Method and apparatus for displaying image signal

• US 8,063,913 B2
• Filed: 07/24/2006
• Issued: 11/22/2011
• Est. Priority Date: 08/12/2005
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Choe, Won-hee, Park, Du-sik
• Primary Examiner(s): Wu; Xiao M.
• Assistant Examiner(s): Welch; David T
• Application Number:
  US11/491,242
• Publication Number:
  US 20070035557A1
• Time in Patent Office: 1,947 Days
• Field of Search: 345/611, 345/613, 345/616
• US Class Current: 345/611
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/10024 Color image
• CPC Class Codes: G06T 2207/20012 Locally adaptive
• CPC Class Codes: G06T 2207/20192 Edge enhancement; Edge preservation
• CPC Class Codes: G06T 5/94 based on local image properties, e.g. for local contrast enhancement
• 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 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• CPC Class Codes: G09G 2340/0457 Improvement of perceived resolution by subpixel rendering
• CPC Class Codes: G09G 2340/06 Colour space transformation
• CPC Class Codes: G09G 3/3208 organic, e.g. using organic light-emitting diodes [OLED]
• CPC Class Codes: G09G 3/36 using liquid crystals
• CPC Class Codes: G09G 5/02 characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607
• CPC Class Codes: G09G 5/22 characterised by the display of characters or indicia using display control signals derived from coded signals representing the characters or indicia, e.g. with a character-code memory

Abstract

A method and apparatus for reducing color error bands occurring due to the abrupt difference in brightness between sub-pixels. In the method of displaying an image signal of an apparatus for displaying the image signal, the apparatus includes a plurality of pixels each having at least two sub-pixels, and the method includes detecting pixels that belong to an edge of an input image, changing pixel values of the sub-pixels constituting the pixels belonging to the edge, and driving a display in accordance with the new pixel value.

Claims

1. A method of displaying an image signal in a display apparatus, the display apparatus including a plurality of pixels each having at least two sub-pixels, the method comprising:

(a) detecting pixels that belong to an edge of an input image;

(b) changing pixel values of the sub-pixels constituting the pixels belonging to the edge; and

(c) driving a display in accordance with the new pixel values,

wherein (b) includes

(b1) decreasing the right sub-pixel component among the sub-pixels in a single pixel if the edge belongs to the falling edge; and

(b2) decreasing the left sub-pixel component among the sub-pixels in a single pixel if the edge belongs to the rising edge,

wherein the decreased right sub-pixel component in (b1) is obtained based on the right sub-pixel component in the current pixel and the right sub-pixel component in the next pixel, and the decreased left sub-pixel component in (b2) is obtained based on the left sub-pixel component in the current pixel and the left sub-pixel component in the previous pixel,

wherein the right sub-pixel component (R′

) in (b1) is obtained by an equation

R′

=α

×

{R(p)−

R(p+1)}+R(p+1)

wherein R(p) and R(p+1) respectively represent the right sub-pixel component in the current pixel and the right sub-pixel component in the next pixel, and α

is a constant between 0 and 1, and

wherein the edge is where a difference between a pixel value of a pixel and a pixel value of a previous or next pixel exceeds a predetermined threshold value.

2. The method of claim 1, wherein (a) includes:

(a1) determining whether the current pixel belongs to the edge; and

(a2) determining whether the edge is a rising edge or a falling edge if the current pixel belongs to the edge.

3. The method of claim 2, wherein (a1) includes determining whether the difference between a brightness value of the current pixel and a brightness value of at least one previous pixel, or the difference between the brightness value of the current pixel and a brightness value of at least one next pixel exceeds a predetermined threshold value.

4. The method of claim 2, wherein (a1) includes determining whether the difference between a brightness value of the current sub-pixel among the sub-pixels constituting the current pixel, and a brightness value of at least one next sub-pixel or at least one previous sub-pixel exceeds a predetermined threshold value.

5. The method of claim 2, wherein (a2) includes:

determining the current pixel as belonging to a falling edge if a resultant value obtained by subtracting a brightness value of the next pixel from a brightness value of the current pixel is a positive number; and

determining the current pixel as belonging to a rising edge if a resultant value obtained by subtracting a brightness value of the previous pixel from the brightness value of the current pixel is a positive number.

6. The method of claim 1, wherein (b) includes:

(b3) increasing the left sub-pixel component in the next pixel of the pixel belonging to the edge by a decreased range in (b1) if the edge belongs to the falling edge; and

(b4) increasing the right sub-pixel component in the previous pixel of the pixel belonging to the edge by a decreased range in (b2) if the edge belongs to the rising edge.

7. The method of claim 1, wherein the display is one of a liquid crystal display (LCD), a plasma display panel (PDP), a light-emitting diode (LED), and an organic light-emitting diode (OLED).

8. A method of displaying an image signal in a display apparatus, the display apparatus including a plurality of pixels each having at least two sub-pixels, the method comprising:

(a) detecting pixels that belong to an edge of an input image;

(b) changing pixel values of the sub-pixels constituting the pixels belonging to the edge; and

(c) driving a display in accordance with the new pixel values,

wherein (b) includes

(b1) decreasing the right sub-pixel component among the sub-pixels in a single pixel if the edge belongs to the falling edge; and

(b2) decreasing the left sub-pixel component among the sub-pixels in a single pixel if the edge belongs to the rising edge,

wherein the decreased right sub-pixel component in (b1) is obtained based on the right sub-pixel component in the current pixel and the right sub-pixel component in the next pixel, and the decreased left sub-pixel component in (b2) is obtained based on the left sub-pixel component in the current pixel and the left sub-pixel component in the previous pixel,

wherein the left sub-pixel component (B′

) in (b2) is obtained by an equation

B′

=α

×

{B(p)−

B(p−

1)}+B(p−

1), and

wherein B(p) and B(p−

1) respectively represent the left sub-pixel component in the current pixel and the left sub-pixel component in the previous pixel, and α

is a constant value between 0 and 1.

9. A method of displaying an image signal in a display apparatus, the display apparatus including a plurality of pixels each having at least two sub-pixels, the method comprising:

(a) detecting pixels that belong to an edge of an input image;

(b) changing pixel values of the sub-pixels constituting the pixels belonging to the edge; and

(c) driving a display in accordance with the new pixel values,

wherein (b) includes

(b1) increasing the left sub-pixel component and the central sub-pixel component among the sub-pixels in a single pixel if the edge belongs to the falling edge; and

(b2) increasing the central sub-pixel component and the right sub-pixel component among the sub-pixels in a single pixel if the edge belongs to the rising edge,

wherein the increased left sub-pixel component and the increased central sub-pixel component among the sub-pixels in the single pixel in (b1) are obtained based on the right sub-pixel component in the current pixel and the right sub-pixel component in the next pixel, respectively, and

the increased central sub-pixel component and the increased right sub-pixel component among the sub-pixels in the single pixel in (b2) are obtained based on the left sub-pixel component in the current pixel and the left sub-pixel component in the previous pixel, respectively.

10. The method of claim 9, wherein an increased range Δ

1 in (b1) is obtained by an equation Δ

1=|R(p)−

[α

×

{R(p)−

R(p+1)}+R(p+1)]|, wherein R(p) and R(p+1) respectively represent the right sub-pixel component in the current pixel and the right sub-pixel component in the next pixel, and α

is a constant between 0 and 1.

11. The method of claim 9, wherein an increased range Δ

2 in (b2) is obtained by an equation Δ

2=|B(p)−

[α

×

{B(p)−

B(p−

1)}+B(p−

1)]|, wherein B(p) and B(p−

1) respectively represent the left sub-pixel component in the current pixel and the left sub-pixel component in the previous pixel, and α

is a constant between 0 and 1.

12. The method of claim 9, wherein (b) includes:

(b3) decreasing the central sub-pixel component and the right sub-pixel component in the next pixel of the pixel belonging to the edge by an increased range in (b1) if the edge belongs to the falling edge; and

(b4) decreasing the left sub-pixel component and the central sub-pixel component in the previous pixel of the pixel belonging to the edge by an increased range in (b2) if the edge belongs to the rising edge.

13. An apparatus for displaying an image signal, comprising:

a plurality of pixels each having at least two sub-pixels;

an edge detector detecting pixels that belong to an edge of an input image;

a signal corrector changing pixel values of the sub-pixels constituting the pixels belonging to the edge; and

a display driver driving a display in accordance with the new pixel values,

wherein the signal corrector decreases a right sub-pixel component among the sub-pixels in a single pixel if the edge belongs to the falling edge, and decreases a left sub-pixel component among the sub-pixels in a single pixel if the edge belongs to the rising edge,

wherein the decreased right sub-pixel component is obtained based on the right sub-pixel component in the current pixel and the right sub-pixel component in the next pixel, and the decreased left sub-pixel component is obtained based on the left sub-pixel component in the current pixel and the left sub-pixel component in the previous pixel,

wherein the left sub-pixel component (B′

) decreased by the signal corrector is obtained by an equation

B′

=α

×

{B(p)−

B(p−

1)}+B(p−

1),

wherein B(p) and B(p−

1) respectively represent the left sub-pixel component in the current pixel and the pixel value of the left sub-pixel component in the previous pixel, and α

is a constant value between 0 and 1, and

wherein the edge is where a difference between a pixel value of a pixel and a pixel value of a previous or next pixel exceeds a predetermined threshold value.

14. The apparatus of claim 13, wherein the edge detector determines whether the current pixel belongs to the edge, and determines whether the edge is a rising edge or a falling edge if the current pixel belongs to the edge.

15. The apparatus of claim 14, wherein the edge detector determines whether the difference between a brightness value of the current pixel and a brightness value of at least one previous pixel, or the difference between the brightness value of the current pixel and a brightness value of at least one next pixel exceeds a predetermined threshold value.

16. The apparatus of claim 14, wherein the edge detector determines whether the difference between a brightness value of the current sub-pixel among the sub-pixels constituting the current pixel and a brightness value of at least one next sub-pixel or at least one previous sub-pixel exceeds a predetermined threshold value.

17. The apparatus of claim 14, wherein the edge detector determines the current pixel as belonging to a falling edge if a resultant value obtained by subtracting a brightness value of the next pixel from a brightness value of the current pixel is a positive number, and determines the current pixel as belonging to a rising edge if a resultant value obtained by subtracting a brightness value of the previous pixel from a brightness value of the current pixel is a positive number.

18. The apparatus of claim 13, wherein the right sub-pixel component (R′

) decreased by the signal corrector is obtained by an equation R′

=α

×

{R(p)−

R(p+1)}+R(p+1), wherein R(p) and R(p+1) respectively represent the right sub-pixel component in the current pixel and the right sub-pixel component in the next pixel, and α

is a constant between 0 and 1.

19. The apparatus of claim 13, wherein the signal corrector increases the left sub-pixel component in the next pixel of the pixel belonging to the edge by a decreased range of the right sub-pixel component, if the edge belongs to the falling edge, and increases the right sub-pixel component in the previous pixel of the pixel belonging to the edge by an increased range of the left sub-pixel component if the edge belongs to the rising edge.

20. An apparatus for displaying an image signal, comprising:

a plurality of pixels each having at least two sub-pixels;

an edge detector detecting pixels that belong to an edge of an input image;

a signal corrector changing pixel values of the sub-pixels constituting the pixels belonging to the edge; and

a display driver driving a display in accordance with the new pixel values,

wherein the signal corrector increases the left sub-pixel component and the central sub-pixel component among the sub-pixels in a single pixel if the edge belongs to the falling edge, and increases the central sub-pixel component and the right sub-pixel component among the sub-pixels in a single pixel if the edge belongs to the rising edge, and

wherein the increased left sub-pixel component and the increased central sub-pixel component among the sub-pixels in the single pixel are obtained based on the right sub-pixel component in the current pixel and the right sub-pixel component in the next pixel, respectively, and

the increased central sub-pixel component and the increased right sub-pixel component among the sub-pixels in the single pixel are obtained based on the left sub-pixel component in the current pixel and the left sub-pixel component in the previous pixel, respectively.

21. The apparatus of claim 20, wherein an increased range Δ

1 of the B and G components is obtained by an equation Δ

1=|R(p)−

[α

×

{R(p)−

R(p+1)}+R(p+1)]|, wherein R(p) and R(p+1) respectively represent the right sub-pixel component in the current pixel and the right sub-pixel component in the next pixel, and α

is a constant between 0 and 1.

22. The apparatus of claim 20, wherein an increased range Δ

2 of the G and R components is obtained by an equation Δ

2=|B(p)−

[α

×

{B(p)−

B(p−

1)}+B(p−

1)]|, wherein B(p) and B(p−

1) respectively represent the left sub-pixel component in the current pixel and the left sub-pixel component in the previous pixel, and α

is a constant between 0 and 1.