Method for processing a digital video stream and corresponding device

• US 8,988,454 B2
• Filed: 10/24/2008
• Issued: 03/24/2015
• Est. Priority Date: 10/25/2007
• Status: Active Grant

• Current Assignee: STMicroelectronics SAS (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SAS (STMicroelectronics NV)
• Inventors: Lebowsky, Fritz, Marsanne, Sebastien
• Primary Examiner(s): Caschera, Antonio A
• Application Number:
  US12/258,168
• Publication Number:
  US 20090135299A1
• Time in Patent Office: 2,342 Days
• Field of Search: None
• US Class Current: 345/604
• CPC Class Codes: G09G 2300/0452 Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
• CPC Class Codes: G09G 2310/0275 Details of drivers for data electrodes, other than drivers for liquid crystal, plasma or OLED displays, not related to handling digital grey scale data or to communication of data to the pixels by means of a current
• CPC Class Codes: G09G 2310/0297 Special arrangements with multiplexing or demultiplexing of display data in the drivers for data electrodes, in a pre-processing circuitry delivering display data to said drivers or in the matrix panel, e.g. multiplexing plural data signals to one D/A converter or demultiplexing the D/A converter output to multiple columns
• CPC Class Codes: G09G 2340/02 Handling of images in compressed format, e.g. JPEG, MPEG
• CPC Class Codes: G09G 3/2003 Display of colours specific for liquid crystal displays G09G3/3607
• CPC Class Codes: G09G 5/005 Adapting incoming signals to the display format of the display terminal
• CPC Class Codes: G09G 5/026 Control of mixing and/or overlay of colours in general G09G5/022 and G09G5/024 take precedence
• CPC Class Codes: G09G 5/04 using circuits for interfacing with colour displays

Abstract

A digital video stream of color images intended to be displayed on a matrix screen is formed of macropixels having at least four subpixels each. During processing, the color components of each image are transformed into an RGB format based on a polygonal representation of the color components and designed for the display of images using at least four colors by activating the four subpixels. The color components of the image are adapted in the course of the transformation.

Claims

1. A method for processing a digital video stream of color images, each color image comprising three color components in a first RGB format, the method comprising:

transforming, by processing circuitry, color components of each color image into three color components of a second RGB format based on the three color components of the first RGB format and three parameters each representing variations in luminosity in one of the three color components of the second RGB format caused by a processing system comprising at least one of a video processor, a display processing unit, and display driver electronics in a display device, the second RGB format for displaying images formed of macropixels using at least four colors by activating at least four subpixels within each macropixel, each macropixel selectably addressable by two row control signals for the respective macropixel and at least two column control signals for a respective macropixel, the three color components for each image being transformed based on;

CR=f₁(R,G,B,Δ

₁),

CG=f₂(R,G,B,Δ

₂), and

CB=f₃(R,G,B,Δ

₃)

wherein CR, CG and CB are the transformed RGB components, f₁, f₂, and f₃ are the functions for transformation into the second RGB format for each RGB component, R, G and B are the three color components according to the first RGB format, and Δ

₁, Δ

₂ and Δ

₃ are the three image color distortion parameters representing variations in luminosity caused by technical characteristics of the processing system, for each transformed component of the image; and

during the transformation of the color components, adapting the three color components of the image using the three image color distortion parameters to at least four color components.

2. The method according to claim 1, further comprising generating the at least two column control signals for each column of based on the transformed color components.

3. The method according to claim 2, wherein the two row signals and the at least two control signals activate six subpixels to display six colors, the six colors comprising three main colors comprising red, green, blue and three secondary colors comprising yellow, cyan, magenta.

4. The method according to claim 3, further comprising, for each image, following transformation:

encoding each of the transformed color components;

transmitting the encoded transformed color components;

receiving and then decoding each of the transformed color components; and

generating the at least two column control signals for columns of a display screen,

wherein generating the at least two column control signals comprises

generating a first column control signal component to activate a subpixel corresponding to yellow by finding a minimum among received and decoded red and green color components,

generating a second column control signal component to activate a subpixel corresponding to cyan by finding a minimum among received and decoded green and blue color components, and

generating a third column control signal component to activate a subpixel corresponding to magenta by finding a minimum among received and decoded red and blue color components.

5. The method according to claim 3, comprising, for each image, following transformation:

determining, based on the three transformed color components, three main color components;

during encoding of the three main color components, associating secondary information representing a value of at least one secondary color component with each main color component;

encoding and transmitting the encoded three main color components according to Point-to-Point Differential Signaling (PPDS); and

receiving the encoded three main color components and, during decoding the main color components reading each piece of secondary information; and

generating a secondary signal representing the secondary color components, wherein generating the at least two column control signals for a column of macropixels comprises

generating a first column control signal component to activate a subpixel corresponding to yellow using the secondary signal to select a minimum among the received and decoded red and green color components,

generating a second column control signal component to activate a subpixel corresponding to cyan using the secondary signal to select a minimum among the received and decoded green and blue color components, and

generating a third column control signal component to activate a subpixel corresponding to magenta using the secondary signal to select a minimum among the received and decoded red and blue color components.

6. The method of claim 1, wherein the transforming color components of each image into three color components of a second RGB format is based on a polyhedral representation of the color components.

7. An apparatus for processing a digital video stream comprising color images, each color image comprising three color components in a first RGB format, the apparatus comprising:

a matrix display screen comprising macropixels having at least four subpixels and configured to display images using at least four colors using the at least four subpixels within each of the macropixels, each macropixel being selectably addressable by two row signals and at least two column signals; and

a processing device connected to the matrix display screen and configured to

transform the color components of each color image into three color components of a second RGB format based on the color components of the first RGB format and three parameters each representing variations in luminosity in one of the three color components of the second RGB format caused by the processing device, and

encode each of the transformed color components, such that the matrix display screen is configured to display each image in the second RGB format,

the processing device being configured to transform an RGB component of a color image from the first RGB format to the second RGB format based on;

CR=f₁(R,G,B,Δ

₁),

CG=f₂(R,G,B,Δ

₂), and

CB=f₃(R,G,B,Δ

₃)

where CR, CG and CB are the RGB components, f₁, f₂, and f₃ are the transformation functions, R, G and B are the three color components in the first RGB format of each image, and Δ

₁, Δ

₂ and Δ

₃ are the three image color distortion parameters representing variations in luminosity caused by technical characteristics of the processing device.

8. The apparatus according to claim 7, further comprising a display controller coupled to the matrix display screen and configured to

control columns of the matrix display screen, and

generate the at least two column control signals for each column of macropixels in the matrix display screen based on the transformed color components.

9. The apparatus according to claim 8, wherein the two row signals and at least two column signals comprise six components to activate six subpixels for the matrix display screen of six colors including three main colors consisting of red, green, and blue, and three secondary colors consisting of yellow, cyan, and magenta.

10. The apparatus according to claim 9, wherein the processing device further comprises:

a transmitter configured to encode and to transmit each of the encoded transformed color components; and

a display control mechanism configured to control the matrix display screen, the display control mechanism comprising the display controller and a receiver configured to receive and to decode each of the encoded transformed color components, wherein the display controller is connected at an output of the receiver and is configured to

generate a first control signal component to activate a subpixel corresponding to yellow by finding a minimum among the red and green color components received and decoded,

generate a second control signal component to activate a subpixel corresponding to cyan by finding a minimum among the green and blue color components received and decoded, and

generate a third control signal component to activate a subpixel corresponding to magenta by finding a minimum among the red and blue color components received and decoded.

11. The apparatus according to claim 9, wherein the processing device comprises:

an intermediate unit configured to determine, based on the three transformed color components, three main color components and three secondary color components;

a transmitter configured to encode the three main color components by associating secondary information representing a value of at least one secondary color component the three main color components, and to transmit the encoded three main color components according to Point-to-Point Differential Signaling (PPDS); and

a receiver configured to receive the encoded three main color components, and to decode the main color components by reading each piece of secondary information to generate a secondary signal representing the secondary color components,

wherein the display controller is connected to output of the receiver and further comprises

a first selector configured to select the first control signal component and to activate the subpixel corresponding to yellow using the corresponding secondary signal to select a minimum among the decoded red and green color components,

a second selector configured to select the second control signal component and to activate the subpixel corresponding to cyan using the corresponding secondary signal to select a minimum among the decoded green and blue color components, and

a third selector configured to select the third control signal component and to activate the subpixel corresponding to magenta using the corresponding secondary signal to select a minimum among the red and blue color components.

12. A television set, comprising the apparatus according to claim 8 and the matrix display screen.

13. A video display screen, comprising the apparatus according to claim 8 and the matrix display screen.

14. A microcomputer, comprising the apparatus according to claim 8 and the matrix display screen.

15. A mobile telephone, comprising the apparatus according to claim 8 and the matrix display screen.

16. A television set, comprising the apparatus according to claim 7 and the matrix display screen.

17. A video display screen, comprising the apparatus according to claim 7 and the matrix display screen.

18. A microcomputer, comprising the apparatus according to claim 7 and the matrix display screen.

19. A mobile telephone, comprising the apparatus according to claim 7 and the matrix display screen.