Invisible or Low Perceptibility of Image Alignment in Dual Projection Systems

• US 20140292817A1
• Filed: 10/19/2012
• Published: 10/02/2014
• Est. Priority Date: 10/20/2011
• Status: Active Grant

• Current Assignee: IMAX Corporation
• Original Assignee: IMAX Corporation
• Inventors: Iversen, Steen Svendstorp, Tan, Weining, O'Dor, Matthew
• Granted Patent: US 10,326,968 B2
• Time in Patent Office: Days
• US Class Current: 345/672
• CPC Class Codes: G03B 17/54 with projector
• CPC Class Codes: G03B 35/20 using two or more projectors
• CPC Class Codes: G06T 3/20 Linear translation of whole images or parts thereof, e.g. panning
• CPC Class Codes: H04N 13/207 using a single 2D image sensor
• CPC Class Codes: H04N 13/236 using varifocal lenses or mirrors
• CPC Class Codes: H04N 13/246 Calibration of cameras
• CPC Class Codes: H04N 13/327 Calibration thereof
• CPC Class Codes: H04N 13/363 using image projection screens volumetric display H04N13/388
• CPC Class Codes: H04N 9/3147 Multi-projection systems displays in general H04N9/12; video walls G06F3/1446, G09G2300/026
• 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 9/3185 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 dual projection system can align displayed images using an alignment pattern. The alignment pattern can be used to modify part of an image content frame of an image data sequence. Two image data sequences can be spatially aligned based on the modification to part of the image content frame using the alignment pattern. An image content frame may be warped and displayed. The displayed warped image content frame can be captured. A set of transformation vectors can be determined based on the captured image content frame and alignment image data. Stored transformation data can be updated using the set of transformation vectors and the updated transformation data can be used to spatially align two image data sequences.

Claims

1. A method comprising:

accessing an alignment pattern having at least one alignment feature;

modifying a portion of image content in a frame of a first digital image sequence by a projection system using the at least one alignment feature; and

spatially aligning the first digital image sequence and a second digital image sequence based on the portion modified by the projection system when displaying the first digital image sequence and the second digital image sequence.

2. The method of claim 1, wherein the portion modified using the at least one alignment feature is at least one color channel.

3. The method of claim 1, further comprising modifying, by the projection system, a second portion of image content of a subsequent frame in the first digital image sequence that is different than the portion,

wherein the frame with the portion of image content modified by the projection system and the subsequent frame with the second portion of image content modified by the projection system comprises all of the alignment pattern.

4. The method of claim 3, further comprising:

converting portions of the frame with the at least one alignment feature, the portions being distributed among multiple frames that are displayed, wherein the portions have a random spatial sequence.

5. The method of claim 1, wherein modifying the portion of the image content in the frame of the first digital image sequence by the projection system using the at least one alignment feature comprises:

replacing at least part of the portion with the at least one alignment feature, the portion having black image pixels around the at least one alignment feature.

6. The method of claim 5, wherein the at least one alignment feature within the portion has an average illumination level substantially corresponding to the at least part of the portion replaced with the at least one alignment feature.

7. The method of claim 5, wherein the at least one alignment feature within the portion has an average color balance corresponding to the at least part of the portion replaced with the at least one alignment feature.

8. The method of claim 5, wherein the at least one alignment feature has a Gaussian illumination profile.

9. The method of claim 1, further comprising:

capturing, as a captured second image sequence frame, a displayed second digital image sequence frame modified with alignment image data that comprises the alignment pattern;

capturing, as a captured first image sequence frame, a displayed first digital image sequence modified with the alignment image data;

determining a set of transformation vectors based on a spatial difference between the alignment image data in the captured second image sequence frame and the captured first image sequence frame; and

spatially aligning a displayed first image of the first digital image sequence and a displayed second image of the second digital image sequence using the set of transformation vectors.

10. The method of claim 1, wherein the portion is a whole image frame of at least one color channel.

11. The method of claim 1, wherein modifying the portion of image content in the frame in the first digital image sequence by the projection system using the at least one alignment feature comprises:

replacing at least part of the portion with the at least one alignment feature, the at least one alignment feature having high frequency content of at least one color channel, the portion having image content pixels around the at least one alignment feature, the image content pixels being low frequency image content of the at least one color channel.

12. A method, comprising:

capturing, as a captured first image sequence frame, a displayed first image sequence content frame having image content modified with alignment data;

capturing, as a captured second image sequence frame, a displayed second image sequence frame having image content modified with the alignment data;

determining a set of transformation vectors based on a spatial difference between the alignment data in the captured second image sequence frame and the captured first image sequence frame;

spatially aligning a displayed first image of a first image sequence and a displayed second image of a second image sequence using the set of transformation vectors.

13. The method of claim 12, further comprising:

modifying image content in at least one frame in the first image sequence and in the second image sequence with the alignment data to generate a modified first image sequence frame and a modified second image sequence frame;

warping the modified second image sequence frame with stored transformation data to generate a warped second image sequence frame;

displaying the warped second image sequence frame as the displayed second image sequence frame and displaying the modified first image sequence frame as the displayed first image sequence frame; and

updating the stored transformation data with the set of transformation vectors to produce updated transformation data,

wherein spatially aligning the displayed first image of the first image sequence and the displayed second image of the second image sequence using the set of transformation vectors comprises using the updated transformation data.

14. The method of claim 13, wherein modifying the at least one frame in the first image sequence and in the second image sequence with the alignment data to generate the modified first image sequence frame and the modified second image sequence frame comprises:

accessing the alignment data comprising an alignment pattern having at least one alignment feature; and

modifying a portion of image content in a frame in the first image sequence by a projection system using the at least one alignment feature, wherein the first image sequence and the second image sequence each comprise digital image data,

wherein spatially aligning the displayed first image of the first image sequence and the displayed second image of the second image sequence using the set of transformation vectors comprises spatially aligning the first image sequence and the second image sequence based on the portion modified by the projection system when displaying the first image sequence and the second image sequence.

15. The method of claim 13, wherein modifying the image content in the at least one frame in the first image sequence and in the second image sequence with the alignment data to generate the modified first image sequence frame and the modified second image sequence frame comprises:

accessing the alignment data comprising an alignment pattern;

modifying a first portion of image content in a frame of the first image sequence using the alignment pattern;

modifying, using the alignment pattern, a second portion of image content in a subsequent frame of the first image sequence that is different than the first portion,

wherein the frame with the first portion modified using the alignment pattern and the subsequent frame with the second portion modified using the alignment pattern comprise all of the alignment pattern.

16. The method of claim 13, wherein modifying the image content in the at least one frame in the first image sequence and in the second image sequence with the alignment data to generate the modified first image sequence frame and the modified second image sequence frame comprises:

modifying the at least one frame in the first image sequence and in the second image sequence based on watermarking the alignment data onto image data in the at least one frame in each of the first image sequence and the second image sequence by one of;

spatial encoding to watermark the alignment data onto the image data;

or

time domain encoding to watermark the alignment data onto the image data, the method further comprising;

extracting the alignment data from at least one of the captured second image sequence frame or the captured first image sequence frame that includes a watermarked frame.

17. The method of claim 12, wherein determining the set of transformation vectors based on the spatial difference between the alignment data in the captured second image sequence frame and the captured first image sequence frame comprises:

determining a first set of transformation vectors based on a difference between the alignment data and the captured second image sequence frame including a modification using the alignment data; and

determining a second set of transformation vectors based on a difference between the alignment data and the captured first image sequence frame including a modification using the alignment data,

wherein spatially aligning the displayed first image of the first image sequence and the displayed second image of the second image sequence using the set of transformation vectors comprises spatially aligning the displayed first image of the first image sequence and the displayed second image of the second image sequence using the first set of transformation vectors and the second set of transformation vectors.

18. The method of claim 12, further comprising:

determining a centroid of alignment features of the captured first image sequence frame and the captured second image sequence frame using a low resolution image sensor.

19. A dual display projection system, comprising:

a server comprising;

a memory unit for storing a first image sequence, a second image sequence, and alignment data that is an alignment pattern having at least one alignment feature; and

a processor device for modifying a portion of image content in a frame in a first image sequence by using the at least one alignment feature and for spatially aligning the first image sequence and a second image sequence based on the modified portion when displaying the first image sequence and the second image sequence.

20. The dual display projection system of claim 19, wherein the processor device is adapted for:

modifying image content in a second frame of the second image sequence with the alignment data that includes the alignment pattern to create a modified second image frame; and

warping the modified second image frame with stored transformation data to generate a warped second image frame,

wherein the dual display projection system further comprises;

a first display device for displaying the warped second image frame;

a second display device for displaying the modified frame in the first image sequence;

an image sensor for capturing the displayed warped second image frame and the displayed modified frame as a captured second image frame and a captured first image frame; and

a calibration circuit for determining a set of transformation vectors based on a spatial difference between the alignment data in the captured second image frame and the captured first image frame,

wherein the processor device is adapted for updating the stored transformation data with the set of transformation vectors to produce updated transformation data and for spatially aligning a displayed first image of the first image sequence and a displayed second image of the second image sequence using the updated transformation data.

21. The dual display projection system of claim 20, wherein the image sensor is adapted for being synchronized for capturing the displayed warped second image content frame and the displayed modified frame.

22. The dual display projection system of claim 20, wherein the image sensor is a camera.

23. The dual display projection system of claim 20, wherein the first image sequence and the second image sequence are stereographic image sequences.