Method for compensating a brightness error of a flat panel display

• US 20070109321A1
• Filed: 01/11/2006
• Published: 05/17/2007
• Est. Priority Date: 11/17/2005
• Status: Abandoned Application

• Current Assignee: Marketech International Corp.
• Original Assignee: Marketech International Corp.
• Inventors: Kao, Hsu-Pin, Shan, Yi-Chia, Yu, Yi-Sheng, Hsu, Kai-Hsiang
• Application Number:
  US11/329,177
• Publication Number:
  US 20070109321A1
• Time in Patent Office: Days
• US Class Current: 345/616
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• 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 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: G09G 3/2059 using error diffusion
• CPC Class Codes: G09G 3/2803 Display of gradations G09G3/288 takes precedence

Abstract

The present invention discloses a method for compensating a brightness error of a flat panel display that compensates the input gray levels under a fixed sustain frequency by an error diffusion compensation circuit. After the gray levels are inputted to the flat panel display, the brightness will be outputted and measured to obtain an actual output brightness, and an ideal output brightness corresponding to the input gray level is calculated according to the linear proportional relation between the input gray level and its ideal output brightness, and then a look up table is created according to the actual output brightness and the ideal output brightness, such that the look up table can be used to overcome the gray level error as well as the error between the actual output brightness and the ideal output brightness of the flat panel display.

Claims

1. A method for compensating a brightness error of a flat panel display, comprising:

inputting a series of gray level signals (Gray) to a flat panel display under a fixed sustain frequency (fs), and measuring an output brightness of said flat panel display to obtain an actual output brightness Y_mea (fs Gray);

calculating an ideal output brightness Y_ideal (fs, Gray) corresponding to said gray level according to the linear proportional relation between said input gray level and said ideal output brightness;

creating a look up table according to said actual output brightness Y_mea (fs Gray) and said ideal output brightness Y_ideal (fs, Gray), and said look up table comprises a series of converted gray levels (Gray′

) and actual output brightness Y_mea (fs Gray′

) corresponding to each of said converted gray levels, and said actual output brightness Y_mea (fs, Gray′

) corresponding to said each converted gray level is closest to said ideal output brightness Y_ideal (fs, Gray) of said each input gray level, such that when a gray level is going to be inputted to said flat panel display, said look up table will be used to look up a corresponding converted gray level according to said gray level in advance and said converted gray level will be inputted to said flat panel display, so as to allow said flat panel display to output a gray level brightness closest to said ideal output brightness Y_ideal (fs, Gray).

2. A method for compensating a brightness error of a flat panel display, comprising:

using an error diffusion compensation circuit to compensate a gray level under a fixed sustain frequency by an error diffusion method, and measuring an output brightness to obtain an actual output brightness Y_mea (fs, Gray) after said compensated gray level is inputted to said flat panel display;

calculating an ideal output brightness Y_ideal (fs, Gray) corresponding to said input gray levels according to the linear proportional relation between said input gray level and said ideal output brightness;

creating a look up table according to said actual output brightness Y_mea (fs, Gray) and said ideal output brightness Y_ideal (fs, Gray), and said look up table comprises a series of converted gray levels (Gray′

) and actual output brightness Y_mea (fs, Gray′

) corresponding to each of said converted gray levels, and said actual output brightness Y_mea (fs, Gray′

) corresponding to said each converted gray level is closest to said ideal output brightness Y_ideal (fs, Gray) corresponding to said each input gray level, such that when a gray level is going to be inputted to said flat panel display, said look up table will be used to look up a corresponding converted gray level according to said gray level in advance, and said converted gray level will be inputted to said flat panel display, so as to allow said flat panel display to output a gray level brightness closest to said ideal output brightness Y_ideal (fs, Gray).

3. A method for compensating a brightness error of a flat panel display, comprising:

using an error diffusion compensation circuit to compensate a gray level under a fixed sustain frequency by an error diffusion method, and measuring an output brightness to obtain an actual output brightness Y_mea (fs, Gray) after said compensated gray level is inputted to said flat panel display;

calculating an ideal output brightness Y_ideal (fs, Gray) corresponding to said input gray levels according to the linear proportional relation between said input gray level and said ideal output brightness;

creating a brightness to gray look up table according to said actual output brightness Y_mea (fs, Gray) and said ideal output brightness Y_ideal (fs, Gray), and said brightness to gray look up table comprises a series of first converted gray level LUT_BG (fs, Gray) and actual output brightness Y_mea (fs, Gray′

) corresponding to each of said converted gray levels, and said actual output brightness Y_mea (fs, Gray′

) corresponding to said each converted gray level is closest to said ideal output brightness Y_ideal (fs, Gray) corresponding to said each input gray level, such that when a gray level is going to be inputted to said flat panel display, said brightness to gray look up table will be used to look up a corresponding first converted gray level LUT_BG (fs, Gray) according to said gray level in advance, and said first converted gray level LUT_BG (fs, Gray) will be inputted to said flat panel display, so as to allow said flat panel display to output a gray level brightness closest to said ideal output brightness Y_ideal (fs, Gray).

4. The method of claim 3, further comprising:

using said actual output brightness Y_mea (fs Gray) as a base to interpolate and calculate a brightness error compensation value LUT_BE (fs, Gray) required for said ideal output brightness Y_ideal (fs, Gray) according to the following formula, provided that the frequency at the time is fs=f, and the gray level value is Gray=g;

$\mathrm{if}<br><br>\text{\hspace{1em}<br><br>}<br><br>Y_{\mathrm{ideal}}<br><br>\left(f,g\right)\ge <br><br>Y_{\mathrm{mea}.}<br><br>\left(f,g\right)$${\mathrm{LUT}}_{\mathrm{BE}}<br><br>\left(f,g\right)=\frac{Y_{\mathrm{ideal}}<br><br>\left(f,g\right)-Y_{\mathrm{mea}.}<br><br>\left(f,g\right)}{Y_{\mathrm{mea}.}<br><br>\left(f,g+1\right)-Y_{\mathrm{mea}.}<br><br>\left(f,g\right)}$$\mathrm{if}<br><br>\text{\hspace{1em}<br><br>}<br><br>Y_{\mathrm{ideal}}<br><br>\left(f,g\right)<<br><br>Y_{\mathrm{mea}.}<br><br>\left(f,g\right)$${\mathrm{LUT}}_{\mathrm{BE}}<br><br>\left(f,g\right)=\frac{Y_{\mathrm{ideal}}<br><br>\left(f,g\right)-Y_{\mathrm{mea}.}<br><br>\left(f,g\right)}{Y_{\mathrm{mea}.}<br><br>\left(f,g\right)-Y_{\mathrm{mea}.}<br><br>\left(f,g-1\right)};<br><br>$

and

creating a brightness error look up table, such that when a gray level is going to inputted to said flat panel display, said brightness error look up table will be used to look up a corresponding brightness error compensation LUT_BE (fs, Gray) according to said gray level in advance, and said input gray level plus said brightness error compensation value LUT_BE (fs, Gray) will be used to obtain a second converted gray level value; and

after said second converted gray level value is inputted to said flat panel display, said flat panel display outputs a brightness close to an ideal output brightness Y_BE (fs, Gray).

5. A method for compensating a brightness error of a flat panel display, comprising:

using an error diffusion compensation circuit to compensate a gray level under a fixed sustain frequency by an error diffusion method, and measuring an output brightness to obtain an actual output brightness Y_mea (fs, Gray) after said compensated gray level is inputted to said flat panel display;

calculating an ideal output brightness Y_ideal (fs, Gray) corresponding to said input gray levels according to the linear proportional relation between said input gray level and said ideal output brightness;

using said actual output brightness Y_mea (fs, Gray) as a base to interpolate and calculate a brightness error compensation value LUT_BE (fs, Gray) required for said ideal output brightness Y_ideal (fs, Gray) according to the following formula, provided that the frequency at the time is fs=f, and the gray level value is Gray=g;

$\mathrm{if}<br><br>\text{\hspace{1em}<br><br>}<br><br>Y_{\mathrm{ideal}}<br><br>\left(f,g\right)\ge <br><br>Y_{\mathrm{mea}.}<br><br>\left(f,g\right)$${\mathrm{LUT}}_{\mathrm{BE}}<br><br>\left(f,g\right)=\frac{Y_{\mathrm{ideal}}<br><br>\left(f,g\right)-Y_{\mathrm{mea}.}<br><br>\left(f,g\right)}{Y_{\mathrm{mea}.}<br><br>\left(f,g+1\right)-Y_{\mathrm{mea}.}<br><br>\left(f,g\right)}$$\mathrm{if}<br><br>\text{\hspace{1em}<br><br>}<br><br>Y_{\mathrm{ideal}}<br><br>\left(f,g\right)<<br><br>Y_{\mathrm{mea}.}<br><br>\left(f,g\right)$${\mathrm{LUT}}_{\mathrm{BE}}<br><br>\left(f,g\right)=\frac{Y_{\mathrm{ideal}}<br><br>\left(f,g\right)-Y_{\mathrm{mea}.}<br><br>\left(f,g\right)}{Y_{\mathrm{mea}.}<br><br>\left(f,g\right)-Y_{\mathrm{mea}.}<br><br>\left(f,g-1\right)};<br><br>$

and

creating a brightness error look up table (Brightness Error LUT), such that when a gray level is going to be inputted to said flat panel display, said brightness error look up table will be used to look up a corresponding brightness error compensation LUT_BE (fs, Gray) according to said gray level in advance, and said input gray level plus said brightness error compensation value LUT_BE (fs, Gray) will be used to obtain a second converted gray level value; and

after said second converted gray level value is inputted to said flat panel display, said flat panel display outputs a brightness close to an ideal output brightness Y_BE (fs, Gray).

6. A method for compensating a brightness error of a flat panel display, comprising:

inputting a series of gray level signals (Gray) to a flat panel display under a fixed sustain frequency (fs), and measuring an output brightness of said flat panel display to obtain an actual output brightness Y_mea (fs Gray);

calculating an ideal output brightness Y_ideal (fs, Gray) corresponding to said gray level according to the linear proportional relation between said input gray level and said ideal output brightness;

using said actual output brightness Y_mea (fs, Gray) as a base to interpolate and calculate a brightness error compensation value LUT_BE (fs, Gray) required for said ideal output brightness Y_ideal (fs, Gray) according to the following formula, provided that the frequency at the time is fs=f, and the gray level value is Gray=g;

$\mathrm{if}<br><br>\text{\hspace{1em}<br><br>}<br><br>Y_{\mathrm{ideal}}<br><br>\left(f,g\right)\ge <br><br>Y_{\mathrm{mea}.}<br><br>\left(f,g\right)$${\mathrm{LUT}}_{\mathrm{BE}}<br><br>\left(f,g\right)=\frac{Y_{\mathrm{ideal}}<br><br>\left(f,g\right)-Y_{\mathrm{mea}.}<br><br>\left(f,g\right)}{Y_{\mathrm{mea}.}<br><br>\left(f,g+1\right)-Y_{\mathrm{mea}.}<br><br>\left(f,g\right)}$$\mathrm{if}<br><br>\text{\hspace{1em}<br><br>}<br><br>Y_{\mathrm{ideal}}<br><br>\left(f,g\right)<<br><br>Y_{\mathrm{mea}.}<br><br>\left(f,g\right)$${\mathrm{LUT}}_{\mathrm{BE}}<br><br>\left(f,g\right)=\frac{Y_{\mathrm{ideal}}<br><br>\left(f,g\right)-Y_{\mathrm{mea}.}<br><br>\left(f,g\right)}{Y_{\mathrm{mea}.}<br><br>\left(f,g\right)-Y_{\mathrm{mea}.}<br><br>\left(f,g-1\right)};<br><br>$

and

creating a brightness error look up table, such that when a gray level is going to be inputted to said flat panel display, said brightness error look up table will be used to look up a corresponding brightness error compensation LUT_BE (fs, Gray) according to said gray level in advance, and said input gray level plus said brightness error compensation value LUT_BE (fs, Gray) will be used to obtain a second converted gray level value; and

after said second converted gray level value is inputted to said flat panel display, said flat panel display outputs a brightness close to an ideal output brightness Y_BE (fs, Gray).