KR101159314B1 - Video modulating device, modulating method thereof, liquid crystal display device having the same and driving method thereof - Google Patents

Abstract

Disclosed are an image processing device having a high speed drive and a low error rate, a processing method thereof, a liquid crystal display device having the same, and a driving method thereof.

The image modulation apparatus of the present invention analyzes the input first image data, processes the first image data by a compression method according to the analyzed result, stores the processed first image data in a frame memory, and stores the first image. The modulated data according to the difference between the data and the second image data output from the frame memory is output.

Therefore, according to the present invention, by using different compression schemes according to image characteristics, reliable image quality can be obtained regardless of image complexity.

Image modulation, high speed drive, compression, image complexity, BTC, YUV, LCD

Description

Image modulating device, processing method thereof, liquid crystal display device having same and driving method thereof {Video modulating device, modulating method, liquid crystal display device having the same and driving method}             

 1 is a waveform diagram showing a luminance change according to data in a conventional liquid crystal display device.

 2 is a view showing a conventional high speed drive type liquid crystal display device.

 3 is a view showing another conventional high speed drive type liquid crystal display device.

4 is a view showing an image modulation device according to an embodiment of the present invention.

5a to 5c are exemplary views for explaining the compression process of the present invention.

6 is a view showing a liquid crystal display device having an image modulation device according to an embodiment of the present invention.

7 is a view showing an image modulation device according to another embodiment of the present invention.

8 illustrates edges included in image data of the present invention.

9 is a view showing a liquid crystal display device having an image modulation device according to another embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

20, 60: image modulation device 21, 33, 39: color space conversion unit

23: compression / restoration 25: compression

27, 37: restoration unit 35, 71: data compensation unit

45, 73: lookup table 61: image analysis unit

63: processor 65: BTC processor

67: frame memory 69: YUV processing unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to image processing, and more particularly, to an image processing device having high speed driving and low error rate, a processing method thereof, a liquid crystal display device having the same, and a driving method thereof.

Light and small and high image display apparatuses capable of displaying images have been developed. The image display device includes a liquid crystal display device, a field emission display device, a plasma display panel, and an electro-luminescence device. .                         

Among these, the liquid crystal display device has advantages of thin, light weight, low power consumption, large panel, and full color.

The liquid crystal display device includes a liquid crystal panel for displaying an image and a driver for driving the liquid crystal panel. The liquid crystal panel includes a first substrate in which pixels defined by each of the gate lines and the data lines are arranged in a matrix form, and thin film transistors are formed in each of the pixels, and are disposed to face the first substrate. And a second substrate having corresponding color filters arranged thereon, and a liquid crystal filled between the first and second substrates. The driver may include a gate driver, a data driver, and a timing controller. The gate driver sequentially generates scan signals for activating the gate lines. The data driver supplies a data signal to pixels on the activated gate lines. The timing controller generates a gate control signal for controlling the gate driver and a data control signal for controlling the data driver.

Therefore, the data signal constituting the image is supplied to the pixels on the gate lines activated by the scan signal, and the light transmittance is controlled by the liquid crystal displaced according to the supplied data signal, thereby displaying a predetermined image.

However, the liquid crystal display device has a disadvantage in that the response speed of the liquid crystal panel is lowered due to the inherent viscosity and elasticity of the liquid crystal. For example, the response speed of the TN mode liquid crystal may vary depending on the physical properties of the liquid crystal material and the cell gap. However, the rising time is 20-80 ms and the falling time is 20-30 ms. The response speed of the liquid crystal is longer than one frame period (NTSC: 16.67ms) of the video. Therefore, as shown in FIG. 1, since the voltage charged in the pixel proceeds to the next frame before reaching the desired voltage, a motion blurring phenomenon in which the screen is blurred in the video appears.

Referring to FIG. 1, in the conventional LCD, when the data VD changes from one level to another level on a frame-by-frame basis due to a slow response speed when a video is implemented, the corresponding display luminance BL does not reach a desired luminance. You will not be able to express the desired color and brightness. As a result, the motion blurring phenomenon appears in the moving picture, and the display quality is deteriorated due to the decrease in the contrast ratio. In order to solve the slow response speed of the liquid crystal display device and to drive it at a high speed, an ODC (Over Driving Circuit), which is a high speed driving method, has been proposed.

2 is a view illustrating a conventional high speed driving type liquid crystal display device.

As shown in FIG. 2, in the conventional LCD, image data composed of a plurality of pixel data is input through an input line 9. Each pixel data is input to the frame memory 1 and the lookup table 3. The pixel data input by the frame memory 1 is delayed for a predetermined period and then output as previous pixel data. Therefore, when current pixel data is input to the lookup table 3, previous pixel data output from the frame memory 1 is input to the lookup table 3. Although only one frame memory 1 is shown in FIG. 2, a conventional liquid crystal display device is provided with at least two frame memories. When the first previous pixel data is stored in the first frame memory, the second previous pixel data may be output from the second frame memory. On the contrary, when the second previous pixel data is stored in the second frame memory, the first previous pixel data may be output from the first frame memory.

The lookup table 3 outputs corresponding modulation pixel data Mdata according to a change between the current pixel data and the previous pixel data. To this end, in the lookup table 3, modulation pixel data mapped by current pixel data and previous pixel data is set as a mapping table. That is, in the lookup table 3, modulation pixel data larger than the current pixel data is set when the current pixel data is larger than the previous pixel data, and conversely, when the current pixel data is smaller than the previous pixel data, the current pixel is set. Modulated pixel data smaller than the data is set.

The timing controller 5 controls the gate control signal GDC and the data driver 7 for controlling the gate driver 6 using the vertical / horizontal synchronization signals V and H and the main clock MCLK. The data control signal DDC is generated.

The gate driver 6 generates a scan signal in response to the gate control signal GDC supplied from the timing controller 5 and supplies the scan signal to the gate lines of the liquid crystal panel 8.

The data driver 7 transmits the modulated pixel data Mdata modulated in the lookup table 3 according to the data control signal DDC supplied from the timing controller 5 to the data lines of the liquid crystal panel 8. To feed.                         

The modulated pixel data Mdata is supplied to the pixels defined by the gate lines and the data lines of the liquid crystal panel 8 to display a predetermined image.

Therefore, the conventional liquid crystal display device can compensate for the slow response speed of the liquid crystal with modulated data, thereby alleviating the motion blur phenomenon in the moving image and displaying an image with a desired color and luminance.

However, the conventional liquid crystal display device has a problem in that the manufacturing cost increases as at least two or more frame memories are required.

In order to solve such a problem, a liquid crystal display (LCD) device which can reduce cost by reducing the number of frame memories using a compression method has recently been proposed.

3 is a view showing another conventional high speed drive type liquid crystal display device. In FIG. 3, the same reference numerals are given to the same elements as in FIG. 2.

As shown in FIG. 3, in the conventional LCD, image data including a plurality of pixel data input through the input line 9 is input to the compression / recovery unit 11 and the lookup table 3.

The compression / recovery unit 11 is a compression unit 12 for compressing block truncation coding (BTC) block data having a predetermined unit of block size among the image data, and the compressed block data via the frame memory 1. The first restoration unit 13 to restore the. The block data may be composed of 2 * 4, 3 * 3, or 4 * 4 pixel data. For example, 16 pixel data may exist in 4 * 4 block data. The block data may be one of R pixel data, G pixel data, or B pixel data. That is, the block data may be designated blocks for each of R, G, and B pixel data.

This BTC compression method is performed by the compression unit 12, which is already well known and will be described briefly below.

First, image data of one frame is divided into a plurality of block data composed of a plurality of pixel data. Each of these block data may be composed of one of 2 * 4, 3 * 3 or 4 * 4 pixel data as described above.

Hereinafter, a block data composed of 2 * 4 pixel data will be described as a sample.

Subsequently, an average value and a standard deviation of each pixel data in the block data are calculated.

The compressed bitmap is calculated using the average value. That is, pixel data above the average value is set to '1', and pixel data below the average value is set to '0'.

The first and second representative values are calculated using the calculated average value and standard deviation. That is, the sum of the average value and the standard deviation is calculated as the first representative value, and the difference value between the average value and the standard deviation is calculated as the second representative value.

The first and second representative values are used when restoring the bitmap to original block data. That is, upon restoration, pixel data set to '1' in the bitmap may be restored to the first representative value, and pixel data set to '0' may be restored to the second representative value. This restoration is performed by the first restoration unit 13.

BTC compression is a lossy compression scheme in which data is lost during compression / restore. Thus, the data compensator 14 is provided to compensate for this loss. The data compensator 14 may include a second decompression unit 15 which restores the block data compressed from the compression unit 12, and block data reconstructed from the first decompression unit 13 (eg, previous block data). ) And a subtraction unit 16 for calculating a difference value between the block data (for example, current block data) restored from the second recovery unit 15, and a current block input to the difference value and the lookup table 3. An adder 17 for calculating the sum with the data is provided.

Therefore, the previous block data may be compensated by the data compensator 14.

The lookup table 3 outputs corresponding modulation data Mdata according to the difference between the current block data input through the input line 9 and the previous block data output from the data compensator 14.

 Since the timing controller 5, the gate driver 6, the data driver 7 and the liquid crystal panel 8 are the same as described above, further description thereof will be omitted.

The conventional liquid crystal display device as described above can reduce the number of frame memories by using BTC compression and enable high-speed driving.

However, the conventional BTC compression method does not become a big problem even if a simple image, that is, an image having few edges, causes a lot of data errors and does not completely restore the original image. However, in the case of a complex image, that is, an image having many edge portions, the edge portion may not be properly restored when compressed by the BTC compression method, thereby causing a problem of degrading image quality. In addition, there is a problem that the desired brightness cannot be obtained due to such data error, resulting in deterioration of image quality.

In addition, as described above, BTC compression requires a complicated calculation process, and a circuit for performing such a calculation process becomes complicated.

Accordingly, an object of the present invention is to provide an image processing device having high speed driving and low error rate, a processing method thereof, a liquid crystal display device having the same, and a driving method thereof.

Another object of the present invention is to provide an image processing device, a processing method thereof, a liquid crystal display device having the same, and a driving method thereof, in which operation is simple and image quality can be improved.

Another object of the present invention is to provide an image processing device, a processing method thereof, a liquid crystal display device having the same, and a driving method thereof, which may improve image quality by changing a compression method according to image characteristics.

According to a first preferred embodiment of the present invention for achieving the above object, a liquid crystal display device comprises: an image modulator for outputting modulation data using a compression method processed differently according to the complexity of the image; A driving unit generating a predetermined driving signal; And a liquid crystal panel displaying the modulated data according to the driving signal.

According to a second preferred embodiment of the present invention, a method of driving a liquid crystal display includes: outputting modulation data by using a compression method processed differently according to an image complexity; Generating a predetermined driving signal; And displaying the modulated data according to the driving signal.

According to a third preferred embodiment of the present invention, an image modulator includes: an image analyzer configured to analyze input first image data; A processor configured to process the input first image data by a compression method according to the analyzed result; A frame memory for storing the processed first image data; And a lookup table configured to output modulation data according to a difference between the input first image data and the second image data output from the frame memory.

According to a fourth preferred embodiment of the present invention, an image modulation method includes: analyzing input first image data; Processing the input first image data by a compression method according to the analyzed result; Storing the processed first image data in a frame memory; And outputting modulation data according to a difference between the input first image data and the second image data output from the frame memory.

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

4 is a diagram illustrating an image modulator according to an exemplary embodiment of the present invention.

As shown in FIG. 4, the image modulation device 20 according to an exemplary embodiment of the present invention may include a first color space converter 21 connected to an input line 47 to which image data is input, and the first color space converter 21. Compression / restoration unit 23 connected to the color space conversion unit 21, frame memory 31 connected to the compression / restoration unit 23, and second color space conversion connected to the compression / restoration unit 23. And a lookup table 45 connected to the input line 47 and the data compensator 35, and a data compensator 35 connected to the second color space converter 33. .

The first color space converter 21 converts adjacent R, G, and B pixel data among R, G, and B image data input to the input line 47 into Y, U, and V data. The R, G, and B image data includes a plurality of R pixel data, G pixel data, and B pixel data. Accordingly, a plurality of Y, U, and V data are generated by the first color space converter 21 from the R, G, and B image data. Each of the Y, U, and V data generated in this way is separated into Y data, U data, and V data.

The predetermined Y, U, and V block data are set using the Y data, U data, and V data separated in this way.

The compression / restore section 23 compresses / restores the Y, U, and V block data. The compression / recovery unit 23 compresses the Y, U, and V block data, and compresses the Y, U, and V block data compressed by the compression unit 25, respectively. A first restoring unit 27 for restoring the V block data is provided. The compression unit 25 is compressed according to the YUV compression method, which will be described later in detail in the operation description.

The Y, U, and V block data compressed from the compression unit 25 before being restored by the first recovery unit 27 are stored in the frame memory 31. Therefore, the frame memory 31 may be connected between the compression unit 25 and the first recovery unit 27. The Y, U, and V block data output from the frame memory 31 are Y, U, and V previous block data, respectively. Hereinafter, the block data output from the frame memory 31 is the previous block data.

The second color space converter 33 converts the Y, U, and V previous block data restored from the first reconstructor 27 into original R, G, and B previous convex data.

The R, G, and B previous block data converted by the second color space converter 33 have a smaller loss than the BTC compression method in the compression / restore process by the compression / recovery unit 23, but some loss occurs. Will be.

To compensate for this slight loss, a data compensator 35 is provided.

The data compensator 35 is connected to the compression unit 25 to restore the Y, U, and V block data (hereinafter, referred to as Y, U, and V current block data) compressed from the compression unit 25. A second color space converter for converting the Y, U, and V current block data restored from the second restorer 37 into original R, G, and B current block data; 39) and a difference value between R, G and B previous block data converted from the second color space converter 33 and R, G and B current block data converted from the third color space converter 39. And a subtractor 41 for calculating a sum of the difference value and the current block data input to the lookup table 45.

Accordingly, data loss may be compensated for by the data compensator 35.

The lookup table 45 outputs the modulation data Mdata corresponding to the difference between the current block data input through the input line 47 and the previous block data output from the data compensator 35.

The operation of the image modulation device 20 according to the exemplary embodiment of the present invention configured as described above will be described.

First, predetermined R, G, and B image data are input through the input line 47. The R, G, and B image data includes a plurality of R pixel data, a plurality of G pixel data, and a plurality of B pixel data capable of displaying an image. In the present invention, description will be given with pixel data having 8 bits each.

The R, G, and B image data are converted into Y, U, and V image data by the first color space converter 21. That is, Y, U, and V data are converted into adjacent R, G, and B pixel data. Accordingly, the Y, U, and V image data may include a plurality of Y, U, and V data. The Y, U and V data are separated into Y data, U data and V data. Each data thus separated is divided into convex data having a predetermined size.

For example, as shown in FIG. 5A, Y, U, and V block data may have a size of 2 * 2. The Y block data includes Y1 to Y4 data each having 8 bits, the U block data includes U1 to U4 data each having 8 bits, and the V block data includes V1 to V4 block data each having 8 bits. do.

The Y1 data, the U1 data and the V1 data are calculated from first R, G and B pixel data, and the Y2 data, the U2 data and the V2 data are calculated from the second R, G and B pixel data. Can be. The remaining Y, U and V data may also be calculated from the third R, G and B pixel data and the fourth R, G and B pixel data. Since the R, G, and B pixel data each have 8 bits, each of the calculated Y, U, and V data also has 8 bits.

Y data is luminance data, and U data and V data mean color difference data. In general, humans are sensitive to U and V data while sensitive to Y data. That is, U and V data are not easily detected by a human even when an error occurs in a moving image represented by many frames, whereas Y data is easily detected by a human even when a slight error occurs.

Therefore, in the present invention, compression is performed at different compression ratios between Y data and U and V data.

As shown in FIG. 5B, the Y block data, the U block data, and the V block data are respectively compressed by the compression unit 25.

The Y block data includes four Y data having eight bits each. Some of the lower bits of the Y data having 8 bits are ignored and do not significantly affect the Y data.

For example, assume that 8-bit Y data consists of 10110110 (= 84). Here, changing the lower two bits to 00 results in 10110100 (= 82). Therefore, the luminance value differs by about two. On the other hand, if the upper two bits are changed to 00, the result is 00110110 (= 30). Therefore, the luminance value differs by about 54 degrees.

Therefore, in Y data having 8 bits, it compresses into Y data having 6 bits from which some less significant bits (lower 2 bits in the present invention) are removed.

Therefore, each Y data included in the Y block data is compressed into remaining bits by removing some lower bits.

The U block data and the V block data include four U data and four V data each having 8 bits.

U block data and V block data may be compressed using an average value. That is, the average of four U data included in the U block data is obtained and the average value Ur is set as the U block data. In addition, an average of four U data included in the V block data is obtained and the average value Vr is set as the V block data. Therefore, the U block data and the V block data can be compressed by increasing four Y data into one U average data Ur and V average data Vr, thereby improving compression efficiency. In this case, each U average data Ur and V average data Vr each have 8 bits.

Then, as shown in FIG. 5C, the U average data Ur and the V average data Vr are compressed into U average data Ur and V average data Vr having 6 bits from which some lower bits are removed. . Accordingly, the U block data and the V block data which are not sensitive to humans are compressed at a high compression rate through two compression processes, and the Y block data which is sensitive to humans is compressed at a low compression ratio by one compression process. In this way, the Y block data is compressed at a low compression rate, and the U and V block data are compressed at a high compression rate, whereby the compression can be performed while suppressing an error occurrence of the Y block data sensitive to a human being as much as possible.

In this way, the Y, U, and V block data compressed by the compression unit 25 are stored in the frame memory 31. Therefore, the Y, U, and Y block data compressed by the YUV compression are stored in the frame memory 31, and the capacity of the frame memory 31 can be greatly reduced by storing the compressed block data. Therefore, only one frame memory 31 may be provided in the image modulation apparatus 20 according to an exemplary embodiment.

As described above, the Y, U and V block data output from the frame memory 31 are the previous block data.

The Y, U, and V previous block data output from the frame memory 31 is restored by the first recovery unit 27 to the original Y, U, and V previous block data. That is, the first restoration unit 27 may be restored in the reverse order of the processing of the compression unit 25. There may be several ways to restore the compressed Y, U and V previous block data. Pixel data included in the compressed Y block data is 6 bits, respectively, and average values Ur and Vr of U and V block data are 6 bits, respectively. In the present invention, the lower partial bits removed from the 6-bit pixel data included in the compressed Y-previous data are treated as '0' and restored to 8-bit pixel data, and the average values of the U and V previous block data each consisting of 6 bits ( The lower part bits removed from Ur and Vr are treated as '0' and the average value (Ur, Vr) of 8 bits is expanded to the original block size. For example, in the case of 2 * 2 previous block data, each of the average values Ur and Vr of U and V previous block data having 8 bits is set equally to four pixel data. Therefore, four pixel data included in 2 * 2 previous block data may be set to an average value Ur and Vr of 8 bits.

Subsequently, the restored Y, U, and V previous block data are converted into original R, G, and B previous block data before being input into the lookup table 45 by the second color space converter 33.

The original R, G, and B old block data converted in this way is better than BTC, but there is a possibility that some data loss occurs. In order to compensate for such data loss, the present invention includes a data compensator 35 including a second reconstructor 37, a third color space converter 39, a subtractor 41, and an adder 43. do.

The Y, U, and V current block data output from the compression unit 25 by the second decompression unit 37 are restored to the original R, G, and B current block data. Subsequently, the reconstructed Y, U, and V current block data are converted into original R, G, and B current block data by the third color space converter 39.

R, G, and B previous block data output by the subtractor 41 from the second color space converter 33 and R, G, and B current blocks output from the third color space converter 39. The difference between the data is calculated. The R, G and B current block data input to the lookup table 45 is added to the difference value by the adder 43 to compensate for the R, G and B previous block data.

Accordingly, the R, G and B current block data input to the input line 47 and the R, G and B previous block data compensated by the data compensator 35 are input to the lookup table 45. In fact, the R, G, and B current block data and the R, G, and B previous block data input to the lookup table 45 are input in pixel data units. For example, the first R current pixel data and the first R previous pixel data adjacent thereto are simultaneously input to the lookup table 45, and the second R current pixel data and the second R previous pixel data adjacent thereto are simultaneously input. Can be. Other pixel data can also be input to the lookup table 45 in this manner.

The lookup table 45 outputs corresponding modulation data Mdata according to the difference between the current pixel data and the previous pixel data. That is, when the difference between the current pixel data and the previous pixel data is 0, the modulation data Mdata of the current pixel data is output. If there is a difference between the current pixel data and the previous pixel data, the modulation according to the difference value is performed. Output data (Mdata). For example, when the current pixel data is larger than the previous pixel data, larger modulation data Mdata may be output. When the current pixel data is smaller than the previous pixel data, smaller modulation data Mdata may be output.

As such, by outputting different modulation data (Mdata) according to the difference between the current pixel data and the previous pixel data, high-speed driving is possible and the image quality can be improved in the liquid crystal display.

In addition, since the image modulation apparatus 20 according to the exemplary embodiment of the present invention is simpler in operation and less likely to generate errors due to compression than conventional BTC compression, a complex image may be implemented at high speed without generating errors. The image modulation apparatus 20 using the YUV compression of the present invention has an excellent data reconstruction ratio, and thus has an advantage of excellent high speed operation in a complex image having many edges.

6 is a diagram illustrating a liquid crystal display device having an image modulation device according to an embodiment of the present invention.

As shown in FIG. 6, the liquid crystal display according to the exemplary embodiment of the present invention includes an image modulation device 20 that outputs modulation data Mdata using YUV compression, a predetermined gate control signal GDC, A timing controller 51 for generating a data control signal DDC, a gate driver 53 for supplying a scan signal in response to the gate control signal GDC, and the modulated data according to the data control signal DDC. A data driver 55 for supplying (Mdata) and a liquid crystal panel (57) for displaying the modulated data (Mdata) are provided.

A detailed configuration of the image modulation device 20 is illustrated in FIG. 3, and a detailed description thereof has already been made, and thus a detailed description thereof will be omitted.

In FIG. 3, the image modulator 20 includes a first color space converter 21 for converting R, G, and B image data into Y, U, and V image data, and the Y, U, and V data. A compression unit 25 for dividing the Y, U, and V block data having a size and compressing the divided Y, U, and V block data, respectively, and storing the Y, U, and V data compressed from the compression unit 25. A frame memory 31, a restoring unit for restoring the Y, U, and V previous block data output from the frame memory 31 to original Y, U, and V previous block data, and a Y restored from the restoring unit. A second color space conversion unit 33 for converting the U and V previous block data into original R, G, and B block data, and R, G, and B conversions converted from the second color space conversion unit 33. A data compensator 35 for compensating block data, and current R, G, and B current block data of the R, R, and V image data; The lookup table 45 outputs the modulation data Mdata according to the difference between the R, G, and B previous block data compensated by the data compensator 35.

For more details, reference may be made to the description of FIG. 3.

The timing controller 51 controls the gate control signal GDC and the data driver 55 to control the gate driver 53 by using the vertical / horizontal synchronization signals V and H and the main clock MCLK. A data control signal DDC is generated for controlling.

The gate driver 53 generates a scan signal in response to the gate control signal GDC supplied from the timing controller 51 and supplies the scan signal to the gate lines of the liquid crystal panel 57.

The data driver 55 receives the modulated pixel data Mdata modulated in the lookup table 45 according to the data control signal DDC supplied from the timing controller 51, and the data lines of the liquid crystal panel 57. To feed.

Accordingly, the modulated pixel data Mdata is supplied to the pixels defined by the gate lines and the data lines of the liquid crystal panel 57 to display a predetermined image.

As such, by applying the image modulator according to the exemplary embodiment of the present invention to the liquid crystal display, high-speed driving is possible and image quality may be improved.

As described above, in the conventional BTC compression method, image quality deterioration does not occur in a simple image having few edges, but image quality deterioration may occur in a complex image having many edges. In contrast, the YUV compression method of the present invention can realize clear image quality regardless of image complexity.

Therefore, when selectively using the BTC compression method or the YUV compression method according to the complexity of the image, it is possible to implement an image capable of high-speed driving without deterioration of image quality.

Hereinafter, a method and apparatus for modulating and displaying an image by changing a compression method according to the complexity of the image will be described.

7 is a diagram illustrating an image modulator according to another exemplary embodiment of the present invention. A part of FIG. 7 may have the same function as that of FIGS. 3 and 4 described above. Hereinafter, the components of FIG. 7 having the same functions as those of FIGS. 3 and 4 will not be described any further. Parts not described will be fully understood from the description of FIGS. 3 and 4.

As shown in FIG. 7, the image modulation device 60 according to another embodiment of the present invention includes an image analyzer 61 for analyzing R, G, and B image data input to the input line 75; A processing unit 63 for processing the inputted R, G, and B image data by a compression method according to the analyzed result, a frame memory 67 for storing the processed R, G, and B image data, and the input And a lookup table 73 for outputting modulation data according to a difference between the R, G, and B image data and the R, G, and B image data output from the frame memory 67. The image modulator 60 according to another embodiment of the present invention may further include a data compensator 71 for compensating the second image data. The data compensator 71 may be provided to compensate for an error occurring in the image data processed by the processor 63.

The image analyzer 61 determines image complexity of the R, G, and B image data. There may be various ways to determine the image complexity. In the present invention, a method of determining the complexity of an image using a difference between adjacent pixels will be described.

As shown in FIG. 8, it is assumed that a total of 80 pixel data is included in image data of one frame. The difference values between the adjacent pixel data P2 and P11 are calculated from P1. For example, the difference value calculated between the first pixel data P1 and the second pixel data P2 is compared with a predetermined first threshold. The first threshold may be arbitrarily set. The first threshold is a variable for determining the edge. That is, when the difference value is greater than or equal to the first threshold value, an edge exists at a boundary between the first pixel data P1 and the second pixel data P2, and the difference value is the value of the difference value. If it is less than or equal to the first threshold, it means that no edge exists at the boundary between the first pixel data P1 and the second pixel data P2. As such, whether or not an edge occurs between the first and second pixel data P1 and P2 is determined by comparing the difference between the first pixel data P1 and the second pixel data P2 and a first threshold value. Detect.

Similarly, whether the edge is generated between the second pixel data P2 and the third pixel data P3 may be detected in the same manner as described above. In this manner, it is detected whether an edge occurs between the first to eightyth pixel data P1 to P80 included in the image data.

In this way, the frequency of the detected edge can be calculated from the image data of one frame.

The frequency of the edge thus calculated is compared with a predetermined second threshold. The second threshold may be set arbitrarily. The second threshold is a variable for determining the complexity of the image. It may be set to half of the total boundaries existing between each pixel data of the image data. For example, when a total of 142 boundaries exist between the pixel data of the image data, the second threshold may be set to 71. When the frequency of the edge is greater than or equal to the second threshold, the image data may be determined as a complex image. When the frequency of the edge is less than or equal to the second threshold, the image data may be determined as a simple image. Accordingly, image complexity of the image data may be determined.

Since the frequency of the edge is 36 in FIG. 8, it is much smaller than the predetermined threshold 71, so that the image data of FIG. 8 may be determined as a simple image.

The image analyzer 61 selects a compression method corresponding to the determined image complexity. The compression method may be either a BTC compression method or a YUV compression method.

The processor 63 processes the R, G, and B image data according to a compression method selected from the image analyzer 61. The processing unit 63 includes a BTC processing unit 65 and a YUV processing unit 69. Accordingly, the processor 63 processes the R, G, and B image data according to the BTC compression method when the compression method selected from the image analyzer 61 is the BTC compression method. In addition, when the compression method selected from the image analyzer 61 is a YUV compression method, the processor 63 converts the R, G, and B image data into Y, U, and V image data, and according to the YUV compression method. Process.

The BTC processor 65 includes the compression / recovery unit 11 of FIG. 3. Since the compression / recovery unit 11 has been described in detail in the description of FIG. 3, further description thereof will be omitted.

The YUV processor 69 includes a first color space converter 21, a compression / restore unit 23, and a second color space converter 33 of FIG. 4. In the description of FIG. 4, since the first color space converter 21, the compression / restore unit 23, and the second color space converter 33 have been described in detail, further description thereof will be omitted. However, since the image data input to the input line 75 is R, G, and B image data, the YUV processing unit 69 converts the R, G, and B image data into Y, U, and V image data in addition to decompression. A process of converting and reconverting to R, G, and B image data after reconstruction may be added.

The frame memory 67 stores the R, G and B image data compressed by the BTC processor 65 or the Y, U and V image data converted and compressed by the YUV processor 69.

The frame memory 67 stores R, G, and B image data (referred to as R, G, and B current image data) input to the input line 75 by the lookup table 73; G and B image data (called pre-R, G and B image data) can be output. The R, G, and B previous image data may be data processed by the BTC processor 65 and stored in the frame memory 67. If Y, U, and V image data are output from the frame memory 67, Y, U, and V image data are converted from R, G, and B image data by the YUV processor 69. , U and V image data may be data stored in the frame memory 67.

Previous image data output from the frame memory 67 may be restored by the BTC processor 65 or the YUV processor 69. That is, the previous R, G, and B image data output from the frame memory 67 may be provided to the BTC processor 65 to be restored to the original R, G, and B previous image data. Alternatively, the Y, U, and V previous image data output from the frame memory 67 are provided to the YUV processor 69 to be restored to the original Y, U, and V previous image data, and then the original R, G, and B can be converted to previous image data.

As described above, the R, G, and B previous image data restored by the BTC processor 65 or the YUV processor 69 may be provided to the lookup table 73. At the same time, the R, G, and B current image data input through the input line 75 may be provided to the lookup table 73.

In the present invention, before the R, G, and B image data restored by the BTC processing unit 65 or the YUV processing unit 69 is provided to the lookup table 73, the R, G, and B previous image data is stored. The data may be compensated by the data compensator 71 and then provided to the lookup table 73.                     

The R, G, and B previous image data reconstructed by the BTC processor 65 or the YUV processor 69 may not be completely restored to the original R, G, and B previous image data. That is, some data values are omitted or modulated during data compression, so when the compressed data values are restored, there is a difference from the original data, which is a data error.

In this case, when the previous image data is directly provided to the lookup table 73 without data compensation and the modulation data according to the difference from the current image data is output, a serious problem may occur. That is, modulation data are set in the lookup table 73 under the assumption that the previous image data provided from the BTC processor 65 or the YUV processor 69 is completely restored. However, when the previous image data provided from the BTC processing unit 65 or the YUV processing unit 69 is not completely restored and thus a difference with the original previous image data is generated, it is desired by the lookup table 73. Unmodulated data can be outputted, and the desired luminance can not be obtained by the outputted modulated data, resulting in deterioration of image quality.

Accordingly, in the present invention, the data compensation unit 71 is provided, and the data error of the previous image data outputted from the BTC processing unit 65 or the YUV processing unit 69 is compensated as much as possible, so that the lookup table 73 is optimal. By outputting the modulated data, the deterioration of image quality can be prevented.

Meanwhile, the R, G and B current image data and the R, G and B previous image data input to the lookup table 73 may be provided in pixel data units, respectively. That is, in the lookup table 73, modulation pixel data mapped by current pixel data and previous pixel data is set as a mapping table. That is, in the lookup table 3, modulation pixel data larger than the current pixel data is set when the current pixel data is larger than the previous pixel data, and conversely, when the current pixel data is smaller than the previous pixel data, the current pixel is set. Modulated pixel data smaller than the data is set.

As such, the lookup table 73 outputs modulation data according to a difference between the current pixel data and the previous pixel data. Previous pixel data are sequentially input to the lookup table 73 from the R, G, and B previous image data output from the data compensator 71. Accordingly, the lookup table 73 outputs modulation data according to a difference value between the current pixel data and the previous pixel data sequentially input.

In general, data errors can be more severe in BTC compression than in YUV compression.

In view of the above, the present invention can obtain a reliable image quality regardless of the complexity of the image by processing a simple image that does not cause a serious problem even if a data error occurs by BTC compression and complex image by YUV compression. have.                     

6, the image modulation device 60 according to another embodiment of the present invention may be applied to a liquid crystal display to display a predetermined image capable of high speed driving.

In the liquid crystal display according to another exemplary embodiment of the present invention, the timing controller 51, the gate driver 53, the data driver 55, and the liquid crystal panel 57 shown in FIG. By employing only the image modulation device 60 according to the example instead of the image modulation device 20 of FIG. It may be displayed on the liquid crystal panel 57.

As described above, according to the present invention, by using the YUV compression method, not only the frame memory capacity but also the number can be reduced, thereby reducing the cost.

According to the present invention, by using the YUV compression method, high speed driving is possible and image quality can be improved.

According to the present invention, by using the YUV compression method, since the calculation process is simple and the circuit is not complicated, high speed driving is possible even in a complicated image.

According to the present invention, by using the YUV compression method with less data loss than the conventional BTC compression, it is possible to prevent the image quality degradation due to data error.

According to the present invention, by using different compression schemes according to image characteristics, reliable image quality can be obtained regardless of image complexity.                     

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (32)

An image modulator for outputting modulated data using a compression scheme processed differently according to the frequency of edges of an image; A driving unit generating a predetermined driving signal; And A liquid crystal panel displaying the modulated data according to the driving signal / RTI &gt; And the image modulator comprises a data compensator to compensate for data generated during the compression and decompression process. The method of claim 1, wherein the image modulator, An image analyzer configured to analyze the input first image data; A processor configured to process the input first image data by the compression method according to the analyzed result; A frame memory for storing the processed first image data; And Look-up table for outputting the modulation data according to the difference between the input first image data and the second image data output from the frame memory Liquid crystal display comprising a. 3. The method of claim 2, And the data compensator compensates for the second image data. The liquid crystal display of claim 2, wherein the first and second image data are R, G, and B image data. The liquid crystal display of claim 2, wherein the first image data is current image data, and the second image data is previous image data. The liquid crystal display of claim 1 or 2, wherein the compression method is one of a block truncation coding (BTC) compression method and a YUV compression method. The liquid crystal display of claim 1, wherein the frequency of the edge is determined based on a first threshold value. The liquid crystal display of claim 1, wherein the edge of the image is determined by comparing a difference value between adjacent pixel data with a second threshold value. Outputting, by the image modulator, modulation data using a compression scheme processed differently according to the frequency of edges of the image; Generating a predetermined driving signal in the driving unit; And Displaying the modulated data on the liquid crystal panel according to the driving signal; Including, And the image modulating unit compensating for the loss of data generated during the compression and decompression process. 10. The method of claim 9, In the image modulator, Analyzing the input first image data by an image analyzer; Processing the input first image data by a processing unit by the compression method according to the analyzed result; Storing the processed first image data in a frame memory; And Outputting modulation data according to a difference between the input first image data and the second image data output from the frame memory in a lookup table; Method of driving a liquid crystal display device further comprising. The method of claim 10, wherein the data compensated by the image modulator is second image data. The method of claim 10, wherein the first and second image data are R, G, and B image data. The method of claim 10, wherein the first image data is current image data, and the second image data is previous image data. The method of claim 9 or 10, wherein the compression method is one of a block truncation coding (BTC) compression method and a YUV compression method. 10. The method of claim 9, wherein the frequency of the edge is determined based on a first threshold value. 10. The method of claim 9, wherein the edge of the image is determined by comparing a difference between adjacent pixel data with a second preset threshold. An image analyzer configured to analyze the input first image data; A processor configured to process the input first image data by a compression method according to the analyzed result; A frame memory for storing the processed first image data; A lookup table configured to output modulation data according to a difference between the input first image data and the second image data output from the frame memory; And And a data compensator for compensating for the loss of the second image data generated during the compression and decompression process. delete 18. The image modulator of claim 17, wherein the first and second image data are R, G, and B image data. 18. The image modulator of claim 17, wherein the first image data is current image data, and the second image data is previous image data. 18. The apparatus of claim 17, wherein the compression method is one of a block truncation coding (BTC) compression method and a YUV compression method. The image modulation apparatus of claim 17, wherein the image analyzer selects a compression method according to a frequency of edges of an image. The image modulation apparatus of claim 22, wherein the frequency of the edge is determined based on a first threshold value. The image modulation apparatus of claim 17, wherein the edge of the image is determined by comparing a difference value between adjacent pixel data with a second preset threshold. The image modulation apparatus of claim 17, wherein the first image data and the second image data are input to the lookup table in pixel data units. Analyzing the input first image data by an image analyzer; Processing the input first image data by a processing unit by a compression method according to the analyzed result; Storing the processed first image data in a frame memory; Compensating for losses incurred during compression and decompression of the second image data output from the frame memory; And Outputting modulation data according to a difference between the input first image data and the compensated second image data in a lookup table; Image modulation method comprising a. delete 27. The method of claim 26, wherein the first and second image data are R, G, and B image data. 27. The method of claim 26, wherein the first image data is current image data, and the second image data is previous image data. 27. The method of claim 26, wherein the compression method is one of a block truncation coding (BTC) compression method and a YUV compression method. The method of claim 26, Analyzing the image in the image analyzer, Select the compression method according to the frequency of the edges of the image, And the frequency of the edge is determined based on a first threshold value. 32. The method of claim 31, wherein the edge of the image is determined by comparing a difference value between adjacent pixel data with a second preset threshold value.

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