Graphics system configured to perform distortion correction

• US 6,940,529 B2
• Filed: 03/16/2001
• Issued: 09/06/2005
• Est. Priority Date: 03/17/2000
• Status: Expired due to Term

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Deering, Michael F.
• Primary Examiner(s): Bella, Matthew C.
• Assistant Examiner(s): Caschera, Antonio
• Application Number:
  US09/810,112
• Publication Number:
  US 20020015052A1
• Time in Patent Office: 1,635 Days
• Field of Search: 315/370, 345/1.3, 345/6, 345/9, 345/428, 345/581, 345/619, 345/629, 345/647, 348/177, 348/178, 348/745, 348/383, 382260-265, 382/275
• US Class Current: 345/647
• CPC Class Codes: G06T 2200/12 involving antialiasing
• CPC Class Codes: G06T 2207/10024 Color image
• CPC Class Codes: G06T 3/153 using elastic snapping
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: G06T 5/50 using two or more images, e.g. averaging or subtraction
• CPC Class Codes: G06T 5/70 Denoising; Smoothing
• CPC Class Codes: G06T 5/80 Geometric correction
• CPC Class Codes: G06T 5/94 based on local image properties, e.g. for local contrast enhancement
• CPC Class Codes: H04N 9/3147 Multi-projection systems displays in general H04N9/12; video walls G06F3/1446, G09G2300/026
• CPC Class Codes: H04N 9/3185 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

Abstract

A graphics system comprises pixel calculation units and a sample buffer which stores a two-dimensional field of samples. Each pixel calculation unit selects positions in the two-dimensional field at which pixel values (e.g. red, green, blue) are computed. The pixel computation positions are selected to compensate for image distortions introduced by a display device and/or display surface. Non-uniformities in a viewer'"'"'s perceived intensity distribution from a display surface (e.g. hot spots, overlap brightness) are corrected by appropriately scaling pixel values prior to transmission to display devices. Two or more sets of pixel calculation units driving two or more display devices adjust their respective pixel computation centers to align the edges of two or more displayed images. Physical barriers prevent light spillage at the interface between any two of the display images. Separate pixel computation positions may be used for distinct colors to compensate for color distortions.

Claims

1. A graphics system for correcting display distortions, wherein the graphics system comprises:

a graphics processor which is operable (a) to receive graphics data, (b) to select sample positions in a two-dimensional viewport, and (c) to compute sample values at the sample positions based on the receive graphics data;

a sample buffer coupled to the graphics processor and configured to store the sample values; and

a first calculation unit operable to select a first plurality of first virtual pixel positions in the two-dimensional viewport, to compute firs pixel color values at the first plurality of first virtual pixel positions, and to provide the first pixel color values as output to be displayed on a first display device;

wherein the first calculation unit is configured to compute the first pixel values by filtering samples, from the sample buffer, neighboring each of the first virtual pixel positions; and

wherein the first calculation unit selects the first plurality of first virtual pixel positions in the two-dimensional viewport in order to compensate for a first physical distortion in positions of a first set of first physical pixels generated by the first display device on a display surface.

2. The graphics system of claim 1, wherein the first calculation unit is configured to receive calibration signals from a user, and to adapt the first plurality of first virtual pixel positions in the two-dimensional viewport in response to the calibration signals.

3. The graphics system of claim 2, wherein the first calculation unit is configured to adapt the first virtual pixel positions in the two-dimensional viewport along a one-parameter family of geometric distortions in response to the calibration signals.

4. The graphics system of claim 2, wherein the first calculation unit is configured to expansively adapt the first virtual pixel positions in the two-dimensional viewport in response to the calibration signals.

5. The graphics system of claim 2, wherein the first calculation unit is configured to contractively adapt the first plurality of first virtual pixel positions in the two-dimensional viewport in response to the calibration signals.

6. The graphics system of claim 1, wherein the first calculation unit includes a first cache memory, wherein the first cache memory is configured to store a first number of memory bins, wherein the first number of memory bins depends on a maximum expected displacement of the first plurality of first virtual pixel positions from corresponding positions in a rectangular array.

7. The graphics system of claim 1, wherein the first calculation unit is further configured to receive sensor data indicating the positions of the first set of first physical pixels on the display surface, and to compute the first plurality of first virtual pixel positions in response to the sensor data.

8. The graphics system of claim 1, wherein the first display device is a first projection device.

9. The graphics system of claim 1, wherein the first calculation unit selects the first plurality of first virtual pixel positions with a first distortion pattern which is geometrically similar to the first physical distortion in positions of the first set of physical pixels on the display surface.

10. The graphics system of claim 1 further comprising:

a second calculation unit operable to select a second plurality of second virtual pixel positions in the two-dimensional viewport, to compute second pixel values at the second plurality of second virtual pixel positions, and to provide the second pixel values as output to a second display device;

wherein the second calculation unit selects the second plurality of second virtual pixel positions in the two-dimensional viewport in order to correct for a second physical distortion in positions of a second set of second physical pixels generated by the second display device on the display surface in response to the second pixel values.

11. The graphics system of claim 10, wherein the first calculation unit and second calculation unit are configured to receive calibration inputs from a user, and to respectively adapt the first virtual pixel positions and the second virtual pixel positions in the two-dimensional viewport in response to the calibration inputs.

12. The graphics system of claim 10, wherein the second display device is a second projection device.

13. The graphics system of claim 10, wherein the second calculation unit selects the second plurality of second virtual pixel positions with a second distortion pattern which is geometrically similar to the second physical distortion of the second set of second physical pixels on the display surface.

14. The graphics system of claim 10, wherein the first calculation unit and second calculation unit are configured to adapt the first plurality of first virtual pixel positions relative to the second plurality of second virtual pixel positions in the two-dimensional viewport in response to the calibration inputs.

15. The graphics system of claim 14, wherein the first calculation unit and second calculation unit are configured to translate the first plurality of first virtual pixel positions relative to the second plurality of second virtual pixel positions in the two-dimensional viewport in response to the calibration inputs.

16. The graphics system of claim 14, wherein the first calculation unit and second calculation unit are configured to scale the first plurality of first virtual pixel positions relative to the second plurality of second virtual pixel positions in the two-dimensional viewport in response to the calibration inputs.

17. A graphics system comprising:

a graphics processor which is operable (a) to receive graphics data, (b) to select sample positions in a two-dimensional field, and (c) to compute sample values at the sample positions based on the received graphics data;

a sample buffer coupled to the graphics processor and configured to store the sample values; and

a first calculation unit configured to compute pixel color values at a first plurality of first filter centers in the two-dimensional field, and to provide the first pixel color values to be displayed on a first display device, wherein the first calculation unit is configured to compute the pixel color values by filtering samples, from the sample buffer, neighboring each of the first filter centers;

wherein the first calculation unit is configured to select the first plurality of first filter centers to compensate for a positional distortion of physical pixels on a display surface generated by the first display device.

18. A graphics system for correcting display distortions, wherein the graphics system comprises:

a graphics processor which is operable to receive graphics data, to select sample positions in a two-dimensional viewport, and to compute sample values at the sample positions based on the received graphics data;

a sample buffer coupled to the graphics processor and configured to store the sample values; and

a first calculation unit coupled to the sample buffer and operable to select a first plurality of first virtual pixel positions in the two-dimensional viewport, to compute first pixel color values at the first virtual pixel positions, and to provide the first pixel color values as output to be displayed on a first display device, wherein the first calculation unit is configured to compute the first pixel color values by filtering samples, from the sample buffer, neighboring each of the first virtual pixel positions;

wherein the first calculation unit selects the first plurality of first virtual pixel positions in the two-dimensional viewport in order to correct for a first positional distortion of first physical pixels generated by the first display device on a display surface.

19. The graphics system of claim 18, wherein the first calculation unit is configured to receive calibration signals from a user, and to adapt the first plurality of first virtual pixel positions in the two-dimensional viewport in response to the calibration signals.

20. The graphics system of claim 19, wherein the first calculation unit is configured to repeatedly compute the first pixel values while adapting the first virtual pixel positions in response to the calibration signals.

21. The graphics system of claim 18 further comprising:

a second calculation unit coupled to the sample buffer and operable to select a second plurality of second virtual pixel positions in the two-dimensional viewport, and to compute second pixel values at the second virtual pixel positions, and to provide the second pixel values as output to a second projection device;

wherein the second calculation unit selects the second plurality of second virtual pixel positions in the two-dimensional viewport in order to correct for a second positional distortion of a second set of second physical pixels generated by the second display device on the display surface.

22. The graphics system of claim 21, wherein the first calculation unit and second calculation unit are configured to adapt the first plurality of first virtual pixel positions relative to the second plurality of second virtual pixel positions in the two-dimensional viewport in response calibration signals supplied by a user.

23. The graphics system of claim 18 wherein, for each first pixel value of the first pixel values, the first calculation unit is operable:

to access a first subset of the sample values residing in a first spatial neighborhood of a corresponding one of the first virtual pixel positions from the sample buffer; and

to filter the first subset of the sample values to generate the first pixel value.

24. A method for correcting display distortions, the method comprising:

receiving graphics data;

selecting sample positions in a two-dimensional viewport;

computing sample values at the sample positions based on the received graphics data;

storing the sample values in a sample buffer;

selecting a first plurality of first virtual pixel positions in the two-dimensional viewport; and

computing first pixel color values at the first plurality of first virtual pixel positions, and providing the first pixel color values as output to be displayed on a first display device, wherein said computing first pixel color values comprises filtering samples, from the sample buffer, neighboring each of the first virtual pixel positions;

wherein the first plurality of first virtual pixel positions in the two-dimensional viewport are selected in order to correct for a first physical distortion in positions of a first set of first physical pixels generated by the first display device on a display surface in response to the first pixel values.