Method and apparatus for adjusting multiple projected raster images

• US 6,115,022 A
• Filed: 05/30/1997
• Issued: 09/05/2000
• Est. Priority Date: 12/10/1996
• Status: Expired due to Fees

• Current Assignee: Barco NV
• Original Assignee: Metavision Corporation
• Inventors: Mayer, Theodore III, Inova, Peter J.
• Primary Examiner(s): Hjerpe, Richard A.
• Assistant Examiner(s): Laneau, Ronald
• Application Number:
  US08/865,854
• Time in Patent Office: 1,194 Days
• Field of Search: 345/112, 345/111, 345/113, 345/47, 345/46, 345/139, 345/150, 345/151, 345/153, 345/199, 345/207, 348/383, 348/576, 348/577, 348/597, 348/687, 348/688, 348/744
• US Class Current: 345/418
• 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

Abstract

A three dimensional smoothing factors lookup table provides detailed control over the full two dimensional space of a composite image composed of multiple projected raster images. The overall displayed image is improved by adjusting the brightness, gamma, and contrast of individual detail elements of the image according to predetermined smoothing factors. A set of smoothing factors is generated by measuring the reflective brightness of detail elements of the projected image to produce a reflective brightness contour map and mathematically inverting the contour map to produce an inverse map. The inverse map is used as smoothing factors to match the colors output by various projectors in an arrayed projection system. The three dimensional smoothing factors lookup table also enables performance of additional image improvement functions, including projector shading, color shift correction, correction of optical vignetting, and automatic edge definition.

Claims

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

a plurality of projectors to display the array of raster images, each raster image including red, green and blue color components, to form a composite projected image;

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

means for applying the smoothing factors to the video signals to remove the projection defects resulting from display of the array of raster images, wherein the three dimensional array of smoothing factors comprises a smoothing factor for each portion of the composite projected image for each of red, green, and blue color signals of the video signals, and wherein each smoothing factor is applied to a selected portion of the composite projected image by multiplying the smoothing factor with video signal values for the selected portion.

2. The system of claim 1, wherein the applying means comprises means for edge blending of adjacent overlapping raster images.

3. The system of claim 1, wherein the applying means comprises means for matching color outputs of the projectors displaying the array of raster images.

4. The system of claim 1, wherein the applying means comprises means for correcting occurrences of improper projector shading for the projectors by applying the smoothing factors.

5. The system of claim 1, wherein the applying means comprises means for correcting occurrences of horizontal, vertical, or geometric color purity shifts for the projectors by adjusting the brightness of the composite projected image according to the smoothing factors.

6. The system of claim 1, wherein the applying means comprises means for correcting occurrences of optical vignetting for the projectors by adjusting the brightness of the composite projected image according to the smoothing factors.

7. The system of claim 1, wherein the applying means comprises means for applying the smoothing factors non-linearly to adjust selected portions of the composite projected image which are brighter to be diminished more strongly than selected portions of the composite projected image which are darker, thereby adjusting the value of the smoothing factors based on a variable intensity of the video signals for the selected portions.

8. The system of claim 1, wherein the applying means comprises means for automatically generating the smoothing factors based on dynamically monitoring output of the projectors.

9. The system of claim 1, wherein the applying means comprises means for automatically generating the smoothing factors at specific times determined according to a regular time base of multi-source video sources providing the video signals.

10. The system of claim 1, wherein the applying means comprises means for determining edges of the composite projected image when the composite projected image is not square or rectangular in shape and for displaying the composite projected image within the determined edges.

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

a plurality of projectors to display the array of raster images, each raster image including red, green and blue color components, to form a composite projected image;

means for storing a three dimensional array of smoothing factors, each smoothing factor being associated with a portion of the composite projected image; and

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

a brightness circuit to adjust the brightness of the video signals;

a mixer coupled to the brightness circuit; and

a smoothing factor multiplier coupled to the mixer and the storing means to apply the smoothing factors to video signals used for generating the composite projected image.

12. The system of claim 11, further comprising a gamma circuit coupled to the mixer to adjust the gamma of the video signals.

13. The system of claim 12, further comprising a contrast circuit coupled to the mixer to adjust the contrast of the video signals.

14. A method of matching arrayed projectors to produce a composite raster image having consistent red, green, and blue color values, comprising the steps of:

(a) focusing at least one light sensor on the projection screen;

(b) displaying a selected one of the color values by a selected one of the projectors on the projection screen;

(c) displaying a pattern of the selected color value by the selected projector on the projection screen;

(d) collecting measurement data from the at least one light sensor sensing the display by the selected projector of the pattern;

(e) repeating steps (b)-(d) for each of the color values;

(f) repeating steps (b)-(e) for each of the projectors;

(g) generating a behavior profile for each of the projectors and for all projectors combined from the collected measurement data; and

(h) adjusting the projectors according to the behavior profiles,

wherein the composite rater image comprises a plurality of raster images, each of the plurality of raster images includes red, green and blue color components, and each raster image is projected on a projection screen by one of the arrayed projectors.

15. The method of claim 14, further comprising the steps of:

(i) analyzing selected locations of each projector'"'"'s projected raster image;

(j) creating a reflective brightness contour map representing the reflective brightness of the composite raster image;

(k) creating an inverse map of the reflective brightness contour map; and

(l) applying the inverse map to the composite raster image.

16. The method of claim 15, wherein the reflective brightness contour map comprises a three dimensional array of smoothing factors.

17. The method of claim 15, wherein the inverse map comprises a three dimensional array of smoothing factors.

18. A system for producing a composite raster image having consistent red, green, and blue color values, the system comprising:

arrayed projectors to project the composite raster image on a projection screen;

at least one light sensor sensing the composite raster image on the projection screen;

means for displaying selected color values by selected projectors on the projection screen;

means for displaying patterns of selected color values by selected projectors on the projection screen;

means for collecting measurement data from the at least one light sensor sensing the display by the selected projector of the patterns;

means for generating a behavior profile for each of the projectors and for all projectors combined from the collected measurement data; and

means for adjusting the projectors according to the behavior profiles,

wherein the composite raster image comprises a plurality of raster images, each of the plurality of raster images includes red, green and blue color components, and the arrayed protectors are matched to provide the consistent red, green, and blue color values to the composite raster image.

19. The system of claim 18, further comprising:

means for analyzing selected locations of each projector'"'"'s projected raster image;

means for creating a reflective brightness contour map representing the reflective brightness of the composite raster image;

means for creating an inverse map of the reflective brightness contour map; and

means for applying the inverse map to the composite raster image.

20. The system of claim 19, wherein the reflective brightness contour map comprises a three dimensional array of smoothing factors.

21. The system of claim 19, wherein the inverse map comprises a three dimensional array of smoothing factors.

22. The system of claim 19, wherein the applying means comprises a signal adjustment card for each of the projectors.

23. The system of claim 19, wherein the signal adjustment card comprises:

a brightness circuit to adjust the brightness of the video signals;

a mixer coupled to the brightness circuit;

means for storing the inverse map; and

a smoothing factor multiplier coupled to the mixer and the storing means to apply the inverse map to video signals used for generating the composite raster image.

24. The system of claim 23, further comprising a gamma circuit coupled to the mixer to adjust the gamma of the video signals.

25. The system of claim 23, further comprising a contrast circuit coupled to the mixer to adjust the contrast of the video signals.

26. The system of claim 18, wherein the at least one light sensor comprises a light measuring spot meter.

27. The system of claim 18, wherein the at least one light sensor comprises a CCD camera.

28. The system of claim 18, wherein the at least one light sensor comprises a photometric detector.