Organic light emitting display apparatus using dithering and method of driving the same

1. An organic light emitting display apparatus, comprising:

a display including a first data line connected to a first pixel;

a comparator to compare first image data of input image data to a first critical grayscale value and a second critical grayscale value, the first image data corresponding to the first pixel;

a data generator to determine one of the first critical grayscale value or the second critical grayscale value as first corrected image data such that the first image data are dithered by using only the first critical grayscale value and the second critical grayscale value of the first corrected image data when the first image data is not less than the first critical grayscale value but not more than the second critical grayscale value;

a source driver to output a data signal corresponding to input data to the first data line; and

an output to output the first corrected image data to the source driver.

2. The apparatus as claimed in claim 1 , wherein:

the first image data ranges not less than a lowest grayscale value but not more than a highest grayscale value,

the first critical grayscale value is the lowest grayscale value, and

when the first image data is more than the second critical grayscale value, the data generator is to determine the first image data as the first corrected image data without correcting the first image data.

3. The apparatus as claimed in claim 1 , further comprising:

a position determiner to determine a position of the first pixel of the display, wherein, when the first image data is not less than the first critical grayscale value but not more than the second critical grayscale value, the data generator is to determine one of the first critical grayscale value or the second critical grayscale value as the first corrected image data based on a dithering algorithm and the determined position of the first pixel.

4. The apparatus as claimed in claim 3 , wherein:

the position determiner is to determine the position of the first pixel as one of a first position or a second position,

when the first image data is not less than the first critical grayscale value but not more than the second critical grayscale value and the position of the first pixel is the first position, the data generator is to determine the second critical grayscale value as the first corrected image data, and

when the first image data is not less than the first critical grayscale value but not more than the second critical grayscale value and the position of the first pixel is the second position, the data generator is to determine the first critical grayscale value as the first corrected image data.

5. The apparatus as claimed in claim 4 , wherein the position determiner is to:

store a plurality of dithering patterns, each of the dithering patterns having data elements, each of the data elements having a first value or a second value,

select one of the dithering patterns corresponding to the first image data,

select one of the data elements of the selected dithering pattern corresponding to the position of the first pixel,

determine the position of the first pixel as the first position when the selected data element has the first value, and

determine the position of the first pixel as the second position when the selected data element has the second value.

6. The apparatus as claimed in claim 3 , further comprising:

an order determiner to determine an order of an image frame including the input image data, wherein:

when the first image data is not less than the first critical grayscale value but not more than the second critical grayscale value, the data generator is to determine one of the first critical grayscale value or the second critical grayscale value as the first corrected image data based on a dithering algorithm, the determined order of the image frame, and the determined position of the first pixel.

7. The apparatus as claimed in claim 6 , wherein:

the position determiner is to determine the position of the first pixel as one of a first position or a second position based on the determined order of the image frame,

when the first image data is not less than the first critical grayscale value but not more than the second critical grayscale value and the position of the first pixel is the first position, the data generator is to determine the second critical grayscale value as the first corrected image data, and

when the first image data is not less than the first critical grayscale value but not more than the second critical grayscale value and the position of the first pixel is the second position, the data generator is to determine the first critical grayscale value as the first corrected image data.

8. The apparatus as claimed in claim 7 , wherein:

when the order of the image frame including the input image data is an odd number, the order determiner is to determine the order of the image frame as a first turn,

when the order of the image frame including the input image data is an even number, the order determiner is to determine the order of the image frame as a second turn,

the position determiner is to store first and second pattern sets, each of the first and second pattern sets includes a plurality of dithering patterns, each of the dithering patterns including data elements, each data element having a first value or a second value, and

the position determiner is to:

select the first pattern set when the order of the image frame is the first turn or the second pattern set when the order of the image frame is the second turn,

select one of the dithering patterns of the selected pattern set that corresponds to the first image data,

select one of the data elements of the selected dithering pattern that corresponds to the position of the first pixel,

determine the position of the first pixel as the first position when the selected data element has the first value, and

determine the position of the first pixel as the second position when the selected data element has the second value.

9. The apparatus as claimed in claim 1 , wherein:

the comparator is to compare the first image data with a third critical grayscale value, and

when the first image data is more than the second critical grayscale value but not more than the third critical grayscale value, the data generator is to determine one of the second critical grayscale value or the third critical grayscale value as the first corrected image data.

10. The apparatus as claimed in claim 9 , wherein:

the first image data ranges not less than a lowest grayscale value but not more than a highest grayscale value,

the second critical grayscale value is greater than the lowest grayscale value, and

the third critical grayscale value is greater than the second critical grayscale value but not more than the highest grayscale value

when the first image data is more than the third critical grayscale value, the data generator is to determine the first image data as the first corrected image data without correcting the first image data.

11. The apparatus as claimed in claim 9 , further comprising:

a position determiner to determine a position of the first pixel on the display, wherein:

when the first image data is more than the second critical grayscale value but not more than the third critical grayscale value, the data generator is to determine one of the second critical grayscale value or the third critical grayscale value as the first corrected image data based on a dithering algorithm and the determined position of the first pixel.

12. The apparatus as claimed in claim 11 , wherein:

the position determiner is to determine the position of the first pixel as one of a first position or a second position,

when the first image data is more than the second critical grayscale value but not more than the third critical grayscale value and the position of the first pixel is the first position, the data generator is to determine the third critical grayscale value as the first corrected image data, and

when the first image data is more than the second critical grayscale value but not more than the third critical grayscale value and the position of the first pixel is the second position, the data generator is to determine the second critical grayscale value as the first corrected image data.

13. The apparatus as claimed in claim 11 , further comprising:

an order determiner to determine an order of an image frame including the input image data, wherein:

when the first image data is more than the second critical grayscale value but not more than the third critical grayscale value, the data generator is to determine one of the second critical grayscale value or the third critical grayscale value as the first corrected image data based on a dithering algorithm, the determined order of the image frame, and the determined position of the first pixel.

14. The apparatus as claimed in claim 13 , wherein:

the position determiner is to determines the position of the first pixel as one of a first position or a second position based on the determined order of the image frame,

when the first image data is more than the second critical grayscale value but not more than the third critical grayscale value and the position of the first pixel is the first position, the data generator is to determine the third critical grayscale value as the first corrected image data, and

when the first image data is more than the second critical grayscale value but not more than the third critical grayscale value and the position of the first pixel is the second position, the data generator is to determine the second critical grayscale value as the first corrected image data.

15. The apparatus as claimed in claim 1 , wherein the first image data ranges not less than a lowest grayscale value but not more than a highest grayscale value, the first critical grayscale value is the lowest grayscale value, and

the second critical grayscale value is a reference value for determining a low grayscale value.

16. The apparatus as claimed in claim 1 , wherein the first image data are dithered by using only a first current corresponding to the first critical grayscale value and a second current corresponding to the second critical grayscale value.

17. A method for driving an organic light emitting display apparatus, the method comprising:

receiving first image data corresponding to a first pixel;

determining a position of the first pixel;

comparing the first image data with a first critical grayscale value; and

when the first image data ranges not less than a lowest grayscale value but not more than the first critical grayscale value, setting one of the lowest grayscale value or the first critical grayscale value as first corrected image data such that the first image data are dithered by using only the lowest critical grayscale value and the first critical grayscale value of the first corrected image data based on a dithering algorithm and the determined position of the first pixel, and

when the first image data is greater than the first critical grayscale value but equal to or lower than a highest grayscale value, setting the first image data as the first corrected image data without correcting the first image data.

18. The method as claimed in claim 17 , wherein:

determining the position of the first pixel includes:

storing a plurality of dithering patterns, each of the dithering patterns including data elements, each of the data elements having a first value or a second value,

selecting one of the dithering patterns corresponding to the first image data,

selecting one of the data elements of the selected dithering pattern corresponding to the position of the first pixel,

determining the position of the first pixel as a first position when the selected data element has the first value, and

determining the position of the first pixel as a second position when the selected data element has the second value,

the setting includes:

determining the first critical grayscale value as the first corrected image data when the first image data ranges not less than the lowest grayscale value but not more than the first critical grayscale value and the position of the first pixel is the first position, or

determining the lowest grayscale value as the first corrected image data when the first image data ranges not less than the lowest grayscale value but not more than first critical grayscale value and the position of the first pixel is the second position.

19. The method as claimed in claim 17 , further comprising:

determining an order of an image frame including the first image data, wherein, when the first image data is not less than the lowest grayscale value but not more than the first critical grayscale value, the setting includes determining one of the lowest grayscale value or the first critical grayscale value as the first corrected image data based on a dithering algorithm, the determined order of the image frame, and the determined position of the first pixel.

20. The method as claimed in claim 19 , wherein:

determining the order of the image frame includes:

determining the order of the image frame as a first turn when the order of the image frame including the first image data is an odd number, and

determining the order of the image frame as a second turn when the order of the image frame including the first image data is an even number,

determining of the position of the first pixel includes:

storing first and second pattern sets, each of the first and second pattern sets including a plurality of dithering patterns, each of the dithering patterns including data elements, each of the data elements having a first value or a second value,

selecting the first pattern set when the order of the image frame is the first turn or the second pattern set when the order of the image frame is the second turn, selecting one of the dithering patterns of the selected pattern set that corresponds to the first image data,

selecting one of the data elements of the selected dithering pattern corresponding to the position of the first pixel,

determining the position of the first pixel as the first position when the selected data element has the first value, and

determining the position of the first pixel as the second position when the selected data element has the second value,

the setting includes:

determining the first critical grayscale value as the first corrected image data when the first image data ranges not less than the lowest grayscale value but not more than the first critical grayscale value and the position of the first pixel is the first position, or

determining the lowest grayscale value as the first corrected image data when the first image data ranges not less than the lowest grayscale value but not more than the first critical grayscale value and the position of the first pixel is the second position.