Method and apparatus for seamless integration of multiple video projectors

• US 20020057361A1
• Filed: 06/06/2001
• Published: 05/16/2002
• Est. Priority Date: 06/13/2000
• Status: Active Grant

• Current Assignee: Projectiondesign AS (Barco NV), Mersive Technologies Incorporated
• Original Assignee: Panoram Technologies Inc
• Inventors: Mayer, Theodore III, Wang, Su Wen
• Granted Patent: US 6,760,075 B2
• Time in Patent Office: Days
• US Class Current: 348/383
• CPC Class Codes: G03B 21/005 Projectors using an electronic spatial light modulator but not peculiar thereto
• CPC Class Codes: H04N 9/12 Picture reproducers H04N9/11 takes precedence
• CPC Class Codes: H04N 9/3147 Multi-projection systems displays in general H04N9/12; video walls G06F3/1446, G09G2300/026
• CPC Class Codes: H04N 9/3182 Colour adjustment, e.g. white balance, shading or gamut white balance per se H04N9/73; control of amplitude of colour signals H04N9/68; colour control circuits for displays in general G09G5/02, G09G3/2003, G09G3/3607

Abstract

Method and apparatus are provided for seamless integration of multiple video projectors. In addition to edge blending, projection artifacts in dark or black image regions caused by residual grays from non-perfect projector black levels are reduced. Overlapped and non-overlapped areas of the image are defined and then the minimum black level of the video signal in non-overlapped areas is boosted without affecting the bright portion of the video signal in order to create uniform black level. The bright portion of the image is then smoothed in the overlapped area with seamless edge blending techniques. The resultant projected image may be passed through a neutral density filter to lower the base black level of the now uniform overlap and non-overlap black regions. The image may also pass through a physical mask which is hard edged or graded and aligned to less than the overall overlap region and that when used, smooths the edge of transition between the non-overlapped and overlapped regions.

Claims

1. A method of generating an apparently seamless composite image from a plurality of video signals, the video signals corresponding to discrete images, at least one of the discrete images having an overlap with at least one other of the discrete images, the method comprising the steps of:

edge blending the video signals to reduce the appearance of a seam in the overlap between the corresponding discrete images; and

adjusting the video signals to raise minimum black levels of non-overlapped regions of the corresponding discrete images, without affecting the rest of the video signals, to match the minimum black level of the overlap.

2. The method according to claim 1, wherein the step of edge blending the video signals comprises the step of adjusting the video signals to ramp the brightness of the corresponding discrete images.

3. The method according to claim 1, wherein the step of edge blending the video signals comprises the steps of generating a plurality of smoothing factors and applying the smoothing factors to the corresponding discrete images.

4. The method according to claim 1, wherein the step of adjusting the video signals comprises the steps of:

generating correction factors; and

applying the correction factors to the video signals to raise the minimum black levels of the non-overlapped regions without affecting the rest of the video signals.

5. The method according to claim 4, wherein at least one of the video signals comprises red, blue and green component signals, and the correction factor is generated for each of the red, blue and green component signals to shade the gray scale of the minimum black levels of the non-overlapped regions to match the minimum black level of the overlap.

6. The method according to claim 1, wherein at least one of the video signals comprises red, blue and green component signals, and black levels, bright levels and color balances of each component signal is adjusted in the overlapped region and the non-overlapped regions to produce the apparently seamless composite image.

7. The method according to claim 1 or 4, wherein the discrete images are projected through a neutral density filter to bring down the minimum black level closer to an absolute black level with zero photonic output.

8. The method according to claim 1 or 4, wherein physical masks are applied to mask areas of the discrete images that are non-raster in nature and are displayed by the projectors.

9. The method according to claim 8, wherein the density of at least one of the physical masks is graded so as to smooth an edge of transition between the non-overlapped region and the overlap.

10. The method according to claim 1 or 4, further comprising the step of determining edges of transition between the overlap and non-overlapped regions.

11. A method of smoothing the brightness and minimum black level of two adjoining overlapping video images, the video images being produced from two discrete video signals, the signals comprising a plurality of detail elements, each detail element having a brightness component, the method comprising the steps of:

applying a predetermined set of smoothing factors to the brightness components of the detail elements of the two video signals, each smoothing factor being associated with a the detail element to which it is applied;

projecting the images, as modified by the smoothing factors, onto a display;

modifying individual smoothing factors independently of one another in response to the appearance of the projected display; and

storing a representation of the smoothing factor modifications,

wherein the smoothing factors are used to adjust the brightness components of the detail elements in an overlapped region to lower a maximum bright level of the overlapped region to match maximum bright levels of non-overlapped regions, and to adjust the brightness components of the detail elements in the non-overlapped regions to raise minimum black levels to match the minimum black level of the overlapped region.

12. The method according to claim 11, wherein the step of modifying individual smoothing factors comprises the steps of:

projecting a cursor indication the image location corresponding to a specific detail element onto the display; and

modifying the smoothing factor associated with the specific detail element.

13. The method of claim 12, wherein the step of modifying individual smoothing factors further comprises the steps of:

moving the projected cursor to indicate the image location of a different specific detail element;

modifying the smoothing factor associated with the different specific detail element; and

repeating the steps of moving the cursor and modifying the smoothing factor until a desired appearance for the projected images has been obtained.

14. The method of claim 11, wherein each detail element comprises a pixel.

15. The method of claim 11, further comprising the step of applying the smoothing factor modifications to the brightness components of the detail elements of the two video signals to correct projection artifacts, wherein the projection artifacts comprise differences in the maximum bright levels and the minimum black levels between the overlap region and the non-overlapped regions.

16. The method according to claim 11, wherein the video signals comprise red, blue and green component signals, and black levels, bright levels and color balances of each component signal is adjusted in the overlapped region and the non-overlapped regions to produce an apparently seamless composite image.

17. The method according to claim 11, wherein the images are projected through a neutral density filter to bring down the minimum black level closer to an absolute black level with zero photonic output.

18. The method according to claim 11, wherein physical masks are applied to mask areas of the images that are non-raster in nature and are projected on the display.

19. The method according to claim 18, wherein the density of at least one of the physical masks is graded so as to smooth an edge of transition between the non-overlapped region and the overlapped region.

20. A system for adjusting video signals representing an array of raster images to compensate for projection defects, the system comprising:

a plurality of projectors to display the array of raster images to form a composite projected image;

an array of smoothing factors, each smoothing factor being associated with a portion of the composite projected image; and

means for applying smoothing factors to the video signals to remove the projection defects resulting from display of the array of raster images,

wherein the projection defects comprise differences in maximum bright levels and minimum black levels between overlapped and non-overlapped regions of the composite projected image.

21. The system according to claim 20, wherein the applying means comprises means for edge blending of adjacent overlapping raster images.

22. The system according to claim 20, wherein the applying means comprises means for boosting the minimum black levels of the non-overlapped regions to match the minimum black level of the overlapped region without affecting rest of the signal levels in the non-overlapped regions.

23. The system according to claim 20, wherein each video signal comprises red, blue and green component signals, and black levels, bright levels and color balances of each component signal is adjusted in the overlapped region and the non-overlapped regions to produce the composite projected image.

24. The system according to claim 20, the system further comprising one or more neutral density filters, each neutral density filter being associated with one of the projectors, and wherein the raster images are projected through associated neutral density filters to bring down the minimum black level of the composite projected image closer to an absolute black level with zero photonic output.

25. The system according to claim 20, wherein the projectors generate non-raster output in addition to the raster images, the system further comprising one or more physical masks, wherein each mask is applied to mask at least a portion of the non-raster output.

26. The system according to claim 25, wherein the density of at least one of the physical masks is graded so as to smooth an edge of transition between the non-overlapped region and the overlapped region.

28. The method according to claim 27, wherein the brightness of bright portions of the non-overlapped regions are raised so that maximum bright levels of the non-overlapped regions match the maximum bright level of the overlap.

29. The method according to claim 28, wherein minimum black levels of the non-overlapped regions are raised so that the minimum black levels of the non-overlapped regions match that of the overlap.

30. The method according to claim 29, wherein the maximum bright levels of the non-overlapped regions are raised by a different factor than the minimum black levels of the non-overlapped regions.

27. A method of generating an apparently seamless composite image from a plurality of video signals, the video signals corresponding to discrete images, at least one of the discrete images having an overlap with at least one other of the discrete images, the method comprising the steps of:

adjusting portions of the video signals corresponding to non-overlapped regions to raise the brightness of the non-overlapped regions to match the brightness of the overlap.