Display data processing device, image display system, and display data processing method

1. A display data processing device that performs color adjustment on gradation values of pixels of a frame image of an input video signal and outputs the adjusted gradation values to a display device, comprising:

a first gamma correction unit configured to, based on first composite correction information according to a first gamma characteristic indicating a correspondence relationship between a first input gradation value and a first normalized brightness value and a first power function indicating a correspondence relationship between the first normalized brightness value and a first corrected gradation value, set the gradation value as the first input gradation value and to convert the first input gradation value into the first corrected gradation value;

a video gain correction unit configured to perform color adjustment on the first corrected gradation value according to video gain correction and to output the result as a video gain corrected gradation value; and

a second gamma correction unit configured to, based on second composite correction information according to a second power function having the same power as the first power function, which indicates a correspondence relationship between a second input gradation value and a second normalized brightness value, and a second gamma characteristic indicating a correspondence relationship between the second normalized brightness value and a second corrected gradation value, set the video gain corrected gradation value as the second input gradation value and to convert the second input gradation value into the second corrected gradation value.

2. The display data processing device according to claim 1 ,

wherein the first gamma correction unit sets the first normalized brightness value corresponding to the first input gradation value in the first gamma characteristic as a power value of the first power function and a power root corresponding to the power value as the first corrected gradation value, and obtains the first corrected gradation value for the first input gradation value according to a correspondence relationship between the first input gradation value and the first corrected gradation value, and

the second gamma correction unit sets the video gain corrected gradation value to a power root of the second power function and a power value corresponding to the power root to the second normalized brightness value in the second gamma characteristic, and obtains the second corrected gradation value corresponding to the video gain corrected gradation value according to a correspondence relationship between the video gain corrected gradation value and the second corrected gradation value.

3. The display data processing device according to claim 2 ,

wherein the first gamma correction unit obtains the first normalized brightness value corresponding to the first input gradation value in the first gamma characteristic, obtains the power root corresponding to the first normalized brightness value in the first power function, includes a first correction lookup table generated as a correspondence relationship between the first input gradation value and the first corrected gradation value that is the power root, and outputs the first corrected gradation value with reference to the first correction lookup table when the first input gradation value is input, and

the second gamma correction unit obtains a power value of the second power function when the video gain corrected gradation value is set to a power root, sets the power value as the second normalized brightness value in the second gamma characteristic, includes a second correction lookup table generated as a correspondence relationship between the video gain corrected gradation value and the second normalized brightness value, and outputs the second corrected gradation value with reference to the second correction lookup table when the video gain corrected gradation value is input.

4. The display data processing device according to claim 1 ,

wherein, when a power in the first power function and the second power function is n, 1<n≤3.

5. The display data processing device according to claim 1 ,

wherein a first adjustment ratio by which the first corrected gradation value is multiplied is a power root of a second adjustment ratio that adjusts a designated brightness in the processing of video gain correction.

6. The display data processing device according to claim 1 ,

wherein the first gamma characteristic is a user setting gamma characteristic that is arbitrarily set, and the second gamma characteristic is a gamma characteristic of a display device that displays a second corrected gradation value.

7. An image display system comprising:

the display data processing device according to claim 1 , and the display device configured to display an image according to the second corrected gradation value,

wherein the second gamma characteristic is a gamma characteristic of the display device.

8. A display data processing method for performing color adjustment on gradation values of pixels of a frame image of an input video signal and outputting the adjusted gradation value to a display device, the method comprising:

a first gamma correction process of setting, by a first gamma correction unit, based on first composite correction information according to a first gamma characteristic indicating a correspondence relationship between a first input gradation value and a first normalized brightness value and a first power function indicating a correspondence relationship between the first normalized brightness value and a first corrected gradation value, the gradation value as the first input gradation value and converting the first input gradation value into the first corrected gradation value;

a video gain correction process of a video gain correction unit performing color adjustment on the first corrected gradation value according to video gain correction by a video gain correction unit and outputting the adjusted gradation value as a video gain corrected gradation value; and

a second gamma correction process of setting, by a second gamma correction unit, based on second composite correction information according to a second power function having the same power as the first power function, which indicates a correspondence relationship between a second input gradation value and a second normalized brightness value, and a second gamma characteristic indicating a correspondence relationship between the second normalized brightness value and a second corrected gradation value, the video gradation value as the second input gradation value and converting the second input gradation value into the second corrected gradation value.