WO2013119674A1

WO2013119674A1 - Apparatus, method and article for generating a three dimensional effect using filtering and stereoscopic images

Info

Publication number: WO2013119674A1
Application number: PCT/US2013/024943
Authority: WO
Inventors: Raif Khassanov
Original assignee: 3D Digital, Llc
Priority date: 2012-02-06
Filing date: 2013-02-06
Publication date: 2013-08-15

Abstract

Example systems and methods for addressing afterglow are described. Example systems for addressing edge color distortion are also described. Example systems for dithering non-standard colors are also described. Example systems for generating complementary stereoscopic images using a color-sequential display are also described. Example systems for producing a three dimensional (3D) effect from displayed images are also described. Images of a video program may be displayed in a complementary primary colors-encoded stereoscopic image format, which includes stereoscopic images of objects or a scene. Corresponding stereoscopic images are displayed in different colors. As the display refreshes, the display alternates the colors of the corresponding stereoscopic images and sends a control signal to active glasses worn by a viewer of the video program that causes a left-eye lens and right-eye lens filter to alternate the color which is filtered in by the respective filter.

Description

APPARATUS, METHOD AND ARTICLE FOR GENERATING A

THREE DIMENSIONAL EFFECT USING FILTERING AND STEREOSCOPIC IMAGES

CROSS REFERENCE TO RELATED APPLICATIONS

[001] This application claims benefit under 35 U.S.C. 1 19(e) to U.S. provisional patent application Serial No. 61/595,160, entitled "USING COLOR COMPENSATION METHOD FOR MINIMIZING COLOR DISTORTION OF THE EDGES OF MOVING OBJECTS IN ACTIVE SHUTTER GLASSES (INCLUDING ACTIVE ANAGLYPH) APPLICATIONS" filed February 6, 2012, which provisional application is incorporated herein by reference in its entirety for any purpose.

[002] This application also claims benefit under 35 U.S.C. 1 19(e) to U.S. provisional patent application Serial No. 61/597,805 entitled "APPARATUS FOR ACTIVE ANAGLYPH SHUTTER GLASSES, AND METHOD TO CONTROL THE STATES OF LENSES IN ACTIVE ANAGLYPH SHUTTER GLASSES AND RELATED APPLICATIONS," filed February 12, 2012, which provisional application is incorporated herein by reference in its entirety for any purpose.

[003] This application also claims benefit under 35 U.S.C. 1 19(e) to U.S. provisional patent application Serial No. 61/602,204 entitled "(DLP) METHOD OF CREATING STEREOSCOPIC 3D IMAGES USING SEQUENTIAL COLOR CONTROL DEVICES AND ACHROMATIC SHUTTER GLASSES," filed February 23, 2012, which provisional application is incorporated herein by reference in its entirety for any purpose.

[004] This application also claims benefit under 35 U.S.C. 1 19(e) to U.S. provisional patent application Serial No. 61/612,353 entitled "ALTERNATING COLORS BETWEEN LEFT AND RIGHT EYE IN ORDER TO IMPROVE A STEREOSCOPIC

3D EFFECT CREATED BY ANAGLYPH IMAGES WHEN 2 COLOR GLASSES ARE USED FOR PROJECTORS, DISPLAYS AND OTHER IMAGE DISPLAYING SOURCES FEATURING 4 AND MORE COLORS PER PIXEL," filed March 18, 2012, which provisional application is incorporated herein by reference in its entirety for any purpose. BACKGROUND

Technical Field

[005] The present disclosure generally relates to providing three dimensional (3D) visual effects from displayed images and may be useful in conjunction with and applicable to a variety of different video displays and video projectors. Examples described include methods and technologies that utilize frame sequential video sequences and displays and particularly to active shutter and active anaglyph glasses in combination with sequentially displaying images for creating stereoscopic three-dimensional (3D) effects. Description of the Related Art

[006] Producing increasingly better 3D visual effects has long since been an endeavor of many in the film industry, television industry and high-technology entertainment industry. Producing and displaying 3D moving pictures may be performed in a variety of ways. The basic requirement is to display offset (stereoscopic) images that are filtered separately to the left and right eye. Using the stereoscopic images is a technique for creating or enhancing the illusion of depth in an image by presenting two offset images separately to the left and right eye of the viewer. Both of these two dimensional (2D) offset images are then combined by one's brain to give the perception of 3D depth. Various techniques have been traditionally used to accomplish this.

[007] One such technique is to have the viewer wear eyeglasses to filter the separate offset images to each eye. A traditional 3D display technology for projecting stereoscopic image pairs to users wearing special eyeglasses is referred to as anaglyphic 3D (with users wearing passive red-blue or red-cyan lenses). In anaglyphic 3D, displayed images are made up of two color layers, superimposed, but offset with respect to each other to produce a depth effect. Usually the main subject is in the center, while the foreground and background are shifted laterally in opposite directions. When viewed through the color- coded anaglyph eyeglasses, they reveal an integrated stereoscopic image. The visual cortex of the brain fuses this into perception of a three dimensional scene or composition. However, problems involving image ghosting, retinal rivalry, wrong colors and difficulty focusing are common.

[008] Another traditional type of anaglyphic 3D technology that is commonly used in 3D television involves using liquid crystal shutter glasses (also referred to as LC shutter glasses or active shutter glasses). Liquid crystal shutter glasses are glasses used in conjunction with a display screen to create the illusion of a three dimensional image, an example of stereoscopy described above. The lens for each eye of the liquid crystal shutter glasses contains a liquid crystal layer which has the property of becoming dark when voltage is applied, being otherwise transparent. The glasses are controlled by a wireless transmitter from the display that sends a timing signal that allows the glasses to alternately darken over one eye, and then the other, in synchronization with the refresh rate of the screen of the display. Meanwhile, the display alternately displays different perspectives for each eye, using a technique referred to as alternate-frame sequencing, which achieves the desired effect of each eye seeing only the image intended for it. However, problems involving flickering at lower refresh rates of the display, pricing and double imaging at higher refresh rates of the display, are common.

[009] In some cases, frame-sequential methods may be affected by a physical inability to replace one frame with another instantaneously. Because of technological imperfections of displays, active shutter glasses, and other limitations, it may take some time for an initial displayed image to disappear while the next image is already being displayed. Sometime this effect is called afterglow or afterimage. Depending on the application, this effect may cause double images or ghosting, color distortions, parasitic images, and other negative effects.

[010] In some cases, frame-sequential methods may be affected by video sequences having relatively high motion. If differences between successive frames are high enough, distortion, particularly at frame edges, may become significant and thereby impact the subjective quality of the frame.

[011] In some cases, displays having more than 3 colors may be particularly difficult to use in 3D applications due to difficulty associated with proper filtering. Additional colors may, for instance, permeate filters and damage resulting images.

[012] In some cases, color-sequential displays may not be configured to display frame- sequential video sequences in 3D applications and may display video sequences having relatively low frame rates when implemented for this purpose.

BRIEF SUMMARY

[013] Methods for providing an updated frame are provided. An example method may include receiving a first frame of a video sequence, receiving a second frame of the video sequence, and generating an updated current frame based, at least in part, on the first and second frames, wherein the first and second frames comprise complementary stereoscopic images having a same color configuration. [014] In an example method, the generating an updated current frame may comprise updating one or more pixel values based, at least in part, on a pixel values of the first frame and a pixel value of the second frame.

[015] In an example method, the generating an updated current frame may comprise generating the updated current frame based, at least in part, on a dynamic weighting factor.

[016] Non-transitory computer-readable media that store instructions executable by a processor to operate an electronic display are provided. An example non-transitory computer-readable medium that stores instructions executable by a processor to operate an electronic display may include instructions for receiving a first frame of a video sequence, receiving a second frame of the video sequence, generating an updated current frame based, at least in part, on the first and second frames, and wherein the first and second frames comprise complementary stereoscopic images having a same color configuration.

[017] Examples of apparatuses are provided. An example apparatus may include a control unit operably coupled to a display, the control unit configured to receive a first frame of a video sequence, receive a second frame of the video sequence, and generate an updated current frame based, at least in part, on the first and second frames, wherein the first and second frames comprise complementary stereoscopic images having a same color configuration.

[018] Methods are provided. An example method may include shuttering active glasses prior to a frame transition responsive, at least in part, to a control signal having a first state and opening the active glasses after the frame transition and before a next frame transition based, at least in part, to the control signal having a second state.

[019] In an example method, the second state may corresponds to a color filtering configuration for the active glasses.

[020] In an example method, the shuttering may comprise shuttering the active glasses for a predetermined period of time.

[021] In an example method, the opening may comprise opening the active glasses based, at least in part, on a magnitude of afterglow being within a threshold.

[022] An example apparatus may include a control unit operably coupled to a display, the control unit configured to cause active glasses to shutter prior to a frame transition and cause the active glasses to open after the frame transition and before a next frame transition.

[023] An example method for creating a three-dimensional effect may include, during projection of a frame by a color-sequential display, filtering a first color for a first eye, filtering a second color for a second eye, and filtering a third color for the second eye.

[024] In an example method, the filtering a first color for a first eye may comprise shuttering active glasses.

[025] In an example method, the active glasses may be achromatic.

[026] In an example method, the filtering a second color for a second eye may comprise opening a lens associated with the first eye.

[027] An example apparatus may include a control unit operably coupled to a color- sequential display, the control unit configured to, during projection of a frame, filter a first color for a first eye, during projection of the frame, filter a second color for a second eye, and during projection of the frame, filter a third color for the second eye.

[028] An example method may include receiving a frame including a plurality of pixels, identifying at least one of the plurality of pixels having a color value for a non-standard color, and selectively dithering the at least one of a plurality of pixels based, at least in part, on the color value.

[029] In an example method, the selectively dithering may comprise comparing the color value for a stereoscopic image against a sum of a color value for a left stereoscopic image and a color value for a right stereoscopic image.

[030] In an example method, the selectively dithering comprises selectively dithering the at least one of the plurality of pixels based, at least in part, on a brightness of the at least one of the plurality of pixels.

[031] In an example method, the selectively may comprise dithering even pixels using a first standard color and dithering odd pixels using a second standard color.

[032] An example non-transitory computer-readable medium that stores instructions executable by a processor to operate an electronic display may include instructions for receiving a frame including a plurality of pixels, identifying at least one of the plurality of pixels having a color value for a non-standard color, and selectively dithering the at least one of a plurality of pixels based, at least in part, on a magnitude of the color value.

[033] An example non-transitory computer-readable medium that stores instructions executable by a processor to operate an electronic display may include instructions for comparing the color value for a stereoscopic image against a sum of a color value for a left stereoscopic image and a color value for a right stereoscopic image.

[034] In an example non-transitory computer-readable medium that stores instructions executable by a processor to operate an electronic display, instructions for selectively dithering comprise instructions may include instructions for selectively dithering the at least one of the plurality of pixels based, at least in part, on a brightness of the at least one of the plurality of pixels.

[035] An example apparatus may include a control unit operably coupled to a display, the control unit configured to receive a frame including a plurality of pixels, identify at least one of the plurality of pixels having a color value for a non-standard color, and selectively dither the at least one of a plurality of pixels based, at least in part, on the color value.

[036] A system for producing a three dimensional (3D) effect from displayed images is provided. Images of a video program are displayed in a complementary primary colors- encoded stereoscopic image format, which includes stereoscopic images of objects or a scene. Example complementary primary colors include red/cyan, green/magenta and blue/yellow. One example of such a format is an anaglyphic image. Corresponding stereoscopic images are displayed in different colors. In one embodiment, as the display refreshes, the display alternates the colors of the corresponding stereoscopic images and sends a control signal to active glasses worn by a viewer of the video program that causes a left-eye lens and right-eye lens filter to alternate the color which is filtered by the respective filter. The viewer is able to view the video program with a perceived 3D effect without either of the lenses of the active glasses having to become opaque during display of the complementary primary colors- encoded stereoscopic image.

[037] A method of providing a three dimensional effect from an electronic display may be summarized as including displaying a first complementary primary colors-encoded stereoscopic image of a video program on the display corresponding to a first refresh of the display, the first complementary primary colors-encoded stereoscopic image including a first left-eye stereoscopic image of a first color and a corresponding first right-eye stereoscopic image of a second color; displaying a second complementary primary colors-encoded stereoscopic image of the video program on the display corresponding to a second refresh of the display, the second complementary primary colors-encoded stereoscopic image including a second left-eye stereoscopic image of the second color and a corresponding second right-eye stereoscopic image of the first color, the second complementary primary colors- encoded stereoscopic image related in a time sequence of the video program to the first complementary primary colors-encoded stereoscopic image; repeating the displaying a first complementary primary colors- encoded stereoscopic image and the displaying a second complementary primary colors- encoded stereoscopic image corresponding to subsequent refreshes of the display during display of at least a portion of the video program; and generating a control signal to be sent to active glasses, for each time the display refreshes during the display of the at least the portion of the video program, to cause the active glasses to alternate between a first state of filtering out the second color while allowing the first color to pass through a left-eye lens of the active glasses and filtering out the first color while allowing the second color to pass through a right-eye lens of the active glasses and a second state of filtering out the first color while allowing the second color to pass through the left-eye lens of the active glasses and filtering out the second color while allowing the first color to pass through the right-eye lens of the active glasses such that a corresponding left-eye stereoscopic image is visible through the left-eye lens of the active glasses, and is not visible through the right-eye lens of the active glasses, and a corresponding right-eye stereoscopic image is concurrently visible through the right-eye lens of the active glasses, and is not visible through the left-eye lens of the active glasses.

] The generating the control signal may include generating the control signal at a frequency equal to a refresh rate of the display. The refresh rate of the display may be approximately 60 Hz or approximately 50 Hz. The refresh rate of the display may be between approximately 60 Hz and approximately 240 Hz or between approximately 50 Hz and approximately 200 Hz. The generating the control signal may include generating the control signal in synchronization with each refresh of the display. The method may further include sending the control signal to the active glasses. The sending the control signal to the active glasses may include sending the control signal to the active glasses in synchronization with each refresh of the display. The sending the control signal to the active glasses may include sending the control signal to the active glasses at a frequency equal to a refresh rate of the display. The first color may be one of red, blue and green and the second color may be another one of red, blue and green different than the first color. The control signal may be a wireless signal. The display of the video program may be in reverse. Neither the left-eye lens nor right eye lens is opaque during the repeating the displaying a first complementary primary colors- encoded stereoscopic image and during the displaying a second complementary primary colors-encoded stereoscopic image for each time the display refreshes.

[039] A method of providing a three dimensional effect from an electronic display may be summarized as including receiving a control signal for active glasses to cause the active glasses to alternate between a first state of filtering out a second color while allowing the first color to pass through a left- eye lens of the active glasses and filtering out the first color while allowing the second color to pass through a right-eye lens of the active glasses and a second state of filtering out the first color while allowing the second color to pass through the left-eye lens of the active glasses and filtering out the second color while allowing the first color to pass through the right-eye lens of the active glasses such that a currently displayed corresponding left-eye stereoscopic image is visible through the left-eye lens of the active glasses while not being visible through the right-eye lens of the active glasses, and a concurrently displayed corresponding right-eye stereoscopic image is visible through the right-eye lens of the active glasses, while not being visible through the left-eye lens of the active glasses, as a video program is displayed on an electronic display, the video program displayed including at least one complementary primary colors-encoded stereoscopic image that alternates between displaying the corresponding left-eye stereoscopic image in the first color concurrently with the corresponding right-eye stereoscopic image in the second color and displaying the corresponding left-eye stereoscopic image in the second color concurrently with the corresponding right-eye stereoscopic image in the first color; and alternating between the first state and the second state according to the received control signal by changing filtering characteristics of the left-eye lens and right-eye lens.

[040] The alternating between the first state and second state may include causing a liquid crystal filter of the left-eye lens to change filtering characteristics of the liquid crystal filter of the left-eye lens; and concurrently causing a liquid crystal filter of the right-eye lens to change filtering characteristics of the liquid crystal filter of the right- eye lens. The changing filtering characteristics may include changing polarization of electronically controlled polarized filters for the left-eye lens and the right-eye lens. The alternating between the first state and the second state may include alternating between the first state and the second state at a frequency equal to a refresh rate of the display. The alternating between the first state and the second state may include alternating between the first state and second state glasses in synchronization with each refresh of the display. The at least one complementary primary colors-encoded stereoscopic image that alternates may be caused by: displaying on the display a first complementary primary colors- encoded stereoscopic image of a video program on the display corresponding to a first refresh of the display, the first complementary primary colors- encoded stereoscopic image including a first left-eye stereoscopic image of a first color and a corresponding first right-eye stereoscopic image of a second color; displaying a second complementary primary colors-encoded stereoscopic image of the video program on the display corresponding to a second refresh of the display, the second complementary primary colors-encoded stereoscopic image including a second left-eye stereoscopic image of the second color and a corresponding second right-eye stereoscopic image of the first color, the second complementary primary colors-encoded stereoscopic image related in a time sequence of the video program to the first complementary primary colors- encoded stereoscopic image; and repeating the displaying a first complementary primary colors-encoded stereoscopic image and the displaying a second complementary primary colors-encoded stereoscopic image corresponding to subsequent refreshes of the display during display of at least a portion of the video program.

1] A pair of active glasses for viewing an electronic display may be summarized as including a left-eye lens; a right eye lens; and a control unit in operable communication with the left-eye lens and right-eye lens, the control unit configured to: receive a control signal for the active glasses to cause the active glasses to alternate between a first state of filtering out a second color while allowing the first color to pass through a left-eye lens of the active glasses and filtering out a first color while allowing the second color to pass through a right-eye lens of the active glasses and a second state of filtering out the first color while allowing the second color to pass through the left-eye lens of the active glasses and filtering out the second color while allowing the first color to pass through the right-eye lens of the active glasses such that a currently displayed corresponding left- eye stereoscopic image is visible through the left-eye lens of the active glasses, while not being visible through the right-eye lens of the active glasses, and a concurrently displayed corresponding right-eye stereoscopic image is visible through the right-eye lens of the active glasses, while not being visible through the left-eye lens of the active glasses, as a video program is displayed on an electronic display, the video program displayed including at least one complementary primary colors-encoded stereoscopic image that alternates between displaying the corresponding left-eye stereoscopic image in the first color concurrently with the corresponding right- eye stereoscopic image in the second color and displaying the corresponding left-eye stereoscopic image in the second color concurrently with the corresponding right-eye stereoscopic image in the first color; and cause the active glasses to alternate between the first state and second state according to the received control signal by changing filtering characteristics of the left-eye lens and right-eye lens.

[042] The left-eye lens and right-eye lens may each include a liquid crystal filter operable to receive voltage caused by the received control signal to change filtering characteristics of the liquid crystal filter. The left-eye lens and right-eye lens may each include: an input polarizer configured to receive light from the display; a wavelength- dependent retarder coupled to the input polarizer configured to circularly polarize light of the first color in a first direction and circularly polarize light of the second color in a second direction; a wavelength-independent retarder coupled to the wavelength- dependent retarder configured to linearly polarize the circularly polarized light of the first color and linearly polarize the circularly polarized light of the second color; and an electronically controllable filter coupled to the wavelength- independent retarder operable to receive voltage to selectively filter the linearly polarized light of the of the first color and the linearly polarized light of the of the second color.

[043] An electronic display may be summarized as including a display screen; a control unit operably coupled to the display screen, the control unit configured to: cause displaying of a first complementary primary colors- encoded stereoscopic image of a video program on the display corresponding to a first refresh of the display, the first complementary primary colors-encoded stereoscopic image including a first left-eye stereoscopic image of a first color and a corresponding first right-eye stereoscopic image of a second color; cause displaying of a second complementary primary colors-encoded stereoscopic image of the video program on the display corresponding to a second refresh of the display, the second complementary primary colors-encoded stereoscopic image including a second left-eye stereoscopic image of the second color and a corresponding second right-eye stereoscopic image of the first color, the second complementary primary colors-encoded stereoscopic image related in a time sequence to the first complementary primary colors-encoded stereoscopic image; repeat the displaying a first complementary primary colors-encoded stereoscopic image and the displaying a second complementary primary colors- encoded stereoscopic image corresponding to subsequent refreshes of the display during display of at least a portion of the video program; and generate a control signal to be sent to active glasses, for each time the display refreshes during the display of the at least the portion of the video program, to cause the active glasses to alternate between a first state of filtering out the second color while allowing the first color to pass through a left-eye lens of the active glasses and filtering out the first color while allowing the second color to pass through a right-eye lens of the active glasses and a second state of filtering out the first color while allowing the second color to pass through the left-eye lens of the active glasses and filtering out the second color while allowing the first color to pass through the right-eye lens of the active glasses such that a corresponding left-eye stereoscopic image is visible through the left-eye lens of the active glasses, while not being visible through the right- eye lens of the active glasses, and a corresponding right-eye stereoscopic image concurrently visible through the right-eye lens of the active glasses, while not being visible through the left- eye lens of the active glasses.

[044] The control signal may be a wireless signal. The display of the video program may be in reverse. The control unit may be configured to generate the control signal at a frequency equal to a refresh rate of the display. The refresh rate of the display may be approximately 60 Hz or approximately 50 Hz. The refresh rate of the display may be between approximately 60 Hz and approximately 240 Hz or between approximately 50 Hz and approximately 200 Hz. The control unit may be configured to generate the control signal in synchronization with each refresh of the display. The control unit may be further configured to send the control signal to the active glasses.

[045] A nontransitory computer-readable medium that stores instructions executable by a processor to operate an electronic display, may be summarized as including displaying a first complementary primary colors- encoded stereoscopic image of a video program on the display corresponding to a first refresh of the display, the first complementary primary colors-encoded stereoscopic image including a first left-eye stereoscopic image of a first color and a corresponding first right-eye stereoscopic image of a second color; displaying a second complementary primary colors-encoded stereoscopic image of the video program on the display corresponding to a second refresh of the display, the second complementary primary colors-encoded stereoscopic image including a second left-eye stereoscopic image of the second color and a corresponding second right-eye stereoscopic image of the first color, the second complementary primary colors-encoded stereoscopic image related in a time sequence to the first complementary primary colors- encoded stereoscopic image; repeating the displaying a first complementary primary colors-encoded stereoscopic image and the displaying a second complementary primary colors-encoded stereoscopic image corresponding to subsequent refreshes of the display during display of at least a portion of the video program; and generating a control signal to be sent to active glasses, for each time the display refreshes during the display of the at least the portion of the video program, to cause the active glasses to alternate between a first state of filtering out the second color while allowing the first color to pass through a left-eye lens of the active glasses and filtering out the first color while allowing the second color to pass through a right-eye lens of the active glasses and a second state of filtering out the first color while allowing the second color to pass through the left-eye lens of the active glasses and filtering out the second color while allowing the first color to pass through the right-eye lens of the active glasses such that a corresponding left-eye stereoscopic image is visible through the left-eye lens of the active glasses, while not being visible through the right-eye lens of the active glasses, and a corresponding right- eye stereoscopic image is concurrently visible through the right-eye lens of the active glasses, while not being visible through the left-eye lens of the active glasses.

[046] The generating the control signal may include generating the control signal at a frequency equal to a refresh rate of the display. The refresh rate of the display may be approximately 60 Hz or approximately 50 Hz. The generating the control signal may include generating the control signal in synchronization with each refresh of the display.

[047] A nontransitory computer-readable medium that stores instructions executable by a processor to operate a pair of active glasses, may be summarized as including receiving a control signal for the active glasses to cause the active glasses to alternate between a first state of filtering out a second color while allowing a first color to pass through a left-eye lens of the active glasses and filtering out the first color while allowing the second color to pass through a right-eye lens of the active glasses and a second state of filtering out the first color while allowing the second color to pass through the left-eye lens of the active glasses and filtering out the second color while allowing the first color to pass through the right-eye lens of the active glasses such that a currently displayed corresponding left-eye stereoscopic image is visible through the left-eye lens of the active glasses, while not being visible through the right-eye lens of the active glasses, and a concurrently displayed corresponding right-eye stereoscopic image is visible through the right-eye lens of the active glasses, while not being visible through the left- eye lens of the active glasses, as a video program is displayed on an electronic display, the video program displayed including at least one complementary primary colors- encoded stereoscopic image that alternates between displaying the corresponding left- eye stereoscopic image in the first color concurrently with the corresponding right-eye stereoscopic image in the second color and displaying the corresponding left-eye stereoscopic image in the second color concurrently with the corresponding right-eye stereoscopic image in the first color; and causing the active glasses to alternate between the first state and the second state according to the received control signal by changing filtering characteristics of the left-eye lens and right-eye lens.

] The causing the active glasses to alternate between the first state and the second state may include causing a liquid crystal filter of the left-eye lens to change filtering characteristics of the liquid crystal filter of the left-eye lens; and substantially simultaneously causing a liquid crystal filter of the right- eye lens to change filtering characteristics of the liquid crystal filter of the right- eye lens. The changing filtering characteristics may include changing polarization of electronically controlled polarized filters for the left-eye lens and right-eye lens. The causing the active glasses to alternate between the first state and the second state may include causing the active glasses to alternate between the first state and the second state at a frequency equal to a refresh rate of the display.

BRIEF DESCRIPTION OF THE DRAWINGS

[049] In the drawings, identical reference numbers identify similar elements or acts. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the shapes of various elements and angles are not drawn to scale, and some of these elements are arbitrarily enlarged and positioned to improve drawing legibility. Further, the particular shapes of the elements as drawn, are not intended to convey any information regarding the actual shape of the particular elements, and have been solely selected for ease of recognition in the drawings.

[050] Figure 1A and Figure IB are schematic views of a system for generating a three dimensional (3D) effect using active glasses, according to one non-limiting illustrated embodiment showing example images being displayed in sequence on a display of the system.

[051] Figure 1C is a schematic illustration of a pixel for a previous frame according to an embodiment of the present invention.

[052] Figure ID is a schematic illustration of a pixel for a current frame according to an embodiment of the present invention.

[053] Figure IE is a schematic illustration of a pixel for an updated current frame according to an embodiment of the present invention.

[054] Figure IF is a flow diagram of a method for providing an updated current frame in accordance with an embodiment of the present invention.

[055] Figure 1G is a flow diagram of a method for selectively dithering non-standard colors in accordance with an embodiment of the present invention.

[056] Figure 2 is a timing diagram of screen refreshes of the display corresponding to what a left eye and a right eye of a user is seeing through the active glasses of the system for generating a 3D effect shown in Figure 1A and Figure IB, according to one non- limiting illustrated embodiment.

[057] Figure 2a is a flow diagram of a method for shuttering active glasses in accordance with an embodiment of the present invention.

[058] Figure 2b is a flow diagram of a method for shuttering active glasses in accordance with an embodiment of the present invention. Figure 3 is a diagram of representations of active liquid crystal filters of the active glasses of the system for generating a 3D effect shown in Figure 1A and Figure IB, according to one non-limiting illustrated embodiment. [059] Figure 4 is a diagram of representations of a stack of polarizers, light wave retarders and filters of the active glasses of the system for generating a 3D effect shown in Figure 1A and Figure IB, according to another non-limiting illustrated embodiment.

[060] Figure 5 is a schematic view of the active glasses 3D control unit and the display 3D control unit of the system for generating a 3D effect shown in Figure 1A and Figure IB, according to one non-limiting illustrated embodiment.

[061] Figure 6 is a flow diagram showing a method of operating the display of the system for generating a 3D effect shown in Figure 1A and Figure IB, according to one non- limiting illustrated embodiment.

[062] Figure 7 is a flow diagram showing a method of operating the active glasses of the system for generating a 3D effect shown in Figure 1A and Figure IB, according to one non-limiting illustrated embodiment.

DETAILED DESCRIPTION

[063] In the following description, certain specific details are set forth in order to provide a thorough understanding of various disclosed embodiments/ However, one skilled in the relevant art will recognize that embodiments may be practiced without one or more of these specific details, or with other methods, components, materials, etc. In other instances, well-known structures associated with 3D television systems, 3D television displays and active liquid crystal glasses have not been shown or described in detail to avoid unnecessarily obscuring descriptions of the embodiments.

[064] Unless the context requires otherwise, throughout the specification and claims which follow, the word "comprise" and variations thereof, such as, "comprises" and "comprising" are to be construed in an open, inclusive sense that is as "including, but not limited to.

[065] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment.

[066] The headings and Abstract of the Disclosure provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.

[067] Figure 1A and Figure IB are schematic views of a system for generating a 3D effect using active glasses 104 and showing example images being displayed for sequential refreshes (Refresh 1, Refresh 2, Refresh 3, Refresh 4) of the display. The refresh rate (also referred to as the "vertical refresh rate" or "vertical scan rate" for cathode ray tube devices) is the number of times in a second that display hardware draws the image data. This is distinct from the measure of frame rate in that the refresh rate may include the repeated drawing of identical frames, while frame rate measures how often a video source can feed an entire frame of new data to a display.

[068] The term color refers to the visual perceptual property corresponding in humans to the categories called red, green, blue and others. Color derives from the spectrum of light (distribution of light energy versus wavelength) interacting in the eye with the spectral sensitivities of the light receptors. The familiar colors of the rainbow in the spectrum include all those colors that can be produced by visible light of a single wavelength. Light of different single or multiple wavelengths within the electromagnetic spectrum have different colors.

[069] For each adjacent subsequent refresh of the screen 1 14, the display 1 12 switches the color of the left stereoscopic image 120 and right stereoscopic image 122 and correspondingly generates the control signal 1 18 to be sent to alternate the color (e.g., color 1 or color 2) that the corresponding left-eye lens 1 10 and right-eye lens 108 is filtering in. This is shown on the display for Refresh 1 and Refresh 2 in Figure 1A. Note that for Refresh 1, the left stereoscopic image 120 is displayed in color 2 and the right stereoscopic image 122 is displayed in color 1. Correspondingly, the left-eye lens 1 10 is illustrated to show (by use of illustrative vertical dashed lines on the left-eye lens 1 10) that it is filtering in color 2 of the left stereoscopic image 120 and the right-eye lens 108 is illustrated to show (by use of illustrative horizontal dashed lines on the right-eye lens 108) that it is filtering in color 1 of the right stereoscopic image 122. As shown in Figure 1 A, this configuration of the color in which the stereoscopic images are displayed and also the color which the left-eye lens 1 10 filters out and color it allows through, and the color which the right-eye lens 108 filters out and the color it allows through automatically alternates, for the image displayed and viewed corresponding to Refresh 2. This alternation continues as shown in Figure I B for Refresh 3, which alternates back to the stereoscopic image color configuration of Frame 1. Then, for Refresh 4, the configuration alternates back to the stereoscopic image color configuration of Refresh 2. This alternation may continue for an entire video program or portions of the video program and may also be applied to the display of video frames in forward or reverse direction or in special play modes such as fast forward, rewind or slow-motion. [070] This alternation occurs substantially at the same frequency and substantially in synchronization with the refresh rate of the display 1 12. This causes the user of the glasses 104 to perceive a full color video image sequence with lessened color distortion and flickering compared to using a system with traditional active shutter glasses or other traditional 3D systems for displays. In one embodiment, the refresh rate of the display 1 12 may be approximately 50/60 Hz (e.g., in accordance with European/U.S. standards). However, the refresh rate may also be greater or less than . 50/60Hz, such as, for example, approximately 200/240 Hz (e.g., in accordance with European/U.S. standards). Preferably, the refresh rate is over approximately 50/60 Hz.

[071] The alternation of the filtering of the two different colors between the left-eye lens 1 10 and right-eye lens 108 occurs in between the display of the images such that a user may see through both corresponding lenses 108, 1 10 during the concurrent display of the left stereoscopic image 120 and right stereoscopic image 122 during the display of each image. Preferably, this alternation occurs in less than approximately 2 ms. The alternation of the filtering as described herein may be applied to a variety of display systems and standards including, but not limited to, interlaced and non-interlaced systems, phase alternate line (PAL), National Television System Committee (NTSC) systems, progressive scan systems, plasma systems, liquid crystal display (LCD) systems, cathode ray tube (CRT) systems and various High Definition (HD) systems, etc.

[072] The two different colors may be any two different colors that are different enough to be distinguished and filtered appropriately by the corresponding left-eye lens 110 and right-eye lens 108 to create the desired 3D effect. For example, color 1 may be any one of red, green and blue or a variation thereof and the color 2 is another one of red, green and blue or a variation thereof. In one embodiment, color 1 is red and color 2 is blue (or vice versa). In another embodiment, color 1 is red and color 2 is blue-green or cyan (or vice versa). In another embodiment, color 1 is green and color 2 is red-blue or magenta

(or vice versa). The display 3D control unit 1 16 may be configured to send a wireless signal to the signal receiver of the control unit 106 of the active glasses 104 to control the filtering characteristics of the active glasses. In other embodiments, the signal may be other than wireless. This signal may be any suitable wireless or other signal for communication between the display 112 and the active glasses 104. For example, the signal may be, but is not limited to, an infrared signal, a radio frequency signal, a Digital

Light Processing Link (DLP® Link) signal or a Bluetooth® signal, etc. Other embodiments include any other configuration or combination of configurations that allow synchronization between the glasses 104 and the display 1 12, including using an emitter from the glasses 104 to the display 1 12, a specific timing signal used by both the display 1 12 and glasses 104, etc.

[073] Accordingly, displays described herein may alternate colors of a left stereoscopic image and right stereoscopic image during each refresh of a display. However, in some examples, when a frame (e.g., complementary stereoscopic image) is displayed there may be a difference between the current frame and the previous frame resulting in edge color distortion. In particular, this problem may result in high motion video sequences, and may occur in a variety of systems, including non-3D systems, systems utilizing active glasses, and/or systems utilizing shutter glasses. The system described with reference to Figures 1A and IB may also experience edge color distortion in some examples.

[074] Examples of the present invention include compensating for frame-sequential methods or other methods that utilize relatively fast switching between images. A current frame and one or more previous frames may be used to provide an updated current frame, and in this manner, edge color distortion may be reduced. As described herein, a current frame may refer to any frame of a video sequence and a previous frame may refer to any frame of the video sequence temporally positioned before the current frame. For example, in some embodiments, a previous frame and a current frame may refer to two successive frames associated with a same color configuration (e.g., first and third frames of a video sequence directed to 3D content), as described above, or may refer to two consecutive frames having different color configurations.

[075] For example, Figures 1C and ID show a pixel 150 for a previous frame and a current frame, respectively, and Figure IE shows a pixel 150 for an updated current frame according to an embodiment of the present invention. By way of example, each pixel 150 may include a red pixel, a green pixel, and a blue pixel. Accordingly, a value for a red pixel 151 of Figure 1C and a value for a red pixel 154 of Figure I D may be used to determine an updated value for a red pixel 157 of Figure IE. Values for a green pixel 158 and for a blue pixel 159 may be determined analogously.

[076] Figure IF is a flow diagram of a method 160 for providing an updated current frame in accordance with an embodiment of the present invention. At step 161, a previous frame may be received. As will be described in further detail, the previous frame may be stored, for instance, in memory for subsequent usage. At a step 162, a current frame may be received. The current frame may also be stored in memory. In one embodiment, the previous frame and/or the current frame may be received by a graphics engine, controller, or other processing unit or units and may be received from any of a variety of sources, e.g. broadcast, CD, DVD, Blu-Ray, or other source of video or other displayable data.

[077] At a step 163, the updated current frame may be generated. This may include, for instance, generating pixel values using respective pixel values of the previous and current frames. The updated current frame may be generated by a graphics engine, controller, or other processing unit or units, and may be provided to a display for display, which may reduce or eliminate edge color distortion in some examples.

[078] In one embodiment, for instance, updated pixel values may be determined in accordance with the following formulas:

R = A * R0 + (l - A) * Rl,

G = A * G0 + (1 - A) * G\,

B = A * B0 + (\ - A) * Bl

[079] wherein R represents an updated red pixel value of the updated current frame, RO and Rl are red pixel values of the previous and current frames respectively, and A is a weighting factor that in at least one embodiment may have a value between 0 and 1. Similarly, G and B may be updated green and blue pixel values of the updated current frame, respectively, GO and Gl may be green pixel values for previous and current frames respectively, and BO and B l may be blue pixel values for previous and current frames respectively. In some embodiments, the factor A may be static or dynamic and/or may be based, at least in part, on a particular video sequence and/or one or more pieces of equipment used to display the particular video sequence.

[080] In other embodiments, updated pixel values may be determined using other formulas and/or may be determined using other frames. An updated current frame may be determined, for instance, using a current frame and 2 previous frames. Moreover, in some embodiments, updated pixel values of an updated current frame may be determined for all pixels, or may only be determined for some pixels of the updated current frame. For example, in one embodiment, only pixels near an edge of a frame may be updated in the manner described herein. It will be appreciated by those having ordinary skill in the art that other implementations may be used without deviating from the scope and spirit of the invention. [081] Examples have been described herein with respect to viewing alternating color configurations of complementary stereoscopic images using active glasses. In some instances, however, one or more frames of a video sequence may be updated such that a user may watch a video sequence with or without active glasses. By way of example, a video sequence may include 2 frame types: frames including left stereoscopic images and right stereoscopic images, and frames including updated left stereoscopic images and right stereoscopic images. In one embodiment, the updated left stereoscopic images may comprise a combination of an inverted and dimmed down left stereoscopic image and a shifted left stereoscopic image. The inversion and dimming of the current left stereoscopic image may render the left stereoscopic image invisible to a user without active glasses as described in co-pending International Application No. PCT/US12/66882, filed November 28, 2012, entitled "APPARATUS, METHOD AND ARTICLE FOR GENERATING A THREE DIMENSIONAL EFFECT INCLUDING USING INVERTED IMAGES AND/OR PASSIVE FILTERS", which application is incorporated herein by reference in its entirety for any purpose. The shifted left stereoscopic image may be shifted such that content of the left stereoscopic image aligns with content of a corresponding right stereoscopic image. Frames including updated left stereoscopic images may be generated and inserted into a video sequence in addition to other frames. To compensate for the additional frames, frame rate may be increased and/or some frames may be eliminated.

[082] Inclusion of the updated left stereoscopic images may allow a user to see a video sequence without active glasses 104. That is, the updated left stereoscopic image may compensate for offset of the left stereoscopic images such that the user may view the video sequence without 3D effect or blur resulting therefrom. For a user viewing the video sequence with active glasses, each updated left stereoscopic image may be filtered out such that the user sees only the left stereoscopic images and right stereoscopic images of the sequence. In one embodiment, active glasses 104 may be configured to shutter during display of the updated left stereoscopic image such that each updated left stereoscopic image is filtered out. While video sequences have been described with respect to an updated left stereoscopic image, in some embodiments, an updated right stereoscopic image or both updated left stereoscopic and updated right stereoscopic images may be used as well.

[083] Similarly, visual information, such as subtitles, may be selectively presented to users as well. For example, in one embodiment, updated left stereoscopic images may include subtitle text. Accordingly, only a user viewing a video sequence without active glasses may see the subtitles as the updated left stereoscopic images may not be visible to users using the active glasses. Additionally or alternatively, visual information may be shown only to users wearing glasses. By way of example, subtitles may be included in left and/or right stereoscopic images. Updated left stereoscopic images may include a dimmed and inverted image such that the subtitles may not be viewable to a user not using active glasses. In this manner, visual information may be selectively shown to one or more of a user using active glasses and a user not using active glasses. Displays described herein are generally directed to displays configured to display frames using 3 standard colors (e.g., red, green, and blue). In some cases, however, displays may be configured to project more than 3 colors to provide a frame. This may be problematic, for instance, as these "non-standard" colors may permeate through color filters and damage a resulting image provided to a user. Accordingly, as will be described, nonstandard colors may be identified in a video sequence and selectively dithered.

[084] Figure 1 G is a flow diagram of a method 190 for selectively dithering non-standard colors in accordance with an embodiment of the present invention. The method 190 will be described with reference to colors green, red, and blue comprising standard colors and all other colors (e.g., yellow) as comprising non-standard colors. It will be appreciated, however, that the method 190 may be directed to other implementations having other known standard colors.

[085] At a step 192, a current frame may be received, for instance, by a graphics engine, controller, or other processing unit or units and/or may be stored in memory, and at a step 194, non-standard colors of the current frame may be identified. For example, in one embodiment, each pixel of the current frame may be analyzed to identify those pixels including one or more non-standard colors.

[086] At a step 196, for each pixel including a non-standard color, the non-standard color value of the pixel may be compared to one or more respective thresholds. In one embodiment, for example, the non-standard color value for a pixel of a left stereoscopic image or a right stereoscopic image may be compared to the sum of color values for pixels of both corresponding left and right stereoscopic images. If the difference between these two values exceeds a predetermined threshold, the pixel may be selected for dithering. The threshold may, for instance, be based on several pixel characteristics, including brightness. In some embodiments, color values for neighboring pixels and/or pixel values of other frames (e.g., previous or subsequent frames) may be considered as well.

[087] At a step 198, selected pixels may be dithered, for instance, using color dithering to subjectively replicate the non-standard color using standard colors, to provide a dithered frame. Any dithering methodology known now or in the future may be used, including thresholding, random, patterning, ordered, and error-diffusion dithering. By way of example, the color yellow may be replaced with green and magenta components for even and odd pixels, respectively, or for odd and even pixels, respectively.

[088] While the method 190 has been described with steps 192-198 as having a particular order, in some embodiments, steps 192-198 may be performed in any order and/or any two or more steps may be performed concurrently, simultaneously, and/or in an overlapping fashion.

[089] Figure 2 is a timing diagram of example screen refreshes of the display 1 12 corresponding to what a left eye and a right eye of a user is seeing through the active glasses 104 of the system for generating a 3D effect shown in Figure 1A and Figure IB. Shown is a timeline 206 corresponding to what the user's left eye is seeing 204 and a timeline 210 corresponding to what the user's right eye is concurrently seeing.

[090] The left eye of the user is seeing a stereoscopic view of an object in a video frame from angle 1, while the right eye of the user is seeing a stereoscopic view of the same object in the same video from angle 2. As shown on timeline 206, at to the left eye is seeing the stereoscopic view of the object in the video frame from angle 1 in color 2. As shown on timeline 212, at to the right eye is simultaneously seeing the stereoscopic view of the object in the video frame from angle 2 in color 1. At tl the screen refreshes and this configuration automatically alternates. In particular, at tl, the left eye is seeing the stereoscopic view of the object in the video frame from angle 1 in color 1 and the right eye is simultaneously seeing the stereoscopic view of the object in the video frame from angle 2 in color 2. This configuration continues to alternate at a frequency substantially equal to and substantially synchronized with the refresh rate of the display 1 12 until tn-

1.

[091] Although the color of the image being seen by the left eye is alternating each time the screen refreshes over a sequence of video images 208, the frequency of this alternation is so high that the user perceives the image in full or nearly full color. The same is true for the stereoscopic image sequence 214 being separately viewed by the right eye of the user. Thus, the 3D effect caused by the viewing of corresponding stereoscopic images individually by each eye of the user appears with lessened color distortion and flickering compared to traditional systems using active shutter glasses and other traditional 3D systems for displays.

[092] Accordingly, displays described herein may alternate colors of a left stereoscopic image and right stereoscopic image during each refresh of a display. However, as described, in some examples, when a next frame is displayed, the previous frame may not yet be completely removed from the display - an artifact which may be referred to as an "afterimage" or "afterglow." This problem may occur in a variety of systems, including non-3D systems, systems utilizing shutter glasses, and systems utilizing active shutter glasses. The system described with reference to Figures 1 A and IB may also experience afterglow in some instances.

[093] Examples of the present invention include compensating for frame sequential or other methods that utilize relatively fast switching between different images. For example, active glasses, such as the active glasses 104 of Figures la and lb, may be configured to "shutter" such that one or more of the lenses 108, 1 10 may filter out all, or nearly all, light at a given time. In at least one embodiment, the active glasses 104 may be shuttered during a frame transition, e.g., when a frame is refreshed with a subsequent frame. In this manner, portions of a video sequence may be filtered such that a user of the active glasses 104 sees little or no afterglow.

[094] Figure 2a is a flow diagram showing a method 250 for shuttering active glasses in accordance with an embodiment of the present invention. The method 250 may be used, for instance, to reduce afterglow seen by a user of active glasses.

[095] At a step 252, the active glasses 104 may be shuttered. For example, the active glasses 104 may be shuttered after a current frame has been displayed for a particular amount of time and/or may be shuttered when a particular frame will be refreshed a particular amount of time after the shuttering occurs. At a step 254, the current frame may be refreshed with a subsequent frame.

[096] At a step 256, the active glasses 104 may be opened, e.g., un-shuttered. In one embodiment, the active glasses 104 may be opened after a particular amount of time has elapsed after the refresh of the current frame, or may open after any resulting afterglow of the refresh has diminished such that the amount of afterglow satisfies a threshold. In one embodiment, for instance, the threshold may correspond to a level of afterglow not detectable by a user of the active glasses 104. In yet another embodiment, active glasses 104 may be opened during a refresh, for instance, after a refresh has been substantially completed.

[097] Thus, in some examples, the active glasses 104 may be shuttered for a predetermined amount of time, such as 0.2 milliseconds. While the active glasses 104 are shuttered, a refresh of a current frame may occur at any point at which the active glasses 104 are shuttered. In other examples, the active glasses 104 may shutter at substantially the same time as a refresh of a current frame and/or responsive to a refresh of a current frame.

[098] Examples of active glasses have been described herein which may be used in active anaglyph applications, and further may respond to a control signal to provide individual filter characteristics of left-eye and right-eye lenses of the active glasses. In some examples, the active glasses may respond to the control signal such that one or more of the active glasses 104 may be shuttered or opened. In one embodiment, for instance, the control signal may comprise a digital signal and include two or more binary bits to control a plurality of states of the active glasses 104. By way of example, the control signal may comprise a binary value of "00" or "1 1" to shutter the active glasses 104, and/or may comprise one or more of the binary values of "10" and "01" control the color filtering characteristics of the active glasses as previously described.

[099] In some embodiments, each lens of active shutter glasses may include two or more polarizers, and control as described herein may be implemented by coupling a first polarizer of a first lens to a second polarizer of a second lens and coupling a second polarizer of a first lens to a first polarizer of a second lens. Each coupled pair may be coupled to a respective channel and receive a bit of the control signal.

[100] Shuttering active glasses to filter (e.g., temporally filter) portions of a video sequence may be used in other applications as well, such as those directed to achromatic active glasses. In some embodiments, for instance, shuttering may be used with color- sequential displays, such as DLP displays. As known, color-sequential displays may sequentially project each of a number of colors such that after a number of passes for each color, a frame having a full color spectrum is generated. Accordingly, in some examples, active glasses may be shuttered such that left-eye stereoscopic images and right-eye stereoscopic images are formed to create a desired 3D effect. Because filtering in this manner is temporally based, a full color spectrum may be used.

[101] Figure 2b is a flow diagram of a method 275 for shuttering lenses of active glasses in accordance with an embodiment of the present invention. The method 275 is described herein with reference to a color-sequential display configured to sequentially display red, green, and blue colors. It will be appreciated, however, that the method 275 may be implemented using color-sequential displays configured to display one or more alternative colors. Moreover, the method 275 is described with reference to a green/magenta (green/blue-red) color scheme. It will further be appreciated that the method 275 may be used with other known color schemes as well (e.g., cyan-red).

[102] At a time when a color-sequential display is projecting a first color for a frame, at a step 282, the first color (e.g., green) may be filtered out for a first eye. As a result, only a second eye (e.g., right eye) of a user may see the first color. For example, a color- sequential display may project green components of a frame, and the active glasses may shutter a lens associated with a left eye of a user while the display projects the green components.

[103] At a time when the color-sequential display is projecting a second color for the frame, at a step 284, the second color (e.g., red) may be filtered out for the second eye of the user. As a result, only the first eye may see the second color. For example, the color-sequential display may project red components of the frame, and the active glasses may shutter a lens associated with a right eye of a user while the display projects the red components.

[104] At a time when the color-sequential display is projecting a third color for the frame, at a step 286, the third color (e.g., blue) may be filtered out for the second eye of the user. As a result, only the first eye may see the third color. For example, the color- sequential display may project blue components of the frame, and the active glasses may shutter a lens associated with a right eye of a user while the display projects the blue components.

[105] In this manner, a first eye of a user may see only the second and third colors of a frame, and the second eye of the user may see only the first color for the frame to create left and right stereoscopic images, respectively. In subsequent frames, the color configuration may be reversed to create a 3D effect as previously described. In some embodiments, color sequences described herein (e.g., green, red, blue) may vary. Accordingly, the steps of the method 275 may be implemented in any order such that the desired filtering is achieved.

[106] Figure 3 is a diagram of representations of active liquid crystal filters 304a and

304b of the active glasses 104 of the system for generating a 3D effect shown in Figure

1 A and Figure IB. Shown is a representation of the left-eye lens filter 304a of the left- eye lens 1 10 of the active glasses 104 and also a representation of a right-eye lens filter 304b of the right-eye lens 108 of the active glasses 104. In the embodiment shown, the left-eye lens filter 304a and right-eye lens filter 304b are active liquid crystal filters operable to individually receive a voltage indicated and/or caused by the received control signal to independently change filtering characteristics of the liquid crystal filter to which the voltage is applied. A different voltage may be applied to the different filters at the same time as indicated and/or caused by the received control signal. In particular, filter 304a and filter 304b use electrically controlled liquid crystal elements to select a specific visible wavelength of light for transmission through the filter at the exclusion of other wavelengths of light. In some embodiments, the filters are controllable by altering the number of red, blue and green pixels, which allow for the reduction of lucidity changes when implemented in the 3D system described herein.

[107] As seen in Figure 3, red, green and blue light from the current complementary primary colors-encoded stereoscopic image being displayed is filtered by the left-eye lens filter 304a to filter out color 2 (and allow color 1 to pass through) emanating from the corresponding left stereoscopic image of the complementary primary colors-encoded stereoscopic image, while the right-eye lens filter 304b filters out color 1 (and allows color 2 to pass through) emanating from the corresponding right stereoscopic image of the complementary primary colors-encoded stereoscopic image. The left-eye lens filter 304a and right-eye lens filter 304b then alternate the color being filtered in synchronization with the refresh rate of the display 1 12 using the control signal from the display as described above.

[108] Figure 4 is a diagram of a stack of polarizers 404a and 404b; light wave retarders 406a, 406b, 408a and 408b; and optical filters 410a and 410b, of the active glasses 104 of the system for generating a 3D effect shown in Figure 1A and Figure IB.

[109] The input polarizers 404a and 404b are configured to receive the full spectrum red, green, blue (RGB) light from the display 1 12 and linearly polarize the light from the display 1 12. If the light from the display 112 is already polarized, the polarizing direction of the input polarizers 404a and 404b should be aligned with the polarization of the light emanating from the display 1 12. The wavelength-dependent retarder 406a is coupled to the input polarizer 404a and is configured to circularly polarize light of the first color (i.e., the color of the left stereoscopic image of the displayed complementary primary colors- encoded stereoscopic image) in a first direction and to circularly polarize light of the second color (i.e., the color of the right stereoscopic image of the displayed complementary primary colors-encoded stereoscopic image) in a second direction opposite to the first direction. The wavelength-dependent retarder 406b is similarly configured.

[110] In one example embodiment, the wavelength-dependent retarders 406a and 406b are configured to shift the incoming light wave 100% along the x axis (1/2 wavelength) and 50% along the y axis (1/4 wavelength) for 650 nm wavelength light. Also, in the example embodiment, the wavelength-dependent retarders 406a and 406b are configured to shift the incoming light wave 50% along the x axis (1/4 wavelength) and 100% along the y axis (1/2 wavelength) for 546 nm wavelength light and 436 nm wavelength light. The axes of the wavelength-dependent retarders 406a and 406b are turned 45 degrees relative to the axis of the input polarizer 404a and 404b, respectively. In this way, the red spectrum light (of a 650 nm wavelength) becomes circularly polarized in one direction and the blue-green light (of a 546 nm wavelength and a 436 nm wavelength) becomes circularly polarized in the opposite direction.

[I l l] The wavelength-independent retarder 408a is coupled to the wavelength-dependent retarder 406a and is configured to linearly polarize the circularly polarized light of the first color and also to linearly polarize the circularly polarized light of the second color. The wavelength-independent retarder 408b is coupled to the wavelength-dependent retarder 406b and is also configured to linearly polarize the circularly polarized light of the first color and to linearly polarize the circularly polarized light of the second color.

[112] The electronically controllable optical filter 410a is coupled to the wavelength- independent retarder 408a and is operable to receive voltage caused and/or indicated by the control signal from the display 112 to selectively filter out the linearly polarized light of the first color and selectively allow light through of the second color. The electronically controllable optical filter 410b is coupled to the wavelength-independent retarder 408b, but instead is operable to receive voltage caused and/or indicated by the control signal from the display 1 12 to selectively filter out the linearly polarized light of the second color and selectively allow light through of the first color. Any electronically controllable optical filter may be utilized. Other applicable filters or layers may be included in the stack described above. A filter configuration including the components as described above, when used in conjunction with the processes described herein, would cause the active glasses 104 to provide the user a 3D effect that results in lessened lucidity loss due to the use of wave retarders to circularly polarize the light of individual corresponding stereoscopic images in different directions and would also result in easier control than traditional 3D systems for electronic displays.

[113] Also, U.S. Patent No. 5,751,384, entitled "Color polarizers for polarizing an additive color spectrum along a first axis and its compliment along a second axis," which is incorporated by reference herein in its entirety, describes a method of producing orthogonally polarized complementary primary colors which may be used in conjunction with the methods and systems described herein.

[114] Figure 5 is a schematic view of the active glasses 3D control unit 106 and the display 3D control unit 116 of the system for generating a 3D effect shown in Figure 1A and Figure IB. The active glasses 3D control unit 106 includes a controller 506, one or more control input components 508, read only memory (ROM) 510, random access memory (RAM) 512, and the active filters/polarizers 514, each operably coupled to each other via a system bus 515. The display 3D control unit 1 16 includes a controller 524, one or more control output components 526, ROM 18, RAM 520, and a display graphics engine 522, each operably coupled to each other via a system bus 530.

[115] For example the controller 506 may be a microprocessor, microcontroller, programmable logic controller (PLC), programmable gate array (PGA), application specific integrated circuit (ASIC) or another controller capable of receiving signals from various inputs (including from the control input components 508), performing logical operations, and sending signals to various components. Typically, the controller 506 may take the form of a microprocessor (e.g., INTEL, AMD, ATOM). As shown, the

Active Glasses 3D control unit 106 may also include one or more non-transitory processor- or computer-readable storage media, for example read only ROM 510 and

RAM 512. The non-transitory processor- or computer-readable storage media 510 and

512 may be in addition to any non-transitory storage medium (e.g., registers) which is part of the controller 506. As shown, the active glasses 3D control unit 106 may include one or more buses 515 (only one illustrated) coupling various components together, for example one or more power buses, instruction buses, data buses, etc. As illustrated the

ROM 510 or RAM 512, stores instructions and/or data or values for variables or parameters. The sets of data may take a variety of forms, for example a lookup table, a set of records in a database, etc. The instructions and sets of data or values are executable by the controller 506. Execution of which causes the controller 506 to perform specific acts to cause the alternation of filtering characteristics of the filters 514 in the individual left- eye and right-eye lenses of the active glasses 104. Specific operation of the alternation of filtering characteristics of the individual left-eye and right-eye lenses of the active glasses 104 is described above and further below with reference to various flow diagrams (Figure 6 and Figure 7).

[116] The controller 506 may use RAM 512 in a conventional fashion, for volatile storage of instructions, data, etc. The controller 506 may store data corresponding to the particular configurations of the filter or filters 514 used by the active glasses 104 and also configuration data related to the display 1 12 or the display 3D control unit 1 16. The instructions are executable by the controller 506 to control operation of the filters 514 of the individual left-eye and right-eye lenses of the active glasses 104.

[117] The control input components 508 are configured to receive control signals 528 from the display 3D control unit 1 16 that are input to the controller 506 which causes the alternation of filtering characteristics of the filters 514 in the individual left-eye and right-eye lenses of the active glasses 104 according to the received control signals 528 indicative of such alternation. Additionally or alternatively, control signals 528 may be provided to control shuttering and/or filtering of active glasses as described. For example, the control input components 508 may be those configured to receive signals including, but not limited to one or more of: infrared signals, radio frequency signals, (Digital Light Processing) Link (DLP® Link) signals or Bluetooth® signals.

[118] Also, the controller 524 of the display 3D control unit 116 may be a microprocessor, microcontroller, programmable logic controller (PLC), programmable gate array (PGA), application specific integrated circuit (ASIC) or another controller capable of sending signals to various outputs (including the control output components 526), performing logical operations, and sending signals to various other components. Typically, the controller 524 may take the form of a microprocessor (e.g., INTEL, AMD, ATOM). As shown, the display 3D control unit 1 16 may also include one or more non-transitory processor or computer-readable storage media, for example read only ROM 518 and RAM 520. The non-transitory processor- or computer-readable storage media 510 and 512 may be in addition to any non-transitory storage medium (e.g., registers) which is part of the controller 524. As shown, the display 3D control unit 1 16 may also include one or more buses 530 (only one illustrated) coupling various components together, for example one or more power buses, instruction buses, data buses, etc.

[119] As illustrated the ROM 518 and RAM 520, stores instructions and/or data or values for variables or parameters. The sets of data may take a variety of forms, for example a lookup table, a set of records in a database, etc. The instructions and sets of data or values are executable by the controller 506. Execution of which causes the controller 524 to perform specific acts to cause the generating and sending of a control signal to cause the alternation of filtering characteristics of the filters 514 in the individual left- eye and right-eye lenses of the active glasses 104 synchronized with the refresh rate of the display 1 12. Execution of instructions by the controller 524 may further cause the generating and sending of a control signal to cause the shuttering of active glasses 104 synchronized with the refresh rate of the display 1 12. Execution of instructions by the controller 524 also causes the controller 524 to perform specific acts to cause the display 1 12 to display complementary primary colors-encoded stereoscopic images with corresponding stereoscopic images of different colors and to switch the colors between the left stereoscopic image and right stereoscopic images each time the display 1 12 refreshes. Specific operation of the signal generation and complementary primary colors-encoded stereoscopic image displaying is described above and further below with reference to various flow diagrams (Figure 6 and Figure 7).

[120] The controller 524 may use RAM 520 in a conventional fashion, for volatile storage of instructions, data, etc. The controller 524 may store data corresponding to the particular configurations of the filter or filters 514 used by the active glasses 104 and also configuration data related to the display 1 12, the codec of the graphics engine 522, the refresh rate of the display 1 12, the format of the video being displayed, or the active glasses 3D control unit 106, etc. The instructions are executable by the controller 524 to control the signal generation for operation of the filters 514 of the individual left-eye and right-eye lenses of the active glasses 104 and to control the color of the complementary primary colors-encoded stereoscopic images displayed on the display 1 12 at any given time.

[121] Moreover, in some examples, instructions and/or data stored by the ROM 518,

ROM 520, other computer readable or executable storage accessible to the controller

524 or graphics engine 522 may cause the controller 524, graphics engine 522, or combinations thereof, to perform specific acts to cause a frame to be developed which includes a combination of a current frame, a previous frame, and/or other visual information (e.g., subtitles). For example, the graphics engine 522 may receive source data, e.g. from a broadcast source, CD, DVD, Blu-Ray, or other source of video data.

The graphics engine 522 may ordinarily encode or decode the source data such that the data may be displayed on a display, e.g. the display 1 12 of Figure 1. In some examples, the graphics engine 522 may provide data for display of a current frame which includes a combination of data for the current frame received in the source data, data for the previous frame and/or other data, as has been described above.

[122] Accordingly, the graphics engine 522 may calculate data for an updated current frame. The previous frame data may, for example, be stored in ROM 518, RAM 520, or other storage media accessible to the graphics engine 522. The updated current frame data may be determined in the manner described herein using current frame data and previous frame data.

[123] The updated current frame data may be provided to the display for display, which in some examples may reduce or eliminate edge color distortion and/or allow viewing of a video sequence with and without active glasses. The updated current frame data may be provided to the controller 524 for the controller 524 to perform the generating and sending of a control signal to cause the alternation of filtering characteristics of the filters 514 in the individual left-eye and right-eye lenses of the active glasses 104 synchronized with the refresh rate of the display 1 12 and in accordance with the updated frame data. Execution of instructions by the controller 524 may also cause the controller 524 to perform specific acts to cause the display 112 to display complementary primary colors-encoded stereoscopic images with corresponding stereoscopic images of different colors in accordance with the updated frame data and to switch the colors between the left stereoscopic image and right stereoscopic images each time the display 1 12 refreshes. In some examples, the graphics engine 522 may perform the specific acts to cause the display 1 12 to display complementary primary colors-encoded stereoscopic images with corresponding stereoscopic images of different colors in accordance with the updated frame data and to switch the colors between the left stereoscopic image and right stereoscopic images each time the display 1 12 refreshes.

[124] While described above that the graphics engine 522 may perform specific acts to improve updated current frame data including a combination of current frame data with previous frame data, in some examples, some or all of those specific acts may be performed by the controller 524.

[125] Additionally, in some examples, instructions and/or data stored by the ROM 518, ROM 520, other computer readable or executable storage accessible to the controller 524 or graphics engine 522 may cause the controller 524, graphics engine 522, or combinations thereof, to perform specific acts to selectively provide dithered frames. [126] For example, the graphics engine 522 may receive source data, e.g. from a broadcast source, CD, DVD, Blu-Ray, or other source of video data. The graphics engine 522 may ordinarily encode or decode the source data such that the data may be displayed on a display, e.g., the display 1 12 of Figure 1. In some examples, the graphics engine 522 may provide data for display of a dithered frame which may include data for one or more dithered pixels.

[127] Data for the dithered frame may be provided to the display for display, which may allow for representation of non-standard colors using standard colors such that filtering may be correctly applied. The data for the dithered frame may be provided to the controller 524 for the controller 524 to perform the generating and sending of a control signal to cause the shuttering of the active glasses 104. In some examples, the graphics engine 522 may perform the specific acts to cause the active glasses 104 to shutter such that a 3D effect is created, as described above.

[128] While described above that the graphics engine 522 may perform specific acts to improve dithered frame data including a combination of current frame data with previous frame data, in some examples, some or all of those specific acts may be performed by the controller 524.

[129] The control output components 526 are configured to send control signals 528 to the active glasses 3D control unit 106 which causes the alternation of filtering characteristics of the filters 514 in the individual left-eye and right-eye lenses of the active glasses 104 according to the received control signals 528 indicative of such alternation. For example the output components 526 may be those configured to send signals including, but not limited to, one or more of: infrared signals, a radio frequency signals, (Digital Light Processing) Link (DLP® Link) signals and Bluetooth® signals.

[130] Figure 6 is a flow diagram showing a method 600 of operating the display 1 12 of the system for generating a 3D effect shown in Figure 1A and Figure IB.

[131] At 602, the display 1 12 may display a complementary primary colors-encoded stereoscopic image of a video program on the display 1 12. The complementary primary colors-encoded stereoscopic image includes a first left- eye stereoscopic image of a first color and a corresponding right-eye stereoscopic image of a second color.

[132] At 604, the display 1 12 may then generate a control signal to be sent to the active glasses 104 to cause the active glasses 104 to alternate between filtering the first color and the second color through a left-eye lens and a right-eye lens of the active glasses. [133] At 606, the display 112 may then display another complementary primary colors- encoded stereoscopic image of the video program on the display 1 12, the other complementary primary colors-encoded stereoscopic image including a left-eye stereoscopic image of the second color and a corresponding right-eye stereoscopic image of the first color.

[134] At 608, the display 1 12 may then generate a control signal to be sent to active glasses 104 to cause the active glasses 104 to alternate between filtering the first color and the second color through a left-eye lens and a right- eye lens of the active glasses 104.

[135] The process may then repeat starting again at 602. For example, the process may repeat each time the display 1 12 refreshes in a manner to synchronize the alternation of the filtering the first color and the second color by the display glasses with the refresh rate and with the corresponding display of the left-eye stereoscopic image and the right- eye stereoscopic image in corresponding different colors.

[136] Figure 7 is a flow diagram showing a method 700 of operating the active glasses 104 of the system for generating a 3D effect shown in Figure 1A and Figure I B.

[137] At 702, the active glasses 104 receive a control signal for the active glasses 104 to cause them to alternate between a first state and second state, each state corresponding to an opposite configuration of filtering one color through a left-eye lens and concurrently filtering different color through a right-eye lens of the active glasses.

[138] At 704, the active glasses 104 alternate between the first state and second state according to the received control signal by changing filtering characteristics of the left- eye lens and right-eye lens substantially concurrently.

[139] The process may then repeat starting at 702. The process may repeat at a rate equal to and in synchronization with the refresh rate of a display displaying a sequence of left- eye stereoscopic images and corresponding right- eye stereoscopic images in different colors corresponding to those being filtered in by the corresponding left-eye lens or right eye-lens.

[140] The various methods described herein may include additional acts, omit some acts, and/or may perform the acts in a different order than set out in the various flow diagrams.

[141] The foregoing detailed description has set forth various embodiments of the devices and/or processes via the use of block diagrams, schematics, and examples.

Insofar as such block diagrams, schematics, and examples contain one or more functions and/or operations, it will be understood by those skilled in the art that each function and/or operation within such block diagrams, flowcharts, or examples can be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, or virtually any combination thereof. In one embodiment, the present subject matter may be implemented via one or more microcontrollers. However, those skilled in the art will recognize that the embodiments disclosed herein, in whole or in part, can be equivalently implemented in standard integrated circuits (e.g., Application Specific Integrated Circuits or ASICs), as one or more computer programs executed by one or more computers (e.g., as one or more programs running on one or more computer systems), as one or more programs executed by on one or more controllers (e.g., microcontrollers) as one or more programs executed by one or more processors (e.g., microprocessors), as firmware, or as virtually any combination thereof, and that designing the circuitry and/or writing the code for the software and/or firmware would be well within the skill of one of ordinary skill in the art in light of the teachings of this disclosure.

[142] When logic is implemented as software and stored in memory, logic or information can be stored on any non-transitory computer-readable medium for use by or in connection with any processor-related system or method. In the context of this disclosure, a memory is a nontransitory computer- or processor-readable storage medium that is an electronic, magnetic, optical, or other physical device or means that non-transitorily contains or stores a computer and/or processor program. Logic and/or the information can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions associated with logic and/or information.

[143] In the context of this specification, a "computer-readable medium" can be any physical element that can store the program associated with logic and/or information for use by or in connection with the instruction execution system, apparatus, and/or device.

The computer-readable medium can be, for example, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus or device. More specific examples (a non-exhaustive list) of the computer readable medium would include the following: a portable computer diskette (magnetic, compact flash card, secure digital, or the like), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM, EEPROM, or Flash memory), a portable compact disc read-only memory (CDROM), and digital tape.

[144] The various embodiments described above can be combined to provide further embodiments. To the extent that they are not inconsistent with the specific teachings and definitions herein, all of the U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and/or listed in the Application Data Sheet, including but not limited to: U.S. provisional patent application Serial No. 61/372,956 entitled "ALTERNATING COLORS BETWEEN LEFT AND RIGHT EYE IN ORDER TO IMPROVE A STEREOSCOPIC 3D EFFECT CREATED BY COMPLEMENTARY PRIMARY COLORS-ENCODED STEREOSCOPIC IMAGES WHEN 2 COLOR GLASSES ARE USED" and filed August 12, 2010 are incorporated herein by reference, in their entirety. Aspects of the embodiments can be modified, if necessary, to employ systems, circuits and concepts of the various patents, applications and publications to provide yet further embodiments. Note that "2 Color Glasses" refers to glasses that filter a different color for each lens, not 2 pairs of glasses.

[145] While generally discussed in the environment and context of providing 3D effects for electronic displays, the teachings herein can be applied in a wide variety of other environments, including, but not limited to, other 3D systems for film, video projectors, screen, theater display systems, medical imaging technology, vision therapy and vision testing and mechanically driven active glasses, etc.

[146] The above description of illustrated embodiments, including what is described in the Abstract, is not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. Although specific embodiments and examples are described herein for illustrative purposes, various equivalent modifications can be made without departing from the spirit and scope of the disclosure, as will be recognized by those skilled in the relevant art.

[147] These and other changes can be made to the embodiments in light of the above- detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.

Claims

CLAIMS We claim:

1. A method for providing an updated frame, the method comprising:

receiving a first frame of a video sequence;

receiving a second frame of the video sequence; and generating an updated current frame based, at least in part, on the first and second frames,

wherein the first and second frames comprise complementary stereoscopic images having a same color configuration.

2. The method of claim 1 , wherein said generating an updated current frame comprises:

updating one or more pixel values based, at least in part, on a pixel values of the first frame and a pixel value of the second frame.

3. The method of claim 1, wherein said generating an updated current frame comprises:

generating the updated current frame based, at least in part, on a dynamic weighting factor.

4. A non-transitory computer-readable medium that stores instructions executable by a processor to operate an electronic display, by:

receiving a first frame of a video sequence;

5. An apparatus, comprising: a control unit operably coupled to a display, the control unit configured to:

receive a first frame of a video sequence;

receive a second frame of the video sequence; and

generate an updated current frame based, at least in part, on the first and second frames,

6. A method comprising:

shuttering active glasses prior to a frame transition responsive, at least in part, to a control signal having a first state; and

opening the active glasses after the frame transition and before a next frame transition based, at least in part, to the control signal having a second state.

7. The method of claim 6, wherein the second state corresponds to a color filtering configuration for the active glasses.

8. The method of claim 6, wherein said shuttering comprises: shuttering the active glasses for a predetermined period of time.

9. The method of claim 6, wherein said opening comprises:

opening the active glasses based, at least in part, on a magnitude of afterglow being within a threshold.

10. An apparatus, comprising:

a control unit operably coupled to a display, the control unit configured to:

cause active glasses to shutter prior to a frame transition; and cause the active glasses to open after the frame transition and before a next frame transition.

1 1. A method for creating a three-dimensional effect, comprising: during projection of a frame by a color-sequential display:

filtering a first color for a first eye;

filtering a second color for a second eye; and

filtering a third color for the second eye.

12. The method of claim 1 1 , wherein said filtering a first color for a first eye comprises;

shuttering active glasses.

13. The method of claim 12, wherein the active glasses are achromatic.

14. The method of claim 1 1 , wherein said filtering a second color for a second eye comprises:

opening a lens associated with the first eye.

15. An apparatus, comprising:

a control unit operably coupled to a color-sequential display, the control unit configured to:

during projection of a frame, filter a first color for a first eye; during projection of the frame, filter a second color for a second eye; and

during projection of the frame, filter a third color for the second eye.

16. A method, comprising:

receiving a frame including a plurality of pixels;

identifying at least one of the plurality of pixels having a color value for a non-standard color; and

selectively dithering the at least one of a plurality of pixels based, at least in part, on the color value.

17. The method of claim 16, wherein said selectively dithering comprises:

comparing the color value for a stereoscopic image against a sum of a color value for a left stereoscopic image and a color value for a right stereoscopic image.

18. The method of claim 16, wherein said selectively dithering comprises:

selectively dithering the at least one of the plurality of pixels based, at least in part, on a brightness of the at least one of the plurality of pixels.

19. The method of claim 1 , wherein said selectively comprises: dithering even pixels using a first standard color and dithering odd pixels using a second standard color.

20. A non-transitory computer-readable medium that stores instructions executable by a processor to operate an electronic display, by:

receiving a frame including a plurality of pixels;

selectively dithering the at least one of a plurality of pixels based, at least in part, on a magnitude of the color value.

21. The non-transitory computer-readable medium of claim 19, that further stores instructions executable by a processor to operate an electronic display, by:

22. The non-transitory computer-readable medium of claim 19, wherein said instructions for selectively dithering comprise instructions for:

23. An apparatus, comprising:

a control unit operably coupled to a display, the control unit configured to:

receive a frame including a plurality of pixels;

identify at least one of the plurality of pixels having a color value for a non-standard color; and

selectively dither the at least one of a plurality of pixels based, at least in part, on the color value.