High resolution high contrast edge projection

• US 8,754,954 B2
• Filed: 05/16/2011
• Issued: 06/17/2014
• Est. Priority Date: 05/16/2011
• Status: Active Grant

• Current Assignee: National Research Council Canada
• Original Assignee: National Research Council Canada
• Inventors: Blais, Francois, Drouin, Marc-Antoine
• Primary Examiner(s): HANNETT, JAMES M
• Application Number:
  US13/108,378
• Publication Number:
  US 20120293700A1
• Time in Patent Office: 1,128 Days
• Field of Search: 348/222.1
• US Class Current: 348/222.1
• CPC Class Codes: G01B 11/2513 with several lines being projected in more than one direction, e.g. grids, patterns
• CPC Class Codes: G02B 3/005 arranged along a single direction only, e.g. lenticular sheets G02B3/0043 takes precedence
• CPC Class Codes: G02B 3/06 with cylindrical or toric faces
• CPC Class Codes: G02B 3/08 with discontinuous faces, e.g. Fresnel lens diffractive Fresnel lenses G02B5/1876
• CPC Class Codes: H04N 9/317 Convergence or focusing systems electronic adjustment of convergence H04N9/3185; convergence or focusing arrangements for cathode ray tubes H04N9/28; means for automatic focusing of projectors not peculiar to the presence of an electronic spatial light modulator G03B21/53
• CPC Class Codes: H04N 9/3188 Scale or resolution adjustment scaling in general G06T3/40; resolution modifying circuits for displays in general G09G5/391

Abstract

Generating a high definition projected illumination pattern from a substantially lower resolution digital projector array involves: selectively illuminating a connected set of pixels to produce a pixellated, high contrast edge feature, and positioning an anisotropically blurring optical element (ABOE) between a light source of the projector array and the projection. The ABOE applies an anisotropic blur pattern to pixels of the at least one connected set, to locally preferentially blur the pixel more (and preferably substantially only) in a direction of equally or more strongly illuminated pixels, and not in directions of less illuminated pixels. Preferably a contour of the connected set has no beginning or end within a periphery of the illumination plane, and has bounded curvature, permitting simple ABOEs to be used. Several images each having several or many edges can be produced using a same ABOE. The ABOE may alleviate interpixel gap effects for non-edge pixels too.

Claims

1. A method for projecting a special purpose image using a lower resolution digital projector array, the method comprising:

choosing a pattern to be illuminated, the pattern having at least one high contrast edge feature that extends continuously across a plane of the illumination;

applying an illumination pattern on the projector array to define a pixellated, high contrast approximation to the edge feature; and

providing an anisotropically blurring optical element between an illumination source and the projection that blurs each pixel of a connected set of pixels of the illumination pattern more in directions of pixels of equal or greater illumination, and less in directions of pixels of lower illumination.

2. The method of claim 1 wherein choosing the pattern comprises choosing a pattern wherein each edge feature extends without end within the illumination plane.

3. The method of claim 1 wherein providing the anisotropically blurring optical element comprises anisotropically blurring each pixel of the connected set of pixels at substantially a same degree and at a fixed angle with respect to the projector array.

4. The method of claim 1 wherein providing the anisotropically blurring optical element comprises providing:

a cylindrical lens;

a plurality of linear strips, each with a respective cylindrical lens;

a Fresnel lens;

a diffraction medium bearing a pattern;

a reflective surface bearing a pattern;

a hologram;

or

an interferometric pattern.

13. The method of claim 2 wherein choosing the pattern further comprises choosing a pattern where one or more edge features extend between two ends, both of which ends lie on a periphery of the illumination plane.

14. The method of claim 13 wherein choosing a pattern where one or more edge features extend between two ends comprises choosing a pattern with a plurality of edge features that extend without intersecting with any other edge feature, within the illumination plane, and wherein providing the anisotropically blurring optical element comprises:

providing a blurring element for each edge feature that is independently movable; and

moving each of the blurring elements and/or modifying the illuminated pixel pattern, for alignment between respective blurring elements and edge features.

15. The method of claim 14 wherein the plurality of edge features are arranged in parallel within the illumination plane.

16. The method of claim 1 wherein choosing a pattern comprises:

choosing a pattern wherein one edge feature is a straight line that extends without ending, or intersecting with any other edge feature, within the illumination plane;

choosing a pattern wherein one edge feature is a straight line that extends without ending, or intersecting with any other edge feature, within the illumination plane, the line being off axis of the projection array to provide a jagged, pixellated, high contrast approximation;

choosing a pattern wherein one edge feature is a curve that extends without ending, or intersecting with other high contrast edges, within the illumination plane to provide a jagged, pixellated, high contrast approximation;

choosing a pattern wherein one edge feature is a curve that extends without end within the illumination plane, wherein a magnitude of the curvature is constant;

choosing a pattern having a plurality of edge features wherein each edge feature is a straight line that extends without end within the illumination plane;

choosing a pattern having a plurality of edge features, each of which extending without end within the illumination plane, wherein each pair of edge features is at a fixed separation in a given direction, and thus they have parallel tangents at each point;

choosing a pattern having a plurality of edge features, each of which is a line extending without end within the illumination plane, wherein each pair of high contrast edges is parallel;

or

choosing a pattern wherein each edge feature extends without end within the illumination plane, the edge having a continuous and uniform intensity profile in a normal direction perpendicular to the local tangent of the edge.

17. The method of claim 1 wherein choosing a pattern comprises choosing a pattern having a plurality of edge features, each of which extending without end within the illumination plane, wherein each pair of edge features is at a fixed separation along a first direction, and thus they have parallel tangents at each corresponding point, and wherein providing the anisotropically blurring optical element comprises:

providing a blurring element that has a 1 dimensional pattern of anisotropic blurring directions to match the tangent when aligned with the first direction.

18. The method of claim 1 wherein choosing a pattern comprises:

choosing a pattern wherein the edge feature has a bright side and a dark side, and wherein providing the anisotropically blurring optical element comprises;

providing a blurring element that blurs the pixellated, high contrast, jagged approximation of the edge feature, and furthermore blurs a bright side of the pattern to remove interpixel gaps within the vicinity of the edge feature, while minimally decreasing contrast of the image;

choosing a pattern wherein the edge feature has a bright side that gradually and smoothly transitions to a dark side, and wherein rotation of the image and the anisotropically blurring optical element with respect to the digital projector array is used to vary an extent of the transition;

choosing a pattern wherein the edge feature has a bright side that gradually and smoothly transitions to a dark side, and wherein rotation of the image and the anisotropically blurring optical element with respect to the digital projector array, and a local degree of blurring of the anisotropically blurring optical element are used to vary an extent of the transition;

or

choosing a pattern wherein the edge feature has a bright side that gradually and smoothly transitions to a dark side, and wherein an extent of the transition is controlled by;

rotation of the image and the anisotropically blurring optical element with respect to the digital projector array, a local degree of blurring of the anisotropically blurring optical element at respective locations; and

selecting a local curvature of the edge feature.

19. The method of claim 3 wherein;

the connected set of pixels include a chain of pixels that extends without end within the plane of illumination;

each connected set of pixels includes a chain of pixels that extends without end within the plane of illumination;

a plurality of connected sets of pixels are anisotropically blurred, and each connected set of pixels includes a chain of pixels that extends without end within the plane of illumination without overlapping any other chain of pixels;

a plurality of connected sets of pixels are anisotropically blurred, and each connected set of pixels includes a chain of pixels that extends without end within the plane of illumination, the chains being parallel;

or

a plurality of connected sets of pixels are anisotropically blurred, and each connected set of pixels includes a chain of pixels that extends without end within the plane of illumination, the chains being parallel lines.

20. The method of claim 1 wherein providing the anisotropically blurring optical element comprises anisotropically blurring in a direction tangential to the edge feature, and substantially not blurring in a direction normal to the edge feature.

5. A system for projecting an image with a lower resolution projector array, the system comprising:

a digital projector array adapted to selectively illuminate at least one connected set of pixels to produce a pixellated, high contrast edge feature;

an anisotropically blurring optical element positioned between a light source of the projector array and the projection, the anisotropically blurring optical element applying an anisotropic blur pattern to the at least one connected set of the pixels, to locally preferentially blur the pixels tangentially, along a contour of the connected set of pixels.

6. The system of claim 5 wherein:

the digital projector array is adapted to produce a number of different images, each image having a respective set of at least one connected set of pixels.

7. The system of claim 5 wherein:

the connected set has no beginning or end within an illumination plane, but may have a beginning and/or an end at a periphery of the illumination plane;

or

the blur pattern has a degree of blurring for a given pixel in the blur pattern that is higher if neighbouring pixels of the contour are more distant, or if at the given pixel the contour is the straightest.

8. The system of claim 5 wherein anisotropically blurring optical element comprises:

a cylindrical lens;

a plurality of linear strips, each with a respective cylindrical lens;

a Fresnel lens;

a diffraction medium bearing a pattern;

a reflective surface bearing a pattern;

a hologram;

or

an interferometric pattern.

9. The system of claim 5 wherein:

the digital projector array is adapted to selectively illuminate an image comprising multiple connected sets of pixels, each defining a respective edge feature;

the digital projector array is adapted to selectively illuminate any one of a set of images, each image comprising multiple connected sets of pixels, each connected set defining a respective edge feature;

or

the digital projector array is adapted to selectively illuminate any one of a set of images, each image comprising multiple connected sets of pixels, each connected set defining a respective edge feature, and one anisotropically blurring optical element with one anisotropic blur pattern preferentially blurs the pixels tangentially, along each contour of each of the connected sets of pixels of each of the images.

10. A kit comprising:

an anisotropically blurring optical element suitable for applying an anisotropic blur pattern to an incident plane wave, the blur pattern preferentially blurring local elements such that blurring follows a substantially continuous, connected polyline; and

instructions for;

positioning the optical element between a light source of the projector array and a projection; and

aligning the optical element with respect to the projector array, whereby one or more patterns of illumination from the digital projector array will emit a pixellated, high contrast edge feature that is anisotropically blurred by the optical element to project an image including a high contrast, high resolution edge feature.

11. The kit of claim 10 further comprising one or more of:

a digital camera for imaging the projected image;

a software program for receiving a digital image of the projected image, and compute a surface topography of a surface on which the image was projected;

a mounting for positioning the optical element;

a software program for receiving a digital image of the projected image, and controlling an alignment of the optical element via a mounting;

the digital projector array;

a software program for receiving a digital image of the projected image, controlling a pattern of illumination of the digital projector array, and/or controlling an alignment of the optical element via a mounting; and

a software program for receiving a digital image of the projected image on a surface, and matching camera pixel information with projection pixel illuminations.

12. The kit of claim 10 wherein the optical element comprises:

a cylindrical lens;

a plurality of linear strips, each with a respective cylindrical lens;

a Fresnel lens;

a diffraction medium bearing a pattern;

a reflective surface bearing a pattern;

a hologram;

or

an interferometric pattern.