Light reflected from an illuminated object is mixed with a reference beam and sensed at a sensor array of a digital hologram apparatus. Digital hologram data, determined from the sensed light, is dependent upon complex valued reflection coefficients of the object and upon phase perturbations in propagation paths between the object and the sensor array. Reflectance values, which may be dependent upon expected values of the absolute square of the reflection coefficients, and phase perturbations are determined for which a test function is at an extremum, where the test function contains a data fidelity term dependent upon the hologram data from a single hologram, a first regularization term dependent upon the phase perturbations and a second regularization term dependent upon the reflectance values. An image of the object may be formed from the reflectance values and a wavefront of the reflected light may be determined from the phase perturbations.

Techniques for verifying identity of a human subject to an identification document are described. In some examples, a computing device may be connected to least two cameras oriented such that a first field of view is a substantially opposite direction from a second field of view. The device may receive images from the first camera that include a human subject. Second images from the second camera may include images of an ID document with a photograph of the human subject. The device may process the first images along with the respective, corresponding second images to determine respective 3D locations for at least one of cameras at the respective times the images were captured. Based on the sequence of 3D locations, along with the first images and the second images, the device may determine whether the human subject is a valid human subject.

An apparatus which analyses a depth of a holographic image is provided. The apparatus includes an acquisition unit that acquires a hologram, a restoration unit that restores a three-dimensional holographic image by irradiating the hologram with a light source, an image sensing unit that senses a depth information image of the restored holographic image, and an analysis display unit that analyzes a depth quality of the holographic image, based on the sensed depth information image, and the image sensing unit uses a lensless type of photosensor.

A method for holographic display calibration using phase modulation includes projecting an initial graphic on a windshield of a vehicle, capturing an image of the initial graphic with a camera inside a vehicle, determining a loss function value between the image of the initial graphic captured by the camera and a target graphic, modulating a phase of a light beam generating the initial graphic using the loss function value to generate an updated graphic, and displaying the updated graphic on the windshield of the vehicle.

A method of calibrating a picture generating unit. The method includes displaying a pattern corresponding to a picture on a spatial light modulator. The method further includes propagating light along a propagation axis wherein the light illuminates the spatial light modulator so as to spatially modulate the light. A first portion of the propagation axis passes through a first lens of the picture generating unit. The method also includes changing the position of the first portion of the propagation axis with respect to an optical axis of the first lens. The first portion of the propagation axis is substantially parallel to the optical axis of the first lens.

A system for training a machine learning algorithm to generate a plurality of ideal hologram phase correction maps includes a holographic head-up display (HUD) configured to display a plurality of duplicates of a graphic based on a hologram phase map. The system further includes a camera system configured to view each of the plurality of duplicates of the graphic. The system further includes a controller in electrical communication with the holographic HUD and the camera system. The controller is programmed to determine a plurality of ground-truth hologram phase correction maps using a genetic algorithm, the holographic HUD, and the camera system. The controller is further programmed to generate a training dataset including a plurality of images of the graphic and train the machine learning algorithm to generate the plurality of ideal hologram phase correction maps.

A method and apparatus for measuring a quality of a holographic image are provided. An image quality measuring method may include acquiring a first image including a holographic image in a background, and a second image that does not include a holographic image, the first image and the second image being on the same background, extracting a gray level value and a dark-noise counted level value from the first image in a selected range of the first image, extracting a gray level value and a dark-noise counted level value from the second image in the same range as the selected range of the first image, and determining a holographic contrast ratio (HCR) of the holographic image based on the extracted gray level values and the extracted dark-noise counted level values.

There is provided a method of calibrating a holographic projector. The method comprises displaying a primary diffractive pattern on a display device, wherein the primary diffractive pattern comprises a first hologram of a first target image and a phase-ramp function. The method further comprises illuminating the primary diffractive pattern to form a first holographic reconstruction of the first target image on a replay plane. The first target image comprises a picture area and a non-picture area. The phase-ramp function is arranged to translate the first holographic reconstruction. The method further comprises blocking at least a portion of the first holographic reconstruction using a mask, wherein the mask is arranged to block the non-picture area in the absence of the phase-ramp function. The method further comprises measuring a property of a boundary between the picture area and the non-picture area. There is further provided a holographic projection system.

A holographic display apparatus includes a backlight unit having a light source configured to emit coherent light, a spatial light modulator configured to diffract incident light from the backlight unit and generate a holographic image, a beam deflector configured to change a traveling direction of the incident light from the backlight unit to change a focal position of the holographic image, an eye-tracking sensor configured to recognize positions of a viewer's eyeballs, and a controller configured to perform, in real time, calibration of the eye-tracking sensor and the beam deflector to focus the holographic image on the recognized positions of the viewer's eyeballs.

An apparatus for measuring a spatial resolution of a hologram reconstructed image optically reconstructed on a space is provided. The apparatus for measuring a spatial resolution of a hologram reconstructed image includes: a measuring unit measuring first spatial frequency resolving powers for a horizontal direction of the hologram reconstructed image and second spatial frequency resolving powers for a vertical direction of the hologram reconstructed image at first spatial positions having a predetermined interval in horizontal and vertical directions within a viewing angle range of the hologram reconstructed image; and an evaluating unit evaluating the spatial resolution of the hologram reconstructed image using the first spatial frequency resolving powers and the second spatial frequency resolving powers measured at each of the first spatial positions.