aberration in a vision system of a viewer viewing a display. Image data for an image to be displayed is received, at least one parameter related to at least one optical aberration in the vision system of a viewer is received and an aberration compensated image to be displayed is computed based on the at least one received parameter related to the vision system of a viewer and on at least one characteristic of the light field element. The aberration compensated image is displayed on the display medium, such that when a viewer whose vision system has the at least one optical aberration views the aberration compensated image displayed on the display medium through a light field element, the aberration compensated image appears to the viewer with the at least one aberration reduced or eliminated.
    Type: Application
    Filed: August 11, 2015
    Publication date: February 11, 2016
    Inventors: Fu-Chung Huang, Gordon Wetzstein, Brian Barsky, Ramesh Raskar
  • Patent number: 9240839
    Abstract: An array of light emitters is arranged single-file along an emitting surface of a transmitting device and emits light in a z-direction normal to the emitting surface. The array of light emitters is aligned along a y-direction normal to the z-direction. A lens assembly is optically coupled to the array of light emitters. The lens assembly includes at least one cylindrical lens and at least one aspherical lens. The lens assembly emits the light in free-space along the z-direction and has a first focal length in the y-direction and a different, second focal length in an x-direction. An encoder is coupled to apply a data signal to the array of light emitters. The data signal causes the array of light emitters to illuminate in a pattern that switches at a rate corresponding to a rolling shutter of a receiving sensor array.
    Type: Grant
    Filed: January 7, 2014
    Date of Patent: January 19, 2016
    Assignee: NOKIA CORPORATION
    Inventors: Ramesh Raskar, Pranav Mishra, Rajeswari Kannan
  • Publication number: 20160014393
    Abstract: A time-of-flight camera images an object around a corner or through a diffuser. In the case of imaging around a corner, light from a hidden target object reflects off a diffuse surface and travels to the camera. Points on the diffuse surface function as a virtual sensors. In the case of imaging through a diffuser, light from the target object is transmitted through a diffusive media and travels to the camera. Points on a surface of the diffuse media that is visible to the camera function as virtual sensors. In both cases, a computer represents phase and intensity measurements taken by the camera as a system of linear equations and solves a linear inverse problem to (i) recover an image of the target object; or (ii) to compute a 3D position for each point in a set of points on an exterior surface of the target object.
    Type: Application
    Filed: July 9, 2015
    Publication date: January 14, 2016
    Applicant: Massachusetts Institute of Technology
    Inventors: Achuta Kadambi, Hang Zhao, Boxin Shi, Ayush Bhandari, Ramesh Raskar
  • Publication number: 20150362743
    Abstract: In exemplary implementations of this invention, two LCD screens display a multi-view 3D image that has both horizontal and vertical parallax, and that does not require a viewer to wear any special glasses. Each pixel in the LCDs can take on any value: the pixel can be opaque, transparent, or any shade between. For regions of the image that are adjacent to a step function (e.g., a depth discontinuity) and not adjacent to a sharp corner, the screens display local parallax barriers comprising many small slits. The barriers and the slits tend to be oriented perpendicular to the local angular gradient of the target light field. In some implementations, the display is optimized to seek to minimize the Euclidian distance between the desired light field and the actual light field that is produced. Weighted, non-negative matrix factorization (NMF) is used for this optimization.
    Type: Application
    Filed: August 26, 2015
    Publication date: December 17, 2015
    Applicant: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
    Inventors: Douglas Lanman, Matthew Hirsch, Yun Hee Kim, Szymon Jakubczak, Ramesh Raskar
  • Publication number: 20150330905
    Abstract: In illustrative implementations of this invention, light sources illuminate a surface with multi-spectral, multi-directional illumination that varies in direction, wavelength, coherence and collimation. One or more cameras capture images of the surface while the surface is illuminated under different lighting conditions. One or more computers take, as input, data indicative of or derived from the images, and determine a classification of the surface. Based on the computed classification, the computers output signals to control an I/O device, such that content displayed by the I/O device depends, at least in part, on the computed classification. In illustrative implementations, this invention accurately classifies a wide range of surfaces, including transparent surfaces, specular surfaces, and surfaces with few features.
    Type: Application
    Filed: April 2, 2015
    Publication date: November 19, 2015
    Applicant: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
    Inventors: Munehiko Sato, Ramesh Raskar, Boxin Shi, Alex Olwal
  • Publication number: 20150304534
    Abstract: In illustrative implementations of this invention, an imaging system includes multiple light sources that illuminate a scene, and also includes a lock-in time of flight camera. While the scene is illuminated by these light sources, each of the light sources is amplitude-modulated by a different modulation pattern, and a reference signal is applied to the lock-in time-of-flight camera. The modulation patterns and the reference signal are carefully chosen such that the imaging system is able to disentangle, in real time, the respective contributions of the different light sources, and to compute, in real-time, depth of the scene. In some cases, the modulation signals for the light sources are orthogonal to each other and the reference signal is broadband. In some cases, the modulation codes for the light sources and the reference code are optimal codes that are determined by an optimization algorithm.
    Type: Application
    Filed: April 17, 2015
    Publication date: October 22, 2015
    Applicant: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
    Inventors: Achuta Kadambi, Ayush Bhandari, Ramesh Raskar
  • Patent number: 9146317
    Abstract: In exemplary implementations of this invention, a time of flight camera (ToF camera) can estimate the location, motion and size of a hidden moving object, even though (a) the hidden object cannot be seen directly (or through mirrors) from the vantage point of the ToF camera (including the camera's illumination source and sensor), and (b) the object is in a visually cluttered environment. The hidden object is a NLOS (non-line-of-sight) object. The time of flight camera comprises a streak camera and a laser. In these exemplary implementations, the motion and absolute locations of NLOS moving objects in cluttered environments can be estimated through tertiary reflections of pulsed illumination, using relative time differences of arrival at an array of receivers. Also, the size of NLOS moving objects can be estimated by backprojecting extremas of NLOS moving object time responses.
    Type: Grant
    Filed: May 23, 2012
    Date of Patent: September 29, 2015
    Assignee: Massachusetts Institute of Technology
    Inventors: Rohit Pandharkar, Andreas Velten, Ramesh Raskar
  • Patent number: 9146403
    Abstract: In exemplary implementations of this invention, two LCD screens display a multi-view 3D image that has both horizontal and vertical parallax, and that does not require a viewer to wear any special glasses. Each pixel in the LCDs can take on any value: the pixel can be opaque, transparent, or any shade between. For regions of the image that are adjacent to a step function (e.g., a depth discontinuity) and not adjacent to a sharp corner, the screens display local parallax barriers comprising many small slits. The barriers and the slits tend to be oriented perpendicular to the local angular gradient of the target light field. In some implementations, the display is optimized to seek to minimize the Euclidian distance between the desired light field and the actual light field that is produced. Weighted, non-negative matrix factorization (NMF) is used for this optimization.
    Type: Grant
    Filed: December 1, 2011
    Date of Patent: September 29, 2015
    Assignee: Massachusetts Institute of Technology
    Inventors: Douglas Lanman, Matthew Hirsch, Yun Hee Kim, Szymon Jakubczak, Ramesh Raskar
  • Patent number: 9148649
    Abstract: In exemplary implementations of this invention, a 3D range camera “looks around a corner” to image a hidden object, using light that has bounced (reflected) off of a diffuse reflector. The camera can recover the 3D structure of the hidden object.
    Type: Grant
    Filed: October 7, 2012
    Date of Patent: September 29, 2015
    Assignee: Massachusetts Institute of Technology
    Inventors: Ramesh Raskar, Andreas Velten
  • Patent number: 9143678
    Abstract: Provided are an apparatus and method for processing a light field image that is acquired and processed using a mask to spatially modulate a light field. The apparatus includes a lens, a mask to spatially modulate 4D light field data of a scene passing through the lens to include wideband information on the scene, a sensor to detect a 2D image corresponding to the spatially modulated 4D light field data, and a data processing unit to recover the 4D light field data from the 2D image to generate an all-in-focus image.
    Type: Grant
    Filed: May 6, 2011
    Date of Patent: September 22, 2015
    Assignee: Samsung Electronics Co., Ltd.
    Inventors: Byung-Kwan Park, Ghulam Ahmed Kirmani, Ramesh Raskar, Rohit Pandharkar
  • Patent number: 9131159
    Abstract: A method and apparatus for optical field communication, wherein incident light is spread on the surface of an image sensor with a diffuser element; a conventional digital image is captured with high exposure pixel rows of the image sensor; and the light intensity on two successive low exposure pixel rows of the image sensor is recorded. The recorded light intensities of the two successive low exposure pixel rows are compared; and in response to comparing the recorded light intensities of the two successive low exposure pixel rows, a value of a bit received via optical field communication is determined.
    Type: Grant
    Filed: June 28, 2013
    Date of Patent: September 8, 2015
    Assignee: Nokia Technologies Oy
    Inventors: Ramesh Raskar, Rajeswari Kannan, Pranav Mishra
  • Patent number: 9106841
    Abstract: In exemplary implementations of this invention, a light source illuminates a scene and a light sensor captures data about light that scatters from the scene. The light source emits multiple modulation frequencies, either in a temporal sequence or as a superposition of modulation frequencies. Reference signals that differ in phase are applied to respective subregions of each respective pixel. The number of subregions per pixel, and the number of reference signals per pixel, is preferably greater than four. One or more processors calculate a full cross-correlation function for each respective pixel, by fitting light intensity measurements to a curve, the light intensity measurements being taken, respectively, by respective subregions of the respective pixel. The light sensor comprises M subregions. A lenslet is placed over each subregion, so that each subregion images the entire scene. At least one temporal sequence of frames is taken, one frame per subregion.
    Type: Grant
    Filed: June 13, 2014
    Date of Patent: August 11, 2015
    Assignee: Massachusetts Institute of Technology
    Inventors: Ramesh Raskar, Christopher Barsi
  • Patent number: 9100562
    Abstract: In exemplary implements of this invention, a lens and sensor of a camera are intentionally destabilized (i.e., shifted relative to the scene being imaged) in order to create defocus effects. That is, actuators in a camera move a lens and a sensor, relative to the scene being imaged, while the camera takes a photograph. This motion simulates a larger aperture size (shallower depth of field). Thus, by translating a lens and a sensor while taking a photo, a camera with a small aperture (such as a cell phone or small point and shoot camera) may simulate the shallow DOF that can be achieved with a professional SLR camera. This invention may be implemented in such a way that programmable defocus effects may be achieved. Also, approximately depth-invariant defocus blur size may be achieved over a range of depths, in some embodiments of this invention.
    Type: Grant
    Filed: April 12, 2010
    Date of Patent: August 4, 2015
    Assignee: Massachusetts Institute of Technology
    Inventors: Ankit Mohan, Douglas Lanman, Shinsaku Hiura, Ramesh Raskar
  • Patent number: 9081262
    Abstract: In exemplary implementations of this invention, a set of two scanning mirrors scans the one dimensional field of view of a streak camera across a scene. The mirrors are continuously moving while the camera takes streak images. Alternately, the mirrors may only between image captures. An illumination source or other captured event is synchronized with the camera so that for every streak image the scene looks different. The scanning assures that different parts of the scene are captured.
    Type: Grant
    Filed: October 7, 2012
    Date of Patent: July 14, 2015
    Assignee: Massachusetts Institute of Technology
    Inventors: Ramesh Raskar, Andreas Velten
  • Publication number: 20150195042
    Abstract: An array of light emitters is arranged single-file along an emitting surface of a transmitting device and emits light in a z-direction normal to the emitting surface. The array of light emitters is aligned along a y-direction normal to the z-direction. A lens assembly is optically coupled to the array of light emitters. The lens assembly includes at least one cylindrical lens and at least one aspherical lens. The lens assembly emits the light in free-space along the z-direction and has a first focal length in the y-direction and a different, second focal length in an x-direction. An encoder is coupled to apply a data signal to the array of light emitters. The data signal causes the array of light emitters to illuminate in a pattern that switches at a rate corresponding to a rolling shutter of a receiving sensor array.
    Type: Application
    Filed: January 7, 2014
    Publication date: July 9, 2015
    Applicant: Nokia Corporation
    Inventors: Ramesh Raskar, Pranav Mishra, Rajeswari Kannan
  • Patent number: 9060718
    Abstract: In exemplary implementations, this invention comprises apparatus for retinal self-imaging. Visual stimuli help the user self-align his eye with a camera. Bi-ocular coupling induces the test eye to rotate into different positions. As the test eye rotates, a video is captured of different areas of the retina. Computational photography methods process this video into a mosaiced image of a large area of the retina. An LED is pressed against the skin near the eye, to provide indirect, diffuse illumination of the retina. The camera has a wide field of view, and can image part of the retina even when the eye is off-axis (when the eye's pupillary axis and camera's optical axis are not aligned). Alternately, the retina is illuminated directly through the pupil, and different parts of a large lens are used to image different parts of the retina. Alternately, a plenoptic camera is used for retinal imaging.
    Type: Grant
    Filed: February 13, 2013
    Date of Patent: June 23, 2015
    Assignee: Massachusetts Institute of Technology
    Inventors: Matthew Everett Lawson, Ramesh Raskar, Jason Boggess, Siddharth Khullar
  • Publication number: 20150138389
    Abstract: In an example embodiment, a method, apparatus and computer program product are provided. The method includes facilitating capture of at least one image of a scene including a foreground object by at least one rolling shutter sensor. The at least one image includes a pattern in an image region of the foreground object comprising a series of alternate dark and bright pixel regions. The at least one image is captured by setting exposure time of the sensor as equal or less than a read-out time of a set of pixel rows of a plurality of pixel rows, and by facilitating a repeating sequence of ON and OFF of flash such that flash is ON while capturing the set of pixel rows, and OFF while capturing subsequent set of pixel rows. The method includes determining a contour of the foreground object in the at least one image based on the pattern.
    Type: Application
    Filed: November 18, 2014
    Publication date: May 21, 2015
    Inventors: Pranav Mishra, Rajeswari Kannan, Ravi Shenoy, Ramesh Raskar
  • Publication number: 20150120241
    Abstract: In illustrative implementations, a time-of-flight camera robustly measures scene depths, despite multipath interference. The camera emits amplitude modulated light. An FPGA sends at least two electrical signals, the first being to control modulation of radiant power of a light source and the second being a reference signal to control modulation of pixel gain in a light sensor. These signals are identical, except for time delays. These signals comprise binary codes that are m-sequences or other broadband codes. The correlation waveform is not sinusoidal. During measurements, only one fundamental modulation frequency is used. One or more computer processors solve a linear system by deconvolution, in order to recover an environmental function. Sparse deconvolution is used if the scene has only a few objects at a finite depth. Another algorithm, such as Wiener deconvolution, is used is the scene has global illumination or a scattering media.
    Type: Application
    Filed: October 24, 2014
    Publication date: April 30, 2015
    Applicant: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
    Inventors: Achuta Kadambi, Refael Whyte, Ayush Bhandari, Lee Streeter, Christopher Barsi, Adrian Dorrington, Ramesh Raskar
  • Publication number: 20150098014
    Abstract: A method comprising reading out first lines of pixels of a sensor, when the first lines are read out in a sequence of the first lines in a first direction along the sensor also reading out different second lines of the pixels of the sensor, when the second lines are read out in a sequence of the second lines in a different second direction along the sensor and interleaving the read outs from the first lines of pixels and the different second lines of pixels.
    Type: Application
    Filed: October 4, 2013
    Publication date: April 9, 2015
    Applicant: Nokia Corporation
    Inventors: Ramesh RASKAR, Rajeswari Kannan, Pranav Mishra
  • Publication number: 20150035880
    Abstract: In exemplary implementations of this invention, light from a backlight is transmitted through two stacked LCDs and then through a diffuser. The front side of the diffuser displays a time-varying sequence of 2D images. Processors execute an optimization algorithm to compute optimal pixel states in the first and second LCDs, respectively, such that for each respective image in the sequence, the optimal pixel states minimize, subject to one or more constraints, a difference between a target image and the respective image. The processors output signals to control actual pixel states in the LCDs, based on the computed optimal pixel states. The 2D images displayed by the diffuser have a higher spatial resolution than the native spatial resolution of the LCDs. Alternatively, the diffuser may be switched off, and the device may display either (a) 2D images with a higher dynamic range than the LCDs, or (b) an automultiscopic display.
    Type: Application
    Filed: August 5, 2014
    Publication date: February 5, 2015
    Applicant: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
    Inventors: Felix Heide, Gordon Wetzstein, James Gregson, Ramesh Raskar, Wolfgang Heidrich