KR20080024796A - Image data processing method for display device - Google Patents

Abstract

A method for processing image data in a display device is provided to prevent a final image from being deteriorated by separately compressing Y data and Cb and Cr data, thereby improving the accuracy of data restored after compression. RGB raw data are received. The RGB raw data are converted into YCrCb format(ST1). Y data and CrCb data of the YCrCb format are separately compressed in different compression types(ST2,ST3). The compressed Y data and the compressed CrCb data are respectively restored in corresponding compression types. The restored Y data and the restored CrCb data are coupled, and the coupled data are converted into RGB restoration data(ST4).

Description

Image data processing method for display device

1 is a diagram illustrating a data overdriving driving method applied in the prior art and a data compression algorithm applied thereto.

2 is a block diagram illustrating a data compression method of the image data processing method for a display device according to the present invention;

<Brief description of the main parts of the drawing>

10: data compression unit 20: frame memory

30: first data restorer 40: second data restorer

50: subtractor 60: adder

70: lookup table

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image data processing method of a display device, and more particularly, to an image data processing method including a data compression and decompression method in which a deterioration of image quality does not occur during data compression driving for overdriving of a display device.

Recently, a data over driving driving method using modulated data for improving pixel response speed and luminance compensation of a display device has been widely used.

Such a data overdriving driving method and a data compression algorithm applied thereto will be briefly described with reference to FIG. 1 as follows.

First, in order to perform data overdriving, data compression, decompression, comparison, and proper data output must be performed.

The data compression unit 10 performs data compression during this process, and the data compression unit 10 generally uses a block truncation coding (BTC) scheme for data compression and restoration.

The data The high-level BTC method in the compression section (10), 2 × 2, 3 × 3 first pixel by pixel for the data compression unit 10, the RGB image data that is input in units of frames (D _RGB), Or divide into arbitrary block units such as 4 × 4 units.

Thereafter, any one data block is selected from among data blocks divided into a plurality of block units, and an average value and a standard deviation of the data included in the selected data block are calculated.

Next, the bitmap is set to "1" if each data value of the data block is equal to or higher than the average value, and to "0" if it is less than the average value.

For example, if a data block divided into 2 × 4 unit blocks is as shown in Table 1 below, the average value of all the data is 52 and the standard deviation is 8, so that the bitmap is written as shown in Table 2.

57 48 65 50 70 55 60 68

            TABLE 1

One 0 One 0 One One One One

      TABLE 2

Of course, the calculated average value, standard deviation and bitmap are stored in the frame memory 20.

Next, the first and second restore values A and B are calculated using the average value and the standard deviation calculated by the first data restorer 30, and the first and second restore values are data. This value is used when restoring.

The method for obtaining the first and second restored values A and B is as follows.

1) First Restored Value (A) = Average + Standard Deviation = 52 + 8 = 60

2) Second Restored Value (B) = Average-Standard Deviation = 52-8 = 44

The first and second restoration values A and B calculated as described above are applied to the bitmap, and the first restoration value A is a restoration value of "1" of the bitmap, respectively, and the second restoration value is applied to the bitmap. The value B is applied as a reconstruction value of "0" of the bitmap to calculate a reconstruction data block as shown in Table 3 below.

60 44 60 44 60 60 60 60

           TABLE 3

However, when comparing the restored data block by the BTC method calculated in the <Table 3> with the first data block of the <Table 1>, it can be seen that the restoration of the data is not completely performed and some data is deformed and lost. The second data restorer 40, the subtractor 50, and the adder 60 are configured to compensate for the data restoration loss.

The second data restorer 40 restores the data compressed from the data compression unit 10, and the subtractor 50 restores the data restored from the first data restorer 30 (that is, the previous block). Data) and a difference value between the data (current block data) restored from the second data restorer 40, and the adder 60 is configured to input RGB image data D _RGB and the subtractor 50. Calculate the sum with the difference value

Therefore, the data restored from the first data restoring unit 30 (that is, the previous block data) is compensated.

The look-up table 70 may convert the corresponding RGB data into the converted data D _{RGB_M} according to the difference between the input RGB image data D _RGB block and the previous block data output from the adder 60. To the () side. Thereafter, the source driver outputs the input converted data to a display panel (not shown) to display an image.

The BTC scheme as described above can be made into a bitmap that simplifies the data value, thereby reducing the memory capacity of the frame memory 20 or the number of memory elements, and enabling high-speed driving.

However, as described above, since a lot of data loss occurs, the image quality of the image is degraded due to the loss of data in an image having many edges or many details.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a data compression algorithm that does not cause deterioration in image quality when driving data compression for overdriving the display device.

In order to achieve the above object, the present invention comprises the steps of receiving RGB raw data; Converting the RGB raw data into a YCrCb format; Compressing the Y data and the CrCb data of the YCrCb format by different compression methods; Restoring the compressed Y data and CrCb data to a restoration scheme corresponding to each compression scheme; A method of processing image data for a display device includes combining the restored Y data and CrCb data and converting the converted Y data into RGB reconstructed data.

The image data processing method for a display device further includes storing the compressed Y data and CrCb data in a frame memory, respectively.

The image data processing method for the display device may include configuring a lookup table and determining and outputting RGB converted data for overdriving of the display device from the lookup table using the RGB reconstruction data and the RGB raw data. It includes more.

In the image data processing method for the display device, the Y data is compressed by a BTC method, and the CrCb data is compressed by a subsampling method.

The image data processing method for the display device further includes compensating for data loss in the restored Y data and CrCb data.

In the image data processing method for the display device, the input RGB raw data includes one block divided into one of 2 × 2, 2 × 4, and 4 × 4 in pixel units among RGB raw data for one frame. It is characterized in that the luminance data.

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

First, in the present invention, in order to calculate RGB converted data from RGB raw data for overdriving of a display device, the BTC method and the subsampling method are mixed to generate RGB converted data, thereby improving image quality and improving compression ratio. In particular, the image data compression in the data compression unit (10 in FIG. 1) and the first data restorer (30 in FIG. 1) in the data overdriving driving method of the display apparatus as described above with reference to FIG. And a new restoration method.

FIG. 2 is a block diagram illustrating a data compression method according to the image data processing method for a display device of the present invention, and is a method applicable to both a liquid crystal or an organic EL display device performing overdriving.

First, a plurality of RGB raw data (D _RGB ) for one frame to be input are divided into data blocks in units of 2 × 2 pixels, and one of the divided blocks is selected. Of course, the divided data blocks may be divided into 2 × 4 units or 4 × 4 units, but it is preferable to divide them into 2 × 2 units in order to minimize data loss due to the restoration after compression. In addition, the input RGB raw data may be one of 8 bits, 16 bits, and 24 bits.

Next, each of the RGB raw data (D _RGB ) included in the selected data block is converted into a YCrCb format. Known and can be converted by the following formula (1) to formula (3).

Formula (1) Y = 0.299R + 0.587G + 0.114B

Formula (2) Cr = R-Y

Formula (3) Cb = B-Y

Where Y is a luminance component and CrCb represents a color component.

After converting the RGB raw data into YCrCb data through the above formulas (1) to (3), the Y data and the CrCb data are separated.

Here, the separated Y data and the CrCB data are respectively compressed by different data compression methods, wherein the Y data is compressed by the BTC method and the CrCb data is compressed by the subsampling method (ST2, ST3).

Since the BTC scheme has already been described in the related art, the subsampling scheme will be briefly described below.

First, when Cr data and Cb data of a 2 × 2 data block are configured as shown in Tables 4 and 5, respectively, an average value of data included in each of the data blocks is calculated.

100 102 98 90

           TABLE 4

110 100 92 96

     TABLE 5

When the average value is calculated, the average value of Cr data of the <Table 4> is 98, and the average value of the Cb data of the <Table 5> is 100. As a result, the data block of Table 4 has a value of 98 as a representative value through compression, and the data block of Table 5 has a value of 100 as a representative value through compression, resulting in a 4: 1 compression ratio. Will be provided.

Next, when each data value of the data block is replaced with the representative value, a restored data block as shown in Tables 6 and 7 below may be configured.

98 98 98 98

       TABLE 6

100 100 100 100

 TABLE 7

As described above, the subsampling method is a method of compressing data of a specific region by selecting one representative value and then restoring data of the specific region again using the representative value. Therefore, this method has a compression ratio twice as large as that of the BTC method which selects and compresses data of a specific region as two representative values. In addition, since it is a method of restoring after compressing by dividing into luminance information and color information, there is an advantage that the loss is very small when restoring data.

In addition, the Y compressed data and the CrCb compressed data calculated in different manners as described above are stored in the frame memory (20 of FIG. 1), respectively.

Accordingly, in the image processing method for overdriving the display device according to the present invention, the Y data compressed by the BTC method and the CrCb data compressed by the subsampling method are used as one compressed data (ST4). The combination of server sampling method that provides twice the compression rate provides higher data compression rate compared to the data compression method that used only BTC method, which provides the advantages of reducing the number of frame memory or reducing the memory capacity. .

Then, after reconstructing the Y data compressed by the BTC method and the CrCb data compressed by the subsampling method to the reconstruction method according to each compression method, the data is reconstructed into the YCrCb format composed of the reconstructed data. This converts it back into RGB format data. Of course, this data restoration operation is performed by the first data restorer 30 of FIG. 1. Here, the compressed data recovery method in the BTC method is described through Table 3, and the compressed data recovery method in the subsampling method is described in Tables 6 through 7.

The data restored to the RGB restored data through the first data restorer 30 may be described later with reference to FIG. 1, such as the second data restorer 40, the subtractor 50, and the adder 60. Through the process of compensating for the loss of the reconstructed data, it is input to a separately configured lookup table (70 in FIG. 1) to calculate separate RGB converted data for overdriving.

As described above, the image data processing method according to the present invention converts RGB image data into a YCrCb format, and compresses and operates the Y data in a BTC scheme and the CrCb data in a subsampling scheme having a higher compression ratio than the BTC scheme. Therefore, it is possible to take advantage of the capacity and number of components of the frame memory according to the increase in the data compression rate. Since the Y data, the Cb, and the Cr data are separately compressed, the accuracy of the reconstructed data after compression is increased, so that the image quality in the final displayed image is increased. It offers the advantage that no degradation occurs.

Claims (6)

Receiving RGB raw data; Converting the RGB raw data into a YCrCb format; Compressing the Y data and the CrCb data of the YCrCb format by different compression methods; Restoring the compressed Y data and CrCb data to a restoration scheme corresponding to each compression scheme; Converting the restored Y data and CrCb data into RGB reconstructed data Image data processing method for a display device including a The method according to claim 1, Storing the compressed Y data and CrCb data in a frame memory, respectively. Image data processing method for a display device further comprising The method according to claim 1, Configuring a lookup table and determining and outputting RGB converted data for overdriving the display device from the lookup table using the RGB reconstruction data and the RGB raw data Image data processing method for a display device further comprising The method according to claim 1, The Y data is compressed by a BTC method, and the CrCb data is compressed by a subsampling method. The method according to claim 1, Compensating for data loss in the restored Y data and CrCb data Image data processing method for a display device further comprising The method according to claim 1, The input RGB raw data is luminance data of one block divided into one of 2 × 2, 2 × 4, and 4 × 4 in pixel units among the RGB raw data for one frame. Image data processing method

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