System and method for correcting multiple axis displacement distortion

• US 7,352,913 B2
• Filed: 06/12/2002
• Issued: 04/01/2008
• Est. Priority Date: 06/12/2001
• Status: Expired due to Term

• Current Assignee: Geo Semiconductor Incorporated
• Original Assignee: Silicon Optix (Renesas Electronics Corporation)
• Inventors: Karuta, Bonaventure, Lee, Louie
• Primary Examiner(s): Bella; Matthew C.
• Assistant Examiner(s): Rosario; Dennis
• Application Number:
  US10/166,692
• Publication Number:
  US 20030043303A1
• Time in Patent Office: 2,120 Days
• Field of Search: 382/275, 382/100, 382/293, 382/215, 382/255, 353/69, 353/70, 348/746
• US Class Current: 382/275
• CPC Class Codes: G02B 27/0025 for optical correction, e.g. distorsion, aberration
• CPC Class Codes: G03B 27/68 Introducing or correcting distortion, e.g. in connection with oblique projection
• CPC Class Codes: G06T 2207/20021 Dividing image into blocks, subimages or windows
• CPC Class Codes: G06T 3/00 Geometric image transformations in the plane of the image
• CPC Class Codes: G06T 5/80 Geometric correction
• CPC Class Codes: H04N 5/74 Projection arrangements for image reproduction, e.g. using eidophor
• CPC Class Codes: H04N 9/3185 Geometric adjustment, e.g. keystone or convergence optical or mechanical adjustment of convergence H04N9/317; using scanning means H04N3/22; optical or mechanical adjustments of projectors not peculiar to the presence of an electronic spatial light modulator G03B21/14
• CPC Class Codes: H04N 9/3194 including sensor feedback

Abstract

A system and method for correcting distortion in projected images caused by the projection of an input image by a projector lens onto a projection screen having a surface that is not orthogonal to the projection axis of the projector. Projection parameters including the focal length of the projector lens and the angles that represent the pan, tilt and roll angle of the projector are obtained. Then the projected area and the best viewable rectangular area that fits within said projected area is determined. The distortion is then characterized by using a distortion transformation which corresponds to the transformation that exists between the vertices of the best viewable rectangular area and the corresponding vertices of the projected area. Finally, the distortion transformation is inverted and applied to input image to obtain a distortion free projected image.

Claims

1. A method for projecting an image onto a viewing surface, wherein the relative orientation of projection axis and the normal direction associated with the viewing surface is characterized by simultaneous presence of at least two of pan, tilt, and roll angles, said method comprising:

(a) obtaining input image data;

(b) obtaining the at least two of pan, tilt, and roll angles;

(c) determining a distorted projected area on the viewing surface in the simultaneous presence of the at least two of pan, tilt, and roll angles, and determining a best viewable area that fits within said distorted projected area such that the best viewable area is optimized with respect to at least one of image area and image resolution, and such that the best viewable area corresponds to the projected image in the absence of the at least two of pan, tilt and roll angles; and

(d) applying a geometric distortion correction transformation to the input image data to obtain a visually distortion free projected image fitting the best viewable area.

2. The method of claim 1, wherein said geometric distortion correction transformation is represented by surface fits.

3. The method of claim 1, wherein optical distortion parameters are also present, further concatenating an optical distortion correction transformation to said geometric distortion correction transformation, thereby forming an overall distortion correction transformation.

4. The method of claim 3, wherein said method comprises applying the overall distortion correction transformation to the input image data to obtain a distortion free projected image on the optimized best viewable area on the viewing surface.

5. The method of claim 3, wherein said method comprises applying the overall distortion correction transformation as a single-pass 2D image transformation.

6. The method of claim 3, wherein said method comprises applying the overall distortion correction transformation as two separate sequential 1D image transformations.

7. The method of claim 3, wherein said method further comprises:

(e) separating the overall distortion correction transformation into a first pass transformation and a second pass transformation;

(f) applying the first pass transformation using one of a first positional polynomial and an incremental polynomial; and

(g) applying the second pass transformation using one of a second positional polynomial and an incremental polynomial.

8. The method of claim 1, further comprising the determination and storage of a set of distortion parameters, and computing and storing a grid set of corresponding distortion correction transformations that span the entire space of distortion parameters, and dynamically accessing said grid set to determine the overall distortion compensation transformation using interpolation methods.

9. The method of claim 1, wherein the input image data corresponds to a distorted input image, and wherein the method further includes generation of an input distortion correction transformation associated with said distorted input image and concatenation of said input distortion correction transformation with said geometric distortion correction transformation to generate a transformation via which a distortion free output image can be formed on said best viewable area on said viewing surface.

10. The method of claim 1, wherein the viewing surface is an irregular surface, and wherein the method further includes generating a surface transformation associated with said irregular surface and concatenation of the surface transformation with the geometric distortion correction transformation to generate a transformation that, when applied to the input image data, generates a visually distortion free output image on a best viewing area optimized in terms of at least one of an optimized area and an optimized resolution.

11. The method of claim 1, wherein the viewing surface is a panoramic surface and wherein the method further includes generation of an anamorphic conversion transformation associated with said panoramic surface using the aspect ratio in the input image data relative to the aspect ratio of the viewing surface and concatenation of the anamorphic conversion transformation with the geometric distortion correction transformation to generate a transformation such that a distortion free output image is formed on said viewing surface.

12. A projection system adapted to project an image onto a viewing surface, wherein the relative orientation of projection axis and the normal direction of the viewing surface is characterized by simultaneous presence of at least two of pan, tilt, and roll angles, said system comprising:

(A) a projection parameter input adapted to obtain the input image data and the simultaneously present at least two of pan, tilt, and roll angles; and

(B) a processor coupled the projection parameter input to determine a distorted projected area on the viewing surface in the presence of the at least two of pan, tilt, and roll angles, and to determine a best viewable area that fits within said distorted_projected area such that the best viewable area is optimized with respect to at least one of image area and image resolution, and such that the best viewable area corresponds to the projected image in the absence of the at least two of pan, tilt and roll angles, said processor being further adapted to apply a geometric distortion correction transformation to the input image data to obtain a visually distortion free projected image fining the best viewable area.

13. The system of claim 12, wherein said processor is adapted to apply the geometric distortion correction transformation is by surface fits.

14. The system of claim 12, wherein optical distortion parameters are also present, and wherein said processor is further adapted to concatenate an optical distortion correction transformation to said geometric distortion correction transformation, thereby forming an overall distortion correction transformation.

15. The system of claim 14, wherein said processor is adapted to apply the overall distortion correction transformation as a single-pass 2 D image transform.

16. The system of claim 14, wherein said processor is adapted to apply the overall distortion correction transformation as two separate sequential 1D image transforms.

17. The system of claim 14, wherein said processor is further adapted:

(D) to separate the overall distortion correction transformation into a first pass transformation and a second pass transformation;

(E) to apply the first pass transformation using one of a first positional polynomial and an incremental polynomial; and

(F) to apply the second pass transformation using one of a second positional polynomial and an incremental polynomial.

18. The system of claim 12, wherein said processor is further adapted to determine and store a set of distortion parameters, and to compute and store a grid set of corresponding distortion correction transformations that span the entire space of distortion parameters, and to dynamically access said grid set to determine the overall distortion correction transformation using interpolation methods.

19. The system of claim 12, wherein the input image data corresponds to a distorted input image, and wherein said processor is further adapted to generate an input distortion correction transformation associated with said distorted input image and to concatenate said input distortion correction transformation with said overall distortion correction transformation to generate a transformation via which a distortion free output image can be formed on said best viewable area on said viewing surface.

20. The system of claim 12, wherein the viewing surface is an irregular surface and wherein the processor is further adapted to generate a surface transformation associated with said irregular surface and to concatenate the surface transformation with the geometric distortion correction transformation of to generate a transformation that, when applied to the input image data, generates a visually distortion free output image on a best viewing area optimized in terms of at least one of an optimized area and an optimized resolution.

21. The system of claim 12, wherein the viewing surface is a panoramic surface and wherein the processor is further adapted to generate an anamorphic conversion transformation associated with said panoramic surface using the aspect ratio of the input image data relative to the aspect ratio of the viewing surface and to concatenate the anamorphic conversion transformation with the overall distortion correction transformation to generate a transformation that can form a distortion free output image in panoramic format on said viewing surface.