KR20160092335A - Method and device for image processing and display device using the method thereof - Google Patents

Abstract

The present invention relates to an image processing method and to a display device using the same for reducing an afterimage. According to the present invention, the image processing method comprises the following steps of: determining whether a logo image is transparent by analyzing inputted image data; and selectively varying the clearness, brightness, and saturation of the logo image by compensating the image data in terms of a result for determining whether the logo image is transparent.

Description

TECHNICAL FIELD The present invention relates to an image processing method and apparatus, and a display device using the same.

The present invention relates to an image processing method and apparatus, and a display apparatus using the same. More particularly, the present invention relates to an image processing method and apparatus capable of reducing afterimage, and a display apparatus using the same.

With the development of electronic communication technology, the development and research of display devices is continuing. Typical examples of the display device include a liquid crystal display device (LCD), a plasma display panel (PDP), a field emission display (FED), an electroluminescence Display device (ELD), an electro-wetting display device (EWD), and an organic light emitting display device (OLED).

Among them, an organic light emitting display device is a self-emission type display device which electrically excites a fluorescent organic compound to emit light, which can be driven at a low voltage, and is easily attracted attention as a next generation display device because of its easy thickness.

However, the organic light emitting display device has a drawback that it is easily deteriorated. For example, when the fixed image is repeated in a specific region, deterioration of the region is accelerated and a persistent afterimage is left. Particularly, as shown in Fig. 1, the logo 10 of the broadcast is displayed, or the regions where the subtitles are displayed continue to be in a state of high brightness as compared with other display regions, so that deterioration proceeds quickly. Therefore, the organic light emitting display device has a problem that the logo 10 of the broadcast is displayed or the afterglow is weak in the area where the subtitles are displayed.

On the other hand, the afterglow defect due to the logo 10 or the caption as described above can be generated not only in the organic light emitting display but also in the above-described display devices, and therefore, a solution is needed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an image processing method and apparatus capable of reducing afterimage and a display device using the same.

Other features and advantages of the invention will be set forth in the description which follows, or may be obvious to those skilled in the art from the description and the claims.

According to another aspect of the present invention, there is provided an image processing method comprising: analyzing input image data to determine whether a logo image is transparent; and determining whether the logo image is transparent or not, And selectively changing the sharpness, brightness, and saturation of the logo image.

According to the solution of the above-mentioned problems, the present invention has the following effects.

The image processing apparatus and method according to the present invention can detect a logo image including a logo or a caption, and selectively reduce the brightness, brightness, and saturation of the logo image, thereby reducing the residual image defect. Particularly, according to the present invention, it is possible to expect an effect of reducing the afterimage deficiency and improving the lifetime of the display device by correcting only the saturation, brightness, and saturation of the translucent logo image so as to lower only the saturation.

In addition to the effects of the present invention mentioned above, other features and advantages of the present invention will be described below, or may be apparent to those skilled in the art from the description and the description.

1 is a view showing an example of a logo image.
2 is a block diagram illustrating an image processing apparatus according to an exemplary embodiment of the present invention.
3 is a flowchart illustrating an image processing method according to an exemplary embodiment of the present invention.
4A and 4B are diagrams illustrating logo images, for example.
FIG. 5 is a flowchart showing a step of the saturation correction method shown in FIG.
6 is a block diagram schematically showing an organic light emitting display device to which an image processing apparatus according to an exemplary embodiment of the present invention is applied.
7 is a block diagram schematically showing a liquid crystal display device to which an image processing apparatus according to an exemplary embodiment of the present invention is applied.

The meaning of the terms described herein should be understood as follows. The word " first, "" second," and the like, used to distinguish one element from another, are to be understood to include plural representations unless the context clearly dictates otherwise. The scope of the right should not be limited by these terms. It should be understood that the terms "comprises" or "having" does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof. It should be understood that the term "at least one" includes all possible combinations from one or more related items. For example, the meaning of "at least one of the first item, the second item and the third item" means not only the first item, the second item or the third item, but also the second item and the second item among the first item, Means any combination of items that can be presented from more than one. The term "on" means not only when a configuration is formed directly on top of another configuration, but also when a third configuration is interposed between these configurations.

Hereinafter, preferred embodiments of a video processing method and apparatus and a display device using the same will be described in detail with reference to the accompanying drawings.

2 is a block diagram illustrating an image processing apparatus according to an exemplary embodiment of the present invention. 3 is a flowchart illustrating an image processing method according to an exemplary embodiment of the present invention. Hereinafter, Fig. 2 and Fig. 3 will be described together.

2 and 3, the image processing apparatus 500 according to an exemplary embodiment of the present invention includes a logo detection unit 510, a determination unit 520, and a data correction unit 530.

The logo detector 510 analyzes the inputted image data (WRGB or RGB) and detects a logo area in which a logo image including a logo or a caption is displayed.

Specifically, the logo detection unit 510 receives the image data (WRGB or RGB) in step S10 (S10). Then, the logo detection unit 510 detects the logo area by analyzing the image data (WRGB or RGB) input in step S20 (S20). The logo area is an area in which a specific image is repeated during a continuous frame period, and is an area where a residual image defect may occur.

The logo detection unit 510 may use the following method to detect the logo area.

The logo detector 510 analyzes the input image data (WRGB or RGB) for a plurality of display block units during a continuous frame period. When a specific image is repeated in a specific display block, the logo detection unit 510 defines the corresponding display block as a logo region, and defines the repeated image as a logo image.

The determination unit 520 determines whether the logo image is transparent, and outputs a determination signal according to the determination result.

Specifically, the determination unit 520 calculates the chroma cumulative data (CD) by analyzing the logo image at step 30 (S30). Then, the determination unit 520 determines whether the logo image is transparent by comparing the saturation accumulation data CD calculated in step 40 (S40) with the reference value, and outputs a determination signal as a determination result. The operation of the determination unit 520 will be described in more detail as follows.

First, the determination unit 520 calculates saturation accumulation data (CD) from the image data (WRGB or RGB) corresponding to the logo image for at least one frame period. Here, the saturation accumulation data CD is calculated through an operation similar to the expression (1).

Referring to Equation (1), the saturation accumulation data CD calculates data deviation by comparing image data (WRGB or RGB) inputted during consecutive frame periods for each color, and outputs the calculated data deviation for accumulation . The saturation accumulation data (CD) has a smaller value for an opaque image of a logo image to be analyzed, and a larger value for a logo image to be analyzed is a transparent image. This is because the logo image is opaque because it means that the logo image is kept constant during the continuous frame period regardless of the change of the surrounding image. In addition, the transparency of the logo image means that the logo image is affected by the change of the surrounding image, and the data is variable during the continuous frame period.

4A and 4B are diagrams illustrating logo images, for example. 4A is a diagram showing an opaque logo image. And FIG. 4B is a diagram showing a translucent logo image.

Red (R) data Green (G) data Blue (B) data nth frame 252 255 255 The (n + 1) th frame 253 255 254 n + 2 < th > 252 255 254

Table 1 shows three-color image data (RGB) values for the opaque logo image as shown in FIG. 4A. The image data (WRGB or RGB) disclosed in Table 1 is applied to Equation (1) to calculate saturation accumulation data (CD) as follows.

CD (k = 2) = (1 + 0 + 1) + (1 + 0 + 0) = 2

Red (R) data Green (G) data Blue (B) data nth frame 214 198 176 The (n + 1) th frame 216 157 152 n + 2 < th > 185 90 75

Table 2 shows data values for the translucent logo image as shown in FIG. 4B. The image data (WRGB or RGB) disclosed in Table 2 is applied to Equation (1) to calculate saturation accumulation data (CD) as follows.

CD (k = 2) = (2 + 41 + 24) + (31 + 67 + 77) = 244

Comparing the results of applying Table 1 and Table 2 to Equation (1), it can be seen that the saturation accumulation data (CD) according to the opaque logo image is smaller than the saturation accumulation data (CD) according to the translucent logo image.

Meanwhile, the determination unit 520 compares the calculated saturation accumulation data CD with a reference value to determine whether the logo image is transparent. That is, the determination unit 520 determines that the logo image is translucent when the saturation accumulation data CD is greater than or equal to the reference value. The determination unit 520 determines that the logo image is opaque when the saturation accumulation data CD is smaller than the reference value. The determination unit 520 generates and outputs a determination signal according to a result of determining whether the logo image is transparent or not. This determination signal is supplied to the data correction unit 530. [

The reference value may be set in advance according to an experiment result of determining the transparency of the logo image with the naked eye of the user. For example, the reference value may be 1000 when the variable k is set to 100 in Equation (1). This is because when the user observes the logo image with the naked eye for about 100 frames, it is confirmed that the user can recognize that the logo image is translucent when the gradation change amount of the three-color image data (RGB) exceeds 1000 Because.

The data correction unit 530 recognizes whether the logo image is transparent according to the determination signal provided from the determination unit 520. [ The data correcting unit 530 corrects the image data (WRGB or RGB) according to whether the logo image is transparent or not, thereby selectively changing the sharpness, brightness, and saturation of the logo image.

Specifically, when the logo image is opaque, the data correction unit 530 corrects the image data (WRGB or RGB) so as to lower the sharpness, brightness, and saturation of the logo image, as shown in step 50 (S50). If the logo image is translucent, the data correction unit 530 corrects the image data (WRGB or RGB) so as to lower the saturation of the logo image, as shown in step 55 (S55). The data correction unit 530 completes the correction of the image data WRGB or RGB in step S50 or S55 and then outputs the corrected image data WRGB or RGB as shown in step S60 Output.

A method of lowering the sharpness of the logo image by the data correcting unit 530 is as follows. That is, the data correcting unit 530 detects an edge region from the inputted image data (WRGB or RGB) to lower the sharpness of the logo image. The data correcting unit 530 applies a blurring effect to the detected edge region by reducing the difference in gray level between the boundary of the logo image and the surrounding image of the logo image.

The data correcting unit 530 may lower the gray level of the color image data (WRGB or RGB) according to the 2.2 gamma curve to lower the brightness of the logo image. The data correcting unit 530 according to an exemplary embodiment of the present invention may use an algorithm proposed by the applicant for correcting the brightness and sharpness of the logo image. Specifically, the data correcting unit 530 corrects brightness and sharpness of the logo image by using a method disclosed in Korean Patent Publication No. 10-2014-0054598, Korean Patent Publication No. 10-2014-0070792, 10-2014-0070793, and Korean Patent Laid-Open No. 10-2014-0070795.

The data correcting unit 530 lowers the sharpness and brightness only when the logo image is opaque, and does not lower the sharpness and brightness when the logo image is translucent. This is because, in the case of the translucent logo image, the luminance difference between the logo image and the surrounding image of the logo image is relatively small, and therefore, the effect of improving the afterimage due to the reduction of the brightness and sharpness of the logo image is small.

Meanwhile, in one example of the present invention, the image data input to the image processing apparatus 500 may include four-color data WRGB including white data W and three-color data RGB. In addition, the image data may be composed of only three color data (RGB) except white data.

If the image data includes the four-color data WRGB including the white data, the data correcting unit 530 reduces only the gray-scale value of the three-color data RGB except for the white data W . The present invention can improve the lifetime of the organic light emitting diode display device.

In general, it is known that the lifetime of an organic light emitting device is higher than that of a three-color organic light emitting device. That is, the three-color organic light emitting devices driven by the three-color data (RGB) of the image data WRGB are relatively weak in after-images and vulnerable to deterioration and have a relatively short life span as compared with white organic light emitting devices. Therefore, the present invention reduces only the gray-scale value of the three-color data (RGB) with respect to the logo image, thereby lowering the brightness of any one of the three-color organic light emitting devices, and consequently improving the lifetime of the OLED display.

Hereinafter, a method of lowering the saturation of the logo image by the data correcting unit 530 will be described.

FIG. 5 is a flowchart showing a step of the saturation correction method shown in FIG.

Referring to FIG. 5, the data correcting unit 530 calculates the chroma value CH from the three-color image data RGB input in step S100. The data correcting unit 530 compares the first saturation value C1 calculated in the previous frame with the second saturation value C2 calculated in the current frame in step 110 (S110). If the second saturation value C2 is larger than the first saturation value C1 in step 120 (S120), the data correcting unit 530 sets the second saturation value C2 as shown in step 130 (S130) Color image data RGB input to the current frame to have a third saturation value C3 equal to or greater than the first saturation value C1. The saturation correction method of the data correction unit 530 will be described below as an example.

Red (R) data Green (G) data Blue (B) data Previous frame 214 198 176 Current frame before correction 206 157 152 Current frame after calibration 185 157 152

Table 3 shows tri-color image data (RGB) values for the logo image in the previous frame and the current frame, and shows a case where the saturation value CH increases in the current frame as compared with the previous frame.

First, the data correcting unit 530 calculates the saturation value CH from the input three-color image data RGB. Here, the saturation value CH is calculated through an operation similar to the expression (2).

When the three-color image data RGB of the previous frame shown in Table 3 is applied to Equation 2, the saturation value CH of the previous frame, i.e., the first saturation value C1 is 1- (176/214) 0.1776. When the three-color image data (RGB) of the current frame shown in Table 3 is applied to Equation 2, the saturation value CH of the current frame, i.e., the second saturation value C2 is 1- (152/206) Lt; / RTI > Therefore, it can be seen that the saturation value CH increases in the current frame as compared to the previous frame.

Then, the data correcting unit 530 corrects the three-color image data (RGB) input to the current frame so that the saturation value C2 of the current frame is greater than or equal to the saturation value C1 of the previous frame. To this end, the data correcting unit 530 corrects the data having the largest value among the three-color image data (RGB) input in the current frame. For example, in the image data (RGB) of the current frame shown in Table 3, the red data has the largest value. Accordingly, the data correcting unit 530 corrects the red data 206 input to the current frame to 185 so that the chroma value CH of the image data RGB input to the current frame is equal to the chroma value CH of the previous frame .

On the other hand, the correction amount of the image data (RGB) for lowering the saturation value CH is not necessarily set to be equal to the level of the previous frame. That is, in the above example, the red data of the current frame may have a value smaller than 206 and equal to or larger than 185. This is because a sudden change in saturation can be recognized by the user when the brightness of the logo image and the brightness of the surrounding image of the logo image are not large.

Specifically, when the correction amount of the image data RGB for lowering the chroma value CH is set to the maximum value in order to make the saturation value C2 of the current frame equal to the saturation value C1 of the previous frame, The weights can be applied and varied. That is, in the above example, the data correcting unit 530 can correct the red data 206 of the current frame to 185 by applying a weight of 100%. The data correcting unit 530 may correct the red data 206 of the current frame to 196 by applying a weight of 50%.

However, it is known that the lifetime of a blue organic light emitting device is remarkably low in an organic light emitting device in red, green, and blue. Accordingly, in the present invention, when the blue image data B has the largest value among the three colors of RGB image data, the weight for lowering the blue image data B is set to a maximum value of 100%. Accordingly, the lifetime of the blue organic light emitting device can be increased, and as a result, the lifetime of the organic light emitting display device can be improved.

A method of applying the weights upon correction of the image data (RGB) for the logo image will be described in more detail as follows.

The data correcting unit 530 compares the first and second saturation values C1 and C2 to calculate a saturation increment. The data correction unit 530 changes a weight for correcting the three-color image data (WRGB or RGB) based on the calculated saturation increment. For example, in the example described in Table 3, the saturation increment is 0.0845 (0.2621-0.1776). The data correcting unit 530 sets a weight corresponding to 0.0845, which is an increase in saturation, with reference to the lookup table to which the increase in chroma of the logo image and the weight are mapped. The data correction unit 530 may correct the red data of the current frame to a value smaller than 206 and equal to or larger than 185 according to the set weight.

As described above, the image processing apparatus 500 and method according to the present invention can detect a logo image including a logo or a caption, and selectively reduce the brightness, brightness, and saturation of the logo image, thereby reducing the afterimage failure. Particularly, according to the present invention, it is possible to expect an effect of reducing the afterimage deficiency and improving the lifetime of the display device by correcting only the saturation, brightness, and saturation of the translucent logo image so as to lower only the saturation.

6 is a block diagram schematically showing an organic light emitting display device to which an image processing apparatus according to an exemplary embodiment of the present invention is applied.

6 includes an image correction unit 510 for detecting a logo image including a logo or a caption from inputted image data and selectively changing the sharpness, brightness, and saturation of the logo image, A driving circuit 1000 for driving the organic light emitting display panel 100 according to correction data provided from the image correction unit 510; ). The driving circuit 1000 includes a data driver 200 for driving a data line DL of the organic light emitting display panel 100 and a gate driver 300 for driving the gate line GL of the organic light emitting display panel 100. [ And a timing controller 400 that aligns the correction data provided from the image correction unit 510 and supplies the correction data to the data driver 200 and controls the data driver 200 and the gate driver 300.

The image correction unit 510 may be configured as the image processing apparatus shown in FIG. The image data correction method of the image correction unit 510 may be replaced with the above description with reference to FIGS.

The OLED display panel 100 displays an image through a pixel matrix in which a plurality of pixels are arranged. Each pixel includes a data line DL, a gate line GL, and a W / R / G / B or R / G / B sub-pixel PXL. Each sub-pixel PXL may include at least switching and driving transistors SM and DM and one capacitor Cst to drive the organic light emitting diode OLED. The switching and driving transistors SM and DM may be PMOS or NMOS transistors.

The driving method of each sub-pixel PXL is as follows. That is, the switching transistor SM is turned on by the gate turn-on voltage supplied to the gate line DL so that the data signal supplied to the data line DL is supplied to the capacitor C with the driving voltage VDD and data And is charged with the difference voltage of the signal. The driving transistor DM supplies the driving current according to the difference voltage charged in the capacitor C to emit the organic light emitting element OLED and the organic light emitting element OLED displays the gradation proportional to the driving current. The organic light emitting diode display panel 100 may improve image persistence and lifetime by displaying image data in which image clarity, luminance and chroma are selectively corrected for the logo image by the image correction unit 510.

The data driver 200 converts the digital image data from the timing controller 400 into an analog data signal (current or voltage signal) using a gamma voltage in response to a data control signal from the timing controller 400, To the data line (DL) of the display panel (100).

The gate driver 300 sequentially drives the gate line GL of the organic light emitting display panel 100 in response to a gate control signal of the timing controller 400.

The timing controller 400 aligns the output data of the image correction unit 510 and outputs the data to the data driver 200. The timing controller 400 controls the driving timing of the data driver 200 using a plurality of synchronizing signals from the image correcting unit 510, that is, a dot clock, a data enable signal, a horizontal synchronizing signal, And a gate control signal for controlling the driving timing of the gate driver 300 are generated and output.

7 is a block diagram schematically showing a liquid crystal display device to which an image processing apparatus according to an exemplary embodiment of the present invention is applied.

7 includes an image correcting unit 512 for detecting a logo image including a logo or a caption from inputted image data and selectively changing sharpness, brightness, and saturation with respect to the logo image, And a driving circuit 1100 for driving the liquid crystal display panel 102 in accordance with correction data provided from the image correction unit 512. The liquid crystal display panel 102 includes a liquid crystal display panel 102, The driving circuit 1100 includes a data driver 202 for driving the data line DL of the liquid crystal display panel 102, a gate driver 302 for driving the gate line GL of the liquid crystal display panel 102, And a timing controller 402 that aligns the correction data provided from the image correction unit 512 and supplies the correction data to the data driver 202 and controls the data driver 202 and the gate driver 302.

The image correction unit 512 may include the image processing apparatus 500 shown in FIG. The image data correction method of the image correction unit 512 may be replaced with the above description with reference to FIGS.

The liquid crystal display panel 102 displays an image through a pixel matrix in which a plurality of pixels are arranged. Each pixel has a W / R / G / B or R / G / B / And a desired color is realized by a combination of G / B sub-pixels. Each sub pixel includes a thin film transistor TFT connected to the gate line GL and the data line DL, a liquid crystal capacitor Clc connected in parallel with the thin film transistor TFT, and a storage capacitor Cst. The liquid crystal capacitor Clc charges the difference voltage between the data signal supplied to the pixel electrode through the thin film transistor TFT and the common voltage Vcom supplied to the common electrode, drives the liquid crystal according to the charged voltage, . The storage capacitor Cst stably maintains the voltage charged in the liquid crystal capacitor Clc. The liquid crystal display panel 102 can improve the afterimage failure and the life span by displaying the data that the image correction unit 512 has selectively corrected the brightness, the brightness, and the saturation for the logo image.

The data driver 202 converts the digital image data from the timing controller 402 into an analog data signal (current or voltage signal) using a gamma voltage in response to a data control signal from the timing controller 402, To the data line (DL) of the panel (102).

The gate driver 302 sequentially drives the gate line GL of the liquid crystal display panel 102 in response to the gate control signal of the timing controller 402.

The timing controller 402 aligns the output data of the image correction unit 512 and outputs the data to the data driver 202. The timing controller 402 controls the driving timing of the data driver 202 using a plurality of synchronizing signals from the image correcting unit 512, that is, a dot clock, a data enable signal, a horizontal synchronizing signal, And a gate control signal for controlling the driving timing of the gate driver 302, and outputs the generated data control signal.

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 general inventive concept as defined by the appended claims and their equivalents. Will be clear to those who have knowledge of. Therefore, the scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be interpreted as being included in the scope of the present invention.

500: image processing apparatus 510: logo detection unit
520: determination unit 530:

Claims (12)

A first step of analyzing inputted image data to detect a logo area in which a logo image including a logo or a caption is displayed;
A second step of determining whether the logo image is transparent or not; And
And a third step of selectively changing the sharpness, brightness, and saturation of the logo image by correcting the image data according to a result of determining whether the logo image is transparent. The method according to claim 1,
The second step
Analyzing image data corresponding to the logo image for at least one frame period to calculate saturation accumulation data;
And comparing the saturation cumulative data with a reference value to determine whether the logo image is transparent. 3. The method of claim 2,
The second step
Determining that the logo image is translucent if the saturation accumulation data is greater than or equal to the reference value; And
And determining that the logo image is opaque if the saturation accumulation data is smaller than the reference value. The method of claim 3,
The step of calculating the saturation accumulation data
Comparing the image data for each color to calculate a data deviation; And
And accumulating the data deviation for a consecutive frame period. The method according to claim 1,
In the third step,
If the logo image is opaque, correcting the image data to lower the sharpness, brightness, and saturation of the logo image; And
And correcting the image data to lower the saturation of the logo image when the logo image is translucent. 6. The method of claim 5,
The step of correcting the image data to lower the saturation of the logo image
Calculating a saturation value from the input three-color image data;
Comparing the first saturation value calculated in the previous frame with the second saturation value calculated in the current frame; And
The image data of the three colors input to the current frame are corrected so that the second saturation value is smaller than the second saturation value and equal to or greater than the first saturation value when the second saturation value is larger than the first saturation value ≪ / RTI > The method according to claim 6,
The step of correcting the image data to lower the saturation of the logo image
Comparing the first and second saturation values to calculate a saturation increment; And
And changing a weight for correcting the three-color image data input to the current frame based on the saturation increment. 8. The method of claim 7,
Wherein the three-color image data includes red image data, green image data, and blue image data,
Wherein the weight has a maximum value when the blue image data has the largest value among the image data of the three colors. A logo detection unit for analyzing input image data and detecting a logo area in which a logo image including a logo or a caption is displayed;
A determination unit that calculates saturation accumulation data from the image data corresponding to the logo image during at least one frame period and outputs a determination signal according to a result of comparing the saturation accumulation data with a reference value; And
And a data correction unit that corrects the image data in response to the determination signal to selectively change the sharpness, brightness, and saturation of the logo image. 10. The method of claim 9,
The data correction unit
Correcting the image data so as to lower the saturation of the logo image when the saturation accumulation data is greater than or equal to the reference value,
And corrects the image data so as to lower the sharpness, brightness, and saturation of the logo image when the saturation accumulation data is smaller than the reference value. An organic light emitting display panel; And
And a driving circuit for aligning the image data output from the image processing apparatus according to claim 9 or 10 and supplying the image data to the organic light emitting display panel. A liquid crystal display panel; And
And a driving circuit for aligning and supplying the image data output from the image processing apparatus according to claim 9 or 10 to the liquid crystal display panel.

Images