Reducing image artifacts in a color sequential display system

• US 8,179,401 B2
• Filed: 05/21/2009
• Issued: 05/15/2012
• Est. Priority Date: 05/21/2009
• Status: Active Grant

• Current Assignee: Spatial Photonics Incorporated (Himax Technologies Incorporated)
• Original Assignee: Spatial Photonics Incorporated (Himax Technologies Incorporated)
• Inventors: Ishii, Takatoshi
• Primary Examiner(s): Sajous, Wesner
• Application Number:
  US12/469,924
• Publication Number:
  US 20100295866A1
• Time in Patent Office: 1,090 Days
• Field of Search: 345/581, 345/589, 345/596, 345/598, 345600-601, 345605-606, 345611-613, 348/254, 348/490, 348/497, 348/571, 348/574, 348/671, 358/1.9, 358/3.01, 358/3.14, 358/518, 358521-525, 375/240.01, 375/240.27, 375/240.29, 382166-167, 382170-171
• US Class Current: 345/596
• 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

Abstract

Methods, systems, and apparatus, including computer program products, for reducing artifacts in a color sequential display system. A frame of a digital image is displayed by receiving frame data, determining dither patterns, applying the dither patterns to the data, and displaying the dithered data. Each pixel of a frame of a digital image is displayed by receiving pixel data, grouping the pixel data for the color channels of the image into a plurality of sub-groups of pixel data; and displaying the pixel according to a sequence that separates each pair of sub-groups for a color channel by a sub-group for another color channel. Modified pixel data can be generated by replacing parent bits in the pixel data with corresponding pluralities of divided child bits, where all the child bits for a given parent bit have a divided weight that adds up to the parent bit'"'"'s weight.

Claims

1. A method for displaying a digital image, the method comprising:

receiving frame data for a frame of the digital image to be displayed;

determining two or more dither patterns for the frame;

applying each of the dither patterns to the frame data, resulting in a sequence of dithered sub-frames; and

displaying the dithered sub-frames in sequence, by operation of an image processor, in place of the frame.

2. The method of claim 1, where determining the dither patterns for each frame comprises:

obtaining dither patterns corresponding to a frame count for the frame and a sub-frame count for each dithered sub-frame.

3. The method of claim 1, where each dither pattern is one of a series of temporal and spatial constant dither patterns generated from a dither ordering table.

4. The method of claim 1, where each dithered sub-frame is represented as respective pixel data for each respective pixel in the sub-frame and a respective color channel in a plurality of color channels.

5. The method of claim 4, where displaying the dithered sub-frames in sequence further comprises performing the following for each respective pixel:

grouping the pixel data for the pixel and each respective color channel into a plurality of sub-groups of pixel data; and

displaying the pixel according to a sequence for the sub-groups of pixel data, where each pair of sub-groups for a color channel is separated by at least a sub-group for another color channel in the sequence.

6. The method of claim 5, where the pixel data for each respective pixel and each respective color channel comprises an initial plurality of bits, each bit having a value and a weight, and where grouping the pixel data for each color channel into a plurality of sub-groups of pixel data comprises:

generating a modified plurality of bits corresponding to the initial plurality of bits where one or more parent bits in the initial plurality of bits is replaced by a plurality of child bits corresponding to the parent bit, where each child bit has a value equal to a value of the parent bit and a divided weight that is proportionate to the weight of the parent bit, and where the divided weights of the child bits corresponding to the parent bit add up to the weight of the parent bit; and

displaying the pixel according to the modified plurality of bits and an order for the modified plurality of bits.

7. The method of claim 1, further comprising using a color lookup table to determine a color value for pixels in the frame before determining a respective dither pattern for each sub-frame.

8. A method for displaying a digital image, the method comprising:

receiving pixel data of the digital image to be displayed for a pixel and each respective color channel in a plurality of color channels, where the data for each pixel comprises a plurality of bits and where each bit in the plurality of bits has a weight;

grouping the pixel data for each color channel into a plurality of sub-groups of pixel data; and

displaying the pixel, by operation of an image processor, according to a sequence for the sub-groups of pixel data, where each pair of sub-groups for a color channel is separated by at least a sub-group for another color channel in the sequence.

9. The method of claim 8, wherein displaying the pixel further comprises:

generating a sequence of sub-frames for the frame; and

displaying the pixel according to the sequence of sub-frames.

10. A method for displaying a digital image, the method comprising:

receiving pixel data of the digital image to be displayed for the pixel and a color channel, where the pixel data comprises an initial plurality of bits, each bit having a value and a weight;

generating a modified plurality of bits corresponding to the initial plurality of bits where one or more parent bits in the initial plurality of bits is replaced by a plurality of child bits corresponding to the parent bit, where each child bit has a value equal to the value of the parent bit and a divided weight proportionate to the weight of the parent bit, and where the divided weights of all child bits corresponding to the parent bit add up to the weight of the parent bit; and

displaying the pixel, by operation of an image processor, according to the modified plurality of bits and an order for the modified plurality of bits.

11. The method of claim 10, where the order separates two bits with a weight above a first threshold by at least one bit with a weight below a second threshold.

12. The method of claim 10, where displaying the pixel according to the modified plurality of bits comprises:

generating a modified plurality of bits for the pixel for each color channel in a plurality of color channels;

grouping the bits in each modified plurality of bits into a plurality of sub-groups of bits according to the order for each modified plurality of bits, where each sub-group includes one or more bits; and

displaying the pixel according to a sequence for the sub-groups of bits, where each pair of sub-groups for a color channel is separated by at least a sub-group for another color channel in the sequence.

13. A display system, comprising:

an image processor configured to display a frame of a digital image, the image processor configured to perform operations comprising;

receiving frame data for the frame;

determining two or more dither patterns for the frame;

applying each of the dither patterns to the frame data, resulting in a sequence of dithered sub-frames; and

displaying the frame by displaying the dithered sub-frames in sequence, in place of the frame.

14. The display system of claim 13, where determining the dither patterns for each frame comprises:

obtaining dither patterns corresponding to a frame count for the frame and a sub-frame count for each dithered sub-frame.

15. The display system of claim 13, where each dither pattern is one of a series of temporal and spatial constant dither patterns generated from a dither ordering table.

16. The display system of claim 13, where each dithered sub-frame is represented as respective pixel data for each respective pixel in the sub-frame and a respective color channel in a plurality of color channels.

17. The display system of claim 16, where displaying the dithered sub-frames in sequence further comprises performing the following for each respective pixel:

grouping the pixel data for the pixel and each respective color channel into a plurality of sub-groups of pixel data; and

displaying the pixel according to a sequence for the sub-groups of pixel data, where each pair of sub-groups for a color channel is separated by at least a sub-group for another color channel in the sequence.

18. The display system of claim 17, where the pixel data for each respective pixel and each respective color channel comprises an initial plurality of bits, each bit having a value and a weight, and where grouping the pixel data for each color channel into a plurality of sub-groups of pixel data comprises:

generating a modified plurality of bits corresponding to the initial plurality of bits where one or more parent bits in the initial plurality of bits is replaced by a plurality of child bits corresponding to the parent bit, where each child bit has a value equal to a value of the parent bit and a divided weight that is proportionate to the weight of the parent bit, and where the divided weights of the child bits corresponding to the parent bit add up to the weight of the parent bit; and

displaying the pixel according to the modified plurality of bits and an order for the modified plurality of bits.

19. The display system of claim 13, where the image processor is further configured to perform operations comprising using a color lookup table to determine a color value for pixels in the frame before determining a respective dither pattern for each sub-frame.

20. A display system, comprising:

an image processor configured to display a pixel of a frame of a digital image, the image processor configured to perform operations comprising;

receiving pixel data for the pixel and each respective color channel in a plurality of color channels, where the data for each pixel comprises a plurality of bits and where each bit in the plurality of bits has a weight;

grouping the pixel data for each color channel into a plurality of sub-groups of pixel data; and

displaying the pixel according to a sequence for the sub-groups of pixel data, where each pair of sub-groups for a color channel is separated by at least a sub-group for another color channel in the sequence.

21. The display system of claim 20, wherein displaying the pixel further comprises:

generating a sequence of sub-frames for the frame; and

displaying the pixel according to the sequence of sub-frames.

22. A display system, comprising:

an image processor configured to display a pixel of a digital image, the image processor configured to perform operations comprising;

receiving pixel data for the pixel and a color channel, where the pixel data comprises an initial plurality of bits, each bit having a value and a weight;

generating a modified plurality of bits corresponding to the initial plurality of bits where one or more parent bits in the initial plurality of bits is replaced by a plurality of child bits corresponding to the parent bit, where each child bit has a value equal to the value of the parent bit and a divided weight proportionate to the weight of the parent bit, and where the divided weights of all child bits corresponding to the parent bit add up to the weight of the parent bit; and

displaying the pixel according to the modified plurality of bits and an order for the modified plurality of bits.

23. The display system of claim 22, where the order separates two bits with a weight above a first threshold by at least one bit with a weight below a second threshold.

24. The display system of claim 22, where displaying the pixel according to the modified plurality of bits comprises:

generating a modified plurality of bits for the pixel for each color channel in a plurality of color channels;

grouping the bits in each modified plurality of bits into a plurality of sub-groups of bits according to the order for each modified plurality of bits, where each sub group includes one or more bits; and

displaying the pixel according to a sequence for the sub-groups of bits, where each pair of sub-groups for a color channel is separated by at least a sub-group for another color channel in the sequence.