Compensating for the chromatic distortion of displayed images

• US 20030206179A1
• Filed: 03/16/2001
• Published: 11/06/2003
• Est. Priority Date: 03/17/2000
• Status: Active Grant

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Deering, Michael F.
• Granted Patent: US 6,924,816 B2
• Time in Patent Office: Days
• US Class Current: 345/589
• 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 5/002 Denoising; Smoothing noise processing or correction adapted to be used in an image pickup device containing and electronic image sensor H04N23/81, H04N25/60 - H04N25/67
• CPC Class Codes: G06T 5/006 Geometric correction correction of chromatic aberrations adapted to be used in an image pickup device containing an electronic image sensor H04N23/10; detecting, correcting, reducing or removing artefacts resulting only from the lens unit, e.g. flare, shading, vignetting or "cos4" H04N25/61
• CPC Class Codes: G06T 5/008 Local, e.g. shadow enhancement
• 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 compensating chromatic distortion in a display device, wherein the graphics system comprises:

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

wherein the first calculation unit is further operable (c) to compute second pixel values at the second plurality of second virtual pixel positions, and (d) to provide the second pixel values as output to the first display device;

wherein the first calculation unit is further operable to select the first virtual pixel positions in the two-dimensional viewport in order to compensate for a first positional distortion of first physical pixels having a first color generated by the first display device on a display surface in response to the first pixel values;

wherein the first calculation unit is configured to select the second virtual pixel positions in the two-dimensional viewport in order to compensate for a second positional distortion of second physical pixels having a second color generated by the first display device on the display surface in response to the second pixel values.

2. The graphics system of claim 1, wherein the first calculation unit is operable to receive first sensor data indicating first positions of the first physical pixels on the display surface, and to select the first virtual pixel positions in response to the first sensor data.

3. The graphics system of claim 2, wherein the first calculation unit is operable to assign zero to the second pixel values while a sensing device is acquiring the first sensor data.

4. The graphics system of claim 2, wherein the first calculation unit is operable to select the first plurality of first virtual pixel positions with a first distortion pattern which is approximately geometrically similar to the first positional distortion of the first physical pixels having the first color on the display device.

5. The graphics system of claim 2, wherein the first calculation unit is operable to receive second sensor data indicating second positions of the second physical pixels on the display surface, and to select the second virtual pixel positions in response to the second sensor data.

6. The graphics system of claim 2, wherein the first sensor data and second sensor data are acquired by a video camera.

7. The graphics system of claim 1 further comprising:

a graphics processor which is operable to receive graphics data, to select sample positions in the 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;

wherein the first calculation unit is coupled to the sample buffer and operable to compute the first pixel values by filtering the samples at each of the first virtual pixel positions in the two-dimensional viewport, and to compute the second pixel values by filtering the samples at each of the second virtual pixel positions in the two-dimensional viewport.

8. The graphics system of claim 7 wherein, for each of the first pixel values, the first calculation unit is operable:

to access a first subset of the sample values corresponding to a first neighborhood of a corresponding one of the first virtual pixel centers;

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

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

10. The graphics system of claim 9, wherein the first calculation unit is operable to assign zero to the second pixel values while the user is providing the first calibration inputs.

11. The graphics system of claim 9, 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 first calibration inputs.

12. The graphics system of claim 9, wherein the first calculation unit is configured to expansively adapt the first virtual pixel positions in the two-dimensional viewport in response to the first calibration inputs.

13. The graphics system of claim 9, wherein the first calculation unit is configured figured to contractively adapt the first plurality of first virtual pixel positions in the two-dimensional viewport in response to the first calibration inputs.

14. The graphics system of claim 9, wherein the first calculation unit is further operable to receive second calibration inputs from the user, and to adapt the second plurality of second virtual pixel positions in the two-dimensional viewport in response to the second calibration inputs.

15. The graphics system of claim 14, wherein the first calculation unit is operable to assign zero to the first pixel values while the user is providing the second calibration inputs.

16. The graphics system of claim 14, wherein the first calculation unit is operable to initiate adaptation of the second virtual pixel positions from a final calibrated state of the first virtual pixel positions.

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

18. The graphics system of claim 1, wherein the first calculation unit is configured to perform (a) and (b) in parallel with (c) and (d).

19. A method for compensating chromatic distortion in a display device, the method comprising:

(a) computing first pixel values at a first plurality of first virtual pixel positions in a two-dimensional viewport;

(b) providing the first pixel values as output to a first display device;

(c) computing second pixel values at the second plurality of second virtual pixel positions;

(d) providing the second pixel values as output to the first display device;

(e) selecting the first virtual pixel positions in the two-dimensional viewport in order to compensate for a first positional distortion of first physical pixels having a first color generated by the first display device on a display surface in responses to the first pixel values;

(f) selecting the second virtual pixel positions in the two-dimensional viewport in order to compensate for a second positional distortion of second physical pixels having a second color generated by the first display device on the display surface in response to the second pixel values.

20. The method of claim 19 further comprising receiving first sensor data indicating first positions of the first physical pixels on the display surface, and selecting the first virtual pixel positions in response to the first sensor data.

21. The method of claim 19, wherein (a) and (c) are performed in parallel.