Display device and display method therefor

1. A display apparatus, comprising:

a display; and

a processor configured to generate a second image and a third image where a dynamic range is expanded by respectively applying a first gain and a second gain to an input first image, generate a degraded image of the second image by applying a predetermined degradation model to the second image, based on a difference value between a pixel of the degraded second image and a pixel of the third image satisfying a predetermined condition, modify a pixel value of the second image based on the difference value, and output the second image where the pixel value is modified through the display.

2. The display apparatus as claimed in claim 1 , wherein the processor is further configured to, based on the difference value not satisfying the predetermined condition, repeat the process by using the second image where the pixel value is modified as the input first image.

3. The display apparatus as claimed in claim 2 , wherein the predetermined condition is at least one of a case where the difference value is smaller than a predetermined threshold value, and a case where a number of repetitions of the process is equal to or greater than a predetermined threshold number.

4. The display apparatus as claimed in claim 2 , wherein the processor is further configured to, based on the difference value not satisfying the predetermined condition, modify the pixel value of the second image by applying a third gain to the difference value, use the second image where the pixel value is modified as the input first image, and repeat the process.

5. The display apparatus as claimed in claim 1 , wherein the processor is configured to set the first gain and the second gain based on a number of output bits of the display apparatus and a number of bits of the input first image, respectively apply the set first and second gains to the input first image, and generate the second image and the third image.

6. The display apparatus as claimed in claim 5 , wherein the first gain and the second gain are calculated based on following equation,

First

⁢

⁢

gain

=

2

k

-

1

2

n

-

1

Second

⁢

⁢

gain

=

2

k

2

n

=

2

k

-

n

where k is a number of bits of the display apparatus, and n is a number of bits of the first image.

7. The display apparatus as claimed in claim 1 , wherein the processor is further configured to divide the first image into a predetermined plurality of areas, and use each of the predetermined plurality of areas as the input first image.

8. The display apparatus as claimed in claim 1 , wherein the degradation model includes at least one of an Inverse Sigmoid function, a Lower Gamma function and an Upper Gamma function.

9. A display method of a display apparatus, the method comprising:

generating a second image and a third image where a dynamic range is expanded by respectively applying a first gain and a second gain to an input first image;

generating a degraded image of the second image by applying a predetermined degradation model to the second image;

based on a difference value between a pixel of the degraded second image and a pixel of the third image satisfying a predetermined condition, modifying a pixel value of the second image based on the difference value; and

outputting the second image where the pixel value is modified.

10. The method as claimed in claim 9 , further comprising:

based on the difference value not satisfying the predetermined condition, repeating the process by using the second image where the pixel value is modified as the input first image.

11. The method as claimed in claim 10 , wherein the predetermined condition is at least one of a case where the difference value is smaller than a predetermined threshold value, and a case where a number of repetitions of the process is greater than a predetermined threshold number.

12. The method as claimed in claim 10 , wherein the repeating of the process comprises, based on the difference value not satisfying the predetermined condition, modifying the pixel value of the second image by applying a third gain to the difference value, using the second image where the pixel value is modified as the input first image, and repeating the process.

13. The method as claimed in claim 9 , wherein the generating of the second image and the third image comprises:

setting the first gain and the second gain based on a number of output bits of the display apparatus and a number of bits of the input first image; and

generating the second image and the third image by respectively applying the set first and second gains to the input first image.

14. The method as claimed in claim 13 , wherein the first gain and the second gain are calculated based on following equation,

First

⁢

⁢

gain

=

2

k

-

1

2

n

-

1

Second

⁢

⁢

gain

=

2

k

2

n

=

2

k

-

n

where k is a number of bits of the display apparatus and n is a number of bits of the first image.

15. The method as claimed in claim 9 , further comprising:

dividing the first image into a predetermined plurality of areas, and using each of the predetermined plurality of areas as the input first image.