KR100480177B1 - Apparatus And Method For Driving Plasma Display Panel Using An Enlarging Method Of Dynamic Range - Google Patents

Abstract

The present invention relates to an apparatus and method for driving a plasma display panel using a dynamic range expansion method for improving image quality deterioration during dark processing of a display screen during moving image display.

The driving device of the plasma display panel using the dynamic range expansion method according to the present invention is a frame memory for storing moving image data input from an external input line in units of frames, and is connected between the frame memory and the panel, and has a minimum distribution of lower and upper gray levels. Dynamic range converter for converting the dynamic range of video data according to the level information, and minimum distribution lower for detecting the highest gray level and lower gray level for one frame by being connected in parallel with the frame memory between the input line and the dynamic range converter. And an inverse gamma correction unit which is connected in series between the upper gray level detector, the dynamic range converter, and the panel to inversely gamma correct the dynamic range-converted video data to linearly convert luminance values according to grayscale values of the video signal. , The frame A delay unit connected in parallel with the dynamic range converter and an inverse gamma correction unit to delay input data from the frame memory for a predetermined time between the memory and the panel, and connected in series between the inverse gamma correction unit and the panel. Compare the delayed data with the gamma corrected data from the inverse gamma correction unit and output the gamma corrected data if the delayed data is greater than or equal to the gamma corrected data, and if the delayed data is smaller than the gamma corrected data, A peak compensator for outputting the delayed data to compensate for peak values of the data; The minimum distributed lower gray level detector is configured to detect the minimum distributed gray level at a lower threshold distribution ratio than the minimum distributed upper gray level detector.

According to this configuration, the driving apparatus and method of the plasma display panel using the dynamic range expansion method according to the present invention reduces the dynamic processing limit on the dark portion for moving picture input image such as a movie through a DVD player having a lot of dark areas. As a result, deterioration of image quality can be prevented.

Description

Apparatus And Method For Driving Plasma Display Panel Using An Enlarging Method Of Dynamic Range}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display panel, and more particularly, to an apparatus and method for driving a plasma display panel using a dynamic range expansion method for improving image quality deterioration during dark processing of a display screen during moving image display.

Plasma Display Panel (hereinafter referred to as "PDP") is a display device using visible light generated from a phosphor when ultraviolet light generated by gas discharge excites the phosphor. PDP is thinner and lighter than Cathode Ray Tube (CRT), which has been the mainstay of display means, and has the advantage of realizing high definition / large screen.

The PDP has an upper substrate and a lower substrate which are installed to face each other with partition walls therebetween. The upper substrate includes a scan electrode and a sustain electrode formed in a direction crossing the partition wall. The lower substrate includes an address electrode formed in a direction parallel to the partition wall, and a dielectric layer formed to cover the address electrode. The discharge cell is positioned at the intersection of the scan electrode, the sustain electrode and the address electrode.

The PDP is driven by dividing one frame into several subfields having different emission counts in order to realize gray levels of an image. Each subfield is divided into a reset period for uniformly causing discharge, an address period for selecting a discharge cell, and a sustain period for implementing gray scale according to the number of discharges.

In the address period, scan pulses are supplied to the scan electrodes, and data pulses synchronized with the scan pulses are supplied to the address electrodes. At this time, an address discharge occurs in the discharge cell supplied with the scan pulse and the data pulse. After the scan pulses are supplied to all the scan electrodes, the sustain pulses are alternately supplied to the scan electrodes and the sustain electrodes. When a sustain pulse is supplied to the scan electrode and the sustain electrode, sustain discharge occurs in the discharge cells in which the address discharge has occurred.

When the image is to be displayed in 256 gradations, the frame period (16.67 ms) corresponding to 1/60 second is divided into eight subfields. Here, the reset period and the address period of each subfield are the same for each subfield, while the sustain period and the number of discharges thereof are 2 ⁿ (n = 0,1,2,3,4,5,6,7) in each subfield. , 8). As described above, since the sustain period is changed in each subfield, gray levels of an image can be realized.

The PDP is driven by enlarging the dynamic range of moving images in order to improve contrast.

1 is a block diagram showing a driving apparatus of a PDP using a dynamic range expansion method according to the prior art.

Referring to FIG. 1, a driving apparatus of a PDP using a dynamic range expansion method according to the related art includes a frame memory 14, lower and upper gray level histogram detectors 22A and 22B, minimum distribution lower and upper gray level value determination units. 24A and 24B, the dynamic range adjusting unit 16, and the PDP driving unit 18 are provided.

The frame memory 14 stores the data from the input line 12 in one frame unit and supplies the data to the dynamic range adjusting unit 16.

The histogram detectors 22A and 22B of the lower and upper gray levels detect the histograms of the lower and upper gray levels for each gray level on the basis of the data from the input line 12 by one frame. This first obtains the overall distribution of each gray level for the input screen of one frame. The histogram H (I), which is a gray level distribution value of the input data, is detected based on the overall distribution. At this time, histograms are mainly detected at gray levels, such as about 0 to 20 gray and 220 to 255, to determine minimum and maximum gray levels (MIN and MAX).

The minimum distribution lower and upper gray level value determination units 24A and 24B determine an arbitrarily set reference ratio and determine lower and upper gray levels (MIN, MAX) having less gray level distribution through histograms of detected lower and upper gray levels. do.

The dynamic range adjusting unit 16 enlarges the dynamic range of the input data using the data input from the frame memory 14, the minimum distribution lower and upper gray level values. The dynamic range adjuster 16 supplies input data having an enlarged dynamic range to the PDP driver 18.

The PDP driver 18 corrects the digital signal input from the dynamic range adjuster 16 and supplies it to the panel. To this end, the PDP driver 18 includes the first inverse gamma correction unit 32A, the gain control unit 34, the error diffusion unit 36, the subfield mapping unit 38, and the data alignment unit 40 as shown in FIG. And a second inverse gamma correction unit 32B, an average picture value (APL) unit 44, a waveform generator 46, and a panel 48.

The first and second inverse gamma correction units 32A and 32B perform inverse gamma correction on the video signal input from the dynamic range adjusting unit 16 to linearly convert the luminance value according to the gray value of the image signal.

The APL unit 44 receives the video data corrected by the second inverse gamma correction unit 32B and generates an N-stage signal for adjusting the number of sustain pulses. The gain controller 34 amplifies the video signal corrected by the first inverse gamma correction unit 32A by the effective gain.

The error diffusion unit 36 finely adjusts the luminance value by diffusing an error component of a cell into adjacent cells. The subfield mapping unit 38 reallocates the video data corrected by the error diffusion unit 36 for each subfield.

The data aligner 40 aligns the video signal to be supplied to the panel 48, and supplies the video signal to an address driving integrated circuit (IC) not shown.

The waveform generator 46 generates a timing control signal based on the N-stage signal input from the APL unit 44, and converts the generated timing control signal into an address driving IC, a scan driving IC, and a sustain driving IC of the panel 48. Supply.

In detail, the second inverse gamma correction unit 32B first performs inverse gamma correction on the video signal input from the dynamic range adjustment unit 16 and supplies the inverse gamma correction unit to the APL unit 44. The APL unit 44 receiving the inverse gamma corrected video signal generates an N-stage signal for adjusting the number of sustain pulses, and supplies it to the waveform generator 46. The waveform generator 46 generates a timing control signal using the N-stage signal input from the APL unit 44, and supplies the generated control signal to the address driving IC, the scan driving IC, and the sustain driving IC.

The first inverse gamma correction unit 32A performs inverse gamma correction on the video signal input from the dynamic range adjustment unit 16 and supplies it to the gain control unit 34. The gain control unit 34 receiving the inverse gamma corrected video signal amplifies the corrected video signal by an effective gain and supplies it to the error diffusion unit 36. The error diffusion unit 36 error-spreads the video signal input from the gain control unit 34 to finely adjust the luminance value. The video signal output from the error diffusion unit 36 is input to the subfield mapping unit 38. The subfield mapping unit 38 reallocates the error-diffused video data for each subfield and supplies the data to the data alignment unit 40. The data aligner 40 aligns the video signal and supplies it to the address driver IC.

Thereafter, an image corresponding to the video signal is displayed on the panel 48 by the control of the address driving IC, the scan driving IC, the sustain driving IC, and the like. In the driving apparatus of the PDP according to the prior art according to the above configuration, it is possible to obtain a clear image by improving contrast through an enlarged dynamic range.

FIG. 3 is a flowchart illustrating the dynamic range expansion method described with reference to FIG. 1.

Referring to FIG. 3, first, input data RGB from the outside is input to the lower and upper gray level histogram detectors 22A and 22B.

The histogram H (I) of each gray level is detected (S12). This first obtains an overall distribution of gray levels for an input screen of one frame. Based on the overall gray level distribution, the ratio of the histogram, which is the number of distributions of 0 to 255 gray levels, can be known. For example, in a PDP with WVGA (853 * 480) resolution mode, if the number of histograms with 2 grays is 245, the distribution ratio is Becomes When the distribution ratio of each gray level is obtained, the histogram ratio with respect to the input data appears as shown in Tables 1 and 2.

Histogram % Of distribution Hist [0] 0.02 Hist [1] 0.04 Hist [2] 0.06 Hist [3] 0.0 … … Hist [17] 0.03 Hist [18] 0.09 Hist [19] 0.1 Hist [20] One

Histogram % Of distribution Hist [220] 1.0 Hist [221] 0.1 Hist [222] 0.06 Hist [223] 0.001 … … Hist [252] 0.03 Hist [253] 0.02 Hist [254] 0.09 Hist [255] 0.05

Here, the histogram distribution ratio (%) for each gray level may vary depending on the input data for one frame.

Based on the histogram distribution ratio (%), the minimum distribution lower and upper gray levels (MIN, MAX) are determined. (S14) First, before determining the minimum distribution lower and upper gray level values, the threshold value of the histogram distribution ratio (%) is determined. Decide In Figure 3, 0.1% was set as the threshold. This sets the first gray level with 0.1% or more as the minimum distributed lower gray level (MIN) and the minimum distributed upper gray level (MAX). (S18) When the distribution ratio is 0.1% or less, the next histogram distribution ratio is continuously searched. (S16)

Thus, in the case of Table 1 and Table 2, the gray level is determined as the minimum distributed lower gray level MIN is 19 and the minimum distributed upper gray level MAX is 221.

The values of the minimum distribution lower and upper gray levels (MIN, MAX) determined as described above are input to the dynamic range determination unit 16. The dynamic range determiner 16 rearranges the input image by using Equation 1 to input the minimum distribution lower and upper gray levels MIN and MAX.

Where X is the gray level of the input data before correction and Y is the gray level of the input data after correction. In addition, MAX is the value of the minimum distributed upper gray level, and MIN is the value of the minimum distributed lower gray level.

When X is 40, the minimum distribution lower and upper gray level values determined through Table 1 and Table 2 are applied to Equation 1. By Y, the minimum gray level value after correction for X becomes 26.5. This changes the input data of 40 to a lower value of 26.5. That is, in the present invention, as shown in FIG. 4, the histogram distribution I according to the gray level in the dotted line form may be obtained as the histogram distribution II according to the gray level in the solid line form in which the dynamic range is expanded. As a result, as the dynamic range is enlarged, the contrast of the screen is improved to obtain a clear screen. In other words, the bright part is displayed brighter and the dark part is displayed darker so that the contrast between the bright part and the dark part of the screen can be clearly displayed.

5A and 5B illustrate changes in the display image before and after applying the dynamic range enlargement method. As the contrast of the light and dark of the screen becomes clearer, the dynamic range is enlarged according to the prior art illustrated in FIG. 5B. It can be seen that the image is clearer than that of FIG. 5A.

FIG. 6 is a view for designating a predetermined area for comparing only a part of the display image shown in FIG. 5B, and FIGS. 7A and 7B are views showing a change in histogram distribution after the dynamic range enlargement process according to the prior art. FIG. 8B is a diagram illustrating a change of a display image of a portion of FIG. 6.

7A and 7B, the distribution of the histogram according to the prior art of FIG. 7B is toward the gray level lower than the distribution of the histogram according to the prior art of FIG. 7A by expanding the dynamic range according to the minimum distribution lower and upper gray level values. You can see that it has been moved. As a result, as described above, the darker portions become darker and the brighter portions appear brighter.

Referring to the results of FIGS. 7A and 7B through FIGS. 8A and 8B, first, FIGS. 8A and 8B compare the area A of FIG. 6, and it can be seen that the dark part of the sky becomes darker. Next, FIGS. 9A and 9B compare the area B of FIG. 6 and show a display screen in which a bright part and a dark part coexist. In this case as well, the contrast between the bright and dark areas can be seen that the contrast is improved.

However, according to the conventional method of increasing the dynamic range of the PDP, the contrast in the moving picture is improved due to the brighter and darker parts of the PDP, which are brighter and darker than the original picture. The same problem occurs.

To illustrate this problem, for example, when the gray levels of red (R), green (G), and blue (B) are 205, 20, and 205, respectively, the minimum distribution upper and lower gray levels (MAX) of the input image are shown. , MIN) has the values 215 and 0, respectively.

In this case, the minimum distribution upper gray level MAX, that is, the gray levels 215 and more than 215 is converted as follows when Equation 1 is applied by the dynamic range expansion method. That is, 215 Is converted to 255 by 220 Is converted to 255 by

As shown in FIG. 10, the graph shows the result of the enlargement of the dynamic range as described above. 10 illustrates a gamma output state during gamma processing after dynamic range expansion of an input image according to the prior art. Here, "I" indicates a gamma output state during gamma processing without the dynamic range enlargement process, and "II" shows a gamma output state during gamma process after the dynamic range enlargement process.

In this case, after the dynamic range expansion process according to the prior art, the input image data having the minimum gray level MAX higher than the minimum distribution in the gamma process is all converted to 255. That is, as shown in FIG. 10, when the minimum distributed upper gray level MAX is set to 215, input image data of 215 gray levels or more is saturated to 255. As a result, there is a problem that the gamma output characteristic for each gray level is not provided between 215 and 255 gray levels.

Accordingly, an object of the present invention is to provide an apparatus and method for driving a plasma display panel using a dynamic range expansion method for improving image quality deterioration during dark processing of a display screen when displaying a moving image.

Another object of the present invention is to provide an apparatus and method for driving a plasma display panel using a dynamic range expansion method to improve contrast of a display image.

In order to achieve the above objects, the driving apparatus of the plasma display panel using the dynamic range expansion method according to the present invention comprises a frame memory for storing moving image data input from an external input line in units of frames, and between the frame memory and the panel. A dynamic range converter which is connected to convert the dynamic range of the video data according to the minimum distribution lower and upper gray level information, and is connected in parallel with the frame memory between the input line and the dynamic range converter and the minimum for one frame. Minimum lower and upper gray level detectors for detecting lower and upper gray levels, and the dynamic range converter and the panel are serially connected between the dynamic range converter and the panel to reverse gamma correct the video data according to the gray level value of the video signal.An inverse gamma correction unit for linearly converting a degree value, a delay unit connected in parallel with the dynamic range conversion unit and an inverse gamma correction unit between the frame memory and the panel to delay input data from the frame memory for a predetermined time; The gamma corrected data is serially connected between the inverse gamma correction unit and the panel to compare the data delayed from the delay unit with the gamma corrected data from the inverse gamma correction unit, and the delayed data is greater than or equal to the gamma corrected data. And a peak compensator for outputting the delayed data and outputting the delayed data to compensate for peak values of the data when the delayed data is smaller than the gamma corrected data. The minimum distributed lower gray level detector is configured to detect the minimum distributed gray level at a lower threshold distribution ratio than the minimum distributed upper gray level detector.

The lower critical distribution ratio in the present invention is characterized in that about 2 times.

In the present invention, the minimum distribution upper gray level distribution ratio of the minimum distribution upper gray level detection unit is 0.1%, and the minimum distribution upper gray level distribution ratio of the minimum distribution lower gray level detection unit is 0.05%.

The delay apparatus of the present invention is characterized in that the input data via the frame memory is delayed for a period of time during which the input data passes the dynamic range converter and the inverse gamma correction unit.

The method for driving a plasma display panel using the dynamic range expansion method according to the present invention includes detecting the minimum distribution lower and upper gray levels of a moving image input image by applying different distribution ratio thresholds, and the minimum distribution lower and upper gray levels. Converting a dynamic range of the input image according to level information, performing gamma correction to linearly convert a luminance value according to a gray value of the input image converted from the dynamic range, and performing the gamma corrected data value and And compensating for peak so as to have a gamma output curve linearly by comparing data values of a moving image input image delayed by a predetermined time.

The threshold of the distribution ratio for the minimum distributed upper gray level in the present invention is characterized by being larger than that for the minimum distributed lower gray level.

In the case of the present invention, the threshold of the distribution ratio with respect to the lowest gray level is 0.1%, and the threshold of the distribution ratio with respect to the lowest gray level is 0.05%.

The detecting of the minimum distribution lower and upper gray levels of the moving image input image may include determining the minimum distribution lower and upper gray levels, setting a threshold value for the histogram distribution ratio, and setting the threshold value. And a step of setting the first gray level to be obtained as the minimum distribution lower and upper gray levels.

The step of enlarging the dynamic range of the input image according to the present invention may include determining a gray level of the image data input from the outside, and correcting the image using the gray level, minimum distribution lower and upper gray levels of the input image data. Determining a gray level of the data.

Other objects and features of the present invention in addition to the above object will become apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 11 to 16.

11 is a view showing a driving device of the PDP using the dynamic range expansion method according to an embodiment of the present invention.

Referring to FIG. 11, a driving apparatus of a PDP using the dynamic range expansion method according to the embodiment of the present invention includes a frame memory 54 for storing red, green, and blue video data from the input line 52, respectively; The dynamic range converter 56, the inverse gamma correction unit 58, the peak compensation unit 60, the gain control unit 62, the error diffusion unit 64 connected between the frame memory 54 and the panel 70, A subfield mapping unit 66 and a data alignment unit 68; An APL unit 76 and a waveform generator 78 connected between the peak compensator 60 and the panel 70; A minimum distributed upper / lower gray level detector 74 connected in parallel with the frame memory 54 between the input line 52 and the dynamic range converter 56; A delay unit 72 is connected between the frame memory 54 and the peak compensator 60 in parallel with the dynamic range converter 56 and the inverse gamma correction unit 58.

The frame memory 54 stores red, green, and blue data from the input line 52 in one frame unit and supplies the data to the delay unit 72 and the dynamic range converter 56.

The minimum distribution lower and upper gray level detector 74 includes histogram detectors 82A and 82B of lower and upper gray levels and minimum distribution lower and upper gray level value determiners 84A and 84B, as shown in FIG.

The histogram detectors 82A and 82B of the lower and upper gray levels detect the histograms of the lower and upper gray levels for each gray level on the basis of the data from the input line 52 by one frame. This first obtains the overall distribution of each gray level for the input screen of one frame. The histogram H (I), which is a gray level distribution value of the input data, is detected based on the overall distribution. At this time, histograms are mainly detected at gray levels, such as about 0 to 20 gray and 220 to 255, to determine minimum and maximum gray levels (MIN and MAX).

The minimum distribution lower and upper gray level value determination units 84A and 84B determine a reference ratio arbitrarily set and determine lower and upper gray levels (MIN, MAX) having less gray level distribution through histograms of the detected lower and upper gray levels. do. The lower and upper gray levels (MIN, MAX) with less determined gray level distribution are supplied to the dynamic range converter 56. At this time, the minimum distribution lower gray level (MIN) becomes excessive emphasis compared to the original image for the dark part when processing a dark part to emphasize the contrast when watching a movie through a DVD player having a lot of dark parts. This is determined when the highlighted region has a distribution about 0.5 times larger than the minimum distribution upper gray level MAX in order to prevent new noise. This is to reduce the treatment limit in the dark areas that are widely recognized by the eye.

As described above, in the present invention, the minimum distributed upper and lower gray levels according to the minimum distributed upper and lower gray level detectors 74 are detected according to different distribution ratios.

The detection method of each of the minimum distribution upper / lower gray levels MAX and MIN will be described below with reference to FIGS. 13 and 14.

Referring to FIG. 13, a method of detecting the minimum distributed upper gray level MAX is first inputted from the outside to the upper gray level histogram detector 82B. (S22) The histogram H (I) of each gray level is detected. (S24) At this time, the distribution of the upper gray level for the input screen of one frame is obtained. In addition, an overall distribution of gray levels for the input screen may be obtained. Here, the histogram distribution ratio (%) for each gray level may vary depending on the input data for one frame.

The magnitude of the histogram according to the upper gray level is compared based on the histogram distribution ratio (%). (S26) At this time, the threshold of the histogram distribution ratio (%) for determining the magnitude of the histogram (H (I)) is 0.1. Set% as the threshold. As a result, the first gray level at which 0.1% or more appears is set as the minimum upper gray level (MAX). (S28) When the distribution ratio is 0.1% or less, the next histogram distribution ratio is continuously searched (S32).

Referring to FIG. 14, a method of detecting the minimum distributed lower gray level MIN is first inputted to the lower gray level histogram detector 82A. The input data RGB from the outside is input to the lower gray level histogram detector 82A. The histogram H (I) of the gray level is detected. (S44) In this case, when the minimum distributed lower gray level MIN is obtained from the histogram H (I), the range of I is 10 or less (I ≤ 10). Restrict. Here, the histogram distribution ratio (%) for each gray level may vary depending on the input data for one frame.

Next, the magnitude of the histogram according to the lower gray level is compared based on the histogram distribution ratio (%). (S46) At this time, the threshold of the histogram distribution ratio (%) for determining the magnitude of the histogram (H (I)). Sets 0.05% as the threshold. The threshold of the lower distribution histogram distribution ratio (%) is set lower than that of the upper distribution in order to prevent the loss of original image data values by over-expanding the images of the dark portion.

As a result, the first gray level with 0.05% or more is set as the minimum distribution lower gray level (MIN). (S48) When the distribution ratio is 0.05% or less, the next histogram distribution ratio is continuously searched (S52).

The values of the minimum distribution lower and upper gray levels (MIN, MAX) determined as described above are input to the dynamic range converter 56 (S30, S50).

The dynamic range converter 56 maintains and enlarges the dynamic range of the input data via the frame memory 54 according to the expression power at the minimum gray level or less. As a result, the dynamic range converter 56 expands the dynamic range using the minimum distribution lower and upper gray level values MIN and MAX as input data. The input data of which the dynamic range is enlarged is supplied to the inverse gamma correction unit 58.

The inverse gamma correction unit 58 inversely gamma corrects the video signal input from the dynamic range converter 56 to linearly convert the luminance value according to the gray value of the video signal. In this case, it has a gamma output curve as shown in FIG. 10 in the prior art. The luminance value according to the linearly converted gray value is supplied to the peak compensator 60.

The delay unit 72 receives input data via the frame memory 54 and delays the input data for a predetermined time. The delay unit 72 delays the input data supplied to the dynamic range converter 56 until it is input to the peak compensator 60 through the inverse gamma correction unit 58.

The peak compensator 60 compares the gamma output value gamma corrected by the inverse gamma correction unit 58 with input data including luminance information delayed by the delay unit 72, and selectively outputs the gray level value according to the gray level to compensate for the peak. Determine the value. These peak compensated data are supplied to the gain control unit 62 and the APL unit 76.

The APL unit 76 receives the video data compensated by the peak compensator 60 and generates an N-stage signal for adjusting the number of sustain pulses. The gain controller 62 amplifies the video data compensated by the peak compensator 60 by the effective gain.

The error diffusion unit 64 finely adjusts the luminance value by diffusing an error component of a cell into adjacent cells. The subfield mapping unit 66 reallocates the video data corrected by the error diffusion unit 64 for each subfield.

The data aligner 68 aligns the video signal to be supplied to the panel 70, and supplies the video signal to an address driving integrated circuit (IC) not shown.

The waveform generator 78 generates a timing control signal based on the N-stage signal input from the APL unit 76, and converts the generated timing control signal into an address driving IC, a scan driving IC, and a sustain driving IC of the panel 70. Supply.

15 is a diagram illustrating a method of driving a PDP using the dynamic range expansion method according to an embodiment of the present invention.

The driving method of FIG. 11 will be described with reference to FIG. 15. First, the dynamic range of the input data is converted. (S61) The dynamic range of the input data includes the minimum distribution lower and upper gray levels according to the flows described with reference to FIGS. 13 and 14. The dynamic range is enlarged using the minimum distribution lower and upper gray level values MIN and MAX detected by the detector 74.

The input data of which the dynamic range is enlarged is input to the inverse gamma correction unit 58 to perform gamma correction. (S62) Gamma correction linearly converts luminance values according to grayscale values of an image signal.

After the gamma correction, the upper gray level gamma curve is compensated. The output signal is selectively output to determine the peak compensation value formed of the gamma output curve. That is, if the input data value including the delayed luminance information is greater than or equal to the gamma output value, the gamma output value is determined as the peak compensation value. This is determined. These determined peak compensation values determine a new gamma output curve. This will be described with reference to FIG. 16. First, the gamma output value in FIG. 10 and the luminance information data value in the form of a straight line input from the frame memory 54 are compared. Thus, based on the "B" area, the input data value including the delayed luminance information is equal to or larger than the gamma output value so that the gamma output value is determined as the peak compensation value, and the "B" area or less is delayed. The input data value including the luminance information is smaller than the gamma output value, and the linear luminance information data value is determined as the peak compensation value. That is, the gray level below the "B" area is used as the gamma curve after dynamic range expansion, and the input data value is output as it is at the gray level above the "B" area.

In operation S63, the gamma output curve is converted as shown in FIG. 16, and then the gain is controlled. (S64) The gain controller 62 amplifies the peak-compensated video signal by the effective gain. Thereafter, the error-diffused luminance value is finely adjusted, and the error-diffused video data is re-allocated for each subfield and supplied to the data alignment unit 68. The data alignment unit 68 aligns the video signal and supplies it to the address driver IC.

As described above, the driving apparatus and method of the plasma display panel using the dynamic range expansion method according to the present invention reduces the limit of the dynamic processing for the dark portion of the moving image input image such as a movie through a DVD player having a lot of dark areas. This can prevent deterioration of image quality.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present 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.

1 is a block diagram illustrating an apparatus for driving a plasma display panel using a dynamic range expansion method according to the related art.

FIG. 2 is a block diagram illustrating in detail the PDP driver shown in FIG. 1.

FIG. 3 is a flow chart for explaining the dynamic range expansion method described with reference to FIG. 1.

4 is a diagram showing a histogram distribution change with respect to a gray level according to the prior art.

5A and 5B illustrate changes in the display image before and after applying the dynamic range expansion method.

FIG. 6 is a diagram for comparing only a part of the display image illustrated in FIG. 5B.

7A and 7B illustrate changes in histogram distribution after dynamic range expansion according to the prior art.

8A and 8B illustrate changes in a display image of a portion of FIG. 6.

9A and 9B are diagrams illustrating changes of a display image with respect to another part of FIG. 6.

10 is a graph illustrating a gamma output state during gamma processing after dynamic range expansion of an input image according to the prior art.

11 is a view showing a driving device of the PDP using the dynamic range expansion method according to an embodiment of the present invention.

FIG. 12 is a detailed diagram illustrating the minimum and upper gray level detectors of FIG. 11.

FIG. 13 is a flowchart for explaining a method for detecting the minimum distributed upper gray level in FIG. 12.

FIG. 14 is a flowchart for explaining a method for detecting the minimum distributed lower gray level in FIG. 12.

15 is a diagram illustrating a method of driving a PDP using the dynamic range expansion method according to an embodiment of the present invention.

FIG. 16 is a diagram illustrating a gamma output state when compensating a gamma curve in the peak compensator of FIG. 11.

<Description of Symbols for Main Parts of Drawings>

12,52 input line 14,54 frame memory

16 dynamic range adjustment unit 18 PDP drive unit

22,62: gray level histogram detector

24: minimum distribution gray level value determination unit

32,58: reverse gamma correction unit 34,62: gain control unit

36,64: error diffusion unit 38,66: subfield mapping unit

40,68: data alignment unit 44,76: APL unit

46,78: waveform generator 48,70: panel

56 dynamic range converting unit 60 peak compensation unit

72: delay

82: histogram detection unit of gray level

84: minimum distribution gray level value determination unit

Claims (16)

A frame memory for storing video data input from an external input line in units of frames, A dynamic range converting unit connected between the frame memory and the panel to convert the dynamic range of the video data according to minimum distribution lower and upper gray level information; A minimum distribution lower and upper gray level detection unit connected in parallel with the frame memory between the input line and the dynamic range conversion unit to detect the minimum distribution lower and upper gray levels during one frame; An inverse gamma correction unit connected in series between the dynamic range converting unit and the panel to inversely gamma correct the dynamic range converted video data to linearly convert luminance values according to grayscale values of an image signal; A delay unit connected in parallel with the dynamic range converter and an inverse gamma correction unit between the frame memory and the panel to delay input data from the frame memory for a predetermined time; The gamma corrected data is serially connected between the inverse gamma correction unit and the panel to compare the data delayed from the delay unit with the gamma corrected data from the inverse gamma correction unit. And a peak compensator for outputting the delayed data and outputting the delayed data to compensate for peak values of the data when the delayed data is smaller than the gamma corrected data. And the minimum distributed lower gray level detector detects the minimum distributed gray level at a lower threshold distribution ratio than the minimum distributed upper gray level detector. The method of claim 1, The lower critical distribution ratio is about twice the driving device of the plasma display panel using the dynamic range expansion method. The method of claim 2, The minimum distributed upper gray level distribution ratio of the minimum distributed upper gray level detection unit is 0.1%, And a minimum distribution upper gray level distribution ratio of the minimum distribution lower gray level detection unit is 0.05%. The method of claim 1, And the retarder delays the input data via the frame memory during the time that the input data passes through the dynamic range converting unit and the inverse gamma correcting unit. The method of claim 1, A gain controller for amplifying the video signal via the peak compensation unit by an effective gain; An error diffusion unit for finely adjusting the luminance value by diffusing an error component of the cell into adjacent cells; A subfield mapping unit for reallocating the video data corrected by the error diffusion unit for each subfield; And a data aligning unit for aligning the video signal to be supplied to the panel. The method of claim 5, wherein An average image value (APL) unit for receiving an video signal via the peak compensation unit and generating an N-stage signal for adjusting the number of sustain pulses; And a waveform generator for generating a timing control signal based on the N-stage signal inputted from the average image value unit and supplying the generated timing control signal to a driving integrated circuit of the panel. An apparatus for driving a plasma display panel using the same. Detecting the minimum distribution lower and upper gray levels of the moving image input image by applying different distribution ratio thresholds; Converting a dynamic range of the input image according to the minimum distribution lower and upper gray level information; Gamma correction to linearly convert a luminance value according to a gray value of the input image having the converted dynamic range; And compensating for a peak to linearly have a gamma output curve by comparing the gamma corrected data value with a predetermined time delayed video input image. Way. The method of claim 7, wherein And a threshold of the distribution ratio with respect to the minimum distributed upper gray level is larger than that for the minimum distributed lower gray level. The method of claim 8, The threshold of the distribution ratio for the minimum distributed upper gray level is 0.1%, And a threshold value of a distribution ratio with respect to the minimum distribution lower gray level is 0.05%. The method of claim 7, wherein And the predetermined delay time is a time for converting the data of the moving image input image into the gamma corrected data after expanding the dynamic range. The method of claim 7, wherein Compensating the peak may include comparing the magnitude of the gamma corrected data value and the data value of the delayed moving image input image; And applying a data value selected according to the comparison information to a gamma output curve. The method of claim 11, The step of applying the data value selected according to the comparison information to the gamma output curve includes selecting the gamma corrected data value when the data value of the delayed moving image input image is greater than or equal to the gamma corrected data value; And selecting a data value of the delayed moving image input image when the data value of the delayed moving image input image is smaller than the gamma corrected data value. The method of claim 7, wherein The detecting of the minimum and lower gray levels of the minimum distribution for the moving image input image may include determining the minimum and lower gray levels of the minimum distribution, and setting a threshold for the histogram distribution ratio. And setting the first gray level coming out above the threshold to a minimum distribution lower and upper gray level. The method of claim 7, wherein The step of enlarging the dynamic range of the input image may include determining a gray level of image data input from the outside; And determining a gray level of the image data corrected using the gray level, the minimum distribution lower and upper gray levels of the input image data. The method of claim 7, wherein Amplifying the peak compensated video signal by an effective gain; Finely adjusting a luminance value by error diffusion of the amplified video signal; And reallocating the error-diffused video signal for each subfield to supply the panel to the panel. The method of claim 15, Generating an N-stage signal for adjusting the number of sustain pulses by receiving the linearly converted signal; And generating a timing control signal by using the input N-stage signal, and supplying the generated control signal to a driving circuit.