Southern Methodist University

Marc P Christensen

Prasanna V Rangarajan

Vikrant R Bhakta

Panos Papamichalis

Manjunath Somayaji

Indranil Sinharoy

The present disclosure describes an imaging system, method, and apparatus for identifying a latent image of a hidden object. A light source generates a first beam of narrow-band light and a second beam of narrow-band light that has temporal fluctuations correlated with the first beam. A frequency modulator shifts a temporal frequency of at least one of the first beam or the second beam. The first beam is directed towards a first scattering surface and the second beam is directed towards a second scattering surface. The first scattering surface scatters the first beam to a scattered light that illuminates a hidden object. The hidden object reflects at least a portion of the scattered light towards the second scattering surface, the reflected light interferes with the second beam and produces an interference pattern on the second scattering surface. A lock-in camera detects an irradiance of the interference pattern, monitors temporal variations of the irradiance caused by the temporal frequency shift introduced by the frequency modulator, and identifies a complex-valued light field that represents information of the hidden object based on the temporal variations of the irradiance.

Imaging hidden objects

The present disclosure includes a method for operating a camera. A lens or a sensor of the camera is rotated about an axis to a plurality of positions, and the rotation generates a rotation of a plane of sharp focus of the camera. At each of the plurality of positions, an image is captured. For each image, a substantially in-focus region is determined. The substantially in-focus regions are combined to generate a composite image.

Angular focus stacking

A system includes a camera and a projector for capturing spatial detail having resolution exceeding that afforded by the imaging optics, and recovering topographic information lost to the projective nature of imaging. The projector projects a spatial pattern onto the scene to be captured. The spatial patterns may include any pattern or combination of patterns that result in complex sinusoidal modulation. Spatial detail such as texture on the objects in the scene modulate the amplitude of the spatial pattern, and produce Moir&#xe9; fringes that shifts previously unresolved spatial frequencies into the camera's optical passband. The images may be demodulated, and the demodulated components may be combined with the un-modulated components. The resulting image has spatial detail previously inaccessible to the camera owing to the band-limited nature of the camera optics. A spatial pattern may also be projected and received by the camera to estimate topographic information about the scene.

Enhancing imaging performance through the use of active illumination

The present disclosure discloses an imaging system, method, and apparatus for identifying information of a hidden object. A light source generates a first beam of narrow-band light and a second beam of narrow-band light that has temporal fluctuations correlated with the first beam. The first beam is directed towards a first scattering surface and the second beam is directed towards a second scattering surface. The first scattering surface scatters the first beam to a scattered light that illuminates a hidden object, the hidden object reflects at least a portion of the scattered light towards the second scattering surface, the reflected light interferes with the second beam and produces an interference pattern on the second scattering surface. An image sensor detects irradiance of the interference pattern on the second scattering surface. An image processor calculates a complex-valued light field that represents information of the hidden object based on the detected irradiance of the interference pattern on the second scattering surface.

Systems and methods can be configured to perform operations related to digital image processing. In a general aspect, this disclosure describes systems and methods relating to processing digital images for imaging system characterization and image quality enhancement. In some implementations, a method for digital image processing includes measuring a first phase transfer function (PTF) of a first digital image and a second PTF of a second digital image. The second digital image captures a spatially shifted version of the first digital image. The first PTF and the second PTF are compared and a spatial shift of the second image to the first image is determined.

Applying phase transfer function

Systems and methods can be configured to perform operations related to determining a phase transfer function of a digital imaging system. A digital image that includes at least one edge is received, the at least one edge includes a plurality of pixels with disparate pixel values. The at least one edge from the digital image is identified and an edge spread function is generated based on the identified edge. The edge spread function can be generated by taking at least one slice across the identified at least one edge. A line spread function is generated based on the edge spread function. An optical transfer function is generated based on a Fourier transform of the line spread function. A phase error is also identified. The phase transfer function of the digital image is identified based on the phase of the generated optical transfer function and the identified phase error.

Determining phase transfer function

A system for capturing super-resolved images includes a camera and a projector. The projector projects a spatially periodic illumination pattern onto the scene to be captured. The spatially periodic illumination patterns may include any pattern or combination of patterns that result in complex modulation. The objects of the scene modulate the spatially periodic illumination patterns, shifting high spatial frequencies into the passband of the camera's optical transfer function. The images may be demodulated, and the demodulated components may be combined with un-modulated components. The resulting image has characteristics of the high spatial frequencies previously beyond the optical passband of the camera.

Growing community of inventors

McKinney, TX, United States of America

Marc P Christensen