Image generation

• US 9,165,538 B2
• Filed: 03/13/2013
• Issued: 10/20/2015
• Est. Priority Date: 03/13/2013
• Status: Active Grant

• Current Assignee: DisplayLink Corporation (Synaptics Incorporated)
• Original Assignee: DisplayLink Corporation (Synaptics Incorporated)
• Inventors: Stoye, William
• Primary Examiner(s): Johnson, M Good
• Application Number:
  US13/798,309
• Publication Number:
  US 20140267321A1
• Time in Patent Office: 951 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 3/1415 with means for detecting differences between the image stored in the host and the images displayed on the displays
• CPC Class Codes: G06F 3/1423 controlling a plurality of local displays, e.g. CRT and flat panel display
• CPC Class Codes: G06T 1/60 Memory management
• CPC Class Codes: G09G 2340/02 Handling of images in compressed format, e.g. JPEG, MPEG
• CPC Class Codes: G09G 2370/12 Use of DVI or HDMI protocol in interfaces along the display data pipeline
• CPC Class Codes: G09G 5/006 Details of the interface to the display terminal specific for a display terminal using a CRT G09G1/167; using a flat panel G09G3/2096; circuits for interfacing with colour displays G09G5/04
• CPC Class Codes: G09G 5/395 Arrangements specially adapted for transferring the contents of the bit-mapped memory to the screen G09G5/399 takes precedence
• CPC Class Codes: H04N 21/4122 additional display device, e.g. video projector digital output for controlling a plurality of local displays G06F3/1423
• CPC Class Codes: H04N 21/43632 involving a wired protocol, e.g. IEEE 1394 high-speed IEEE 1394 serial bus H04L12/40052

Abstract

A method of generating an image comprises receiving a signal over a USB interface comprising encoded display data for one or more rectangular group of pixel tiles within an image and position data for the or each group of pixel tiles. The coefficients are obtained from the encoded display data, maybe by converting variable bit length fields into AC coefficients and an inverse Haar transform performed on them to generate pixel data for each rectangular group of pixel tiles. A frame buffer, which may be part of the display, is then updated with the generated pixel data ready for output to the display device. Copy protection may also be incorporated using AES negotiated over HDPC.

Claims

1. A method of generating an image comprising:

maintaining, at a display control device, a frame buffer having display data for an entire image, the display data comprising pixel data for each pixel of the image;

receiving a signal over a general purpose data connection at the display control device, the signal comprising encoded display data for one or more rectangular groups of pixel tiles within the image, the display data comprising display data for less than the whole of the image, and position data indicating a position of the or each rectangular group of pixel tiles within the image, the display data being encoded using a Haar transform,

obtaining a coefficient for the or each rectangular group of pixel tiles from the encoded display data,

performing an inverse Haar transform on the obtained coefficients to generate pixel data for the or each rectangular group of pixel tiles,

updating the frame buffer with the generated pixel data for the or each rectangular group of pixel tiles according to the position data for the or each rectangular group of pixel tiles, whereby the one or more groups of rectangular groups of pixel tiles of display data provide a partial update of the image, and

outputting at least a portion of the frame buffer to a display over a display-specific data standard connection.

2. A method according to claim 1, wherein a pixel tile comprises an 8×

8 array of pixels.

3. A method according to claim 1, wherein a rectangular group of pixel tiles comprises fewer than twenty pixel tiles.

4. A method according to claim 1, wherein obtaining a coefficient for the or each rectangular group of pixel tiles from the encoded display data comprises converting variable length bit fields in the encoded display data into AC coefficients.

5. A method according to claim 1, wherein the general purpose data connection comprises a USB connection or an Ethernet connection.

6. A method according to claim 1, wherein the display-specific data standard connection comprises a VGA, HDMI, DVI or DisplayPort connection.

7. A method according to claim 1, wherein the one or each rectangular group of pixel tiles of display data is located anywhere within the image.

8. A method according to claim 1, wherein the position data separately identifies the intended location of the one or each rectangular group of pixel tiles in the frame buffer.

9. A device for generating an image comprising:

a frame buffer configured to store display data for an entire image, the display data comprising pixel data for each pixel of the image;

a receiver arranged to receive a signal over a general purpose data connection, the signal comprising display data for one or more rectangular groups of pixel tiles within the image, the display data comprising display data for less than the whole of the image, and position data indicating a position of the or each rectangular group of pixel tiles within the image, the display data being encoded using a Haar transform,

a processor arranged to obtain a coefficient for the or each rectangular group of pixel tiles from the encoded display data, to perform an inverse Haar transform on the obtained coefficients to generate pixel data for the or each rectangular group of pixel tiles and to update the frame buffer with the generated pixel data for the or each rectangular group of pixel tiles according to the position data for the or each rectangular group of pixel tiles, whereby the one or more groups of rectangular groups of pixel tiles of display data provide a partial update of the image, and

an output device arranged to output at least a portion of the frame buffer to a display over a display-specific data standard connection.

10. A device according to claim 9, wherein a pixel tile comprises an 8×

8 array of pixels.

11. A device according to claim 9, wherein a rectangular group of pixel tiles comprises fewer than twenty pixel tiles.

12. A device according to claim 9, wherein the processor is arranged, when obtaining a coefficient for the or each rectangular group of pixel tiles from the encoded display data, to convert variable length bit fields in the encoded display data into AC coefficients.

13. A device according to claim 9, wherein the receiver comprises a USB port or an Ethernet port.

14. A device according to claim 9, wherein the display-specific data standard connection comprises a VGA, HDMI, DVI or DisplayPort connection.

15. A device according to claim 9, wherein the one or each rectangular group of pixel tiles of display data is located anywhere within the image.

16. A device according to claim 9, wherein the position data separately identifies the intended location of the one or each rectangular group of pixel tiles in the frame buffer.

17. A system for generating an image comprising:

a computer arranged to encode display data for one or more rectangular groups of pixel tiles within an image and position data indicating a position of each of the rectangular groups of pixel tiles within the image, the display data being less than the display data for an entire image, the encoding using a Haar transform for each pixel tile and transmit an encoded signal of the encoded display data to a display control device over a general purpose data connection,

a display control device comprising;

a frame buffer configured to store display data for an entire image, the display data comprising pixel data for each pixel of the image;

a receiver arranged to receive the signal over the general purpose data connection, the signal comprising the encoded display data for one or more rectangular groups of pixel tiles within the image and the position data for the or each rectangular group of pixel tiles,

a processor arranged to obtain a coefficient for the or each rectangular group of pixel tiles from the encoded display data, to perform an inverse Haar transform on the obtained coefficients to generate pixel data for the or each rectangular group of pixel tiles and to update the frame buffer with the generated pixel data for the or each rectangular group of pixel tiles according to the position data for the or each rectangular group of pixel tiles, whereby the one or more groups of rectangular groups of pixel tiles of display data provide a partial update of the image, and

an output device arranged to output at least a portion of the frame buffer to a display over a display-specific data standard connection.

18. A system according to claim 17, wherein a pixel tile comprises an 8×

8 array of pixels.

19. A system according to claim 17, wherein a rectangular group of pixel tiles comprises fewer than twenty pixel tiles.

20. A system according to claim 17, wherein the processor is arranged, when obtaining a coefficient for the or each rectangular group of pixel tiles from the encoded display data, to convert variable length bit fields in the encoded display data into AC coefficients.

21. A system according to claim 17, wherein the receiver comprises a USB port or an Ethernet port.

22. A tangible non-transitory computer readable medium including executable instructions which, when executed in a processing system, cause the processing system to:

maintain, at a display control device, a frame buffer having display data for an entire image, the display data comprising pixel data for each pixel of the image;

receive a signal over a general purpose data connection at the display control device, the signal comprising display data for one or more rectangular groups of pixel tiles within the image, the display data comprising display data for less than the whole of the image, and position data indicating a position of the or each rectangular group of pixel tiles within the image, the display data being encoded using a Haar transform,

obtain a coefficient for the or each rectangular group of pixel tiles from the encoded display data,

perform an inverse Haar transform on the obtained coefficients to generate pixel data for the or each rectangular group of pixel tiles,

update the frame buffer with the generated pixel data for the or each rectangular group of pixel tiles according to the position data for the or each rectangular group of pixel tiles, whereby the one or more groups of rectangular groups of pixel tiles of display data provide a partial update of the image, and

output at least a portion of the frame buffer to a display over a display-specific data standard connection.

23. A tangible non-transitory computer readable medium according to claim 22, wherein a pixel tile comprises an 8×

8 array of pixels.

24. A tangible non-transitory computer readable medium according to claim 22, wherein a rectangular group of pixel tiles comprises fewer than twenty pixel tiles.

25. A tangible non-transitory computer readable medium according to claim 22, wherein causing the processing system to obtain a coefficient for the or each rectangular group of pixel tiles from the encoded display data comprises causing the processing system to convert variable length bit fields in the encoded display data into AC coefficients.

26. A tangible non-transitory computer readable medium according to claim 22, wherein the general purpose data connection comprises a USB connection or an Ethernet connection.