Image processing apparatus and method of plasma display panel

• US 20060152441A1
• Filed: 12/29/2005
• Published: 07/13/2006
• Est. Priority Date: 01/13/2005
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Baek, Seung Chan
• Granted Patent: US 7,633,468 B2
• Time in Patent Office: Days
• US Class Current: 345/60
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/2059 using error diffusion
• CPC Class Codes: G09G 3/288 using AC panels
• CPC Class Codes: G09G 3/298 using surface discharge panels

Abstract

This document relates to a display apparatus, and more particularly, to an image processing apparatus and method of a plasma display panel. An image processing apparatus of a plasma display panel according to an embodiment of the present invention comprises an inverse gamma correction unit that gamma-corrects an image signal through pervious stored gamma data, a half-toning unit that adds an error diffusion error value (Ei) of neighboring pixels to a noise value (n(i, j)) of a predetermined pattern and diffuses the added result into the inverse gamma corrected image signal, and a sub-field mapping unit that maps the half-toned image signal to a sub-field mapping table. According to the present invention, in the case where an error diffusion method is used in a plasma display panel screen, a noise value that is repeated every frame is used. It is thus possible to prevent the sizzling of the screen from occurring through a random noise process used to prevent static error diffusion noise.

Claims

1. An image processing apparatus of a plasma display panel comprising:

an inverse gamma correction unit for gamma-correcting an image signal through perviously stored gamma data;

a half-toning unit for adding an error diffusion error value (Ei) of neighboring pixels to a noise value (n(i, j)) of a predetermined pattern and for diffusing the added result into the inverse gamma corrected image signal; and

a sub-field mapping unit for mapping the half-toned image signal to a sub-field mapping table.

2. The image processing apparatus as claimed in claim 1, wherein the half-toning unit comprises:

a noise pattern unit for outputting the noise value (n(i, j)) of “

1 or “

−

1”

as predetermined pattern;

an adder for adding the noise value (n(i, j)) received from the noise pattern unit and an error diffusion error value (Ei) received from a system and for outputting the added result;

an error diffusion coefficient look-up table for storing error diffusion coefficients (e1 to e4, c1 to c4) so that the sum of the error diffusion coefficients becomes “

1”

; and

an error diffusion unit for confirming the error diffusion coefficients of the error diffusion coefficient look-up table using a value received from the adder, for calculating the error diffusion coefficients and a value received from the adder, and for outputting a carry if the calculated result is a predetermined value or higher.

3. The image processing apparatus as claimed in claim 2, wherein the noise value (n(i, j)) has a noise pattern comprising of the following 4×

4 matrix.

$n<br><br>\left(i,j\right)=\left(\begin{array}{cccc}1& -1& 1& -1\\ -1& 1& -1& 1\\ 1& -1& 1& -1\\ -1& 1& -1& 1\end{array}\right)$

4. The image processing apparatus as claimed in claim 3, wherein the i value of the noise value (n(i, j)) is a current frame counter value.

5. The image processing apparatus as claimed in claim 3, wherein the j value of the noise value (n(i, j)) is a x coordinate of a current pixel.

6. The image processing apparatus as claimed in claim 3, wherein the i value is a remnant value which is the current frame counter value divided by 4 and has any one of 0, 1, 2 and 3.

7. The image processing apparatus as claimed in claim 3, wherein the j value is a remnant value which is the current frame counter value divided by 4 and has any one of 0, 1, 2 and 3.

8. The image processing apparatus as claimed in claim 2, wherein the error diffusion unit calculates the value received from the adder and the error diffusion coefficients of the error diffusion coefficient look-up table according to the following equations.

E=Ei+n+(e1*c1)+(e2*c1)+(e3*c3)+(e4*c4)
where c1+c2+c3+c4=1

9. An image processing method of a plasma display apparatus for representing gray levels,

wherein to maintain a noise amount to a minimum, a noise value (n(i, j)) is set to 1 or −

1, and

the noise value (n(i, j)) has a noise pattern comprising of the following a 4×

4 matrix.

$n<br><br>\left(i,j\right)=\left(\begin{array}{cccc}1& -1& 1& -1\\ -1& 1& -1& 1\\ 1& -1& 1& -1\\ -1& 1& -1& 1\end{array}\right)$

10. The image processing method as claimed in claim 9, wherein the i value of the noise value (n(i, j)) is a current frame counter value.

11. The image processing method as claimed in claim 9, wherein the j value of the noise value (n(i, j)) is a x coordinate of a current pixel.

12. The image processing method as claimed in claim 9, wherein the i value is a remnant value which is the current frame counter value divided by 4 and has any one of 0, 1, 2 and 3.

13. The image processing method as claimed in claim 9, wherein the j value is a remnant value which is the current frame counter value divided by 4 and has any one of 0, 1, 2 and 3.