Driving controller, display apparatus including the same and method of driving display panel using the same

1. A driving controller comprising:

an image analyzer which analyzes input image data to determine a peak luminance;

a grayscale setter which receives a gamma value and the peak luminance and sets a boundary grayscale value and a minimum grayscale value; and

a time-and-space arranger which temporally and spatially arranges first data having the boundary grayscale value and second data having the minimum grayscale value,

wherein the driving controller is configured to drive a display panel using the first data and the second data for a low grayscale range of which a grayscale is equal to or less than the boundary grayscale value and to drive the display panel based on a data signal corresponding to a grayscale value of the input image data for a normal grayscale range of which a grayscale is greater than the boundary grayscale value.

2. The driving controller of claim 1 , wherein the grayscale setter is configured to set the boundary grayscale value and the minimum grayscale value such that a difference between the boundary grayscale value and the minimum grayscale value is decreased as the peak luminance increases.

3. The driving controller of claim 2 , wherein the minimum grayscale value is fixed, and

wherein the boundary grayscale value is set to be decreased by the grayscale setter as the peak luminance increases.

4. The driving controller of claim 1 , wherein the grayscale setter is configured to set the boundary grayscale value and the minimum grayscale value such that a difference between the boundary grayscale value and the minimum grayscale value is decreased as the gamma value decreases.

5. The driving controller of claim 4 , wherein the minimum grayscale value is fixed, and

wherein the boundary grayscale value is decreased as the gamma value decreases.

6. The driving controller of claim 1 , wherein the grayscale setter is configured to define a plurality of digital driving grayscale ranges,

wherein the grayscale setter is configured to set a first boundary grayscale value and a first minimum grayscale value for a first input grayscale range, and

wherein the grayscale setter is configured to set a second boundary grayscale value and a second minimum grayscale value for a second input grayscale range which has lower grayscale values than grayscale values of the first input grayscale range.

7. The driving controller of claim 6 , wherein the first boundary grayscale value is greater than the second boundary grayscale value.

8. The driving controller of claim 7 , wherein the first minimum grayscale value is equal to the second minimum grayscale value.

9. The driving controller of claim 7 , wherein the first minimum grayscale value is greater than the second minimum grayscale value.

10. The driving controller of claim 1 , further comprising a halftone setter which sets a maximum value of a number of pixels having the minimum grayscale value based on the boundary grayscale value, the minimum grayscale value and the gamma value.

11. The driving controller of claim 10 , wherein the maximum value of the number of pixels having the minimum grayscale value is decreased as a luminance difference of the boundary grayscale value and the minimum grayscale value increases.

12. The driving controller of claim 10 , wherein the grayscale setter is configured to define a plurality of digital driving grayscale ranges,

wherein the grayscale setter is configured to set a first boundary grayscale value and a first minimum grayscale value for a first input grayscale range, and

wherein the grayscale setter is configured to set a second boundary grayscale value and a second minimum grayscale value for a second input grayscale range which has lower grayscale values than grayscale values of the first input grayscale range.

13. The driving controller of claim 12 , wherein the halftone setter is configured to set the maximum value of the number of pixels having the minimum grayscale value to be fixed regardless of an input grayscale value of the input image data.

14. The driving controller of claim 12 , wherein the halftone setter is configured to set the maximum value of the number of pixels having the minimum grayscale value to be varied according to an input grayscale value of the input image data.

15. The driving controller of claim 14 , wherein the maximum value of the number of pixels having the minimum grayscale value is increased as the input grayscale value of the input image data decreases.

16. The driving controller of claim 1 , wherein the grayscale setter is configured to further receive characteristic values of a red subpixel, a green subpixel and a blue subpixel,

wherein the grayscale setter is configured to set boundary grayscale values of the red subpixel, the green subpixel and the blue subpixel and the minimum grayscale values of the red subpixel, the green subpixel and the blue subpixel based on the gamma value, the peak luminance and the characteristic values of the red subpixel, the green subpixel and the blue subpixel, respectively.

17. The driving controller of claim 16 , further comprising a halftone setter which sets a maximum value of the number of pixels having the minimum grayscale value of the red subpixel, a maximum value of the number of pixels having the minimum grayscale value of the green subpixel and a maximum value of the number of pixels having the minimum grayscale value of the blue subpixel based on the boundary grayscale values of the red subpixel, the green subpixel and the blue subpixel, the minimum grayscale values of the red subpixel, the green subpixel and the blue subpixel and the gamma value.

18. A display apparatus comprising:

a display panel which displays an image based on input image data;

a gate driver which outputs a gate signal to the display panel;

a driving controller which analyzes input image data to determine a peak luminance, set a boundary grayscale value and a minimum grayscale value based on a gamma value and the peak luminance, temporally and spatially arranges first data having the boundary grayscale value and second data having the minimum grayscale value to generate a data signal, drives the display panel for a low grayscale range in a digital driving method and drives the display panel for a normal grayscale range of which a grayscale is greater than the boundary grayscale value in an analog driving method, wherein the boundary grayscale value is a grayscale value of a boundary between the normal grayscale range and the normal grayscale range; and

a data driver which generates a data voltage based on the data signal and outputs the data voltage to the display panel.

19. The display apparatus of claim 18 , wherein the driving controller is configured to set a maximum value of a number of pixels having the minimum grayscale value based on the boundary grayscale value, the minimum grayscale value and the gamma value.

20. A method of driving a display panel, the method comprising:

analyzing input image data to determine a peak luminance;

setting a boundary grayscale value and a minimum grayscale value based on a gamma value and the peak luminance; and

temporally and spatially arranging first data having the boundary grayscale value and second data having the minimum grayscale value to generate a data signal.

21. The method of claim 20 , further comprising converting the data signal into a data voltage; and

outputting the data voltage to the display panel.

22. The method of claim 20 , wherein the boundary grayscale value and the minimum grayscale value are set such that a difference between the boundary grayscale value and the minimum grayscale value is decreased as the peak luminance increases.

23. The method of claim 22 , wherein the minimum grayscale value is fixed, and

wherein the boundary grayscale value is decreased as the peak luminance increases.

24. The method of claim 20 , wherein the boundary grayscale value and the minimum grayscale value are set such that a difference between the boundary grayscale value and the minimum grayscale value is decreased as the gamma value decreases.

25. The method of claim 24 , wherein the minimum grayscale value is fixed, and

wherein the boundary grayscale value is decreased as the gamma value decreases.