KR102539536B1 - Display device and method for driving the same - Google Patents

Abstract

A display device according to an embodiment of the present invention includes a display panel including a plurality of pixels, a control unit correcting an image signal and generating a corrected image signal for driving the display panel, wherein the control unit includes a gray level value of the image signal. a reference difference value obtained by dividing the gray level value of the reference signal obtained by correcting the video signal based on the reference gamma and the gray level value of the first signal obtained by correcting the video signal based on the first gamma from the gray level value of the reference signal A storage unit for storing difference data including a first difference value, a first summing unit for generating a first difference summation value obtained by summing absolute values of respective difference values of the difference values, the gray level value of the video signal and a first adder for generating the corrected video signal based on a result of adding the first difference summation value, and the reference gamma and the first gamma are different from each other.

Description

Display device and its driving method {DISPLAY DEVICE AND METHOD FOR DRIVING THE SAME}

The present invention relates to a display device and a method for driving the same, and more particularly, to a display device for gamma correction of an image signal and a method for driving the same.

In order for the video display device to display the video signal, gamma correction is performed on the video signal so that the gamma characteristic of the video signal matches the gamma characteristic of the video display device, because the video display device is configured according to the type of the video display device. This is because it has a changing gamma characteristic. For example, assuming that the available display is a cathode ray tube (CRT) display, current television broadcasting, at the transmitting end, undergoes gamma correction for the gamma characteristics of the CRT display.

Meanwhile, the types of video display devices are increasing in recent years, and in addition to CRT displays, liquid crystal displays (LCDs), plasma display panels (PDPs), and the like are also widely used. When a video display device such as an LCD or PDP other than a CRT display displays a video signal for current television broadcasting, the video signal undoes the gamma correction performed on this video signal at the transmitting end, and the video display device when in use It is necessary to undergo a process for matching the gamma characteristics of the video signal with the gamma characteristics of the video signal.

The present invention relates to a display device and a method for driving the same, and more particularly, to a display device for gamma correction of an image signal and a method for driving the same.

A display device according to an embodiment of the present invention includes a display panel including a plurality of pixels, a control unit correcting an image signal and generating a corrected image signal for driving the display panel, wherein the control unit controls the control of the image signal. The grayscale value of the first signal obtained by correcting the video signal based on the first gamma from the grayscale value of the reference signal and the reference difference value obtained by dividing the grayscale value of the reference signal obtained by correcting the video signal based on the reference gamma from the grayscale value. a storage unit for storing difference data including first difference values obtained by dividing the values; and a first summing unit for generating a first difference summation value obtained by summing absolute values of respective difference values of the difference values of the difference data. and a first adder for generating the corrected video signal based on a result of adding the value and the first difference summation value, wherein the reference gamma is different from the first gamma.

The difference data further includes a second difference value obtained by difference between the gray level value of the first signal and the gray level value of the second signal obtained by correcting the image signal based on the second gamma, and the reference gamma and the first gamma Each is different from the second gamma, and the first sum difference value is a sum of absolute values of each of the reference difference value, the first difference value, and the second difference value.

The first gamma has a value between the reference gamma and the second gamma.

The reference gamma is smaller than the first gamma and the second gamma.

The absolute value of the reference difference value is greater than the absolute value of the first difference value, and the absolute value of the first difference value is greater than the absolute value of the second difference value.

The difference data is a reference grayscale value obtained by correcting the nearby grayscale value based on the reference gamma in a nearby grayscale value adjacent to the grayscale value of the video signal among a plurality of sample grayscale values within an allowable range of the grayscale value of the video signal. and a second sample difference value obtained by difference between a first sample difference value and a first sample difference value obtained by correcting the neighboring tone value based on the first gamma from the reference tone value; a second summing unit generating a second difference summation obtained by summing the one-sample difference value and the second sample difference value, performing an interpolation operation based on the grayscale value of the video signal and the second difference summation value; It further includes an interpolation operation unit that generates an interpolated output value, and a second adder that generates the corrected video signal based on a value obtained by adding the grayscale value of the video signal and the interpolated output value. The difference data further includes a third sample difference value obtained by obtaining a difference between a second grayscale value obtained by correcting the neighboring grayscale value based on a second gamma from the first grayscale value, and the sum of the second difference values is the first sample difference value. It is a sum of absolute values of the difference value, the second sample difference value, and the third sample difference value.

The number of the neighboring gradation values is plural.

A display device according to another embodiment of the present invention includes a control unit that corrects an image signal and generates a corrected image signal for driving the display panel, wherein the control unit corrects the image signal based on a reference gamma to a reference signal. A reference difference value obtained by differentiating the gradation value of the first signal obtained by correcting the video signal based on the first gamma from the gradation value of , and the gradation value obtained by correcting the video signal based on the second gamma from the gradation value of the first signal. a storage unit for storing difference data including a first difference value obtained by dividing the grayscale values of the two signals; a summing unit for generating a difference summation value obtained by adding the absolute value of the reference difference value and the absolute value of the first difference value; a square operation unit that performs a square operation of the gray level value of the video signal, and generates the corrected video signal based on a result of adding the sum of the differences to a value obtained by squaring the gray level value of the video signal; An adder is included, and the reference gamma, the first gamma, and the second gamma are different from each other.

The first gamma has a value between the reference gamma and the second gamma.

The reference gamma is smaller than the first gamma and the second gamma.

An absolute value of a difference between the gray level value of the video signal and the gray level value of the signal obtained by correcting the video signal based on the reference gamma is greater than the absolute value of the reference difference value.

A method of driving a display device according to an embodiment of the present invention includes the steps of receiving an image signal, calculating a grayscale value of a reference signal obtained by correcting the image signal based on a reference gamma from a grayscale value of the image signal from a storage unit, and calculating a differential reference. Selecting a first difference between the difference value and the gray level value of the reference signal based on the first gamma, and summing the absolute values of each of the selected difference values. and generating a corrected image signal based on a result of adding the grayscale value of the image signal and the sum difference value, wherein the reference gamma and the first gamma are different. do.

In a method of driving a display device according to an embodiment of the present invention, a second difference value obtained by calculating a difference between a grayscale value of a second signal obtained by correcting the image signal based on a second gamma from the grayscale value of the first signal is stored in a storage unit. The step of generating a sum difference value includes summing absolute values of each of the reference difference value, the first difference value, and the second difference value, and wherein the reference gamma and each of the first gammas is different from the second gammas.

The first gamma has a value between the reference gamma and the second gamma.

The reference gamma is smaller than the first gamma and the second gamma.

The absolute value of the reference difference value is greater than the absolute value of the first difference value, and the absolute value of the first difference value is greater than the absolute value of the second difference value.

The grayscale value of the reference signal obtained by correcting the video signal based on the reference gamma in the grayscale value of the video signal is corrected using the result of summing the difference between the reference difference value and the difference values in the vicinity of the reference gamma, and stored in the storage unit. It is possible to reduce the capacity of the storage unit by reducing the allocated amount of data to be used.

1 is a schematic block diagram of a display device according to an exemplary embodiment of the present invention.
2a and 2b are block diagrams of a control unit according to an embodiment of the present invention.
3A to 3C are graphs for explaining difference values of difference data.
4 and 5 are graphs for explaining an interpolation function.
6 is a graph for explaining difference values stored in the storage unit 104 according to an embodiment of the present invention.
7 is a block diagram of a controller 100' according to another embodiment of the present invention.
8 is a graph for explaining difference values stored in the storage unit 104 according to another embodiment of the present invention.

Since the present invention may have various changes and various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, it should be understood that this is not intended to limit the present invention to the specific disclosed form, and includes all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Like reference numerals have been used for like elements throughout the description of each figure. In the accompanying drawings, the dimensions of the structures are shown enlarged than actual for clarity of the present invention. Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. Terms are only used to distinguish one component from another. For example, a first element may be termed a second element, and similarly, a second element may be termed a first element, without departing from the scope of the present invention. Expressions in the singular number include plural expressions unless the context clearly dictates otherwise.

In this application, the terms "include" or "have" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that it does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof. In addition, when a part such as a layer, film, region, plate, etc. is said to be "on" or "on" another part, this includes not only the case where it is "directly on" the other part, but also the case where there is another part in the middle thereof. . Conversely, when a part such as a layer, film, region, plate, etc. is said to be "under" another part, this includes not only the case where it is "directly below" the other part, but also the case where another part exists in the middle.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

1 is a schematic block diagram of a display device 1000 according to an embodiment of the present invention.

Referring to FIG. 1 , a display device 1000 according to an embodiment of the present invention includes a display panel 400 displaying an image, a gate driver 200 and a data driver 300 driving the display panel 400, The controller 100 controls driving of the gate driver 200 and the data driver 300 .

The controller 100 receives an image signal IPS and a plurality of control signals CS from the outside of the display device 1000 . The control unit 100 converts the data format of the video signal IPS to meet the interface specifications of the data driver 300 to generate the corrected video signal OPS, and converts the corrected video signal OPS to the data driver 300. to provide.

In addition, the control unit 100, based on a plurality of control signals (CS), the data control signal (DCS, eg, output start signal, horizontal start signal, etc.) and gate control signal (GCS, eg, vertical start signal) , a vertical clock signal, and a vertical clock bar signal) are generated. The data control signal DCS is provided to the data driver 300 and the gate control signal GCS is provided to the gate driver 200 .

The gate driver 200 sequentially outputs gate signals in response to the gate control signal GCS provided from the controller 100 .

The data driver 300 converts the corrected image signal OPS into data voltages in response to the data control signal DCS provided from the controller 100 and outputs the converted data voltages. The output data voltages are applied to the display panel 400 .

The display panel 400 includes a plurality of gate lines GL1 to GLn, a plurality of data lines DL1 to DLm, and a plurality of pixels PX. Although one pixel PX is shown in FIG. 1 for convenience of explanation, a plurality of pixels PX may be substantially arranged in a matrix form.

Each of the pixels PX may display different main colors among red, green, and blue. However, it is not limited thereto, and the pixels PX may display various colors.

The plurality of gate lines GL1 to GLn extend in the second direction DR2 and are arranged parallel to each other in the first direction DR1 perpendicular to the second direction DR2. A plurality of gate lines GL1 to GLn are connected to the gate driver 200 to receive gate signals from the gate driver 200 .

The plurality of data lines DL1 to DLm extend in the first direction DR1 and are arranged parallel to each other in the second direction DR2. A plurality of data lines DL1 to DLm are connected to the data driver 300 to receive data voltages from the data driver 300 .

Each of the pixels PX may be driven by being connected to a corresponding gate line among the plurality of gate lines GL1 to GLn and a corresponding data line among the plurality of data lines DL1 to DLm.

2A and 2B are block diagrams of the controller 100 according to an embodiment of the present invention. 3A to 3C are graphs for explaining difference values of difference data. 4 and 5 are graphs for explaining an interpolation function. 6 is a graph for explaining difference values stored in the storage unit 104 according to an embodiment of the present invention.

Referring to FIG. 2A , the control unit 100 includes a storage unit 104, an input terminal 108, and a correction unit ( CU) may be included.

The storage unit 104 obtains a first sample difference between sample grayscale values set equidistantly between the allowable minimum grayscale value and the maximum grayscale value of the image signal IPS and a reference grayscale value obtained by correcting the sample grayscale value based on the reference gamma. Difference data including the value DB may be stored.

The contents of the first sample difference value (DB) can be expressed as Equation (1) below.

Equation (1): DB =

는 샘플 계조값을 나타낼 수 있다.in equation (1)

may represent a sample grayscale value.

The reference gamma is a value that can be arbitrarily determined, and will be described below on the assumption that the reference gamma is 1.8. However, it goes without saying that the reference gamma may be set in various ways other than 1.8. That is, in the present specification, the reference grayscale values may be values obtained by correcting the sample grayscale values based on the reference gamma of 1.8.

The difference data may further include a second sample difference value D1 and a third sample difference value D2.

The second sample difference value D1 may be a difference value of a first grayscale value obtained by correcting the sample grayscale value based on the first gamma from the reference grayscale value.

The contents of the second sample difference value D1 can be expressed as Equation (2) below.

Equation (2): D1 =

는 샘플 계조값을 나타낼 수 있다.in equation (2)

may represent a sample grayscale value.

The first gamma may be different from the reference gamma. In this specification, it is assumed that the first gamma is 2.2 and will be described below. However, the first gamma may be set in various ways other than 2.2. That is, in the present specification, the first grayscale value may be a value obtained by correcting the sample grayscale value based on the first gamma of 2.2.

The third sample difference value D2 may be a difference between the sample grayscale value and the second grayscale value based on the second gamma from the first grayscale value.

The contents of the third sample difference value D2 can be expressed as Equation (3) below.

Equation (3): D2 =

는 샘플 계조값을 나타낼 수 있다.in equation (3)

may represent a sample grayscale value.

The second gamma may be different from each of the reference gamma and the first gamma. In this specification, it is assumed that the second gamma is 2.4 and will be described below. However, the second gamma may be set in various ways other than 2.4. That is, in this specification, the second grayscale value may be a value obtained by correcting the sample grayscale value based on the second gamma of 2.4.

Accordingly, the first gamma may have a value between the reference gamma and the second gamma.

Hereinafter, the difference values will be described in detail with reference to FIGS. 3A to 3C.

In FIGS. 3A to 3C , a horizontal axis X and a vertical axis Y may each represent a grayscale value of a signal. L may represent the maximum allowable grayscale value of the image signal IPS. As an example, the image signal IPS may be a 6-bit signal, and in this case, the minimum grayscale value may be “000000” and the maximum grayscale value may be “111111”. Hereinafter, the video signal IPS will be described assuming that it is a 6-bit signal. However, the video signal IPS is not limited to 6 bits.

3A shows a reference graph G1 of Y=X and a reference gamma (1.8) correction graph G2. Referring to FIG. 3A , the operating range of the gray level value A of the image signal IPS may be divided into a 3-bit width (000-111). For example, the number of sample grayscale values is 9, "000000", "001000", "010000", "011000", "100000", "101000", "110000", "111000" and "1000000". can

That is, the first sample difference value DB may be a difference between a sample grayscale value and a reference grayscale value corresponding to the sample grayscale value. Arrow a1 may indicate a difference between one sample grayscale value “111000” and a reference grayscale value corresponding to the sample grayscale value “111000”.

3B shows a reference gamma (1.8) correction graph G2 and a first gamma (2.2) correction graph G3. Referring to FIG. 3B , the second sample difference value D1 may be a difference between the first grayscale value corresponding to the sample grayscale value and the reference grayscale value corresponding to the sample grayscale value. Arrow a2 may indicate a difference between a reference grayscale value corresponding to one sample grayscale value "111000" and a first grayscale value corresponding to the sample grayscale value "111000".

3C shows a first gamma (2.2) correction graph G3 and a second gamma (2.4) correction graph G4. Referring to FIG. 3C , the third sample difference value D2 may be a difference between a first grayscale value corresponding to the sample grayscale value and a second grayscale value corresponding to the sample grayscale value. Arrow a3 may indicate a difference between a first grayscale value corresponding to one sample grayscale value "111000" and a second grayscale value corresponding to the sample grayscale value "111000".

Consequently, the difference data may include a first sample difference value DB, a second sample difference value D1, and a third sample difference value D2 corresponding to each of the sample grayscale values. However, it is not limited thereto, and the difference data may further include a third sample difference value and a fourth sample difference value calculated in the same manner as described above. Hereinafter, the difference data will be described by being limited to including the first sample difference value DB, the second sample difference value D1, and the third sample difference value D2.

The correction unit CU may perform a tertiary operation using the difference data, add the result of the operation and the gradation value A of the image signal IPS, and obtain the corrected image signal OPS based on the calculation result. . The cubic operation is a cubic interpolation operation, which may be an interpolation algorithm using a cubic polynomial, and a function of the cubic operation may be defined as a kernel function h(x), and may be defined as Equation (4) below.

... 식 (4)

... Equation (4)

In Equation (4), a is a constant for controlling the characteristics of the interpolation function, and a value between -0.5 and -2 can usually be used for a. 4 is a graph of a kernel function expressed assuming that a is -0.5. The kernel function h(x) may be referred to below as a kernel coefficient.

In Equation (4), “x” may represent a distance between the sample grayscale value and the grayscale value A of the input image signal IPS. In Equation (4), the sample gradation value required to obtain the gradation value of the corrected image signal OPS corresponding to the gradation value A of the image signal IPS is one sample gradation in the x range of -2 or more and less than -1. value (B1), one sample tonal value (B2) in the range of x between -1 and less than 0, one sample tonal value in the range of x between 0 and less than 1 (B3), and one in the range of x between 1 and less than 2 It may be a sample grayscale value (B4) of , a total of four sample grayscale values (B1, B2, B3, B4). Hereinafter, four sample grayscale values B1, B2, B3, and B4 are indicated as nearby grayscale values B1, B2, B3, and B4. As described above, the number of nearby grayscale values B1, B2, B3, and B4 may be plural, and is not limited to four.

In this specification, the function of the correction unit CU is described by taking a process for obtaining a grayscale value of the corrected image signal OPS corresponding to the input grayscale value “A” shown in FIG. 3A.

2A and 3A, the correction unit CU includes a difference value selection unit 103, a coefficient memory unit 102, a coefficient selection unit 101, a summing unit 105, an interpolation operation unit 106, and an adder ( 107) may be included.

The difference value selection unit 103 may input and receive the highest three bits of the gray level value “A” of the image signal IPS. In this specification, it is described as three bits, but may not be limited thereto, and may be two most significant bits and four most significant bits. The difference value selector 103 selects neighboring grayscale values k-1, k. Difference values corresponding to k+1 and k+2 may be selected. For example, when the gradation value "A" of the video signal IPS is "100011", the values of the three most significant bits are 4, and the gradation values corresponding to 4 are 3 (B1, 011000), 4 (B2, 100000), 5 (B3, 101000), and 6 (B4, 110000), and the difference value selector 103 may select difference values corresponding to each of B1, B2, B3, and B4.

Referring to FIGS. 3A to 3C , the difference value selector 103 selects two neighboring grayscale values B1 and B2 smaller than "A" among the nearby grayscale values located near "A" and First sample difference values (d11-d14, DB) corresponding to the two neighboring grayscale values (B3, B4) greater than "A", second sample difference values (d21-d24. D1), and third sample difference values (d21-d24. D1). Sample difference values (d31-d34, D2) can be selected. Referring to FIG. 3A , the first sample difference values corresponding to each of the neighboring grayscale values B1 to B4 are d11, d12, d13, and d14, respectively. Referring to FIG. 3B, the neighboring grayscale values B1 to B4 ) are d21, d22, d23, and d24 respectively, and referring to FIG. 3C, the third sample difference values corresponding to each of the neighboring grayscale values B1 to B4 are d31 and d32 respectively. , d33, d34.

The difference values DB, D1, and D2 selected by the difference value selection unit 103 may be received by the summing unit 105 .

The summing unit 105 may generate a summed difference value MSV by summing the absolute values of each of the difference values corresponding to each of the neighboring grayscale values B1 to B4 . Specifically, the summing unit 105 may sum the difference values by Equation (5) below.

...식 (5)

...Eq. (5)

For example, when gamma-correcting the image signal IPS based on the second gamma, the summing unit 105 performs first sample difference values d11-d14 corresponding to the neighboring grayscale values B1-B4, respectively. , DB), the second sample difference value (d21-d24, D1), and the third sample difference value (d31-d34, D2). At this time, the difference sum value MSV corresponding to the grayscale value "A" of the video signal IPS is d11+d21+d31 at the nearby grayscale value 3 (011000) and d12+d22+ at the nearby grayscale value 4 (100000). d32, d13+d23+d33 at the nearby grayscale value 5 (101000), and d14+d24+d34 at the nearby grayscale value 6 (110000). The generated four differential sum values (MSV) may be output to the interpolation operation unit 106 .

The interpolation operation unit 106 is configured for the four summed-up differences (MSV, that is, d11+d21+d31, d12+d22+d32, d13+d23+d33, d14+d24+d34) received from the difference summation unit 105. By performing weighted addition, an interpolation output value FMV corresponding to the grayscale value A of the image signal IPS may be obtained. The weighting coefficient for the weighted addition is a kernel coefficient expressed in equation (4), which can be selected by the coefficient selection unit 101 from the coefficient memory unit 102. The coefficient memory unit 102 has a coefficient group input terminal ( 110) can store the input kernel coefficients. The coefficient memory unit 102 may store the value of the kernel coefficient h(x) expressed in Equation (4) and x corresponding thereto. The x value is the distance between the grayscale value A of the image signal IPS and the grayscale values adjacent to the grayscale value A of the image signal IPS, and as shown in FIG. 4, x and h(x) relationship can be expressed. Also, x values can be normalized to binary. Therefore, when the variable x input to the kernel function is normalized to a binary number by taking values of -2 or more and 2 or more, x is -10000 (binary number) or more, 10000 (binary number) as shown in FIG. ) can take the following ranges (assuming that a = -0.5 in this specification)

Since the kernel coefficients stored in the coefficient memory unit 102 can be obtained in units of quantization bits of the video signal IPS, the coefficient memory unit 102 can store a total of 32 kernel coefficients.

The coefficient selector 101 may receive an input of three least significant bits of the grayscale value A of the image signal IPS. The coefficient selection unit 101 may select four kernel coefficients h1, h2, h3, and h4 from the coefficient memory unit 102 and output the kernel coefficients to the interpolation operation unit 106. In more detail, the coefficient selector 101 generates four differential sum values (output by the adder 105) based on the values of three bits input from the gradation value (A) of the image signal (IPS). MSV) to nearby gradation values (B1-B4) corresponding to distances x1 to x4 are calculated, and kernel coefficients h1 to h4 corresponding to these four distances can be selected. The coefficient selector 101 selects four kernel coefficients, that is, x=(k-16), x=(k-8), x=k, and x=(k+8), for the input three-bit values. choose For example, when the input grayscale value "A" is "100011", the lowest three bit values are 3. Accordingly, kernel coefficients corresponding to the four x values "-13", "-5", "3" and "11" can be selected.

The interpolation operation unit 106 uses the four kernel coefficients h1 to h4 selected by the coefficient selection unit 101 as weighting coefficients to obtain four sum values d11+d21+d31 and d12+d22+ output from the summing unit 105. For d32, d13+d23+d33, and d14+d24+d34, the interpolated output value FMV may be generated by performing the weighted addition expressed in Equation (6).

Equation (6): FMV = h1 × (d11 + d21 + d31) + h2 × (d12 + d22 + d32) + h3 × (d13 + d23 + d33) + h4 × (d14 + d24 + d34)

The adder 107 may receive the grayscale value (A) of the image signal (IPS) and the interpolation output value (FMV). The adder 107 adds the gradation value (A) of the image signal (IPS) and the interpolated output value (FMV), and based on the resultant value, corrects the image signal (IPS) based on the second gamma to obtain a corrected image signal (OPS) ) can be output.

As such, the storage unit 104 stores the first sample difference value DB, the second sample difference value D1, and the third sample difference value D2, etc., so that the image signal IPS is corrected based on the reference gamma. is performed, the first sample difference value (DB) is used, and when the video signal (IPS) is corrected based on the first gamma, the first sample difference value (DB) and the second sample difference value ( D1) is used and the image signal IPS is corrected based on the second gamma, the first sample difference value DB, the second sample difference value D1, and the third sample difference value D2 ) can be used. That is, correction of the image signal IPS based on a gamma different from the reference gamma (1.8 in this specification) (for example, 2.4 in this specification) is based on difference values in gammas near the reference gamma to the first sample difference value DB. This can be achieved by summing (D1, D2) and adding the interpolated result value and the gray level value (A) of the image signal (IPS).

In FIG. 2A , in gamma-correction of the image signal IPS, adjacent grayscale values B1 to B4 adjacent to the grayscale value of the image signal IPS are used.

However, referring to FIGS. 2B and 3A to 3B , in gamma-correcting the image signal IPS, the gradation value A of the image signal IPS is The difference value corresponding to can be used directly. That is, in the case of FIG. 2B , the image signal IPS may be gamma corrected without performing the interpolation operation of FIG. 2A . The correction process of FIG. 2B may be applied even when the gray level value of the image signal IPS is the same as the sample gray level value described in FIGS. 3A to 3C .

Hereinafter, FIG. 2B will be described, and overlapping content with FIG. 2A will be omitted.

Referring to FIGS. 2B and 3A to 3C , the difference data is the gray level value (STS) of the reference signal obtained by correcting the video signal (IPS) based on the reference gamma in the gray level value (A) of the video signal (IPS) as a difference standard. A first difference value (D1') obtained by dividing the gray level value (SS1) of the first signal obtained by correcting the image signal (IPS) based on the first gamma from the difference value (DB') and the gray level value (STS) of the reference signal; and a second difference value D2′ obtained by calculating a difference between the grayscale value SS1 of the first signal and the grayscale value SS2 of the second signal obtained by correcting the image signal IPS based on the second gamma.

The contents of the reference difference value DB' can be expressed as Equation (6) below.

Equation (6): DB' =

The contents of the first difference value D1' can be expressed as Equation (7) below.

Equation (7): D1' =

The content of the second difference value D2' can be expressed as Equation (8) below.

Equation (8): D2' =

는 영상 신호(IPS)의 계조값(A)을 나타낼 수 있다.In equations (6), (7), and (8)

may represent the gray level value (A) of the image signal (IPS).

The difference value selection unit 103 may select and transmit the reference difference value DB′, the first difference value D1′, and the second difference value D2′ to the summing unit 105 . The summing unit 105 may generate a summed difference value MSV' obtained by summing absolute values of the reference difference value DB', the first difference value D1', and the second difference value D2'. . The adder 107 may generate the corrected image signal OPS based on a result of adding the gradation value of the image signal IPS and the difference sum value MSV'. The corrected image signal OPS may be a signal obtained by correcting the image signal IPS based on the second gamma.

In this way, by storing the reference difference value DB', the first difference value D1', the second difference value D2', etc. in the storage unit 104, the image signal IPS is corrected based on the reference gamma. In the case of performing correction of the image signal IPS based on the first gamma, the reference difference value DB' and the first difference value D1' are used. and, when the image signal IPS is corrected based on the second gamma, the reference difference value DB', the first difference value D1', and the second difference value D2' may be used. there is. That is, the correction of the video signal IPS based on a gamma different from the reference gamma (1.8 in this specification) (for example, 2.4 in this specification) is based on the difference values in gammas near the reference gamma to the reference difference value DB' ( This can be achieved by adding the result of summing D1' and D2') and the gray level value of the image signal IPS.

Referring to FIG. 6 , the first difference value D1' and the second difference value D2' are relatively small compared to the reference difference value DB' of the gray level value A of the image signal IPS. You can check what you have. That is, by performing correction using the result of summing the reference difference value DB' and the difference values D1' and D2' at gammas near the reference gamma, the allocated amount of data stored in the storage unit 104 is reduced. As a result, the capacity of the storage unit 104 can be reduced. Of course, this can be equally applied to the case of correcting an image signal using the above-described sample grayscale values of FIG. 2A.

7 is a block diagram of a controller 100' according to another embodiment of the present invention. 8 is a graph for explaining a difference value according to another embodiment of the present invention.

In FIG. 2, the reference gamma is assumed to be 1.8, but in contrast to this, in FIG. 7, the reference gamma is assumed to be 2.0. The first gamma and the second gamma are the same as those described with reference to FIG. 2 , and portions overlapping those of FIG. 2 are omitted in the following description.

Unlike the correction unit CU of FIG. 2 , the correction unit CU' of the controller 100' of FIG. 7 may further include a square operator 109 .

Referring to FIGS. 7 and 8 , the storage unit 104 corrects the sample grayscale value based on the reference gamma in the sample grayscale value set equidistant between the allowable minimum grayscale value and the maximum grayscale value of the image signal IPS. A first sample difference value DB'' obtained by dividing the reference grayscale value, and a second sample difference value D1'' obtained by dividing the first grayscale values obtained by correcting the sample grayscale value based on the first gamma from the reference grayscale value. difference data to be stored.

The contents of the first sample difference value DB'' can be expressed as Equation (9) below.

Equation (9): DB''=

는 샘플 계조값을 나타낼 수 있다.in equation (9)

may represent a sample grayscale value.

The content of the second sample difference value D1'' can be expressed as Equation (10) below.

Equation (10): D1'' =

는 샘플 계조값을 나타낼 수 있다.in equation (10)

may represent a sample grayscale value.

The summing unit 105 generates a summed difference value MSV″ by summing the difference values DB″ and D1″ corresponding to each of the sample grayscale values and selected by the difference value selection unit 103. can do. Further, the interpolation operation unit 106 may generate an interpolated output value FMV' by performing weighted addition on the summed difference value MSV''.

The square operator 109 may generate a value (DIPS) obtained by squaring the grayscale value (A) of the image signal (IPS).

The adder 107 may generate the corrected video signal OPS' based on a result of adding the interpolated output value FMV' to the value DIPS obtained by squaring the gradation value A of the video signal IPS. there is.

That is, the corrected image signal OPS′ may be a signal obtained by correcting the image signal IPS based on the second gamma.

The rest of the contents are the same as those of FIG. 2A, so they are omitted.

As shown in FIG. 7, the storage unit 104 stores difference data including the first sample difference value DB″ using a virtual reference gamma (2.0 in this specification), and unlike FIG. 2, the image signal IPS The capacity of the storage unit 104 may be reduced by not storing the difference value (the first sample difference value DB in FIG. 2 ) using the grayscale value of .

Likewise, although not shown as a block diagram in the drawing, in gamma-correcting the video signal IPS as shown in FIG. 2B, a difference value corresponding to the video signal can be directly used without using a neighboring grayscale value.

In this case, referring to FIG. 8 , difference data may include a reference difference value DB''' and a first difference value D1'''.

The reference difference value DB''' is a gradation value of a signal obtained by correcting the video signal IPS based on the first gamma in the gradation value A of the signal obtained by correcting the video signal IPS based on the reference gamma. It can be a calm value.

The contents of the reference difference value DB''' can be expressed as Equation (11) below.

Equation (11): DB''' =

는 영상 신호(IPS)의 계조값(A)을 나타낼 수 있다.in equation (11)

may represent the gray level value (A) of the image signal (IPS).

The first difference value D1''' is the difference between the gray level value of the signal obtained by correcting the image signal IPS based on the second gamma and the gray level value of the signal obtained by correcting the image signal IPS based on the first gamma. can be a value

The contents of the first difference value D1''' can be expressed as Equation (12) below.

Equation (12): D1''' =

는 영상 신호(IPS)의 계조값(A)을 나타낼 수 있다in equation (12)

may represent the gray level value (A) of the image signal (IPS).

The summing unit 105 may generate a summed difference value by summing the reference difference value DB''' selected by the difference value selector 103 and the first difference value D1'''.

Similarly to FIG. 7 , the square operator 109 can generate a value DIPS obtained by squaring the grayscale value of the image signal IPS. The adder 107 obtains a sum difference value obtained by adding a value (DIPS) obtained by squaring the gradation value of the video signal (IPS), a reference difference value (DB'''), and a first difference value (D1'''). A corrected image signal OPS' may be generated based on the result of the addition, and the corrected image signal OPS' may be a signal obtained by correcting the image signal IPS based on the second gamma.

Therefore, referring to FIGS. 5 and 8 , the reference difference value DB' corresponding to the gray level value A of the image signal IPS of FIG. 5 is smaller than the reference difference value DB''' of FIG. 8 . , and it can be confirmed that the remaining difference values are smaller than the remaining difference values except for the corresponding reference difference value DB' of FIG. 5 . As a result, compared to FIGS. 2A and 2B , the capacity of the storage unit 104 ′ can be further reduced than FIGS. 2A and 2B by further reducing the allocated amount of data stored in the storage unit 104 . This may be equally applied to the case of FIG. 7 using sample grayscale values.

Although described with reference to the above embodiments, those skilled in the art will understand that the present invention can be variously modified and changed without departing from the spirit and scope of the present invention described in the claims below. You will be able to. In addition, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, and all technical ideas within the scope of the following claims and their equivalents should be construed as being included in the scope of the present invention. .

104: storage unit DB': standard difference value
105: summing unit D1': first difference value
106: interpolation operation unit D2': second difference value

Claims (17)

a display panel including a plurality of pixels;
A control unit correcting an image signal and generating a corrected image signal for driving the display panel;
The control unit
The first gamma corrected the video signal based on the first gamma of the gray level value of the reference signal and the reference difference value obtained by differentiating the gray level value of the reference signal obtained by correcting the video signal based on the reference gamma from the gray level value of the video signal. a storage unit for storing difference data including first difference values obtained by dividing grayscale values of 1 signal;
a first summing unit generating a first summed difference value obtained by summing absolute values of each of the difference values of the difference data;
a first adder configured to generate the corrected video signal based on a result of adding the grayscale value of the video signal and the first difference sum value;
The reference gamma and the first gamma are different from each other,
The difference data further includes a second difference value obtained by difference between the gray level value of the first signal and the gray level value of a second signal obtained by correcting the image signal based on a second gamma;
each of the reference gamma and the first gamma is different from the second gamma;
The first difference sum value is a sum of absolute values of each of the reference difference value, the first difference value, and the second difference value,
the reference gamma is smaller than the first gamma and the second gamma;
The absolute value of the reference difference value is greater than the absolute value of the first difference value, and the absolute value of the first difference value is greater than the absolute value of the second difference value.
delete According to claim 1,
The display device of claim 1, wherein the first gamma has a value between the reference gamma and the second gamma.
delete delete According to claim 1,
The difference data is a reference grayscale value obtained by correcting the nearby grayscale value based on the reference gamma in a nearby grayscale value adjacent to the grayscale value of the video signal among a plurality of sample grayscale values within an allowable range of the grayscale value of the video signal. further comprising a first sample difference value obtained by differencing the value, and a second sample difference value obtained by differencing the first tone value obtained by correcting the neighboring tone value based on the first gamma from the reference tone value;
The control unit
a second summing unit generating a second difference summation value obtained by summing absolute values of respective sample difference values of the difference data;
an interpolation unit configured to generate an interpolation output value by performing an interpolation operation based on the grayscale value of the image signal and the sum of the second differences; and
and a second adder configured to generate the corrected image signal based on a value obtained by adding the grayscale value of the image signal and the interpolated output value.
According to claim 6,
The difference data further includes a third sample difference value obtained by difference between a second grayscale value obtained by correcting the nearby grayscale value based on a second gamma from the first grayscale value;
The second sum difference value is a value obtained by summing absolute values of the first sample difference value, the second sample difference value, and the third sample difference value.
According to claim 6,
A display device according to claim 1 , wherein a plurality of neighboring gradation values are provided.
a display panel including a plurality of pixels;
A control unit correcting an image signal and generating a corrected image signal for driving the display panel;
The control unit
From the gray level value of the reference signal obtained by correcting the video signal based on the reference gamma, the gray level value of the first signal obtained by correcting the video signal based on the first gamma is obtained by dividing the reference difference value and the gray level value of the first signal. a storage unit configured to store difference data including first difference values obtained by calculating differences between grayscale values of a second signal obtained by correcting the image signal based on a second gamma;
a summing unit generating a summed difference value obtained by adding an absolute value of the reference difference value and an absolute value of the first difference value;
a square operation unit performing a square operation on the grayscale value of the image signal; and
an adder configured to generate the corrected video signal based on a result of adding a value obtained by squaring the grayscale value of the video signal and the sum of the differences;
The display device according to claim 1 , wherein the reference gamma, the first gamma, and the second gamma are different from each other.
According to claim 9,
The display device of claim 1, wherein the first gamma has a value between the reference gamma and the second gamma.
According to claim 9,
The display device according to claim 1 , wherein the reference gamma is smaller than the first gamma and the second gamma.
According to claim 9,
wherein an absolute value of a difference between the gray level value of the video signal and the gray level value of the signal obtained by correcting the video signal based on the reference gamma is greater than the absolute value of the reference difference value.
receiving a video signal;
The image signal is obtained from a storage unit based on a reference difference value obtained by dividing the grayscale value of the reference signal obtained by correcting the video signal based on the reference gamma from the grayscale value of the video signal and a first gamma from the grayscale value of the reference signal. selecting a first difference value obtained by difference between the gradation values of the corrected first signal;
generating a summed difference value by summing absolute values of each of the selected difference values; and
generating a corrected video signal based on a result of adding the grayscale value of the video signal and the sum of the differences;
The reference gamma and the first gamma are different from each other,
Selecting, from a storage unit, a second difference value by which a grayscale value of a second signal obtained by correcting the video signal based on a second gamma is different from the grayscale value of the first signal;
The step of generating the difference sum value is
Summing absolute values of each of the reference difference value, the first difference value, and the second difference value;
Each of the reference gamma and the first gamma is different from the second gamma,
the reference gamma is smaller than the first gamma and the second gamma;
The absolute value of the reference difference value is greater than the absolute value of the first difference value, and the absolute value of the first difference value is greater than the absolute value of the second difference value. method.
delete According to claim 13,
The first gamma has a value between the reference gamma and the second gamma.

delete delete

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