KR20180032305A - Gamma correction device and method of gamma correction using the same - Google Patents

Abstract

Provided are a gamma correction device, and a gamma correction method using the same. The gamma correction device comprises a receiving unit, a memory, and a processing unit. The receiving unit is configured to receive image data. The memory is configured to store a first representative correction value corresponding to a first representative value of a first data group and a first reference position in which a correction value is changed within the first data group. When a data value of the image data is included in the first data group, the processing unit is configured to determine whether the data value of the image data corresponds to a position before or after the first reference position, to output the first representative correction value when the data value of the image data corresponds to the position before the first reference position, and to add a first variation of the correction value, changed with respect to the first reference position, to the first representative correction value to be output when the data value of the image data corresponds to the first reference position or to the position after the first reference position.

Description

[0001] The present invention relates to a gamma correction apparatus and a gamma correction method using the gamma correction apparatus.

The present invention relates to a gamma correction apparatus and a gamma correction method using the gamma correction apparatus, and more particularly, to a gamma correction apparatus capable of reducing a capacity of a memory required to perform gamma correction and a gamma correction method using the gamma correction apparatus.

BACKGROUND ART Demands for a display device for displaying an image have been increasing in various forms as an information society has developed. Recently, a liquid crystal display device, a plasma display panel, an organic light emitting display device Organic Light Emitting Display Device) are being utilized.

Such a display device displays an image by operating each pixel of the display device with a luminance corresponding to gray information of each pixel included in the image data. However, due to the nonlinear luminance characteristics of the display device, a linear change in the data value of the image data can be realized with a nonlinear brightness change. Gamma correction is performed on the image data to correct the non-linear luminance implementation of the display device. The gamma correction means that the gamma characteristic of the display device is linearly converted by correcting the data value of the image data. That is, the image data is changed nonlinearly so that the linear change of the data value of the image data is linearly viewed to the human eye, and the display device includes the gamma correction device for processing the image data nonlinearly.

The gamma correction device is configured to output a correction value corresponding to the data value of the received image data. For example, the gamma correction device non-linearly maps data values of image data using gamma curves, outputs correction values, and generates output image data. The correction value corresponding to the data value of the image data is stored in a nonvolatile memory in the form of a lookup table (LUT), and the gamma correction device includes a processing unit configured to search for and output the correction value stored in the memory.

However, the large-area display device and the high-quality display device are receiving the limelight, and the data amount of the video data is increasing. As the data amount of the image data increases, the correction value to be stored in the memory is also increased, and the capacity of the memory is increased. The increase in the capacity of the memory increases the size of the gamma correction device, which makes it difficult to miniaturize the display device, and the high-capacity memory increases the manufacturing cost of the gamma correction device.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a gamma correction device capable of reducing the memory capacity of a gamma correction device by reducing the amount of data to be stored for gamma correction and a gamma correction method using the gamma correction device.

It is another object of the present invention to provide a gamma correction apparatus that can be manufactured with a small size and a low manufacturing cost by reducing the memory capacity of the gamma correction apparatus, and a gamma correction method using the gamma correction apparatus.

The problems of the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided a gamma correction apparatus including a receiving unit, a memory, and a processing unit. The receiving unit is configured to receive the image data. The memory is configured to store a first representative correction value corresponding to the first representative value of the first data group and a first reference position where the correction value changes within the first data group. When the data value of the image data belongs to the first data group, the processing unit determines whether the data value of the image data corresponds to before the first reference position or after the first reference position, When the data value of the image data corresponds to the first reference position or after the first reference position, a correction value that is changed based on the first reference position, Value to the first representative correction value and outputs the first change amount.

According to an aspect of the present invention, there is provided a gamma correction method comprising: receiving image data; searching an nth data group to which a data value of image data belongs in a plurality of data groups; And outputting a correction value corresponding to a data value of the image data when the data value of the image data is before the reference position where the correction value changes in the nth data group, And outputs a correction value corresponding to the data value of the image data when the data value of the image data corresponds to the reference position or after the reference position, (Where n is an integer of 1 or more).

The details of other embodiments are included in the detailed description and drawings.

The present invention stores all the correction values corresponding to the data values of the image data in the memory and stores the representative correction values of the data group and the reference positions at which the correction values change in the data group in the memory, The storage capacity of the memory can be reduced.

In addition, since the present invention reduces the storage capacity of the memory used for gamma correction, it is possible to reduce the size of the gamma correction apparatus, reduce the manufacturing cost of the gamma correction apparatus, There is an advantage that the gamma correction can be efficiently performed.

The effects according to the present invention are not limited by the contents exemplified above, and more various effects are included in the specification.

1 is a schematic block diagram of a gamma correction apparatus according to an embodiment of the present invention.
2 is a schematic graph for explaining a gamma correction curve applied to the gamma correction apparatus according to an embodiment of the present invention.
3 is a flowchart illustrating a gamma correction method using a gamma correction apparatus according to an exemplary embodiment of the present invention.
4 is an illustration of a data group used in the gamma correction method of FIG.
5 is a schematic block diagram for explaining an amount of data stored in a memory used in the gamma correction method of FIG.
FIG. 6 is an exemplary diagram of a plurality of data groups used in the gamma correction method of FIG. 3;
FIG. 7 is an exemplary diagram illustrating a process in which gamma correction is performed using the plurality of data groups of FIG. 6. FIG.
8A and 8B are diagrams illustrating a plurality of data groups applied to a gamma correction method using a gamma correction apparatus according to an exemplary embodiment of the present invention.
9A to 9C are diagrams illustrating another example of a plurality of data groups applied to the gamma correction method using the gamma correction apparatus according to an embodiment of the present invention.
10 is a diagram illustrating an example of a data group applied to the gamma correction method using the gamma correction apparatus according to another embodiment of the present invention.
11 is an exemplary diagram illustrating a process of performing gamma correction using the data group of FIG.
12 is a schematic block diagram illustrating a display device including a gamma correction device according to an embodiment of the present invention.

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. The present invention may, however, 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 scope 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.

The shapes, sizes, ratios, angles, numbers, and the like disclosed in the drawings for describing the embodiments of the present invention are illustrative, and thus the present invention is not limited thereto. Like reference numerals refer to like elements throughout the specification. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Where the terms "comprises", "having", "done", and the like are used in this specification, other portions may be added unless "only" is used. Unless the context clearly dictates otherwise, including the plural unless the context clearly dictates otherwise.

In interpreting the constituent elements, it is construed to include the error range even if there is no separate description.

In the case of a description of the positional relationship, for example, if the positional relationship between two parts is described as 'on', 'on top', 'under', and 'next to' Or " direct " is not used, one or more other portions may be located between the two portions.

It is to be understood that an element or layer is referred to as being another element or layer " on ", including both intervening layers or other elements directly on or in between.

Although the first, second, etc. are used to describe various components, these components are not limited by these terms. These terms are used only to distinguish one component from another. Therefore, the first component mentioned below may be the second component within the technical spirit of the present invention.

Like reference numerals refer to like elements throughout the specification.

The sizes and thicknesses of the individual components shown in the figures are shown for convenience of explanation and the present invention is not necessarily limited to the size and thickness of the components shown.

It is to be understood that each of the features of the various embodiments of the present invention may be combined or combined with each other, partially or wholly, technically various interlocking and driving, and that the embodiments may be practiced independently of each other, It is possible.

Various embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

1 is a schematic block diagram of a gamma correction apparatus according to an embodiment of the present invention. Referring to FIG. 1, a gamma correction apparatus 100 includes a receiving unit 110, a processing unit 120, and a memory 130. The gamma correction apparatus 100 receives the image data RGB and corrects gamma of the image data RGB so that the luminance realized in the display device is linearly recognized based on human vision, And to generate corrected output image data RGB '.

The receiving unit 110 receives the image data RGB. The image data (RGB) includes various information on the image represented by the display device, and includes, for example, gray information for each pixel of the display device.

The processing unit 120 corrects the gamma of the image data RGB to generate output image data RGB '. The data value of the output image data RGB 'corresponds to the data value of the gamma-corrected image data RGB and is referred to as the correction value of the image data RGB. The image implemented by the output image data (RGB ') is linearly recognized in human vision.

The memory 130 stores a representative correction value PV of the data group to which the data value of the image data RGB belongs so that the gamma of the image data RGB is corrected by the processing unit 120, And to store the position RP.

The output image data RGB 'output by the processing unit 120 and the image data RGB received by the receiving unit 110 correspond to each other non-linearly. The nonlinear correspondence relationship between the image data (RGB) and the output image data (RGB ') is shown by the gamma correction curve of FIG.

2 is a schematic graph for explaining a gamma correction curve applied to the gamma correction apparatus according to an embodiment of the present invention. Figure 2 shows a 2.2 gamma correction curve commonly used in display devices.

Referring to FIG. 2, the gamma correction curve is a curve for correcting the gamma of the image data (RGB), and maps the data value of the image data RGB to the output data value of the output image data RGB ' . For example, when the data value of the image data (RGB) received through the receiving unit 110 is 4096, the processing unit 120 maps the data value of 4096 to the corresponding value 545 on the gamma correction curve, Outputs 545 as a correction value of 4096. [ In this case, the processing unit 120 uses the representative correction value PV and the reference position RP stored in the memory 130 to output the correction value 545 of 4096. [ Reference is now made to FIG. 3 to further describe the gamma correction method according to an embodiment of the present invention.

3 is a flowchart illustrating a gamma correction method using a gamma correction apparatus according to an exemplary embodiment of the present invention.

Referring to FIG. 3, a gamma correction method according to an embodiment of the present invention receives image data (S310). The image data RGB are received from the host system outside the display unit through the receiving unit 110. As mentioned above, the image data RGB includes information on the image to be implemented in the display device . In order to realize a high-resolution image, the image data (RGB) can have a large amount of data. For example, the image data (RGB) may have a data amount of 14 bits. In this case, the data value of the image data (RGB) may have a value from 0 to 16383.

Then, an n-th data group to which the data value of the video data belongs is searched in a plurality of data groups (S320). A data group is a set of image data (RGB), which means a data set in which a predetermined number of data values that the image data (RGB) can have. For example, a data group may consist of 16 data values. See Figure 4 together for a detailed description of data groups.

4 is an illustration of a data group used in the gamma correction method of FIG. Referring to FIG. 4, 16 data values from 4096 to 4111 among the data values of the image data (RGB) are composed of one data group 440. The data values from 4096 to 4111 are described in the left column of FIG. The data values of 4096 to 4111 correspond to the data values of the output image data RGB ', respectively. The data values of the output image data RGB 'corresponding to the respective data values are described in the right column of FIG. As described above, the image data RGB is non-linearly mapped to the output image data RGB 'for gamma correction of the image data RGB, and the output image data RGB' described in the right column of FIG. Is a correction value for the gamma-corrected image data (RGB). As shown in FIG. 2, since the gamma correction curve has a low slope in an interval larger than 4096, the correction values corresponding to the data values of 4096 to 4011 can be almost the same. That is, the correction value corresponding to the data value of 4096 to 4011 may be 545 or 546. [ Here, the correction value may correspond to the gradation of the display device. That is, the output data value of the output image data RGB 'corresponds to the gradation of each pixel, and the output image data RGB' is converted to the analog data voltage and can be transmitted to each pixel of the display device.

The output image data RGB 'may have a bit number lower than that of the image data RGB received through the receiving unit 110. For example, the output image data (RGB ') has a bit number of 10 bits.

Referring again to FIG. 3, a gamma correction method according to an exemplary embodiment of the present invention outputs a correction value corresponding to a data value of image data (S330). Specifically, when the data value of the image data (RGB) is before the reference position (RP) at which the correction value changes in the data group 440, the processing unit 120 of the gamma correction apparatus calculates the representative correction value When the data value of the image data RGB corresponds to the reference position RP or after the reference position RP, the correction value PV is corrected based on the reference position RP, And outputs a sum of the amount of change.

The representative correction value PV of the data group 440 means a correction value corresponding to the representative value selected from the data values of the data group 440. [ The representative value of the data group 440 may be selected from among the data values of the data group 440 and may be selected as the data value of the first row of the data group 440. For example, the representative value of the data group 440 may be selected to be 4096, and in this case, the representative correction value of the data group 440 is 545, which is the correction value of 4096. [

The reference position RP means a reference position at which the correction value changes in the data group 440. [ As shown in FIG. 2, since the gamma correction curve has a low slope in an interval larger than 4096, there is almost no change in the correction value in the data group 440 including the data values of 4096 to 4111. [ The data group 440 shown in FIG. 4 can be generated once in the range of 4096 through 4111, and the data group 440 includes one reference position RP. The reference position RP is located in the thirteenth row of the data group 440, in which case the reference position RP is represented by a data value of 13. That is, all the data values correspond to the correction value of 545 from the 13th row to the 12th row based on the 13th row in the data group 440, and all the data values after the 13th row correspond to the correction value of 546. [

The amount of change means the degree of change of the correction value that varies based on the reference position RP. In the data group 440 shown in FIG. 4, the correction value changes from 545 to 546 based on the reference position RP, and in this case, the amount of change becomes 1.

The representative correction value PV and the reference position RP of the data group 440 may be stored in the memory 130 of the gamma correction apparatus 100. [ For example, a representative correction value (PV) 545 corresponding to the representative value 4096 of the data group 440 and a reference position (RP) 13 varying from 545 to 546 are stored in the memory 130, respectively. In this case, the representative correction value PV may be stored at an address corresponding to the representative value. For example, the representative correction value (PV) 545 can be stored at 4096 addresses. In this case, by retrieving the address of the representative correction value PV, the representative value of the data group 440 can be known, and the representative value of the data group 440 does not need to be stored separately. Thus, the storage capacity of the memory 130 can be reduced. On the other hand, the amount of change of the correction value varying with reference to the reference position RP is 1, and thus is not separately stored in the memory 130. [

The correction value corresponding to the data value of the image data RGB can be determined based on the representative correction value PV of the data group 440, the reference position RP and the amount of change of the correction value. For example, when the data value of the image data (RGB) is 4109, 4109 is located in the 14th row of the data group 440. [ 4109 is located after the reference position RP, the correction value corresponding to 4109 is determined by adding the variation amount 1 of the correction value that varies based on the reference position (RP) to the representative correction value (PV) 545 of the data group 440 . That is, the correction value of 4109 is determined as 546 = 545 + 1.

When the data value of the image data (RGB) is 4101, 4101 is located in the 6th row of the data group 440. Since the sixth row is before the reference position RP, the correction value does not change. Therefore, the correction value of 4101 is determined by the representative correction value (PV) 545 of the data group 440. [

The gamma correction method according to an exemplary embodiment of the present invention can determine the correction value for all the data values in the data group 440 by the method described above, thereby effectively reducing the amount of data to be stored in the memory. See FIG. 5 together to describe this in detail.

5 is a schematic block diagram for explaining an amount of data stored in a memory used in the gamma correction method of FIG.

5, the memory 130 does not store all the correction values corresponding to the data values of the image data RGB, and stores the representative correction value PV of the data group 440 and the information of the reference position RP Only. If the memory 130 stores all the correction values corresponding to all the data values of the image data RGB, all 16 correction values corresponding to the 16 data values must be stored. As described above, when the correction value is composed of 10-bit data, the memory 130 requires a total of 160-bit data storage space for the data group 440. However, since the gamma correction method according to the embodiment of the present invention can determine the correction value corresponding to the image data (RGB) through the representative correction value PV, the reference position RP and the change amount, Only the 4-bit data including the representative correction value (PV) 10 bit and the position information of the reference position (RP) can be stored. Here, the data value of the reference position RP may be determined by the number of the row in which the correction value is changed in the data group 440. When the data group 440 is composed of 16 data values, the data value of the reference position RP can have a value between 1 and 16, so that the reference position RP can be represented by 4-bit data. On the other hand, since the change of the correction value in the data group 440 occurs only once, the variation amount for the data group 440 need not be stored separately. That is, when the data value is before the reference position RP, the processing unit 140 outputs the representative correction value of the data group 440, and when the data value corresponds to the reference position RP or after the reference position RP , The correction value corresponding to the data value can be output by adding 1 to the representative correction value of the data group 440. [

As a result, the gamma correction method according to an exemplary embodiment of the present invention can correct for all data values in the data group 440 based on the representative correction value PV, the reference position RP, Value can be determined. Accordingly, the memory 130 stores only 4 bits of the data related to the representative correction value PV and the reference position RP, and the amount of data to be stored in the memory 130 can be reduced from 160 bits to 14 bits.

In the same way, a data group composed of 4112 to 4127, a data group composed of 4128 to 4143, and a data group composed of 4144 to 4159 can be defined. In this case, the capacity of the memory 130 necessary for performing the gamma correction on the image data (RGB) belonging to each data group can be reduced. In this case, not all of the representative correction values PV of each data group need be stored, and only the representative correction value GV of the representative data group selected from among the plurality of data groups is stored in the memory 130, All correction values for the data group can be determined. 6 and 7 together to describe this in more detail.

FIG. 6 is an exemplary diagram of a plurality of data groups used in the gamma correction method of FIG. 3; FIG. 7 is an exemplary diagram illustrating a process in which gamma correction is performed using the plurality of data groups of FIG. 6. FIG.

Referring to FIG. 6, 16 data values 4096 through 4159 of image data (RGB) can be grouped into four data groups 640, 650, 660, and 670. A data group 640 composed of 4096 to 4111 is referred to as a first data group 640 and a data group 650 composed of 4112 to 4127 is referred to as a second data group 650 and data composed of 4128 to 4143 The group 660 is referred to as a third data group 660, and the data group 670 composed of 4144 to 4159 is referred to as a fourth data group 670. [ The reference positions RP1, RP2, RP3 and RP4 at which the correction values are changed in the first to fourth data groups 640, 650, 660 and 670 are referred to as first to fourth reference positions RP1, RP2, RP3 , RP4).

In this case, the correction value for the data value of the image data (RGB) is the representative value of the first representative value PV1 of the first data group 640, the representative value of each of the data groups 640, 650, 660, Based on the amount of change in the correction value that varies based on the difference between the correction values, the first to fourth reference positions RP1, RP2, RP3, and RP4, and the first to fourth reference positions RP1, RP2, RP3, ≪ / RTI >

Here, the difference value between the representative correction values of the data groups 640, 650, 660, and 670, which are successive to each other, is calculated by, for example, the second representative correction value PV2 546 of the second data group 650, The difference value 1 between the first representative correction value PV1 545 of the data group 640 and the third representative correction value PV3 547 of the third data group 660 and the second representative value of the second data group 650 The difference value 1 between the correction value PV2 546 and the fourth representative correction value PV4 548 of the fourth data group 670 and the third representative correction value PV3 545 of the third data group 660 Means the difference value 1.

7, the first representative correction value PV1 of the first data group 640, the difference value between the representative correction values of the successive data groups 640, 650, 660, and 670, To fourth reference positions RP1, RP2, RP3, and RP4 are stored in the memory 130. [ That is, the first representative correction value PV1 545 of the first data group 640 and the difference values 1, 1, 1, and 1 between the representative correction values of the data groups 640, 650, 660, The position data 13, 14, 15, and 15 of the first to fourth reference positions RP1, RP2, RP3, and RP4 are stored in the memory 130, respectively. In this case, since the amount of change in the correction value that varies based on the first to fourth reference positions RP1, RP2, RP3, and RP4 is all 1, the amount of change CV need not be stored separately.

The processing unit 120 may calculate the first representative correction value PV1 of the first data group 640 stored in the memory 130 and the first representative correction value PV1 of the first data group 640 stored in the memory 130 to determine a correction value corresponding to the data value of the image data RGB, The difference between the representative correction values of the groups 640, 650, 660, and 670, and the first to fourth reference positions RP1, RP2, RP3, and RP4. If the data value of the image data (RGB) is 4126, the processing unit 120 first searches the data group to which the 4126 belongs. As shown in FIG. 6, since the data group is composed of 1696 units from 4096, the data group to which 4126 belongs can be determined by calculating (4126 - 4096) / 16. That is, since 4126 - 4096 = 30 and 30/16 = 1.875> 1, 4126 belongs to the second data group 650.

Then, the processing unit 120 determines whether the position of 4126 is located before the second reference position RP2 or after the second reference position RP2. The processing unit 120 calculates a second representative value of the second data group 650 to determine the position of the first data group 4126. The second representative value of the second data group 650 may be determined from the first representative value of the first data group 640 and the first representative value of the first data group 640 may be determined from the first representative value of the first data group 640. [ Can be known by inquiring the address of the first representative correction value PV1. That is, the address 4096 of the first representative correction value PV 1 545 becomes the first representative value of the first data group 640. The second representative value of the second data group 650 is determined by adding 16 to the first representative value of the first data group 640. [ That is, the second representative value of the second data group 650 is 4096 + 16 = 4112. The processing unit 120 then determines whether the position of 4126 from the second reference position RP2 stored in the memory 130 is before or after the second reference position RP2. That is, since 4126 is located at the 15th row, which is larger than the data value 14 of the second reference position RP2, 4126 is located after the second reference position RP2.

The processing unit 120 determines the correction value of 4126 by adding the variation amount CV of the correction value that varies based on the second reference position RP2 to the second representative correction value PV2 of the second data group 650 do. The second representative correction value PV2 is set such that the second representative correction value PV2 of the second data group 650 and the first representative correction value PV1 of the first data group 640 are equal to the first representative correction value PV1, (DV1) < / RTI > That is, the processing unit 120 determines whether the difference (PV1) between the second representative correction value PV2 of the second data group 650 stored in the memory 130 and the first representative correction value PV1 of the first data group 640 The first representative value DV1 is read out and the second representative correction value PV2 is determined by adding the difference value DV1 to the first representative correction value PV1. Thereafter, the correction value 547 for 4126 is calculated by adding the variation amount (CV) 1 of the correction value that varies based on the second reference position RP2 to the second representative correction value PV2 546. [ The processing unit 120 outputs the correction value 547 as output image data RGB '.

The gamma correction method according to an exemplary embodiment of the present invention may include a first representative correction value PV1 of the first data group 640 and a difference between representative correction values of the successive data groups 640, 650, 660, Based on the amount of change in the correction value that varies based on the difference value, the first to fourth reference positions RP1, RP2, RP3, and RP4 and the first to fourth reference positions RP1, RP2, RP3, and RP4, The correction value corresponding to the data value of RGB can be determined. Thus, the amount of data stored in the memory 130 can be significantly reduced. If all the correction values for 4096 to 4159 are stored in the memory 130, the memory 130 needs a storage capacity of 10 bits * 64 = 640 bits and all correction values for 14 bits of image data (RGB) Is stored in the memory 130, a large storage capacity of 10 bits * 16384 = 163840 bits is required.

In this case, in order to reduce the storage capacity of the memory 130, there is a method of storing the difference value between the one representative correction value and the correction values of two data values successive to each other without storing all the correction values for 4096 through 4159 Can be considered. That is, the method includes calculating a difference value (e.g., a difference between the representative correction value 545 for the representative value 4096 and the correction values (e.g., 545 and 545) of two consecutive data values (e.g., 4096 and 4097) For example, 0). However, this method also fails to reduce the storage capacity of the memory 130 efficiently. Specifically, for the 4096 to 4159, a storage capacity is required to store 63 differential values between one representative correction value and the correction values of two consecutive data values, and the memory 130 is still 10bit + (1bit * 63) = 73bit storage capacity is required.

However, the gamma correction method according to an exemplary embodiment of the present invention is different from the gamma correction method in that the difference value 1bit * 3 between the representative correction values of the first representative correction value PV1 of 10 bits and the consecutive data groups 640, 650, 660, 4 bits and 4 bits of data for the first to fourth reference positions 641, 651, 661 and 671, the memory 130 stores the total of 10 bits + 3 bits + 16 bits = 29 bits Capacity. This is because the capacity of the memory 130 can be saved by 96% or more as compared with the method of storing all the correction values of the image data (RGB), and the capacity of the memory 130 Can save more than 50%.

That is, since the storage capacity of the memory 130 can be effectively reduced, the size of the memory 130 can be reduced and the size of the gamma correction apparatus 100 can be reduced have. In addition, the manufacturing cost of the gamma correction apparatus 100 can be reduced as compared with the gamma correction apparatus 100 equipped with the high-capacity memory 130. On the other hand, since a large amount of storage capacity is available in the memory 130, gamma correction for high-resolution image data RGB having a large amount of data can be effectively performed.

The gamma correction method according to an exemplary embodiment of the present invention may apply a data group including a different number of data values for each section of the image data (RGB) based on the gradient change of the gamma correction curve. As shown in FIG. 2, since the gamma correction curve has a slope higher than the slope in the section after 4096 in the section before 4096, the change in the correction value can be generated more frequently. Therefore, in the gamma correction method according to an embodiment of the present invention, the number of data values constituting the data group can be reduced and a more detailed divided data group can be applied to the 4096 interval. See also FIGS. 8A and 8B for a detailed description thereof.

8A and 8B are diagrams illustrating a plurality of data groups applied to a gamma correction method using a gamma correction apparatus according to an exemplary embodiment of the present invention.

Referring to FIG. 8A, a gamma correction method may apply a data group including 8 data values to 1024 to 4095 intervals of image data (RGB). In FIG. 8A, data groups for 1024 through 1055 intervals are illustrated by way of example. In this case, the change of the correction value in one data group can be generated only once, and each of the data groups including eight data values includes one or less reference positions. As described above, the gamma correction method can determine the correction value in the data group through the amount of change in the correction value that varies based on the representative correction value, the reference position, and the reference position of the data group.

Referring to FIG. 8B, the gamma correction method may apply a data group including four data values to 256 to 1023 sections of image data (RGB). In FIG. 8B, data groups for the 256th to 271th intervals are exemplarily shown. In this case, the change of the correction value in one data group can be generated only once, and each of the data groups including four data values includes one or less reference positions.

On the other hand, since the slope of the gamma correction curve is very high in the interval of 0 to 255, and the change of the correction value occurs frequently, the gamma correction method does not apply the data group and stores all the correction values corresponding to the data values of 0 to 255 in the memory Or storing the representative correction value for 0 and storing the difference value between the correction values of two consecutive data values in the memory 130, Can be performed.

The gamma correction method according to an exemplary embodiment of the present invention can efficiently perform gamma correction on image data RGB by applying groups of data having different sizes according to intervals of image data RGB. That is, in the gamma correction method, a large-sized data group is applied to a high gradation period in which a slope of a gamma correction curve is low and a correction value is hardly changed according to a change of image data (RGB), and a gradient of a gamma correction curve The data group of a small size is applied to a low gradation period in which a correction value is frequently changed according to a change of image data (RGB). Accordingly, the amount of data to be stored in the memory 130 is minimized, and the gamma correction for the image data (RGB) can be performed quickly.

Although the gamma correction method according to an embodiment of the present invention described with reference to FIGS. 1 to 8B performs gamma correction of image data (RGB) based on a gamma correction curve of 2.2, The gamma correction method may perform the gamma correction of the image data (RGB) based on the 2.4 gamma correction curve. To explain this in detail, reference is made to Figs. 9A to 9C.

9A to 9C are diagrams illustrating another example of a plurality of data groups applied to the gamma correction method using the gamma correction apparatus according to an embodiment of the present invention.

9A to 9C, the gamma correction method may perform gamma correction of image data (RGB) on the basis of a gamma correction curve of 2.4. In this case, as shown in FIG. 9A, a data group including 16 data values may be applied to 4096 to 16383 sections of the image data (RGB). FIG. 9A illustrates an exemplary data group for 4096 through 4159 intervals.

Also, as shown in FIG. 9B, a data group including 8 data values may be applied to 1024 to 4095 intervals. In Fig. 9B, data groups for 1024 to 1055 intervals are illustrated by way of example.

As shown in FIG. 9C, a data group including four data values may be applied to 256 to 1023 intervals. FIG. 9C shows an exemplary data group for the 255th to 271th intervals.

As shown in FIGS. 9A to 9C, the gamma correction method applies a data group including four data values for the 256 to 1023 intervals and a data group including 8 data values for the 1024 to 4095 intervals And applies a data group including 16 data values to 4095 to 16383 sections. In this case, the change of the correction value within each data group may occur less than once, and each of the data groups includes one or less reference positions. Therefore, the storage capacity of the memory 130 can be efficiently reduced for the gamma correction curve of 2.4.

10 is a diagram illustrating an example of a data group applied to the gamma correction method using the gamma correction apparatus according to another embodiment of the present invention. 11 is an exemplary diagram illustrating a process of performing gamma correction using the data group of FIG. The gamma correction method according to another embodiment of the present invention shown in Figs. 10 and 11 is similar to the gamma correction method shown in Figs. 1 to 8B except that a plurality of reference positions (RP1, RP2, RP3, RP4) Since the gamma correction method according to the embodiment of the present invention is the same as the gamma correction method according to an embodiment of the present invention, a duplicate description thereof will be omitted.

Referring to FIG. 10, in the gamma correction method according to another embodiment of the present invention, a data group 1040 including 64 data values may be applied to the 4096 through 4159 periods. The data group 1040 has 4096 as a representative value and the correction value in the data group 1040 is the first reference position RP1, the second reference position RP2, the third reference position RP3, And changes based on the position RP4.

11, a representative correction value (PV) 545 corresponding to a representative value of the data group 1040 is stored in the memory 1130 of the gamma correction apparatus, and the first to fourth reference positions RP1, RP2, RP3 , RP4) are stored in the memory (13, 30, 47, 63). The gamma correction method according to another embodiment of the present invention may include a representative correction value PV of the data group 1040, first to fourth reference positions RP1, RP2, RP3, RP4, and first to fourth reference positions The correction value of the image data (RGB) is determined based on the amount of change CV of the correction value that varies with the reference values RP1, RP2, RP3, and RP4.

Specifically, when the data value of the image data (RGB) is before the n-th reference position among the plurality of reference positions, the processing unit of the gamma correction apparatus adds the representative correction value PV of the data group 1040 to the first reference position RP1 1) of the correction value that varies based on the first change amount CV of the correction value changed on the basis of the n-1th reference position and the n-1 change amount of the correction value that changes on the basis of the n-1th reference position are successively added to the data value of the image data RGB (CV) to the representative correction value PV of the data group 1040 when the data value of the image data RGB is the nth reference position or more among the plurality of reference positions, The correction value corresponding to the data value of the image data (RGB) is output by sequentially adding the n-th change amount of the correction value that varies based on the n-th reference position.

For example, when the data value of the image data (RGB) is 4126, the processing unit determines which reference position 4126 is located after the first to fourth reference positions RP1, RP2, RP3, and RP4. Specifically, the processor retrieves the representative value 4096 of the data group 1040 by searching for the address of the representative correction value PV stored in the memory 1130. [ The processor retrieves the location of the data value to determine how many rows 4126 are located relative to the representative value 4096. 4126 is located at the 31st row with respect to 4096, so that the position of 4126 is 31. [ Then, the processor retrieves from the position information of the first to fourth reference positions (RP1, RP2, RP3, RP4), which reference position the 4126 is located after. The position information 31 of 4126 is larger than the position information 30 of the second reference position RP2 and smaller than the position information 47 of the third reference position RP3 so that 4126 is present after the second reference position RP2 . The processing section sets the representative correction value PV of the data group 1040 to the first variation amount CV1 of the correction value varying on the basis of the first reference position RP1 and the first variation amount CV1 of the correction value varying on the second reference position RP2 By sequentially adding the second change amount CV2, a correction value corresponding to 4126 is output. Since the first variation amount CV1 and the second variation amount CV2 correspond to 1, the processing section 547 sequentially adds the first variation amount CV1 1 and the second variation amount CV2 1 to the representative correction value PV 545 As a correction value for 4126. [ In this case, since the first variation amount CV1 and the second variation amount CV2 both correspond to 1, the first variation amount CV1 and the second variation amount CV2 may not be separately stored in the memory 1130, The correction value for 4126 can be calculated based only on the representative correction value PV and the position information of the second reference position RP2.

A gamma correction method according to another embodiment of the present invention determines a correction value corresponding to a data value of image data (RGB) using a data group 1040 including a plurality of reference positions. In this case, since only the position information of the representative correction value PV and the first to fourth reference positions RP1, RP2, RP3, and RP4 of the data group 1040 is stored in the memory 1130, The storage capacity can be effectively reduced. For example, when the data group 1040 includes 64 data values, the first to fourth reference positions RP1, RP2, RP3, and RP4 may be represented by data values of 1 to 64, 1130) requires 5-bit data storage space. Therefore, for the data group 1040 including 64 data values, the representative correction value PV 10 bits and the position information 5 bits * 4 = 20 bits for the first to fourth reference positions RP1, RP2, RP3, and RP4 Only data is required. Accordingly, the gamma correction for the 4096 to 4159 intervals can be performed with 30-bit storage data, and the storage capacity of the memory 1130 can be effectively reduced.

Although only the data group 1040 for the 4096 through 4159 intervals is shown in FIG. 10, a plurality of data groups including 64 data values for the 4159 through 16383 intervals may be applied in the same manner. Since the memory 1130 only requires a storage capacity of 30 bits for one data group, the gamma correction for the image data (RGB) having a large amount of data can be performed in the small memory 1130. Thus, there is an advantage that the size of the gamma correction device can be reduced, and the manufacturing cost of the gamma correction device can be reduced. The gamma correction apparatus described with reference to Figs. 1 to 11 may be configured to be mounted on a display device. To explain this in detail, refer to FIG.

12 is a schematic block diagram illustrating a display device including a gamma correction device according to an embodiment of the present invention. 12, a display device 1200 includes a display panel 1240, a data driver 1220, a gate driver 1230, and a timing controller 1210.

The display panel 1240 includes a plurality of sub-pixels SP. The plurality of sub-pixels SP are arranged in a row direction and a column direction and arranged in a matrix form. The plurality of sub pixels SP each emit light of a specific color. For example, the plurality of sub-pixels SP may be composed of a red sub-pixel that emits red, a green sub-pixel that emits green, and a blue sub-pixel that emits blue. In this case, the group of the red sub-pixel, the green sub-pixel and the blue sub-pixel may be referred to as one pixel.

The plurality of sub-pixels SP of the display panel 1240 are connected to the gate line GL and the data line DL, respectively. The plurality of sub-pixels SP are configured to operate based on the gate voltage transferred from the gate line GL and the data voltage transferred from the data line DL.

The timing controller 1210 supplies various control signals DCS and GCS to the data driver 1220 and the gate driver 1230 to control the data driver 1220 and the gate driver 1230.

The timing controller 1220 starts scanning in accordance with the timing implemented in each frame and outputs the image data RGB received from the external host system 10 to a data signal format that can be processed by the data driving integrated circuit 1220 And outputs the output image data (RGB ') and controls the data driving at a proper time according to the scan.

The gamma correction apparatus according to an embodiment of the present invention may be mounted on the timing controller 1220. [ That is, the timing controller 1220 performs gamma correction on the image data RGB received from the external host system 10 to output the output image data RGB ', and the data driver 1220 outputs the output image data RGB' ) To an analog data voltage and provide it to the sub-pixel SP of the display panel 1240. [ In this case, since the data voltage provided to the sub-pixel SP is a gamma-corrected voltage, the image represented through the display panel 1240 can be visually recognized linearly with human vision.

The timing controller 1210 also includes a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a data enable signal DE, a clock signal CLK, and the like in addition to the video data RGB. And receives various timing signals from an external host system 10.

The timing controller 1210 receives image data RGB from the host system 10 and converts the image data RGB into a data signal format that can be processed by the data driver 1220 to output the output image data RGB ' A timing signal such as a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a data enable signal DE and a clock signal CLK is inputted to control the data driver 1220 and the gate driver 1230 And outputs various control signals DCS and GCS to the data driver 1220 and the gate driver 1230, respectively.

For example, in order to control the gate driver 1230, the timing controller 1210 includes a gate start pulse (GSP), a gate shift clock (GSC), a gate output enable signal Gate Output enable (GOE), and the like.

Here, the gate start pulse controls the operation start timing of one or more gate circuits constituting the gate driver 1230. The gate shift clock is a clock signal commonly input to one or more gate circuits, and controls the shift timing of the scan signal (gate pulse). The gate output enable signal specifies timing information of one or more gate circuits.

The timing controller 1210 controls the data driver 1220 such that a source start pulse SSP, a source sampling clock SSC, a source output enable signal Souce Output Enable (SOE), and the like.

Here, the source start pulse controls the data sampling start timing of one or more data circuits constituting the data driver 1220. The source sampling clock is a clock signal that controls the sampling timing of data in each data circuit. The source output enable signal controls the output timing of the data driver 1220.

A timing controller 1210 including a gamma correction device may be connected to a source PCB and a flexible flat cable (FFC) or a flexible printed circuit (FPC) May be disposed on a control printed circuit board (PCB) connected via a connection medium.

A power controller for controlling various voltages or currents to supply or supply various voltages or currents to the display panel 1240, the data driver 1220, the gate driver 1230, and the like may further be disposed on the control printed circuit board. The power controller may be referred to as a power management IC (PMIC).

The source printed circuit board and the control printed circuit board described above may be constituted by one printed circuit board.

The gate driver 1230 sequentially supplies a scan signal of an On voltage or an Off voltage to the gate line GL in accordance with the control of the timing controller 1210 to sequentially supply the gate line GL .

The gate driver 1230 may be located only on one side of the display panel 1240, or on both sides of the display panel 1240, depending on the driving method.

The gate driver 1230 may be connected to a bonding pad of the display panel 1240 by a tape automated bonding (TAB) method or a chip on glass (COG) In Panel type and may be directly disposed on the display panel 1240 or integrated on the display panel 1240 as the case may be.

The data driver 1220 converts the output image data RGB 'received from the timing controller 1210 into analog data voltages and supplies the data voltages to the data lines DL when the specific gate lines are opened. .

The data driver 1220 may be connected to the bonding pad of the display panel 1240 in a tape automation bonding method or a chip on glass method or may be disposed directly on the display panel 1240 and may be mounted on the display panel 1240 As shown in FIG.

In addition, the data driver 1220 may be implemented by a chip on film (COF) method. In this case, one end of the data driver 1220 is bonded to at least one source printed circuit board, and the other end is bonded to the display panel 1240.

The gamma correction apparatus according to an exemplary embodiment of the present invention may be mounted on the timing controller 1210 of the display apparatus 1200 to linearly correct nonlinear luminance characteristics of the display apparatus 1200. [ Thus, the image implemented through the display device 1200 can be viewed linearly in the human eye. In particular, the timing controller 1210 corrects the gamma of the image data (RGB) based on the representative correction value of the data group, the reference position at which the correction value is changed in the data group, and the amount of change of the correction value, can do. Therefore, the memory capacity required for gamma correction of the image data (RGB) can be reduced, and the size of the memory can be reduced. Thus, the size of the timing controller 1210 can be reduced, and the timing controller 1210 can be manufactured at a low cost, so that the manufacturing cost of the display device 1200 can be reduced.

The gamma correction apparatus and gamma correction method using the gamma correction method according to embodiments of the present invention can be described as follows.

A gamma correction apparatus according to an exemplary embodiment of the present invention includes a receiver, a memory, and a processor. The receiving unit is configured to receive the image data. The memory is configured to store a first representative correction value corresponding to the first representative value of the first data group and a first reference position where the correction value changes within the first data group. When the data value of the image data belongs to the first data group, the processing unit determines whether the data value of the image data corresponds to before the first reference position or after the first reference position, When the data value of the image data corresponds to the first reference position or after the first reference position, a correction value that is changed based on the first reference position, Value to the first representative correction value and outputs the first change amount. The gamma correction apparatus according to an embodiment of the present invention does not store all the correction values corresponding to the data values of the image data in the memory but stores the representative correction values and reference positions of the data group in the memory, It is possible to efficiently reduce the capacity of the memory required to perform the operation.

According to another aspect of the present invention, the memory is further configured to store a difference value between representative correction values of each of two consecutive data groups in a plurality of data groups including the first data group, When the data value of the n-th data group belongs to the n-th data group among the plurality of data groups, the processing unit calculates the difference between the second representative correction value of the second data group and the first representative correction value, Th data group and the (n-1) -th representative correction value of the (n-1) -th data group to the first representative correction value to calculate an n-th representative correction value, And outputs the n-th representative correction value. When the data value of the image data corresponds to the n-th reference position or after the n-th position, If, and can be configured in addition to the output to the n-th change of the correction value which varies in n relative to the reference position in the n-th representative correction value (where, n is an integer of 1 or more).

According to another aspect of the present invention, a memory stores a first representative correction value of a first data group as 10-bit data, stores first to n-th reference positions as 4-bit data, The difference value between the representative correction values of two consecutive data groups may be stored as 1-bit data.

According to another aspect of the present invention, the memory may store a first representative correction value of the first data group at an address corresponding to the first representative value.

According to still another aspect of the present invention, the memory further stores a second reference position to an m-th reference position in which the correction value changes in the first data group after the first reference position, In the case of the pre-reference position, the processor outputs a value obtained by sequentially adding to the first representative correction value the (m-1) -th change amount of the correction value changed on the basis of the first to (m-1) -th reference positions, When the value corresponds to the m-th reference position or after the m-th reference position, the processing unit sequentially multiplies the first representative correction value by the m-th change amount of the correction value changed on the basis of the first to m- (Where m is an integer of 1 or more).

According to another aspect of the present invention, when the first change amount to the m-th change amount are 1 and the data value of the image data is before the m-th reference position, the processing unit adds a value obtained by adding m-1 to the first representative correction value And outputs a value obtained by adding m to the first representative correction value when the data value of the image data corresponds to the m-th reference position or after the m-th reference position.

A gamma correction method according to an exemplary embodiment of the present invention includes receiving image data, retrieving an n-th data group to which a data value of image data belongs in a plurality of data groups, Outputting the n-th representative correction value of the n-th data group when the data value of the image data is before the reference position where the correction value changes in the n-th data group, And outputting a correction value corresponding to the data value of the image data, which is added to the n-th representative correction value and added to the change amount of the correction value changed based on the reference position Provided that n is an integer of 1 or more). The gamma correction method according to an embodiment of the present invention performs gamma correction of image data using the representative correction value of the data group to which the data value of the image data belongs and the reference position where the correction value changes in the data group, It is not necessary to store all the correction values corresponding to the data values of the data in the memory, thereby reducing the storage capacity of the memory.

According to another aspect of the present invention, the step of outputting the correction value corresponding to the data value of the image data may include the step of outputting, from among the plurality of data groups, the second representative correction value of the second data group and the first representative correction value Th data group and the (n-1) -th representative correction value of the (n-1) -th data group are sequentially added to the first representative correction value to obtain the n-th representative correction value And a step of determining the number

According to still another aspect of the present invention, an n-th data group includes a plurality of reference positions whose gamma values are changed, and the step of outputting a correction value corresponding to a data value of the image data includes: The m-th reference position is shifted from the m-th reference position to the (m-1) -th reference position by the m-th reference correction value, When the data value of the image data corresponds to the m-th reference position or after the m-th reference position, the correction value corresponding to the data value of the image data is added to the n-th representative correction value By sequentially adding the m change amounts of the correction values changed based on the first change amount to the first change amount based on the first change amount to the m change reference position, (Where m is an integer of 1 or more).

Although the embodiments of the present invention have been described in detail with reference to the accompanying drawings, it is to be understood that the present invention is not limited to those embodiments and various changes and modifications may be made without departing from the scope of the present invention. . Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. Therefore, it should be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

10: Host system
100: gamma correction device
110:
120:
130, 1130: memory
440, 1040: data group
640: first data group
650: second data group
660: third data group
670: fourth data group
1200: display device
1210: Timing controller
1220:
1230: Gate driver
1240: Display panel

Claims (9)

A receiving unit configured to receive image data;
A memory configured to store a first representative correction value corresponding to a first representative value of the first data group and a first reference position where a correction value is changed within the first data group; And
Determining whether a data value of the image data corresponds to before the first reference position or after the first reference position if the data value of the image data belongs to the first data group, When the data value of the video data corresponds to the first reference position or after the first reference position, the first representative correction value is outputted when the value of the video data corresponds to the first reference position, And a processing unit configured to output a first variation amount of the correction value changed based on the first reference position to the first representative correction value. The method according to claim 1,
Wherein the memory is further configured to store a difference value between representative correction values of each of two consecutive data groups in a plurality of data groups including the first data group,
When the data value of the image data belongs to the n-th data group among the plurality of data groups, the processing unit calculates the difference between the second representative correction value of the second data group and the first representative correction value, Th representative correction value by sequentially adding a difference value between an n-th representative correction value of the data group and the (n-1) -th representative correction value of the (n-1) -th data group to the first representative correction value,
And outputs the n-th representative correction value when the data value of the image data corresponds to the n-th reference position before the correction value changes in the n-th data group, N-th reference position, and when the n-th reference position corresponds to or after the n-th reference position, the n-th change amount of the correction value changing based on the n-th reference position is added to the n-th representative correction value.
(Where n is an integer of 1 or more) 3. The method of claim 2,
Wherein the memory stores the first representative correction value of the first data group as 10-bit data, stores the first reference position to the n-th reference position as 4-bit data, And the difference between the representative correction values of the two data groups is stored as 1-bit data. 3. The method of claim 2,
Wherein the memory stores the first representative correction value of the first data group at an address corresponding to the first representative value. The method according to claim 1,
Wherein the memory further stores a second reference position to an m-th reference position in which the correction value changes in the first data group after the first reference position,
If the data value of the image data is before the m-th reference position, the processing unit sets the first representative correction value to the m-1 variation amount of the correction value that varies based on the first variation amount to the (m-1) When the data value of the image data corresponds to the m-th reference position or after the m-th reference position, the processor outputs the first representative value to the first variation amount to the m- And outputting a value obtained by sequentially adding the m-th change amount of the correction value that varies based on the reference position.
(Where m is an integer of 1 or more) 6. The method of claim 5,
The first change amount to the m-th change amount is 1,
The processing unit outputs a value obtained by adding m-1 to the first representative correction value when the data value of the image data is before the m-th reference position, and when the data value of the image data corresponds to the m-th reference position Or after the m-th reference position, outputs a value obtained by adding m to the first representative correction value. Receiving image data;
Retrieving an n-th data group to which a data value of the image data belongs in a plurality of data groups; And
And outputting a correction value corresponding to a data value of the image data when the data value of the image data is before a reference position where the correction value changes in the nth data group, And outputs a correction value when the data value of the image data corresponds to the reference position or after the reference position, and adds the variation of the correction value, which is changed based on the reference position, to the n-th representative correction value, And outputting a correction value corresponding to a data value of the image data.
(Where n is an integer of 1 or more) 8. The method of claim 7,
Wherein the step of outputting the correction value corresponding to the data value of the image data comprises:
And the n-th representative correction value of the n-th data group and the n-th representative correction value of the n-th data group and the (n-1) Th representative correction value by sequentially adding the difference value of the (n-1) -th representative correction value of the n-th representative correction value to the first representative correction value. 8. The method of claim 7,
Wherein the n-th data group includes a plurality of reference positions whose gamma values are changed,
Wherein the step of outputting the correction value corresponding to the data value of the image data comprises:
The first variation amount to the (m-1) th reference correction value varying from the first reference position to the (n-1) -th reference correction value when the data value of the image data is before the m- And sequentially outputting a correction value corresponding to the data value of the image data by adding the m-1 change amount of the correction value,
When the data value of the image data corresponds to the m-th reference position or after the m-th reference position, the correction value changing unit changes the n-th representative correction value to the and sequentially outputting a correction value corresponding to the data value of the image data.
(Where m is an integer of 1 or more)

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