Field Sequential Color Encoding For Displays

• US 20100073568A1
• Filed: 09/22/2009
• Published: 03/25/2010
• Est. Priority Date: 09/22/2008
• Status: Active Grant

• Current Assignee: Rambus Delaware
• Original Assignee: Uni-Pixel Displays Incorporated (Uni-Pixel Incorporated)
• Inventors: King, Carey, Cox, Berry Todd, Van Ostrand, Daniel K.
• Granted Patent: US 8,405,691 B2
• Time in Patent Office: Days
• US Class Current: 348/578
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• CPC Class Codes: G09G 2320/0266 Reduction of sub-frame artefacts
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/2003 Display of colours specific for liquid crystal displays G09G3/3607
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/3433 using light modulating elements actuated by an electric field and being other than liquid crystal devices and electrochromic devices using liquid crystal devices G09G3/36; using electrochromic devices G09G3/38
• CPC Class Codes: H04N 9/3111 for displaying the colours sequentially, e.g. by using sequentially activated light sources sequential projection in colour photography G03B33/08
• CPC Class Codes: H04N 9/3123 using pulse width modulation
• CPC Class Codes: H04N 9/3197 using light modulating optical valves
• CPC Class Codes: H04N 9/68 for controlling the amplitude of colour signals, e.g. automatic chroma control circuits H04N9/71, H04N9/73 take precedence; camera processing pipelines for controlling the colour saturation of colour signals H04N23/86

Abstract

The optical performance is enhanced of display systems that use field sequential color and pulse width modulation to generate color and color gray scale values. Such enhancement may be achieved by various data encoding methods disclosed herein that may include temporal redistribution of bit values to mitigate color motional artifacts associated with field sequential color-based display systems, selective combination of intensity modulation, pulse width modulation, and/or the noncontiguous sequencing of primary colors. There is further an intelligent real-time dynamic manipulation of gray scale values in portions of an image that are computationally determined to be images of objects moving against a global background, so as to temporally front load or concentrate the bits comprising such moving objects and thereby further mitigate said motional artifacts using both actual and virtual aggregate pulse truncation across all primary colors being modulated.

Claims

1. A method comprising:

determining in a received plurality of video frames that an object to be displayed in a foreground of a video image is in motion relative to a background of the video image; and

modifying a gray scale of the video frames associated with the object to be displayed in the foreground of the video image.

2. The method as recited in claim 1, wherein the modifying step requantizes a gray scale depth of the object to increase front-loading of data in the video frames associated with the object.

3. The method as recited in claim 1, wherein the motion determined is rapid movement of the object relative to the background.

4. The method as recited in claim 1, further comprising displaying the plurality of video frames after the modifying step.

5. The method as recited in claim 4, wherein the plurality of video frames are displayed by temporally segregating primary color components of the video images by presenting each frame of video information by rapid consecutive generation of each primary component.

6. The method as recited in claim 4, wherein the video images are displayed with at least one non-tristimulus primary color.

7. The method as recited in claim 5, wherein the modifying step further comprises:

shortening a pulse width of the most significant bit of one of the primary color components associated with the object to be displayed in the foreground of the video image.

8. The method as recited in claim 7, wherein the pulse width of the most significant bit of one of the primary color components has an amplitude greater than an amplitude of other pulse widths of bits of one of the primary color components.

9. The method as recited in claim 5, wherein the modifying step further comprises:

re-arranging an order of the bits of the primary color components associated with the object to be displayed in the foreground of the video image.

10. The method as recited in claim 5, wherein the modifying step further comprises:

subdividing a pulse width of one of the bits of one of the primary color components.

11. In a display system that temporally segregates color components of a video image and presents each frame of video information by rapid consecutive generation of each color component, a method for removing field sequential color artifacts that arise when the color components making up a composite frame of video information do not all reach a same region of an observer'"'"'s retina due to relative motion of the retina and the video image to be displayed, the method comprising:

receiving a video signal for displaying the video image comprising a foreground object and a background image, the video signal further comprising a plurality of video frames, each video frame comprising a plurality of bits representing a gray scale of one of a plurality of the color components used by the display system to display the video image;

determining that the foreground object is moving relative the background image; and

modifying a video frame containing color gray scale information associated with display of the foreground object.

12. The method as recited in claim 11, wherein the modifying step requantizes a gray scale depth of the foreground object to increase front-loading of data in the video frames associated with the foreground object.

13. The method as recited in claim 11, wherein the modifying step further comprises:

shortening a time one of the plurality of bits is generated in the video frame containing the color gray scale information associated with display of the foreground object.

14. The method as recited in claim 13, wherein the modifying step further comprises:

increasing an amplitude of the one of the plurality of bits

15. The method as recited in claim 11, wherein the modifying step further comprises:

subdividing and re-arranging an order of the plurality of bits in the video frame containing the color gray scale information associated with display of the foreground object.

16. The method as recited in claim 11, wherein the modifying step further comprises:

re-arranging most significant bits from a plurality of video frames representing the foreground object so that the most significant bits are processed in succession.

17. A display system comprising:

a display panel for displaying a video image using field sequential color encoded in a plurality of video frames;

a video cache for receiving the plurality of video frames for displaying a foreground object and a background image in the video image;

a motion analyzer processing the plurality of video frames for determining whether the foreground object is moving relative to the background image;

the motion analyzer determining that the foreground object is moving relative to the background image and further comprising circuitry for modifying at least one of the plurality of video frames in response thereto;

an encoder for encoding the plurality of video frames including the modified video frame for image generation; and

displaying the encoded plurality of video frames, including the modified video frame.

18. The system as recited in claim 17, wherein the modifying circuitry shortens a pulse width of the most significant bit of the at least one of the plurality of video frames.

19. The system as recited in claim 18, wherein the pulse width is also modified to have an amplitude greater than an amplitude of other pulse widths of bits in the video frame.

20. The system as recited in claim 17, wherein the modifying circuitry further comprises:

circuitry for re-arranging an order of the bits in the at least one of the plurality of video frames