KR20160082889A - Data conveter device and display device including thereof - Google Patents

Abstract

An embodiment of the present invention relates to a data conversion device and a display device comprising the same. According to the present invention, the data conversion device comprises a W data conversion unit configured to detect average brightness of an image based on red (R), green (G), blue (B), and white (W) data signals of the image in order to stretch a W data histogram depending on the detected average brightness. The present invention provides a data conversion device with improved brightness by additionally including a white pixel.

Description

TECHNICAL FIELD [0001] The present invention relates to a data conversion device and a display device including the data conversion device.

The present invention relates to a data conversion apparatus and a display device including the same.

Recently, there has been a growing interest in implementing a high image quality and reducing power consumption by increasing the brightness of a display device. Especially, the high-contrast image is realized by using the multi-frame HDR technology and the histogram stretching technique is additionally applied to emphasize the image additionally. However, conventionally, in the process of outputting an input image, the gradation of RGB (R, G, and B) image data is varied variously without considering an average picture level and an overall brightness and gradation. And focused on making use of detailed information of image quality.

FIG. 9 is a histogram of RGB input image data and shows a change of a histogram by enlarging the RGB input image data. FIG. 10 is a view of a change of a screen according to the histogram. Referring to FIG. 9 and FIG. 10, HDR means a high luminance display of about 1000 nit or more. In contrast to the conventional display, the low gradation region has more noise and the high gradation region has high luminance. As described above, the histogram expansion technique of the conventional RGB image data has not been optimized for a high luminance display having problems such as generation of glare and contour of an image.

The embodiment of the present invention can provide a data conversion device having a white pixel further enhanced in brightness and a display device including the data conversion device.

The embodiment of the present invention also provides a data conversion device capable of optimizing the image enhancement technique by varying the extension value of the histogram in consideration of the average image brightness of the white data signal, the maximum brightness of the input image, and the image gradation, . ≪ / RTI >

A data conversion apparatus and a display device including the data conversion apparatus according to the embodiments of the present invention can be applied to a data conversion apparatus and a display apparatus including the same. ) Data signal, and when the histogram of the W data is stretched according to the detected average brightness brightness, the brightness contrast ratio, which is an advantage of HDR when the luminance display range is increased, The expression of the luminance region is maintained as it is, so that noise of a low gradation and glare of a high luminance image can be prevented, and further, power consumption can be reduced.

The display device according to an embodiment of the present invention detects a maximum luminance pixel based on the RGBW data and compares the detected maximum luminance pixel with a maximum luminance reference value and sets the luminance of the maximum luminance pixel equal to or greater than the maximum luminance reference value to the maximum luminance reference value So that it is possible to prevent the glare of the image and the rapid increase of the power consumption.

The embodiment according to the present invention can improve the image enhancement technique by increasing the brightness by further providing white pixels and by varying the extension value of the histogram in consideration of the average image brightness and the maximum brightness of the white data signal and the image gradation, A conversion device and a display device including the conversion device can be provided.

1 is a block diagram of a data conversion unit according to an embodiment of the present invention.
2 is a flowchart illustrating an operation of the W data conversion unit according to the first embodiment.
FIG. 3 is a detailed block diagram of the W data conversion unit according to the first embodiment and shows the operation relationship therebetween.
4 is a flowchart illustrating an operation of the W data conversion unit according to the second embodiment.
5 is a detailed block diagram of the W data conversion unit according to the second embodiment and shows the operation relationship therebetween.
6 is a diagram illustrating an image quality improvement and power consumption reduction effect when image data passed through a data conversion unit according to an embodiment of the present invention is displayed as an image.
7 is a diagram illustrating a display device including a data conversion unit according to an embodiment of the present invention.
8 is a diagram showing the arrangement relationship of sub-pixels.
9 is a view showing a conventional histogram stretching system.
FIG. 10 is a diagram showing a screen transformation according to a conventional histogram stretch; FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a data conversion apparatus and a display device including the same according to embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the size and thickness of an apparatus may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. However, it should be understood that the present invention is not limited to the embodiments disclosed herein but may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification. The dimensions and relative sizes of the layers and regions in the figures may be exaggerated for clarity of illustration.

It will be understood that when an element or layer is referred to as being another element or "on" or "on ", it includes both intervening layers or other elements in the middle, do. On the other hand, when a device is referred to as "directly on" or "directly above ", it does not intervene another device or layer in the middle.

The terms spatially relative, "below," "lower," "above," "upper," and the like, And may be used to easily describe the correlation with other elements or components. Spatially relative terms should be understood to include, in addition to the orientation shown in the drawings, terms that include different orientations of the device during use or operation. For example, when inverting an element shown in the figures, an element described as "below" or "beneath" of another element may be placed "above" another element. Thus, the exemplary term "below" can include both downward and upward directions.

The terminology used herein is for the purpose of describing embodiments only and is not intended to be limiting of the invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. &Quot; comprise "and / or" comprising ", as used in the specification, means that the presence of stated elements, Or additions.

<Data Conversion Unit>

1 is a block diagram of a data conversion unit according to an embodiment of the present invention.

1, a data conversion apparatus 100 according to an embodiment of the present invention converts input red (R), green (G), and blue (B) It is possible to convert the signal into a white (W) data signal, enhance the saturation of the RGB data signal, and enhance the brightness of the W signal. The data conversion apparatus 100 may include an inverse gamma unit 110, an RGB to RGBW conversion unit 130, a W data conversion unit 150, a color temperature compensation unit 170, and a rendering unit 190 .

The de-gamma unit 110 may de-gamma-process RGB data signals of an input image frame by frame. In more detail, the inverse gamma unit 110 converts received inverse gamma to inverse gamma (gamma) in order to prevent bit overflow, etc. occurring during the operation of converting RGB data signals to RGBW data signals. And the bit stream is bit stretched after being changed into a linear form. The inverse gamma unit 110 may perform bit stretching using a de-gamma look-up table (DE-Gamma LUT). As a result, the RGB data signals (RGB) can be output by changing the number of bits upward by bit stretching by the inverse gamma unit 110.

The RGB to RGBW conversion unit 130 converts RGB data signals output through the inverse gamma unit 110 into RGBW data signals. The reason for converting RGB data signals to RGBW data signals using the RGB to RGBW conversion unit 130 is to drive a display panel including RGBW subpixels. The RGB to RGBW converting unit 130 converts the RGB data signals based on the measured values or the calculated values having the same luminance and the same color coordinates as the W data signal in the RGB data signals to optimize the power consumption without changing the color coordinates W data signal can be added. As an example, the RGB to RGBW converting unit 130 extracts a common gray level value as shown in Equation (1) or a minimum gray level value as shown in Equation (2) from R, G, and B data, , G, and B input data to generate the R, G, and B data by subtracting the W data.

Equation 1

Equation 2

As another example, the RGB to RGBW conversion unit 130 may convert R, G, and B based on the data conversion method set according to the luminance characteristics of each sub-pixel according to the characteristics of luminance and / or driving of each sub-pixel (or sub- G and B data can be converted into 4-index R data, and G data B data can be converted into W data.

In this case, mapping from the RGB gradation to the WRGB gradation can be performed according to the conversion method disclosed in Korean Patent Laid-Open Publication No. 10-2013-0060476 or No. 10-2013-0030598.

Hereinafter, the RGB data signals input to the RGB to RGBW conversion unit 130 are referred to as RGB data signals, and RGB data signals among RGBW data signals output from the RGB to RGBW conversion unit 130 are converted into RGB data signals .

The W data converter 150 calculates the average brightness (APL) of the image in units of one screen based on the input RGBW data and adjusts the gain of the histogram stretch based on the calculated average brightness of the image A new histogram of the W data can be generated based on the adjusted histogram stretch gain.

The color temperature compensation unit 170 may compensate the color temperature of the RGB data. As an example of the color temperature compensation for realizing this, the RGB data signal outputted from the W data converter 150 and W obtained by converting the stretch of the histogram may be inputted and the RGB data may be compensated by sensing the light source of the display panel 200 . In this case, the color temperature compensator 170 may include an optical sensor. When the ambient light of the display panel 200 measured by the optical sensor is blue, the red color of the input image and the green The green color of the input image and the green color of the input image may be compensated for if either the red color or the green color of the input image is strong and the measured ambient light is strong. . If the measured ambient light has a strong green color, it is possible to compensate either or both of the red and blue colors of the input image.

The rendering unit 190 may improve the resolution by reproducing one pixel using two or more pixels based on the input RGBW data signals.

&Lt; W Data Conversion Unit According to First Embodiment >

2 is a flowchart illustrating an operation of the W data conversion unit according to the first embodiment. And FIG. 3 is a detailed block diagram of the W data conversion unit according to the first embodiment and its operation relationship.

2, the RGB to RGBW converting unit 130 generates an RGBW data signal based on input RGB data, and the W data converting unit 150, which is different from the first embodiment, The average image brightness APL can be calculated and the stretch gain can be adjusted according to the calculation result to change the histogram stretch of the W data based on the adjusted stretch gain. 3, the W data conversion unit 150 may include an average image brightness detector 151, a stretch gain adjuster 152, and a histogram stretch application unit 153. In this case, have.

The average image brightness detector 151 detects the average brightness (APL) of the image in units of frames based on the RGB data signal, and converts the detected average image brightness into an arithmetic value of 0 to 100, Can be compared with a reference value. The brightness reference values a and b may include a lower brightness reference value a and an upper brightness reference value b. When the average image brightness value is greater than 0 and less than the lower brightness reference value a, The average image brightness is determined as the average image brightness, and when the average image brightness is equal to or greater than the lower brightness reference value (a) but less than the upper brightness reference value (b), the average image brightness is determined as the second- If it is equal to or greater than the brightness reference value (b) but less than 100, the average image brightness of the third level can be determined. Meanwhile, the brightness reference value may further include an additional reference value in addition to the lower and upper brightness reference values (a, b), so that the classification of the average image brightness of the detected image may be further subdivided.

The stretch gain adjuster 152 may adjust the stretch gain, which is the stretch degree of the W data, based on the average image brightness. Specifically, in the first step, the W data among the RGBW data generated based on the RGB data signal can be histogrammed. The histogram may be defined as a set of numbers indicating the frequency of occurrence of pixels having specific intensities in the W data. In the second step, a low grayscale gain and a high grayscale gain for stretching the histogram of the W data to emphasize a specific grayscale can be set based on the detected average image brightness.

For example, when the average image brightness of the input image is detected as a low-level average image brightness of the first level, the low gradation gain is set to 0.2 and the high gradation gain is set to 0.8. And when the average image brightness of the input image is detected as the average image brightness of the second level which is the middle level, the low gradation gain is set to 0.4 and the high gradation gain is set to 0.6 so that the low gradation and high gradation When the average image brightness of the input image is detected as the average image brightness of the third level which is high level, the low gradation gain is set to 0.5 and the high gradation gain is set to 0.5 To 0.5, so that the image can be converted into an image in which the low gradation and the high gradation are emphasized in a balanced manner.

The histogram stretch applying unit 153 may stretch the histogram of the W data using the low grayscale and high grayscale gain input from the stretch gain adjuster 152 and output the histogram. That is, it is possible to change the distribution state of all the W data by gradation by using the low gradation and the high gradation gain.

&Lt; W data conversion unit according to the second embodiment >

4 is a flowchart illustrating an operation of the W data conversion unit according to the second embodiment. And FIG. 5 is a detailed block diagram of the W data conversion unit according to the second embodiment and shows an operation relationship therebetween.

Referring to FIG. 4, the RGB to RGBW conversion unit 130 generates an RGBW data signal based on input RGB data, and the W data conversion unit 150 according to the second embodiment generates an RGBW data signal based on input RGBW data The average image brightness APL can be calculated and the stretch gain of the W data can be adjusted according to the calculation result to change the histogram stretch of the W data based on the adjusted stretch gain. Also, a maximum luminance pixel is detected based on RGBW data based on a maximum luminance limit signal as an externally input control signal, and compared with a predetermined maximum luminance reference value. If the maximum luminance pixel is equal to or greater than the maximum luminance reference value, The brightness can be lowered. 5, the W data converting unit 150 according to the second embodiment includes an average image brightness detector 151, a stretch gain adjuster 152, a histogram stretch applying unit 153 and a maximum luminance pixel detection unit 154. [

The average image brightness detector 151 detects the average brightness (APL) of the image in units of frames based on the RGB data signal, and converts the detected average image brightness into an arithmetic value of 0 to 100, Can be compared with a reference value. The brightness reference values a and b may include a lower brightness reference value a and an upper brightness reference value b. When the average image brightness value is greater than 0 and less than the lower brightness reference value a, The average image brightness is determined as the average image brightness, and when the average image brightness is equal to or greater than the lower brightness reference value (a) but less than the upper brightness reference value (b), the average image brightness is determined as the second- If it is equal to or greater than the brightness reference value (b) but less than 100, the average image brightness of the third level can be determined. Meanwhile, the brightness reference value may further include an additional reference value in addition to the lower and upper brightness reference values (a, b), so that the classification of the average image brightness of the detected image may be further subdivided.

The stretch gain adjuster 152 may histogram the W data signal in a first step. In the second step, a low grayscale gain value and a high grayscale gain value for stretching the histogram to emphasize a specific grayscale can be set based on the average image brightness, respectively. The low gray level and the high gray level are not absolute values. For example, the 150 gray level may be set to the low gray level at the 0 gray level and the 255 gray level may be set to the high gray level at the 150 gray level.

The maximum luminance pixel detector 154 may output the maximum luminance pixel to the histogram stretch application unit 153 when the maximum luminance pixel is greater than or equal to a predetermined maximum luminance reference value, based on the RGBW data signal. The maximum luminance pixel detector 154 can prevent the glare of the image and the rapid increase of power consumption. In this case, the maximum luminance pixel detector 154 operates when a maximum luminance limit signal, which is a control signal provided from a timing controller 500 to be described later, is input, and calculates a maximum luminance pixel based on the input RGBW data signal, It is possible to judge whether or not it is the reference value or more. Whether or not the timing controller 500 outputs the maximum brightness limit signal may depend on the mode setting of the user or the type of the displayed image. Therefore, when a realistic image is displayed by expressing a very bright brightness like sunlight, the maximum brightness limit signal becomes a low logic level to deactivate the maximum brightness pixel detector 154 and display a very bright brightness The maximum luminance limit signal may be at a high logic level and the maximum luminance pixel detector 154 may be activated.

The histogram stretch applying unit 153 stretches the histogram of the W data using the low grayscale and the high grayscale gain input from the stretch gain adjuster 152 and outputs the histogram of the maximum The RGBW data can be outputted by lowering the luminance of the luminance pixel to the maximum luminance reference value.

Meanwhile, the maximum luminance pixel detector 154 may be included in the W data converter 150 and the data converter 100.

6 is a diagram illustrating an image quality improvement and power consumption reduction effect when image data passed through a data conversion unit according to an embodiment of the present invention is displayed as an image.

As shown in FIG. 6, when the range of brightness expression is increased, the increase in the contrast ratio, which is an advantage of HDR, and the expression of the high luminance region are maintained, while the noise of low gradation and the glare of the high luminance image are prevented, It can be seen that it has an effect. Also, the image enhancement technique can be optimized by varying the histogram extension value in consideration of the average image brightness of the white data signal, the maximum brightness of the input image, and the image gradation.

<Display Device Including Data Conversion Unit>

FIG. 7 is a diagram illustrating a display device including a data conversion unit according to an embodiment of the present invention, and FIG. 8 is a diagram illustrating the arrangement relationship of sub-pixels.

7, a display device 600 according to an exemplary embodiment of the present invention may include a display panel 200, a data driver 300, a gate driver 400, and a timing controller 500. Referring to FIG. The timing controller 500 may include a data conversion apparatus 100 and the data conversion apparatus 100 may be provided separately from the timing controller 500.

The data conversion apparatus 100 may be a part of the timing controller 500 and may be a separate device from the timing controller 500. Although the data conversion apparatus 100 is described as being included in the display device 600, the data conversion apparatus 100 may include a wireless communication device (such as a wireless mobile handset) or a digital camera, a video camera, a digital multimedia Player, a personal digital assistant (PDA), a video game console, another video device, or a portion of a dedicated viewing station (e.g., a television).

The display device 600 may also be a display device, such as, for example, image data captured by a digital video or still photo camera, image data obtained from a video or still-port archive, image data generated by a software application or broadcast and streaming media Various types of image data including image data can be displayed. Such a display device 600 may be a variety of devices, such as a desktop computer or a laptop computer, a computer workstation, a personal digital assistant, a mobile device such as a mobile phone, a wireless communication device, a multimedia device, May be coupled to the various devices, and may be associated with various devices. The display device 600 may include a liquid crystal display (LCD), a cathode ray tube (CRT) display, a plasma display, a projection display, and an organic light emitting diode display.

The display panel 200 includes a plurality of gate lines GL1 to GLn and a plurality of data lines DL1 to DLm and a plurality of gate lines GL1 to GLn and a plurality of data lines DL1 to DLm, A sub-pixel Pix may be formed at an intersection of the sub-

The gate driver 400 correspondingly supplies a plurality of scan signals SP to a plurality of gate lines GL1 to GLn in response to a gate control signal GCS from the timing controller 500. [ The plurality of scan signals (SP) enable the plurality of gate lines (GL1 to GLn) to be sequentially enabled for one horizontal synchronous signal period. The gate driver 400 may include a plurality of gate integrated circuits.

The data driver 300 generates a data voltage every time one of the plurality of gate lines GL1 to GLn is enabled in response to data control signals DCS from the timing controller 500, To the plurality of data lines DL1 to DLm of the display panel 200, respectively.

The timing controller 500 controls the gate driver 500 using various control signals O_CS supplied from an external system (for example, a graphics module of a computer system or a video demodulation module of a television receiving system, not shown) A gate control signal GCS for controlling the data driver 300 and a data control signal DCS for controlling the data driver 300 can be generated.

The sub-pixel (Pix) of the display panel 200 may include sub-pixels (pixels) corresponding to R, G, B, and W colors. The subpixels for each color may be arranged as shown in FIG. More specifically, in the odd-numbered horizontal line (n), each color subpixel is consecutively arranged in the order of a W subpixel 101, an R subpixel 102, a G subpixel 103 and a B subpixel 104 And each color sub-pixel in the even horizontal line (n + 1) is arranged in the order of the G sub-pixel 103, the B sub-pixel 104, the W sub-pixel 101 and the R sub- . That is, the subpixels for each color in the odd-numbered horizontal line (n) and the respective subpixels for each color in the even-numbered horizontal line (n + 1) may be arranged in a zigzag have. For example, the W subpixel 101 may be arranged at a point where the mth vertical line intersects the odd-numbered horizontal line (n), the m + 2th vertical line intersects the even horizontal line (n + 1) have. That is, any subpixel of W, R, G, or B of the odd-numbered horizontal line (n) in an arbitrary vertical line is vertical to the vertical line (n + 1) The same can be arranged on the line. The zigzag structure in which the same subpixel in the odd-numbered horizontal line (n + 1) and the even-numbered horizontal line (n + 1) It is possible to prevent a phenomenon that a line is visually compared with a structure in which the same sub-pixel appears.

When the display panel 200 is a liquid crystal display panel, the sub pixel Pix includes a thin film transistor (TFT) connected to the gate line GL and the data line DL, and a pixel connected to the thin film transistor TFT Electrode. The thin film transistor TFT supplies data from the data lines DL1 to DLm to the liquid crystal cell in response to a scan signal SP from the gate lines GL1 to GLn. To this end, the gate electrode of the thin film transistor TFT is connected to the gate lines GL1 to GLn, the source electrode thereof is connected to the data lines DL1 to DLm, and the drain electrode thereof is connected to the pixel electrode of the liquid crystal cell. In addition, a storage capacitor for holding the voltage of the liquid crystal cell is formed on the lower glass substrate of the display panel 200. In the upper glass substrate of the display panel 200, a color filter corresponding to each pixel region in which the thin film transistor (TFT) is formed, and the gate lines GL1 to GLn and the data lines DL1 to GLn, DLm, a thin film transistor (TFT), and the like. The liquid crystal cells included in each of the R, G, B, and W sub-pixels may be liquid crystal cells for R, G, B, and W colors.

In addition, when the display panel 200 is an organic light emitting diode display panel, each of the R, G, B, and W sub-pixels may include an organic light emitting diode, and light emitted from each sub- So that the image can be displayed. The organic light emitting diode may have a structure of a hole transporting layer / an organic light emitting layer / an electron transporting layer or a structure of a hole injecting layer / a hole transporting layer / an organic light emitting layer / an electron transporting layer / an electron injecting layer. Further, the organic light emitting cell may further include a functional layer for improving the luminous efficiency and / or lifetime of the organic light emitting layer.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

100 data conversion device
101 W sub-pixel
102 R sub-pixel
103 G sub-pixel
104 B sub-pixel
110 reverse gamma unit
130 RGB to RGBW conversion section
150 W data conversion unit
151 average image brightness detector
152 Stretch Gain Adjustment
153 Histogram Stretch application part
154 maximum luminance pixel detector
170 Color temperature compensation unit
190 rendering unit
200 display panel
300 data driver
400 gate driver
500 Timing Controller
600 display device

Claims (11)

An average luminance brightness of the image is detected based on red (R), green (G), blue (B) and white (W) And a W data conversion unit for stretching a histogram of the W data according to the average brightness of brightness. The method according to claim 1,
Wherein the W data conversion unit comprises:
And an average brightness brightness detector for calculating the average brightness of the image in units of one frame to detect the average brightness brightness. 3. The method of claim 2,
Wherein the W data conversion unit comprises:
And a stretch gain adjuster for adjusting the histogram stretch gain of the W data on the basis of the detected average brightness brightness by histogramming the W data. 3. The method of claim 2,
And a maximum luminance pixel detection unit that detects a maximum luminance pixel based on the RGBW data and compares it with a maximum luminance reference value. 5. The method of claim 4,
And lowering the luminance of the maximum luminance pixel above the maximum luminance reference value to the maximum luminance reference value. A data conversion device according to claim 1;
A display panel including subpixels corresponding to each of the RGBW data; And
And a timing controller for aligning the RGBW data output from the data conversion device according to the subpixel. The method according to claim 6,
Wherein the W data conversion unit comprises:
And an average brightness brightness detector for calculating the average brightness of the image in units of one frame to detect the average brightness brightness. 8. The method of claim 7,
Wherein the W data conversion unit comprises:
And a stretch gain adjuster for adjusting the histogram stretch gain of the W data on the basis of the detected average brightness of brightness by histogramming the W data. 9. The method of claim 8,
And a maximum luminance pixel detection unit that detects a maximum luminance pixel based on the RGBW data and compares it with a maximum luminance reference value. 10. The method of claim 9,
And lowering the luminance of the maximum luminance pixel above the maximum luminance reference value to the maximum luminance reference value. 11. The method of claim 10,
The maximum luminance pixel detection unit;
And is driven by a maximum luminance limit signal provided from the timing controller.

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