KR102248376B1 - Transparent display and method of controlling image quality thereof - Google Patents

Abstract

The present invention relates to a transparent display and a method for controlling its image quality, comprising: a calculation unit that analyzes an input image to calculate a ratio of a transmissive portion and a non-transmissive portion in a display panel; when the transmissive portion increases, a first gamma curve is selected and the transmissive portion is small. And a gamma curve selector for modulating data of the input image by selecting a second gamma curve lower than the first gamma curve when it is lost.

Description

Transparent display and its quality control method {TRANSPARENT DISPLAY AND METHOD OF CONTROLLING IMAGE QUALITY THEREOF}

The present invention relates to a transparent display in which a gamma curve is applied differently according to a ratio of a transmissive portion and a non-transmissive portion, and a method for controlling image quality thereof.

The transparent display may show an image displayed on the transparent display panel together with a background behind the transparent display panel. The transparent display can be used for various purposes such as a show window, a refrigerator door, a billboard, and a public display. These transparent displays are attracting attention as future displays because of their advantages, but there is a task to improve image quality, such as improving transmittance and securing visibility.

In the paper "Optimal Tone Curve Characteristics of Transparent Display for Preferred Image Reproduction (Youngshin Kwak, UNIST)" disclosed in SID 2014, a gamma compensation of 1.6 gamma power is obtained in order to obtain a brightness similar to the 2.2 gamma compensation method of a general display in a transparent display. Proposed a method. The author simulated a transparent display with 10% transmittance of a general display and compared and evaluated the preferences for each gamma curve by adjusting the input image with a gamma curve value ranging from 1.5 to 2.3. As a result, the author proposed a 1.6 gamma curve for a transparent display based on the experimental results in which the 1.6 gamma curve is similar to the 2.2 gamma curve for a general display.

The transparent display has a higher gradation brightness of the output image reproduced on the transparent display panel than the gradation of the input image compared to a general display, and reproduces the image with higher brightness at each gradation than that of a general display. According to the experimental results of applying the 1.6 gamma curve to such a transparent display, applying the 1.6 gamma cover to the transparent display further increases the output gradation compared to the input gradation, so the visibility of the image reproduced on the transparent display, contrast ratio, and It was confirmed that the colorfulness was deteriorated.

The present invention provides a transparent display capable of improving image quality and a method for controlling the image quality.

The transparent display of the present invention includes a display panel, a calculation unit, a gamma curve selection unit, and a display panel driving unit.

The calculation unit analyzes the input image and calculates the ratio of the transmissive portion and the non-transmissive portion in the display panel.

The gamma curve selector modulates the data of the input image by selecting a first gamma curve when the transmissive portion becomes larger and selects a second gamma curve lower than the first gamma curve when the transmissive portion becomes smaller.

The display panel driver writes modulated pixel data to pixels of the display panel.

The method for controlling the quality of the transparent display includes: analyzing an input image and calculating a ratio of the transmissive portion and the non-transmissive portion in the display panel; Modulating data of the input image by selecting a first gamma curve when the transmission portion becomes large and a second gamma curve when the transmission portion becomes small; And writing the modulated pixel data to pixels of the display panel.

The present invention optimizes the gamma curve according to the ratio of the transmissive area and the non-transmissive area of the transparent display to improve the visibility, contrast, and color of the image reproduced in the transparent display and the rear image in consideration of human brightness perception characteristics, thereby increasing power consumption. You can improve the picture quality without it.

1 is a flowchart illustrating a method of controlling image quality of a transparent display according to an exemplary embodiment of the present invention.
2 is a diagram showing a transmissive portion and a non-transmissive portion in a transparent display.
3A and 3B are diagrams illustrating an example in which sizes of a transmissive portion and a non-transmissive portion are different in a transparent display.
4 is a diagram illustrating an example of gamma curves selected according to a non-transmissive portion ratio (RTA) of a transparent display.
5 is a diagram showing an S gamma curve.
6 is a diagram illustrating an example in which a different gamma curve is selected according to a low gradation value from a low gamma curve.
7 is a block diagram illustrating a display device according to an exemplary embodiment of the present invention.
8 and 9 are block diagrams showing a picture quality control apparatus according to an embodiment of the present invention.
10 is a circuit diagram showing a pixel configuration of a transparent LCD.
11 is a circuit diagram showing a pixel configuration of a transparent OLED display.

The present invention improves visibility, contrast, and color in a transparent display without increasing power consumption by adjusting a gamma curve in consideration of the ratio of the transmissive area and the non-transmissive area of the transparent display based on the brightness perception characteristics of humans.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same reference numbers throughout the specification mean substantially the same constituent elements. In the following description, when it is determined that a detailed description of a known function or configuration related to the present invention may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted.

1 is a flowchart illustrating a method of controlling image quality of a transparent display according to an exemplary embodiment of the present invention. 2 is a diagram showing a transmissive portion and a non-transmissive portion in a transparent display. 3A and 3B are diagrams illustrating an example in which sizes of a transmissive portion and a non-transmissive portion are different in a transparent display.

The transparent display of the present invention may be implemented with a transparent liquid crystal display (LCD) and a transparent organic light-emitting diode (OLED) display. Transparent LCD is a non-light-emitting device that requires a backlight. Transparent OLED is a self-luminous device. A touch screen may be coupled to the display panel of the transparent display.

1 to 3, the transparent display reproduces an image of an input image on the display panel 21, and transmits light from the display panel 21 to provide an image ( Rear image). The rear image may be a real image, a printed image, or an image reproduced on another display panel.

The non-transmissive portion 21a is an area in which an image of an input image reproduced on the display panel 21 is displayed. Information on the rear image may be displayed on the non-transmissive portion 21a, but is not limited thereto. The transmissive portion 21b is a region in which the rear image is more visible than the non-transmissive portion 21a. The transmissive part image may be an image having a pure color tone such as red (R), green (G), and blue (B), or an image having a white tone.

In the method for controlling image quality of a transparent display according to an exemplary embodiment of the present invention, a ratio of a non-transmissive part (Ration of non-transparent Area, hereinafter referred to as "RTA") is calculated by analyzing a received input image (S1 and S2).

RTA is a ratio of the transmissive portion 21a and the non-transmissive portion 21b in the display panel, and may be determined as a gray scale of an input image. RTA is small when the ratio of the transmission part is large, and has a large value when the ratio of the transmission part is small. RTA is shown in Equation 1 below.

Here, Gray _tp is the gray scale of the area determined as the transmission part 21a. Gray _in is the gray level of the pixel data of the input image. Gray _th (LCD) is a reference gray level that distinguishes the transmissive portion 21a from the non-transmissive portion in a transparent LCD. Gray _th (OLED) is a reference gray level that distinguishes the transmissive portion 21a from the non-transmissive portion in a transparent OLED. Gray _th (LCD) is _{higher than Gray th} (OLED).

When the pixel data of the input image is 8-bit data representing 0 to 255, Grayth (LCD) may be 250, and Grayth (OLED) may be 50. Gray _th (LCD) and gray _th (OLED) can be determined experimentally because they vary depending on the manufacturer of the display device, the characteristics of the display panel, and the driving method of the display panel.

In a transparent LCD, if pixel data of an input image is a gray scale value of 250 or more, the pixel data is determined as transmission part data. On the other hand, if the gray scale value is less than 250, the pixel data is determined as non-transmissive part data.

In the transparent OLED, if the pixel data of the input image is a gray scale value of 50 or less, the pixel data is determined as transmission part data. On the other hand, if the grayscale value is greater than 50, the pixel data is determined as non-transmissive part data.

Gray _in may be any one of RGB data or a luminance value (Y). The luminance value (Y) is shown in Equation 2. If RTA is calculated based on the luminance value (Y), it is as shown in Equation 3.

Here, R denotes data of a red sub-pixel, G denotes data of a green sub-pixel, and B denotes data of a blue sub-pixel.

Here, Y _tp is the pixel luminance of the region determined as the transmission part 21a. Y _in is the pixel luminance of the input image. Y _{_ th LCD} (LCD) is a reference brightness to distinguish between the transmission portion (21a) and cucurbit widow on the transparent LCD. Y _{OLED _ th} (OLED) is a reference luminance that distinguishes the transmissive portion 21a from the non-transmissive portion in a transparent OLED. Y _{LCD _ th} (LCD) is _{higher than Y OLED _ th} (OLED).

When the pixel data of the input image is 8-bit data representing 0 to 255, Y _{LCD _ th} (LCD) may be 250, and Y _{OLED _ th} (OLED) may be 50.

In a transparent LCD, if the pixel luminance value (Y) of the input image is 250 or more, the pixel data is determined as transmission data. On the other hand, if it is smaller than 250, the pixel data is judged as non-transmissive part data.

In the transparent OLED, if the pixel luminance value (Y) of the input image is 50 or less, the pixel data is determined as transmission part data. On the other hand, if it is greater than 50, the pixel data is judged as non-transmissive part data.

In the transparent display, when an image of a general 2.2 gamma curve (FIGS. 4 and 43) is input, the image quality is deteriorated due to a decrease in visibility and contrast ratio. The present invention improves image quality of a transparent display by brightening an image while preventing high gradation aggregation by changing a gamma curve according to a ratio of a transmissive portion and a non-transmissive portion in a transparent display.

When the transmission portion ratio is large, the rear image of the display panel viewed through the transmission portion 21b is more visible to the observer than the information displayed on the non-transmissive portion 21a of the display panel. The present invention can increase the transmittance of pixels by increasing the brightness of the transmitting pixels in a transparent LCD by selecting a high gamma curve when the transmitting part ratio is high, and increasing the brightness of the non-transmissive pixels to make the non-transmissive parts that are relatively invisible more visible. .

In the present invention, when the ratio of the transmissive portion is small in the transparent display, the image reproduced in the non-transmissive portion 21a is more conspicuous than the transmissive portion 21b. Therefore, the high gradation of the input image is emphasized within a range that does not deteriorate the image quality. Emphasizes the bright part to make the non-transmissive image appear brighter.

In a transparent display, when the transmissive portion 21b increases, the non-transmissive portion 21a becomes relatively small. The inventors of the present invention repeat the experiment of evaluating the perceived image quality perceived by the test subject when the ratio of the non-transmitting part 21a and the transmitting part 21b is different, so that the image displayed on the non-transmitting part 21a is changed when the size of the transmitting part 21b is changed. It was confirmed that the visibility, contrast, and color were changed. The inventors of the present invention change the gamma curve according to the RTA so that the visibility, contrast, and color of the non-transmissive image perceived by the observer are not degraded even if the RTA varies in the transparent display.

The present invention selects a high gamma curve (FIGS. 4 and 41) when the transmissive portion 21b is large as shown in FIG. 3A, whereas a low gamma curve (FIGS. 4 and 42) when the transmissive portion 21b is small as shown in FIG. 3B Select (S3).

When the transmissive portion 21b increases, the visibility, contrast, and color of the non-transmissive portion 21a decrease due to the brightness of the transmissive portion 21b. Accordingly, the present invention selects the first gamma curve 41 that can further increase the output gradation compared to the second gamma curve when the transmission part 21b increases, thereby increasing the brightness of the pixels. Improves. When the pixel data is modulated based on the first gamma curve 41, the transmittance of the transmissive portion 21b is higher. Accordingly, the first gamma curve 41 may improve the image quality of the rear image of the transmissive portion 21b and the image reproduced by the non-transmissive portion 21a.

In the present invention, the second gamma curve 42 is selected when the transmission part 21b becomes small. The second gamma curve 42 lowers the brightness of the pixel by lowering the output gradation (Dout of Equation 4) compared to the first gamma curve 41 in the input gradation (Din of Equation 4) of low gradation below the middle gradation, In high gradation, the output gradation (Dout of Equation 4) is increased compared to the input gradation (Din of Equation 4). The second gamma curve 42 increases the brightness of pixels in the high gradation to brighten the reproduced image, while lowering the low gradation below the middle gradation compared to the input gradation, thereby increasing the contrast ratio of the image.

In the present invention, pixel data of an input image modulated by a selected gamma curve is written on the display panel 21 to reproduce the input image on the display panel 21 (S4).

Each of the gamma curves 41 and 42 may be implemented as a look-up table (LUT).

Each of the gamma curves 41 and 42 may be implemented as an S gamma curve as shown in FIG. 5. In the first gamma curve 41, an S gamma curve is selected in order to increase the contrast ratio and saturation at an increased output gray scale. S gamma curve is defined for the input / output gray level of the concave curve, and a high gradation region (a≤D _in ≤255) defining the input / output gray level of the low gray scale region (0≤D _in ≤a) as shown in Equation (4) It can be divided into a convex curve. The concave curve and the convex curve are connected via the inflection point (a). In FIG. 5, NP is an inflection point (a).

In Equation 2, a is an inflection point (Fig. 4, NP) between the concave curve and the convex curve, and is a parameter for adjusting the amount of saturation compensation. α(alpha) is a low gradation enhancement parameter, and β(beta) is a high gradation enhancement parameter.

Compared to the 2.2 gamma curve, the S gamma curve lowers the output gradation (Dout) in low gradations and increases the output gradation (Dout) in high gradations. Accordingly, the S gamma curve darkens the brightness of pixels in low gradations and increases the brightness of pixels in high gradations without gradation expression or gradation aggregation, thereby improving contrast and saturation. The appropriate range of the S gamma cover is shown in Table 1.

α(alpha) 0.9 to 1.5 β(beta) 1.2 to 1.8 a(NP) 150 to 250

When the second gamma curve 42 is applied as an S gamma curve, parameters of the S gamma curve may be changed according to a low gradation value less than the middle gradation. When the output gray scale value is lower than the existing 2.2 gamma curve 43 in the low gray scale, the S gamma curve 422 in which α (alpha) is reduced and β (beta) is increased may be selected. On the other hand, when the output gradation value is higher than the existing 2.2 gamma curve 43 in low gradation, the S gamma curve 421 in which α (alpha) is increased and β (beta) is decreased may be selected.

7 shows a transparent display according to an embodiment of the present invention. 8 and 9 are block diagrams showing a picture quality control device.

7 to 9, the transparent display of the present invention includes a display panel 100 and a display panel driver that writes pixel data of an input image to a pixel array of the display panel 100.

The display panel driver includes a data driver 102, a gate driver 104, a timing controller 110, a host system (not shown), and the like.

A plurality of data lines 11 and a plurality of scan lines (or gate lines) 12 cross the pixel array of the display panel 100. The pixel array of the display panel 100 includes pixels that are arranged in a matrix form to display an input image. Each of the pixels includes an R sub-pixel, a G sub-pixel, and a B sub-pixel. Each of the pixels may further include a white (W) sub-pixel.

The data driver 102 converts the pixel data received from the timing controller 110 into an analog gamma compensation voltage, generates a data voltage, and outputs the data voltage to the data lines 11. Pixel data input to the data driver 102 is digital video data of an input image.

The gate driver 104 supplies scan pulses (or gate pulses) synchronized with the output voltage of the data driver 102 to the scan lines 12 under the control of the timing controller 110. The gate driver 104 sequentially selects pixels to which data is written by sequentially shifting the scan pulses in units of lines.

The timing controller 110 receives pixel data of an input image and timing signals synchronized therewith from the host system. The timing controller 110 transmits the pixel data of the input image to the data driver 102. The timing controller 110 controls operation timings of the data driver 102 and the gate driver 104 based on timing signals input in synchronization with pixel data of an input image. The timing signals include a vertical synchronization signal (Vsync), a horizontal synchronization signal (Hsync), a data enable signal (DE), and the like. The timing controller 110 generates a data timing control signal and a gate timing control signal based on the timing signals to synchronize the data driver 102 and the gate driver 104. The data timing control signal defines the operation timing and output timing of the data composition unit 102. The gate timing control signal defines the operation timing and output timing of the gate driver 104.

The host system may be implemented as any one of a TV (Television) system, a set-top box, a navigation system, a DVD player, a Blu-ray player, a personal computer (PC), a home theater system, and a phone system.

Any one of the host system, the timing controller 110, and the data driver 102 includes a picture quality control device as shown in FIGS. 8 and 9.

The image quality control apparatus includes an RTA calculation unit 70, a plurality of lookup tables 71a, 71b, and 71c, and a gamma curve selection unit 72, as shown in FIGS. 8 and 9.

The RTA calculation unit 71 calculates the RTA based on the gray level of the input image. The RTA calculation unit 71 generates a selection signal for selecting a gamma curve according to the RTA calculation result.

Each of the lookup tables LUT modulates the pixel data of the input image by outputting an output gray scale defined by the gamma curves 41 and 42 corresponding to the pixel data of the input image and transmits the modulated pixel data to the data driver 102.

The first lookup table 71a stores data of the first gamma curve 41 in FIG. 4. The first lookup table 71a modulates pixel data by receiving pixel data of an input image and outputting an output gray level value of the first gamma curve 41 previously stored at an address indicated by the gray level of the pixel data.

The second lookup table 71b stores data of the second gamma curve 42 in FIG. 4. The first lookup table 71a modulates pixel data by receiving pixel data of an input image and outputting an output gray level value of the second gamma curve 42 previously stored at an address indicated by the gray level of the pixel data.

As described above, the gamma curve selector 72 selects the first gamma curve 41 when the transmissive portion 21b becomes large and selects the second gamma curve 42 when the transmissive portion 21b decreases. The gamma curve selection unit 72 is implemented as a multiplexer (MUX) that selects one of the outputs of the first and second lookup tables 71a and 71b in response to a selection signal from the RTA calculation unit 70. Can be.

The low gamma curve 41 may change the gamma curve as shown in FIG. 6 according to a low gradation value below the middle gradation. In this case, as shown in FIG. 9, when the transmission portion 21b selecting the low gamma curve 41 is small, the number of selected lookup tables 71b and 71c increases.

The data driver 102 converts the data modulated by the gamma curve selection unit 72 into a data voltage and supplies the data to the pixels through the data lines 11.

As shown in FIG. 10, the pixels of the transparent OLED display include a switch TFT (SWTFT), a driving TFT (DRTFT), an organic light emitting diode (OLED), a storage capacitor (Cst), and the like.

The switch TFT (SWTFT) supplies the data voltage (DATA) to the gate of the driving TFT (DRTFT) in response to the gate pulse. The driving TFT (DRTFT) is connected between the power line to which the pixel power source ELVDD is supplied and the OLED and controls the current flowing through the OLED according to the data voltage applied to its gate. OLED is a hole injection layer (HIL), a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), and an electron injection layer (EIL). ) Has a structure in which organic compound layers such as) are stacked. OLED emits light when electrons and holes combine in a light emitting layer. The storage capacitor Cst maintains the gate-source voltage Vgs of the driving TFT DRTFT for one frame period.

The pixel may further include an internal compensation circuit. The internal compensation circuit includes one or more switch TFTs and one or more capacitors to initialize the gate of the driving TFT DRTFT and then sense the threshold voltage and mobility of the driving TFT DRTFT to compensate the data voltage DATA. Any known internal compensation circuit can be applied.

As shown in FIG. 11, a pixel of a transparent LCD includes a liquid crystal cell (Clc), a storage capacitor (Cst), a thin film transistor (TFT), and the like. The liquid crystal cell Clc uses liquid crystal molecules driven by an electric field between a pixel electrode to which a data voltage (DATA) is applied through a TFT and a common electrode to which a common voltage (Vcom) is applied to delay the phase of light according to the data. Adjust the transmittance. The storage capacitor Cst maintains the voltage of the liquid crystal cell Clc for one frame period. The TFT is turned on in response to a gate pulse (or scan pulse, SCAN) from the gate line 12 to transfer the data voltage from the data line 11 to the pixel electrode of the liquid crystal cell Clc. To supply.

The liquid crystal display may be implemented in any known liquid crystal mode such as a twisted nematic (TN) mode, a vertical alignment (VA) mode, an in plane switching (IPS) mode, and a fringe field switching (FFS) mode. In addition, the liquid crystal display may be implemented in various forms such as a transmissive liquid crystal display, a transflective liquid crystal display, and a reflective liquid crystal display. A transmissive liquid crystal display device or a transflective liquid crystal display device includes a backlight unit and a backlight driver.

The backlight unit may be implemented as an edge type backlight unit or a direct type backlight unit. The backlight unit is disposed under the rear surface of the display panel 100 of the liquid crystal display device and irradiates light to the display panel 100. The backlight driver supplies current to light sources of the backlight unit to emit light. Light sources may be implemented as a light emitting diode (LED). The backlight driver adjusts the luminance of light sources with PWM control selected according to the illuminance.

It will be appreciated by those skilled in the art through the above description that various changes and modifications can be made without departing from the technical idea of the present invention. Accordingly, the technical scope of the present invention should not be limited to the content described in the detailed description of the specification, but should be determined by the claims.

100: display panel 102: data driver
104: gate driver 106: timing controller
70: RTA calculation unit 71a, 71b, 71c: lookup table
72: Gamma curve selection unit

Claims (13)

A display panel having a non-transmissive portion in which an input image is reproduced and a transmission portion in which a rear image is visible;
A calculation unit that analyzes the input image and calculates a ratio of the transmissive portion and the non-transmissive portion in the display panel;
A gamma curve selector configured to modulate data of the input image by selecting a first gamma curve when the transmissive portion becomes larger and a second gamma curve lower than the first gamma curve when the transmissive portion becomes smaller; And
A transparent display comprising a display panel driver for writing pixel data modulated by the gamma curve selection unit into pixels of the display panel. The method of claim 1,
The first gamma curve is a transparent display that further increases the output gray level compared to the input gray level compared to the second gamma curve. The method of claim 2,
The first and second gamma curves,
A transparent display including a concave curve defining input/output gradations in a low gradation section, a convex curve defining input/output gradations in a high gradation section, and an inflection point between the concave curve and the convex curve. The method of claim 1,
A transparent display in which the display panel is any one of a transparent LCD and a transparent OLED. delete delete Analyzing the input image and calculating a ratio of the transmissive portion and the non-transmissive portion of the display panel;
Modulating data of the input image by selecting a first gamma curve when the transmissive portion becomes larger and selecting a second gamma curve lower than the first gamma curve when the transmissive portion becomes smaller; And
Writing modulated pixel data to pixels of the display panel,
The ratio of the transmissive portion and the non-transparent portion (Ration of non-transparent Area, RTA) is defined by the following equation.

Here, Gray _tp is the gradation of the transmissive part, Gray _in is the gradation of pixel data of the input image, and Gray _th (LCD) is a reference gradation for distinguishing the transmissive part and the non-transmissive part in a transparent LCD, and Gray _th (OLED) Is a reference gray level that distinguishes the transmissive portion and the non-transmissive portion in a transparent OLED. Analyzing the input image and calculating a ratio of the transmissive portion and the non-transmissive portion of the display panel;
Modulating data of the input image by selecting a first gamma curve when the transmissive portion becomes larger and selecting a second gamma curve lower than the first gamma curve when the transmissive portion becomes smaller; And
Writing modulated pixel data to pixels of the display panel,
The ratio of the transmissive portion and the non-transparent portion (Ration of non-transparent Area, RTA) is defined by the following equation.

Here, Y _tp is the pixel luminance of the transmissive part, Y _in is the pixel luminance of the input image, Y _{LCD_th} (LCD) is a reference luminance that distinguishes the transmissive part from the non-transmissive part in a transparent LCD, and Y _{OLED_th} (OLED) is It is a reference luminance that distinguishes the transmissive portion and the non-transmissive portion in a transparent OLED. Analyzing the input image and calculating a ratio of the transmissive portion and the non-transmissive portion of the display panel;
Modulating data of the input image by selecting a first gamma curve when the transmissive portion becomes larger and selecting a second gamma curve lower than the first gamma curve when the transmissive portion becomes smaller; And
Writing modulated pixel data to pixels of the display panel,
Each of the first and second gamma curves is defined by the following equation.

Here, D _out is the output gradation, D _in is the input gradation, a is the inflection point with a value between 150 and 250 between the concave curve and the convex curve, and α(alpha) is a low level with a value between 0.9 and 1.5. It is a gradation enhancement parameter, and β is a high gradation enhancement parameter having a value between 1.2 and 1.8. A display panel including a pixel array in which a plurality of data lines and a plurality of scan lines cross, pixels arranged in a matrix form, and the pixel array has a non-transmissive portion in which an input image is reproduced and a transmission portion in which a rear image is visible ;
A calculation unit that analyzes the input image and calculates a ratio of the transmissive portion and the non-transmissive portion in the display panel;
A gamma curve selector configured to modulate data of the input image by selecting a first gamma curve when the transmissive portion becomes larger and a second gamma curve lower than the first gamma curve when the transmissive portion becomes smaller;
A data driver for converting pixel data of the input image into an analog gamma compensation voltage to generate a data voltage and output the data voltage to the data lines; And
A scan driver configured to select pixels to which the pixel data is written by supplying a scan pulse synchronous to the data voltage to the scan lines, and sequentially shifting the scan pulses,
The data driver,
A transparent display configured to convert pixel data modulated by the gamma curve selection unit into the data voltage and supply the data to the pixels through the data lines. The method of claim 10,
The first gamma curve is a transparent display that further increases the output gray level compared to the input gray level compared to the second gamma curve. The method of claim 11,
The first and second gamma curves,
A transparent display including a concave curve defining input/output gradations in a low gradation section, a convex curve defining input/output gradations in a high gradation section, and an inflection point between the concave curve and the convex curve. delete

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