Compositing images from multiple sources

• US 6,903,753 B1
• Filed: 10/31/2000
• Issued: 06/07/2005
• Est. Priority Date: 10/31/2000
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Tardif, John Allen, Gray, Donald M. III
• Primary Examiner(s): Brier, Jeffery A.
• Application Number:
  US09/702,505
• Time in Patent Office: 1,680 Days
• Field of Search: 345/592, 345/611, 345/634, 348/564, 348/565, 348/584, 348/586, 348/588, 725/40, 725/41, 725/42, 725/43
• US Class Current: 345/634
• CPC Class Codes: G06F 3/14 Digital output to display device ; Cooperation and interconnection of the display device with other functional units
• CPC Class Codes: G09G 2340/10 Mixing of images, i.e. displayed pixel being the result of an operation, e.g. adding, on the corresponding input pixels
• CPC Class Codes: G09G 2340/125 wherein one of the images is motion video
• CPC Class Codes: G09G 2370/04 Exchange of auxiliary data, i.e. other than image data, between monitor and graphics controller
• CPC Class Codes: G09G 5/14 Display of multiple viewports

Abstract

Systems and methods for compositing an image directly from multiple source image data for reducing system memory footprint and bandwidth and for improving color quality of the image. The image is divided into spans, lines, and slices. Each line includes at least one span and each slice includes at least one line. All lines in a slice have spans associated with identical sources. An image is composited by reading the image data directly from one or more sources of each span. If necessary, the sources are blended. A control structure is used to provide the image context and identifies the sources of the spans. The control structure includes headers for each data stream from each source of each span. Also, the color quality of the image is improved by reducing the number of color space conversions that occur as the image is composited. All sources in the same color space are blended before being blended with sources from other color spaces. Preferably, no more than a single color conversion is required.

Claims

1. In a system including a display device for displaying an image, the image having a plurality of sources, a method for compositing the image, the method comprising the acts of:

dividing the image into slices, each slice including at least one line;

dividing each line in each slice into at least one span, wherein each span has at least one associated source included in the plurality of sources and each span in each slice has the same at least one associated source;

for each span in each line, reading data directly from the associated source without reading the data as part of a composite image from a buffer;

identifying portions of the image that are opaque and portions of the image that are translucent;

for each portion of the image that is translucent, reading, blending and displaying the data from the sources corresponding to the translucent portion;

for each portion of the image that is opaque, reading only from the sources that correspond to the opaque portion and that would be visible within the opaque portion during display of the image, and without reading data from any sources that would otherwise be obscured in the opaque portion during display of the image.

2. A method as defined in claim 1, wherein the act of reading data from the associated source further comprises the step of loading each associated source in memory.

3. A method as defined in claim 1, further comprising the act of creating a control structure having context information for the image.

4. A method as defined in claim 3, wherein the control structure comprises:

an image header;

one or more slice headers associated with the image header;

one or more span headers associated with each slice header; and

one or more stream headers associated with each span header.

5. A method as defined in claim 3, wherein the act of reading data further comprises the act of reading contiguous pixel data for each span from each associated source,

6. A method as defined in claim 1, wherein the blending comprises blending data from more than two sources.

7. A method as defined in claim 1, wherein the act of blending the sources further comprises the acts of:

blending, in a first blend unit, each of two or more sources having a first color space;

blending, in a second blend unit, each of two or more sources having a second color space;

converting an output of the first blend unit to the second color space; and

blending the converted output of the first blend unit with a second output of the second blend unit to produce a blended output.

8. A method as defined in claim 1, wherein the act of reading data further comprises the act of filtering a span using vertically adjacent spans.

9. A method as recited in claim 1, wherein each of the portions of the image comprise a different span, such that the opaque portion comprises a span and such that the translucent portion comprises a different span.

10. In a system that composites images from one or more sources for display on a display device, a method for blending data streams from the one or more sources, the method comprising the acts of:

receiving data streams at a blending module, each of the data streams having a color space;

directing the data streams having the same color space to blending units of the blending module, each blending unit having an associated color space;

blending, by each blending unit, the data streams having the color space that is the same as the associated color space of the blending unit to produce outputs;

converting the outputs to a single color space; and

blending the outputs to produce an image data stream.

11. A method as defined in claim 10, wherein the single color space is one of RGB and YUV.

12. A method as defined in claim 10, further comprising the act of reading the image data directly from the one or more sources to the display device, and without reading the image data from a double image buffer.

13. A method as defined in claim 10, wherein the act of receiving the data streams further comprises the act of offsetting the data streams.

14. A method as defined in claim 13, wherein the act of offsetting the data streams further comprises the act of centering the data streams around zero by removing an offset that was added to the data stream during prior encoding of the data stream.

15. A method as defined in claim 10, wherein the act of blending, by each of the blending units, further comprises the act of zeroing the data streams received at the blending units whose color space is different from the associated color space of the blending units, such that the data streams having the different color space are not blended by the blending units.

16. A method as defined in claim 10, wherein the act of directing the data streams further comprises the act of multiplying the data streams by an alpha factor.