Graphics system having a super-sampled sample buffer with hot spot correction

• US 6,771,272 B2
• Filed: 12/29/2000
• Issued: 08/03/2004
• 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): Jankus, Almis R.
• Application Number:
  US09/751,375
• Publication Number:
  US 20020070944A1
• Time in Patent Office: 1,313 Days
• Field of Search: 345/581, 345/589, 345/606, 345/611, 345/1.3, 345/5, 345/158, 382/274, 348/658, 348/744
• US Class Current: 345/581
• 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 5/80 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 flattening a distribution of light energy perceived by a viewer of a displayed image generated on a display surface by one or more display devices, the graphics system comprising:

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 received graphics data;

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

a sample-to-pixel calculation unit coupled to said sample buffer and operable to select a first plurality of first virtual pixel positions in the two-dimensional viewport, wherein, for each first virtual pixel position in said first plurality, said sample-to-pixel calculation unit is operable (d) to access one or more sample values corresponding to sample positions in a neighborhood of the first virtual pixel position from the sample buffer, (e) to filter said one or more sample values to generate a first pixel value, (f) to scale the first pixel value by an intensity correction value which depends on the first virtual pixel position in the 2-D viewport, and (g) to provide the scaled first pixel value as output to a first projection device;

wherein the intensity correction value is configured to correct for a non-uniformity in the perceived distribution of light by the viewer.

2. The graphics system of claim 1, wherein the intensity correction value varies with respect to the first virtual pixel positions in the two-dimensional viewport so as to compensate for one or more perceived hot spots in the displayed image.

3. The graphics system of claim 1, wherein the intensity correction value varies with respect to the first virtual pixel positions in the two-dimensional viewport so as to smooth a discontinuity at a boundary between a first screen and a second screen comprising the display surface.

4. A method for flattening a distribution of light energy perceived by a viewer of two or more images generated on a display surface by two or more corresponding projection devices, the method comprising:

generating first pixel values, comprising;

computing the first pixel values by filtering the samples at the first plurality of first virtual pixel positions;

scaling a first subset of the first pixel values by first intensity scaling values;

providing the first pixel values to a first projection device;

generating second pixel values, comprising;

computing second pixel values by filtering the samples at the second plurality of second virtual pixel positions;

scaling a second subset of the second pixel values by second intensity scaling values;

providing the second pixel values to a second projection device;

wherein the first projection device is configured to generate a first array of first physical pixels on the display surface in response to the first pixel values, wherein the second projection device is configured to generate a second array of second physical pixels on the display surface in response to the second pixel values, wherein the first subset of first pixel values control intensities of a first subset of the first physical pixels in a first overlap region between the first array and the second array, wherein the second subset of second pixel values control intensities of a second subset of the second physical pixels in the first overlap region.

5. A graphics system for flattening a distribution of light energy perceived by a viewer of two or more images generated on a display surface by two or more corresponding projection devices, the graphics system comprising:

a first sample-to-pixel calculation unit configured to compute first pixel values by selecting and filtering samples, to scale a first subset of the first pixel values by first intensity scaling values, and to provide the first pixel values to a first projection device;

a second sample-to-pixel calculation unit configured to compute second pixel values by selecting and filtering the samples, to scale a second subset of the second pixel values by second intensity scaling values, and to provide the second pixel values to a second projection device;

wherein the first sample-to-pixel calculation unit is configured to compute the first pixel values by selecting and filtering the samples at a first plurality of first virtual pixel positions, wherein the second sample-to-pixel calculation unit is configured to compute the second pixel values by selecting and filtering the samples at a second plurality of second virtual pixel positions.

6. The graphics system of claim 5, wherein the samples populate a two-dimensional viewport, wherein the first virtual pixel positions and second virtual pixel positions define locations in the two-dimensional viewport.

7. The graphics system of claim 5, wherein the first projection device is configured to generate a first array of first viewable pixels on the display surface in response to the first pixel values, wherein the second projection device is configured to generate a second array of second viewable pixels on the display surface in response to the second pixel values;

wherein the first subset of the first pixel values control intensities of a first subset of the first viewable pixels in a first overlap region between the first array and the second array, wherein the second subset of the second pixel values control intensities of a second subset of the second viewable pixels in the first overlap region.

8. The graphics system of claim 7, wherein the first intensity scaling values and the second intensity scaling values are assigned numeric values in order to blend an edge between the first array of first viewable pixels and the second array of second viewable pixels.

9. The graphics system of claim 7, wherein the first intensity scaling values and the second intensity scaling values are assigned numeric values in order to blend the first array of first viewable pixels and the second array of second viewable pixels in the first overlap region.

10. The graphics system of claim 7, wherein the first intensity scaling values and the second intensity scaling values are assigned numeric values so that the composite light intensity of the first viewable pixels and the second viewable pixels in the first overlap region approximates a light intensity of the first array of first viewable pixels outside the first overlap region.

11. The graphics system of claim 7, wherein the first intensity scaling values transition from a first value to a second value from a first side of the first overlap region to a second side of the first overlap region.

12. The graphics system of claim 11, wherein the first value is substantially 1 and the second value is substantially 0.

13. The graphics system of claim 11, wherein the second intensity scaling values transition from the second value to the first value from the first side of the first overlap region to the second side of the first overlap region.

14. The graphics system of claim 11, wherein the first intensity scaling values transition linearly from the first value to the second value from the first side of the first overlap region to the second side of the first overlap region.

15. The graphics system of claim 11, wherein the first intensity scaling values transition from the first value to the second value in a non-linear fashion from the first side of the first overlap region to the second side of the first overlap region.

16. The graphics system of claim 7, wherein the first intensity scaling values are computed based on a first intensity scaling function, and the second intensity scaling values are computed based on a second intensity scaling function, wherein the first intensity scaling function and the second intensity scaling function add to one on the first overlap region.

17. The graphics system of claim 7, wherein the first pixel values and the second pixel values control the intensity of a single color component of the first viewable pixels and second viewable pixels, respectively.

18. The graphics system of claim 5, wherein the first sample-to-pixel calculation unit generates the first intensity scaling values by multiplying a first horizontal intensity scaling function and a first vertical intensity scaling function.

19. The graphics system of claim 5, wherein the first sample-to-pixel calculation unit is configured to scale the first subset of the first pixel values by multiplying each first pixel value of said first subset by a corresponding one of the first intensity scaling values.

20. The graphics system of claim 5, wherein the first sample-to-pixel calculation unit is operable to provide the first pixel values directly to the first projection device without buffering frames of the first pixel values.

21. The graphics system of claim 5, wherein the first sample-to-pixel calculation unit is configured to filter samples to form the first pixel values to the first projection device on one of:

a real time basis or an on-the-fly basis.

22. A graphics system for flattening a distribution of light energy perceived by a viewer of two or more images generated on a display surface by two or more corresponding projection devices, the graphics system comprising:

a first sample-to-pixel calculation unit configured to compute first pixel values by selecting and filtering samples, to scale a first subset of the first pixel values by first intensity scaling values, and to provide the first pixel values to a first projection device;

a second sample-to-pixel calculation unit configured to compute second pixel values by selecting and filtering the samples, to scale a second subset of the second pixel values by second intensity scaling values, and to provide the second pixel values to a second projection device; and

a collection of sample-to-pixel calculation units including the first sample-to-pixel calculation unit and the second sample-to-pixel calculation unit, wherein the K^th sample-to-pixel calculation unit of said collection is configured;

to compute K^th pixel values by selecting and filtering the samples;

to scale a K^th subset of the K^th pixel values by K^th intensity scaling values, to provide the K^th pixel values to a K^th projection device in a plurality of projection devices including the first projection device and the second projection device;

wherein the K^th projection device is configured to generate a K^th array of K^th viewable pixels on the display surface in response to the K^th pixel values, wherein the K^th subset of K^th pixel values control intensities of a K^th subset of the K_th viewable pixels in a K^th region of overlap between the K^th array and one or more other arrays of viewable pixels generated by one or more other projection devices of said plurality of projection devices.

23. The graphics system of claim 22, wherein the K^th sample-to-pixel calculation unit is configured to compute the K^th pixel values by selecting and filtering the samples at a K^th plurality of virtual pixel positions.

24. A graphics system for flattening a distribution of light energy perceived by a viewer of two or more images generated on a display surface by two or more corresponding projection devices, the graphics system comprising:

a first sample-to-pixel calculation unit configured to compute first pixel values by selecting and filtering samples, to scale a first subset of the first pixel values by first intensity scaling values, and to provide the first pixel values to a first projection device;

a second sample-to-pixel calculation unit configured to compute second pixel values by selecting and filtering the samples, to scale a second subset of the second pixel values by second intensity scaling values, and to provide the second pixel values to a second projection device;

a sample buffer which stores the samples, wherein the first sample-to-pixel calculation unit and the second sample-to-pixel calculation unit are coupled to the sample buffer; and

a graphics processor coupled to the sample buffer which is operable to render the samples into the sample buffer.

25. The graphics system of claim 24, wherein said sample buffer is configured to double buffer at least a portion of each stored sample.