Magic Leap Patent | Eye Image Selection
Patent: Eye Image Selection
Publication Number: 20200097080
Publication Date: 20200326
Applicants: Magic Leap
Systems and methods for eye image set selection, eye image collection, and eye image combination are described. Embodiments of the systems and methods for eye image set selection can include comparing a determined image quality metric with an image quality threshold to identify an eye image passing an image quality threshold, and selecting, from a plurality of eye images, a set of eye images that passes the image quality threshold.
CROSS-REFERENCE TO RELATED APPLICATIONS
 This application is a continuation of U.S. application Ser. No. 15/408,197, filed on Jan. 17, 2017, entitled “EYE IMAGE SELECTION”, which claims the benefit of priority under 35 U.S.C. .sctn. 119(e) to U.S. Provisional Application No. 62/280,456, filed on Jan. 19, 2016, entitled “EYE IMAGE COLLECTION;” U.S. Provisional Application No. 62/280,515, filed on Jan. 19, 2016, entitled “EYE IMAGE COMBINATION;” and U.S. Provisional Application No. 62/280,437, filed on Jan. 19, 2016, entitled “EYE IMAGE SET SELECTION;” the content of each of the foregoing is hereby incorporated by reference herein in its entirety.
 The present disclosure relates to virtual reality and augmented reality imaging and visualization systems and in particular to systems and methods for collecting and processing eye images.
 Modern computing and display technologies have facilitated the development of systems for so called “virtual reality” or “augmented reality” experiences, wherein digitally reproduced images or portions thereof are presented to a user in a manner wherein they seem to be, or may be perceived as, real. A virtual reality “VR” scenario typically involves presentation of digital or virtual image information without transparency to other actual real-world visual input; an augmented reality “AR” scenario typically involves presentation of digital or virtual image information as an augmentation to visualization of the actual world around the user; or a mixed reality “MR” scenario that typically involves merging real and virtual worlds to produce new environment where physical and virtual objects co-exist and interact in real time. As it turns out, the human visual perception system is very complex, and producing a VR, AR, or MR technology that facilitates a comfortable, natural-feeling, rich presentation of virtual image elements amongst other virtual or real-world imagery elements is challenging. Systems and methods disclosed herein address various challenges related to VR, AR, and MR technology.
 Examples of wearable display devices that can process eye images, such as selecting eye images, collecting eye images, and combining eye images are described.
 In one aspect, a method for eye image set selection is disclosed. The method is performed under control of a hardware computer processor. The method comprises obtaining a plurality of eye images; for each eye image of the plurality of eye images, determining an image quality metric associated with each eye image, and comparing each determined image quality metric with an image quality threshold to identify an eye image passing the image quality threshold, wherein the image quality threshold corresponds to an image quality level for generating an iris code; selecting, from the plurality of eye images, a set of eye images each passing the image quality threshold; and utilizing the set of eye images for generating an iris code. A head mounted display system can include a processor that performs the method for eye image set selection.
 In another aspect, a method for eye image collection is described. The method is performed under control of a hardware computer processor. The method comprises displaying a graphic along a path connecting the plurality of eye pose regions; obtaining eye images at a plurality of locations along the path; and generating an iris code based at least partly on at least some of the obtained eye images. A head mounted display system can include a processor that performs the method for eye image collection.
 In another aspect, a method for eye image combination is described. The method is performed under control of a hardware computer processor. The method comprises accessing a plurality of eye images; and performing (1) an image fusion operation on the plurality of eye images, (2) an iris code fusion operation on the plurality of eye images, or both (1) and (2). The image fusion operation comprises fusing at least some of the plurality of eye images to provide a hybrid image and generating a hybrid iris code from the hybrid image. The iris code fusion operation comprises generating an iris code for at least some of the eye images in the plurality of eye images and merging the generated iris codes to provide a hybrid iris code. A head mounted display system can include a processor that performs the method for eye image combination.
 Details of one or more implementations of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, the drawings, and the claims. Neither this summary nor the following detailed description purports to define or limit the scope of the inventive subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS
 FIG. 1 depicts an illustration of an augmented reality scenario with certain virtual reality objects, and certain actual reality objects viewed by a person.
 FIG. 2 schematically illustrates an example of a wearable display system.
 FIG. 3 schematically illustrates aspects of an approach for simulating three-dimensional imagery using multiple depth planes.
 FIG. 4 schematically illustrates an example of a waveguide stack for outputting image information to a user.
 FIG. 5 shows example exit beams that may be outputted by a waveguide.
 FIG. 6 is a schematic diagram showing a display system including a waveguide apparatus, an optical coupler subsystem to optically couple light to or from the waveguide apparatus, and a control subsystem, used in the generation of a multi-focal volumetric display, image, or light field.
 FIG. 7 shows a flow diagram of an illustrative eye image set selection routine.
 FIG. 8 schematically illustrates an example scene on a display of a head mounted display system for eye image set collection.
 FIG. 9 shows a flow diagram of an illustrative eye image collection routine.
 FIG. 10 shows a flow diagram of an illustrative eye image combination routine.
 Throughout the drawings, reference numbers may be re-used to indicate correspondence between referenced elements. The drawings are provided to illustrate example embodiments described herein and are not intended to limit the scope of the disclosure.
Example Eye Image Set Selection
 Certain eye images obtained from one or more imaging sources, such as a camera, can be selected and used for various biometric applications. For example, after obtaining eye images, image quality metrics can be determined for some or all of the eye images obtained. An image quality metric can be determined based on, for example, the amount of blurring, the number or percentage of unoccluded pixels, the degree of color saturation, the image resolution such as the resolution of a region of interest, or any combination thereof. Different eye images can be associated with different types of image quality metrics. A determined image quality metric for each eye image can be compared to a respective image quality threshold.
 A set of eye images can be selected with each eye image in the set having an image quality metric that satisfies the corresponding image quality threshold. Additionally or alternatively, the set of eye images selected may include a fixed number of eye images (such as eye images with top image quality metrics). The selected set of eye images can be used for various biometric applications such as eye pose determination (e.g., direction of the wearer’s eye or eyes) or iris code generation. For example, the selected eye images can be used to generate one or more iris codes.
Example Eye Image Collection
 Eye images for a number of eye pose regions can be obtained for various biometric applications. For example, a display (e.g. a display of a head mounted display system) can be associated with a number of eye pose regions (e.g., 2, 3, 4, 5, 6, 9, 12, 18, 24, 36, 49, 64, 128, 256, 1000, or more), one or more eye images can be obtained for some or all of the eye pose regions. The eye pose regions can have the same or different sizes or shapes (such as rectangular, square, circular, triangular, oval, diamond). An eye pose region can be considered as a connected subset of a two-dimensional real coordinate space .sup.2 or a two-dimensional positive integer coordinate space (>.sub.0).sup.2, which specifies that eye pose region in terms of the angular space of the wearer’s eye pose. For example, an eye pose region can be between a particular .theta..sub.min and a particular .theta..sub.max in azimuthal deflection (measured from a fiducial azimuth) and between a particular .phi..sub.min and a particular .phi..sub.max in zenithal deflection (also referred to as a polar deflection).
 A graphic (such as a butterfly, a bumble bee, or an avatar) or an animation of a graphic can be displayed in an eye pose region or across two or more eye pose regions such that one or both eyes of a user of the display are directed or attracted to the eye pose region. The graphic can be displayed in an eye pose region or across two or more eye pose regions in a random mode, a flight mode, a blinking mode, a fluctuating mode, or a story mode. The speed of the moving graphic can be substantially constant or can be variable. For example, the graphic may slow down or stop in certain eye pose regions (e.g., where one or more eye images are taken) or the graphic may speed up or skip through other eye pose regions (e.g., where eye images are not needed or desired). The path of the graphic can be continuous or discontinuous (e.g., the graphic 805 may skip over or around certain eye pose regions).
 An eye image of a user associated with an eye pose region can be obtained while the graphic is displayed in the eye pose region. After determining an image quality metric (e.g., the amount of blurring, or the number or percentage of unoccluded pixels) of the graphic passes or satisfies a corresponding image quality threshold, a graphic or an animation of a graphic can be displayed in another eye pose region. The graphics displayed in two eye pose regions can be the same or different. Another eye image of the user associated with the other eye pose region can be obtained while the graphic is displayed in the other eye pose region. An image quality metric of the graphic can be determined to pass or satisfy a corresponding image quality threshold. The image quality metrics (or the corresponding image quality thresholds) can be the same or different for eye images obtained for different eye pose regions. The process can be repeated for other eye pose regions of the display. For example, the graphic can move along a path from an eye pose region to another eye pose region.
 If an eye image associated with a certain eye pose region does not pass or satisfy a corresponding image quality threshold, the graphic can be displayed in that particular region, until an eye image of a sufficient eye image quality is obtained. Alternatively or in addition, if an eye image cannot be obtained for a certain eye pose region after a threshold number of attempts (e.g., three), the eye image collection may skip or pause collection on that eye pose region for a period of time, while obtaining eye images from one or more other pose regions. An eye image may not be obtained for a certain eye pose region if an eye image cannot be obtained after a threshold number of attempts. After eye images are obtained for a sufficient number of eye pose regions or eye pose regions of interest, one or more eye images can be used for various biometric applications (e.g., an iris code can be generated based on one or more of the eye images obtained).
Example Eye Image Combination
 Eye images obtained from one or more imaging sources can be combined or fused into one or more hybrid eye images (also referred to as combined or fused eye images), which can be used in turn for biometric applications. For example, after obtaining eye images, an eye pose can be identified for each eye image. The eye pose can be associated with a particular display classification, such as an eye pose region assignment of a display. One or both of image fusion or iris code fusion can be applied to the eye images obtained. For image fusion, some or all of the eye images obtained can be fused into a hybrid eye image using, for example, super resolution, spatial domain fusion, or transform domain fusion. An iris code can be extracted, generated, or determined from the hybrid eye image. For iris code fusion, an iris code can be generated for each of some or all of the eye images obtained. The iris codes obtained can then be merged into a hybrid iris code using, for example, a media filter or a Bayes filter. Each iris code associated with a particular eye pose region can contribute to the overall hybrid iris code. A confidence score can be generated or determined for the iris code or the hybrid iris code. The confidence score can be based on the fraction of eye pose regions sampled. One or both of the iris codes generated using image fusion or the hybrid iris code generated using image fusion can be used for further utilization in one or more biometric applications.
Example Augmented Reality Scenario
 FIG. 1 depicts an illustration of an augmented reality scenario with certain virtual reality objects, and certain actual reality objects viewed by a person. FIG. 1 depicts an augmented reality scene 100, wherein a user of an AR technology sees a real-world park-like setting 110 featuring people, trees, buildings in the background, and a concrete platform 120. In addition to these items, the user of the AR technology also perceives that he “sees” a robot statue 130 standing upon the real-world platform 120, and a cartoon-like avatar character 140 (e.g., a bumble bee) flying by which seems to be a personification of a bumble bee, even though these elements do not exist in the real world.
 In order for a three-dimensional (3-D) display to produce a true sensation of depth, and more specifically, a simulated sensation of surface depth, it is desirable for each point in the display’s visual field to generate the accommodative response corresponding to its virtual depth. If the accommodative response to a display point does not correspond to the virtual depth of that point, as determined by the binocular depth cues of convergence and stereopsis, the human eye may experience an accommodation conflict, resulting in unstable imaging, harmful eye strain, headaches, and, in the absence of accommodation information, almost a complete lack of surface depth.