KR101674046B1

KR101674046B1 - Method, computer-readable medium and controller for controlling panel voltage of display device

Info

Publication number: KR101674046B1
Application number: KR1020150102895A
Authority: KR
Inventors: 김영진; 박준혁
Original assignee: 아주대학교산학협력단
Priority date: 2015-07-21
Filing date: 2015-07-21
Publication date: 2016-11-08

Abstract

Provided are a method for controlling a panel voltage of a display device, a computer-readable medium and a controller, capable of minimizing power consumption of the display device while maintaining image quality of an image outputted through the display device at a certain level. In one aspect according to the technical concept of the present invention, the controlling method, which is the method for controlling the panel voltage supplied to a panel of the display device, includes the steps of: determining a category to which an input image belongs, among a plurality of categories; color-transforming the input image based on a preset optimum color transformation distance with respect to the determined category; determining a pixel value corresponding to a preset optimum saturation limit with respect to the determined category, among pixel values of pixels of the color-transformed input image; and determining the panel voltage among a plurality of effective voltages capable of compensating, without saturation, for pixels having pixel values which is equal to the determined pixel value or lower.

Description

TECHNICAL FIELD The present invention relates to a method of controlling a panel voltage of a display device, a computer readable medium and a controller,

Technical aspects of the present invention relate to a panel voltage control method of a display device, a computer readable medium, and a controller. More particularly, the technical idea of the present invention relates to a panel voltage control method, a computer-readable medium, and a controller capable of reducing the power consumption of a display device through reduction of panel voltage based on color conversion.

Along with the development of smart phones, power consumption in battery-powered mobile devices is an important issue. Since the display device among the components of the mobile device has a large amount of power consumption, various measures for reducing the power consumption of the display device have been proposed.

Up to now, liquid crystal display (LCD) devices have been widely used in mobile devices. Backlight dimming techniques have been proposed as techniques for reducing power consumption of LCD devices.

Recently, an AMOLED (Active Matrix Organic Light Emitting Diode) display device having a flexibility, a bright color, a wide viewing angle, and a quick response characteristic has been spotlighted as an alternative to an LCD device. Unlike backlit LCD devices, AMOLED displays emit individual pixels because of their self-illuminating characteristic. Therefore, the proposed power consumption reduction techniques with respect to LCD devices can not be applied to AMOLED displays, and other measures for reducing the power consumption of AMOLED displays are required.

A method of controlling a panel voltage of a display device, a computer-readable medium, and a controller according to the technical idea of the present invention is to minimize the power consumption of a display device while maintaining the image quality of an image output through the display device at a predetermined level I have to.

According to an aspect of the present invention, there is provided a control method for controlling a panel voltage supplied to a panel of a display device, the method comprising: determining a category to which an input image belongs among a plurality of categories; Color transforming the input image based on a preset optimal color conversion distance for the determined category; Determining a pixel value corresponding to an optimal saturation limit preset for the determined category among pixel values of the pixels of the color-converted input image; And determining the panel voltage from a plurality of valid voltages capable of compensating for pixels having pixel values below the determined pixel value without saturation.

In some embodiments, prior to determining the category, classifying the plurality of reference images into the plurality of categories according to the average brightness of the pixels; Selecting a representative image for each of the plurality of categories; And setting an optimal color conversion distance and an optimal saturation limit for each of the plurality of categories using the selected representative images.

In some embodiments, the step of setting the optimal color conversion distance and the optimal saturation limit comprises performing at least one simulated test on the representative image based on a plurality of candidate pairs comprised of a candidate color conversion distance and a candidate saturation limit Obtaining a power consumption amount of the display apparatus when each of the plurality of candidate pairs is applied, and a similarity between an original of the representative image and the color-converted representative image displayed on the panel; And setting, based on the obtained power consumption amounts and similarities, the candidate color conversion distance and the candidate saturation limit of the pair of the plurality of candidate pairs to an optimal color conversion distance and an optimal saturation limit of a category to which the representative image belongs The method comprising the steps of:

In some embodiments, the simulated test includes color converting the representative image according to one candidate color conversion distance; Determining a mock pixel value corresponding to a candidate saturation limit of one of the pixel values of the pixels of the color-converted representative image; Determining a simulated panel voltage from among a plurality of simulated valid voltages capable of compensating for pixels having pixel values below the determined simulated pixel value without saturation; Compensating a pixel value of pixels of the color-converted representative image according to the determined simulated panel voltage; Calculating power consumption of the display device according to the determined simulated panel voltage; And calculating the similarity between the pixel-compensated representative image displayed on the panel and the original image of the representative image when the determined simulated panel voltage is supplied to the display device.

In some embodiments, the step of setting the candidate color conversion distance and the candidate saturation limit of any one of the plurality of candidate pairs to the optimal color conversion distance and optimal saturation limit of the category to which the representative image belongs, The pair of candidate color conversion distances and the candidate saturation limit that satisfy the condition that the smallest among the power consumption amounts and the degree of similarity is equal to or greater than a predetermined reference value can be set as the optimal color conversion distance and the optimal saturation limit of the category to which the representative image belongs .

In some embodiments, the converting color comprises: converting a color of pixels of the input image from an RGB color space to a CIELab color space; Converting the color of the pixels according to the optimal color conversion distance in the CIELab color space; And re-converting the converted color of the pixels from the CIELab color space to the RGB color space.

In some embodiments, determining the panel voltage comprises determining a pixel value corresponding to the optimal saturation limit for each of the red (R), green (G), and blue (B) channels of the color- ; Determining a valid voltage capable of compensating for pixels having pixel values below the determined pixel value without saturation for each of the R, G, and B channels of the color-converted input image; And determining the highest effective voltage among the effective voltages of the R, G, and B channels as the panel voltage.

In some embodiments, determining the effective voltage for each of the R, G, and B channels may include compensating for pixels having pixel values below the determined pixel value for each of the R, G, and B channels without saturation Determining the lowest voltage of the plurality of voltages that is smaller than the reference panel voltage as the effective voltage of the corresponding channel.

A computer readable medium according to another aspect of the technical idea of the present invention is a computer readable medium having stored thereon at least one program for controlling a panel voltage supplied to a panel of a display device, Determining a category of the category to which the input image belongs; Color-converting the input image based on a preset optimal color conversion distance for the determined category; Determining a pixel value corresponding to an optimal saturation limit preset for the determined category among pixel values of the pixels of the color-converted input image; And determining the panel voltage from a plurality of valid voltages capable of compensating for pixels having pixel values below the determined pixel value without saturation.

According to another aspect of the present invention, there is provided a controller for controlling a panel voltage supplied to a panel of a display device, the controller comprising: a category determination unit for determining a category to which an input image belongs among a plurality of categories; A color conversion unit for performing color conversion on the input image based on an optimal color conversion distance set in advance for the determined category; And determining a pixel value corresponding to a predetermined optimal saturation limit for the determined category among pixel values of the pixels of the color-converted input image, and compensating for pixels having pixel values below the determined pixel value without saturation And a panel voltage controller for determining the panel voltage among the plurality of effective voltages.

In some embodiments, the category determination unit classifies the plurality of reference images into the plurality of categories according to the average brightness of the pixels, selects the representative images of the plurality of categories, and the controller displays the selected representative images And a variable setting unit for setting an optimal color conversion distance and an optimal saturation limit for each of the plurality of categories.

In some embodiments, the variable setting unit has performed at least one simulated test on the representative image based on a plurality of candidate pairs composed of a candidate color conversion distance and a candidate saturation limit to apply each of the plurality of candidate pairs Obtaining a similarity between the power consumption of the display device and the color-converted representative image displayed on the panel, based on the obtained power consumption amounts and similarities, The candidate color conversion distance and the candidate saturation limit can be set to the optimal color conversion distance and optimal saturation limit of the category to which the representative image belongs.

In some embodiments, the simulation test may be performed such that the variable setting unit color-converts the representative image according to the one candidate color conversion distance, and the variable setting unit sets one of the pixel values of the pixels of the color- Determining a simulated pixel value corresponding to a saturation limit and determining a simulated panel voltage from among a plurality of simulated effective voltages capable of compensating for pixels having pixel values below the determined simulated pixel value without saturation, And the variable setting unit calculates the power consumption of the display device according to the decided simulated panel voltage, and the variable setting unit calculates the power consumption of the display device based on the determined simulated panel voltage, When the voltage is supplied to the display device, It may be configured to calculate the degree of similarity between the original image and the representative image representing damaged.

In some embodiments, the variable setting unit sets a pair of candidate color conversion distances and a candidate saturation limit that satisfy the condition that the power consumption is the smallest among the obtained power consumption amounts and the similarity is equal to or greater than a predetermined reference value, The optimum color conversion distance and the optimal saturation limit of the category to which it belongs.

In some embodiments, the color conversion unit converts the color of the pixels of the input image from the RGB color space to the CIELab color space, converts the color of the pixels according to the optimal color conversion distance in the CIELab color space, The converted color of the pixels can be reconverted from the CIELab color space to the RGB color space.

In some embodiments, the panel voltage controller determines a pixel value corresponding to the optimal saturation limit for each of the R, G, and B channels of the color-converted input image, Channel and B channel, the effective voltage capable of compensating for pixels having a pixel value equal to or less than the determined pixel value without saturation is determined, and the maximum effective voltage among the R, G, and B channel- Can be determined by the panel voltage.

In some embodiments, the panel voltage controller may compensate for the pixels having a pixel value less than the determined pixel value by saturation, for each of the R channel, the G channel, and the B channel, The lowest voltage can be determined as the effective voltage of the corresponding channel.

In some embodiments, the display device may include a conversion unit for supplying a predetermined voltage to the panel, and the panel voltage control unit may control the conversion unit such that the determined panel voltage is supplied to the panel.

The method for controlling panel voltage of a display device according to embodiments of the present invention, a computer-readable medium and a controller may minimize the power consumption of a display device while maintaining the image quality of an image output through the display device at a predetermined level .

Accordingly, it is possible to increase the driving time of a mobile device such as a smart phone on which the display device is mounted.

BRIEF DESCRIPTION OF THE DRAWINGS A brief description of each drawing is provided to more fully understand the drawings recited in the description of the invention.
1 is a graph showing power consumption according to pixel values of R, G, and B subpixels in an AMOLED display device.
2 is a view schematically showing a part of a display device including a controller according to an embodiment of the present invention.
3 is a flowchart illustrating a control method according to an embodiment of the present invention.
FIGS. 4 to 8 are views for explaining step S310 of FIG. 3 in more detail.
FIG. 9 is a view schematically showing a part of a controller according to an embodiment of the present invention.
FIG. 10 is a diagram for comparing an original image with an image to which a control method according to an embodiment of the present invention is applied.

While the present invention has been described in connection with certain exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and similarities. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description of the present invention, detailed description of known related arts will be omitted when it is determined that the gist of the present invention may be unnecessarily obscured. In addition, numerals (e.g., first, second, etc.) used in the description of the present invention are merely an identifier for distinguishing one component from another.

Also, in this specification, when an element is referred to as being "connected" or "connected" with another element, the element may be directly connected or directly connected to the other element, It should be understood that, unless an opposite description is present, it may be connected or connected via another element in the middle.

It should be noted that the terms such as " unit, "" to, "and" to module ", as used herein, mean units for processing at least one function or operation, Or a combination of hardware and software.

It is to be clarified that the division of constituent parts in this specification is merely a division by each main function of each constituent part. That is, two or more constituent parts to be described below may be combined into one constituent part, or one constituent part may be divided into two or more functions according to functions that are more subdivided. In addition, each of the constituent units described below may additionally perform some or all of the functions of other constituent units in addition to the main functions of the constituent units themselves, and that some of the main functions, And may be carried out in a dedicated manner.

In terms of software, techniques for implementing low power of display devices have been developed with two techniques. For example, there are a technique for reducing power consumption through color transformation first and a dynamic voltage scaling (DVS) for supplying power to a panel of a display device. There is a technique.

The color conversion technique converts the color of each pixel constituting the panel of the display device into a color having low power consumption.

As shown in FIG. 1, which shows power consumption according to pixel values of R, G, and B subpixels in an AMOLED display device, R, G, and B subpixels in an AMOLED display device have different power consumption characteristics. Therefore, power consumption of the display device can be reduced when the source color of the pixel is converted into a color with low power consumption considering the power consumption characteristics of the R, G, and B sub-pixels.

A dynamic voltage variable technique (DSV) is a technique for dynamically varying the voltage supplied to a display device (more specifically, a panel voltage supplied to a panel) according to image content, thereby reducing power. In general, the panel voltage is set based on the highest luminance of the pixel, that is, when the pixel value is 255. If the pixel value is not 255, the same luminance can be obtained with a lower voltage. The extra voltage is dissipated as heat, which can save power by eliminating unnecessary wasted voltage. Therefore, when the optimum panel voltage is selected according to the image contents, the power consumption can be reduced without degrading the image quality.

Conventional color conversion techniques focus on USability rather than fidelity between images, focusing on only a part of colors or performing a color conversion on a saliency of an image rather than an entire image . In addition, the application of these techniques has been limited to specific fields such as games and web browsers. In addition, color conversion and DVS techniques have been applied separately.

The method of controlling the panel voltage according to embodiments of the present invention, the computer readable medium and the controller can greatly reduce the power consumption of the display device by dynamically controlling the panel voltage magnitude based on the color conversion technique .

Hereinafter, this will be described in detail with reference to FIG. 2 to FIG.

FIG. 2 is a view schematically showing a part of a configuration of a display device 20 including a controller 200 according to an embodiment of the present invention.

The display device 20 includes a panel unit 21, a driving unit 22, a converting unit 23, a first adjusting unit 24, a second adjusting unit 25, a power supply unit 26, and a controller 200 .

The panel unit 21 can display an image transmitted from the controller 200 using the panel voltage supplied from the converting unit 23. [ For example, the panel unit 21 may be constituted by an AMOLED display panel.

The panel unit 21 may include a plurality of pixels. Each of the plurality of pixels may be composed of a plurality of subpixels, for example, first through third subpixels. However, the present invention is not limited thereto. Depending on the manner of implementing one pixel, each of the plurality of pixels may be composed of more kinds of sub-pixels. For convenience of explanation, it is assumed that the plurality of subpixels are composed of the first through third subpixels.

Each of the first through third sub-pixels may implement one of red, green, and blue colors according to the image data. However, the technical idea of the present invention is not limited thereto. It is needless to say that each of the first to third sub-pixels may implement any one of colors other than R, G, and B. Hereinafter, it is assumed that the first sub-pixel is an R sub-pixel, the second sub-pixel is a G sub-pixel, and the third sub-pixel is a B sub-pixel.

The driving unit 22 can drive the panel unit 21, more specifically, the plurality of first to third sub-pixels using the driving voltage supplied from the first and second adjusting units 24 and 25. [ The driving part 22 may be constituted by an analog part 22-1 and a digital part 22-1 in accordance with a signal processing type in which the analog part 22-1 is driven by a drive And the digital part 22-2 can receive the driving voltage transmitted from the second adjusting unit 25. [

Although the panel unit 21 and the driving unit 22 are shown as separate components in FIG. 1, the technical idea of the present invention is not limited thereto. The panel unit 21 and the driving unit 22 may include one module . &Lt; / RTI >

The converting unit 23 may convert the supply voltage supplied from the power supply unit 26 to a predetermined level to generate the panel voltage and may transmit the generated panel voltage to the panel unit 21. [ For example, the converting section 23 may include a DC-DC converter. Although not shown in FIG. 1, the conversion unit 23 can transmit the negative panel voltage and the positive panel voltage to the panel unit 21.

The first adjusting unit 24 may adjust the supply voltage supplied from the power supply unit 26 to a predetermined level to generate the first driving voltage. The first adjusting unit 24 may supply the generated first driving voltage to the driving unit 22, specifically, the analog part 22-1. The second adjusting unit 25 may adjust the supply voltage supplied from the power supply unit 26 to a predetermined level to generate the second driving voltage. The second adjusting unit 25 may supply the generated second driving voltage to the driving unit 22, particularly, the digital part 22-2. The power supply unit 26 may supply the supply voltage to the converting unit 23 and the first and second adjusting units 24 and 25. [

The controller 200 can transmit an image input from an external device (not shown) to the panel unit 21. [ For example, the image may include R data, G data, B data, but is not limited thereto.

The controller 200 controls the converting unit 23 to adjust the panel voltage supplied to the panel unit 21. [ For example, the controller 200 may perform at least some of the steps of the color conversion based panel voltage control method (see FIGS. 3 through 8) according to the technical concept of the present invention to generate a reference voltage 9V) can be determined as the panel voltage for displaying the input image, and the conversion unit 23 can be controlled so that the determined panel voltage is supplied to the panel unit 21. [ The method of controlling the panel voltage of the controller 200 will be described in more detail below.

Here, the control method for the panel voltage may be implemented as at least one program including program code for performing various process steps by the controller 200. [ However, the present invention is not limited to this, and the control method for the panel voltage may be implemented as at least one program including program code for performing by at least one computing device.

The program code may be in any language that causes the computing device having information processing capabilities to perform a particular function after any combination of processes, such as direct or translation into another language, reproduction and / or compression in a different data format Means a representation, code or notation of a set.

The program may be stored in at least one of storage means of the controller 200 and storage means (not shown) of the display device 20, and may be executed by the controller 200. [ Depending on the implementation, the program may be stored in a computer-readable medium and downloaded from the computer-readable medium to the control means 200 or to the storage means of the display device 20 to be executed by the controller 200 have.

For example, the computer-readable medium may be a computer readable medium, such as a memory, a magnetic tape, a removable computer diskette, a random access memory (RAM), a read only memory (ROM), a tape, a rigid magnetic disk, Or solid state memory. Current examples of the optical disc include a CD-ROM (Compact Disk Read Only Memory), a CD-R / W (Compact Disc Read / Write) and a DVD.

3 is a flowchart illustrating a control method according to an embodiment of the present invention. The process steps of the control method shown in Fig. 3 can be processed in a time-series or parallel manner in the controller 200 shown in Fig. However, it is not so limited, and one of the process steps of the control method shown in FIG. 3, for example step S310, may be executed by at least one external computing device. In this case, the image category defined by the external computing device, the optimal color conversion distance per set category, and the optimal saturation limit may be stored in at least one of the storage means of the controller 200 and the storage means of the display device 20 . The controller 200 may process step S320 to step S350 in a time series or in parallel using the stored image category, the optimum color conversion distance, and the optimal saturation limit. Hereinafter, for the sake of convenience, it is noted that the process steps of the control method shown in FIG. 3 are performed by the controller 200 as an example.

Referring to FIG. 3, in step S310, the controller 200 defines an image category, and sets an optimal color conversion distance and an optimal saturation limit for each category.

4, which is a drawing for explaining an embodiment of step S310, in step S410, the controller 200 may classify a plurality of reference images into a plurality of categories. The controller 200 can classify a plurality of reference images into a plurality of categories according to an average luminance range, but the method of dividing a plurality of reference images into categories is not limited thereto. The plurality of reference images may be stored in a separate storage device, or may be transferred from an external computing device.

In step S420, the controller 200 can select a representative image of each of a plurality of categories. For example, the controller 200 may select a reference image having the average luminance of the lowest pixels among the reference images included in each of the plurality of categories as the representative image.

In step S430, the controller 200 sets an optimal color conversion distance and an optimal saturation limit for each category using the representative images selected for each category.

Small changes in the CIELab color space, which is a visually uniform color system, do not affect the human visual system (HVS). Therefore, if the color of all the pixels of the image in the CIELab color space is uniformly converted to a color with low power consumption, the power consumed in the display device can be greatly reduced while satisfying the HVS.

The Euclidean distance of two colors in the CIELab color space represents the perceived difference in HVS. That is, a color separated by the same distance is recognized as a color difference of the same size in the human eye. The Euclidean distance formula in the CIELab color space is shown in Equation 1 below. H represents the distance between the original color (L, a, b) and the converted color (L ', a', b '), that is, the color conversion distance (hereinafter referred to as h).

To implement low-power color conversion, a low-power direction vector that satisfies HVS must be found while minimizing power consumption in the CIELab color space. Since the low power direction vector varies depending on the panel characteristics of the display device 20, different direction vectors are obtained depending on the panel type. For example, when the original image is color-transformed by using a plurality of unit direction vectors having a distance of 1, the unit direction vector having the lowest power consumption and the highest similarity to the original image is displayed on the panel Directional direction vector of the output signal. The method of determining the low power direction vector can be performed in various ways.

The converted color (L ', a', b ') is obtained by moving the original color (L, a, b) by the color conversion distance h in the direction of the low power direction vector. At this time, the power reduction amount and the image quality of the image are determined according to the size of h. If h is too large, the power consumption is reduced but the picture quality is degraded. Therefore, the optimal h should be selected considering image quality.

When DVS is applied, if the supplied panel voltage is set lower than the voltage required to achieve the same luminance as when it is the basic panel voltage, there will be distorted pixels whose luminance is lower than the original. At this time, pixel compensation is performed to increase the pixel value to obtain the same luminance as the original luminance. The pixel compensation can prevent the luminance drop caused by the voltage drop.

When the panel voltage falls from 9V to 7V, as shown in FIG. 5, which shows the pixel compensation in the G channel when the panel voltage drops from the basic 9V to 7V, the 216 pixel value falls from 73.1 to 90.1 At this time, the pixel value can be increased from 216 to 255 to output the original luminance 90.1. However, since the maximum luminance that can be outputted is determined according to the magnitude of each panel voltage, the pixel compensation can be performed within the maximum luminance range that each voltage can output. In other words, if the panel voltage falls from 9V to 7V, pixel values below the 216 pixel value can output the original luminance with pixel compensation, but pixel values above the 216 pixel value will not cause the original luminance Can not be output.

If the luminance value of a pixel at a basic panel voltage (for example, 9V) exceeds the maximum luminance of a panel voltage (for example, 7V) for which the luminance value of the pixel is intended to be reduced . The percentage of pixels that are not saturated in the whole pixel and can maintain the original luminance is called the saturation threshold. h, the amount of power reduction and image quality are determined by the saturation limit.

In order to achieve high image quality while minimizing the power consumption of the display device by scaling the panel voltage according to the image contents, an optimal pair of the color conversion distance h and the saturation limit should be obtained. Because there is a characteristic, we categorize the images and find the optimal value pair of h and saturation limits for each category.

When the optimal color conversion distance and the optimal saturation limit are determined for each of the plurality of categories, the panel voltage can be scaled through the optimal color conversion distance and the optimal saturation limit of the corresponding category when a subsequent arbitrary image is input, Power consumption can be optimally reduced.

6, in step S610, the controller 200 determines whether at least one of the candidate images has at least one representative image for the category based on a plurality of candidate pairs consisting of the candidate color conversion distance and the candidate saturation limit To obtain the power consumption of the display device when each of a plurality of candidate pairs is applied and the similarity between the original of the representative image and the color-converted representative image displayed on the panel.

For example, when a, b, and c exist as candidate color conversion distances and x%, y%, and z% exist as the candidate saturation limits, representatives of all nine candidate pairs (3 * 3) The power consumption and the similarity of each of the nine candidate pairs can be obtained by performing a simulation test on the images. The simulation test will be described in more detail below with reference to FIGS. 7 and 8. FIG.

In step S620, the controller 200 sets an optimal color conversion distance and an optimal saturation limit pair of the category to which the representative image belongs based on the obtained power consumption amounts and similarities.

For example, the controller 200 searches for a pair of candidate color conversion distances and candidate saturation limits that satisfy the condition that the power consumption among the plurality of candidate pairs is the smallest among the obtained power consumption amounts and the similarity is equal to or greater than a preset reference value And a pair of candidate color conversion distances and candidate saturation limits that satisfy the searched condition can be set to the optimal color conversion distance and optimal saturation limit of the category to which the representative image belongs.

The above-described simulation test will be described in further detail with reference to FIGS. 7 and 8. FIG. Figures 7 and 8 illustrate exemplary process steps when applying a simulated test to a representative image based on any one candidate pair consisting of one candidate color conversion distance and one candidate saturation limit, The process steps shown in Figures 7 and 8 may also be performed for candidate pairs.

Referring to Fig. 7, in step S710, the controller 200 performs color conversion on the representative image according to one candidate color conversion distance. Specifically, the color of the pixels of the representative image is converted from the RGB color space to the CIELab color space, the color of the pixels is converted according to one candidate color conversion distance in the CIELab color space, and the converted color of the pixels is extracted from the CIELab color space It can be reconverted to RGB color space.

In step S720, the controller 200 determines a mock pixel value corresponding to the candidate saturation limit of one of the pixel values of the pixels of the color-converted representative image. The controller 200 may use a histogram of a predetermined representative image in order to determine a mock pixel value corresponding to one candidate saturation limit.

In step S730, the controller 200 determines a simulated panel voltage from among a plurality of simulated valid voltages that can compensate for pixels having pixel values below the determined simulated pixel value without saturation.

More specifically, the lowest voltage among a plurality of voltages capable of pixel-compensating pixels having a pixel value lower than the determined pixel value by the R, G, and B channels of the representative image, And the largest simulated effective voltage among the simulated effective voltages for each channel can be determined as the simulated panel voltage.

8 for explaining a method for determining the simulated effective voltage in the G channel of the representative image, when the candidate saturation limit is 90%, the candidate saturation limit 810 in the representative image 810 shown in Fig. The simulated pixel value 830 satisfying the limit 90% is 164. That is, the maximum value of the pixels included in the ratio of 90% of the total pixels of the representative image is 164. Next, referring to a table 870 that shows the maximum pixel value that can be compensated for by the panel voltage with respect to the basic panel voltage, voltages that can compensate for pixels having pixel values of the maximum pixel value 164 or less without saturation are determined. In the voltage table 870 of FIG. 8, when the panel voltage is 9V vs. the basic panel voltage 9V, pixel values of pixel value 216 or less can be pixel-compensated without being saturated. Thus, voltages above 7V can compensate pixel values of pixel values below 216 without saturation, and the lowest of these 7V can be determined as the simulated effective voltage in the G channel.

The simulated effective voltages determined in FIG. 8 are determined only in the G channel, and simulated effective voltages can be determined in substantially the same manner as in FIG. 8 for the R and B channels of the representative image, and the R channel, G channel, and B channel The largest effective voltage among the simulated effective voltages of the first and second modules may be determined as the final simulated panel voltage.

In step S740, the controller 200 compensates the pixel value of the pixels of the color-converted representative image according to the determined simulated panel voltage. The controller 200 may compensate the pixel values of the pixels of the color-converted representative image based on the pixel compensation information corresponding to the determined simulated panel voltage among preset pixel compensation information corresponding to the various sizes of the panel voltage . Here, the pixel compensation information may indicate a maximum compensation value of pixels that are not saturated according to the magnitude of the panel voltage. As the look-up table (LUT), the storage means of the controller 200, ) Storage means.

In step S750, the controller 200 calculates the power consumption of the display device according to the determined simulated panel voltage. The controller 200 may calculate the power consumption of the display device based on the determined size of the simulated panel voltage.

In step S760, the controller 200 calculates the similarity between the original image of the representative image and the pixel-compensated representative image displayed on the panel. The controller 200 may calculate the similarity degree according to a Structural SIMilarity (SSIM) image evaluation technique, but is not limited thereto. Since the SSIM image evaluation technique is a technique known in the art, a detailed description thereof will be omitted herein.

The following pseudo code 1 indicates a method for setting the optimum color conversion distance and the optimal saturation limit, and pseudo code 2 indicates a method for color conversion.

// pseudo code 1

Input: Representative images by category, basic panel voltage, low power direction vector, compensation LUT (LOOK UP TABLE)

Output: Optimal value pair for each category (sth_opt, h_opt)

1. Representative images for each category

2. for saturation threshold = sth_min to sth_max

3. for h = h_min to h_max

4. Low power color conversion function call;

5. Compute the sth_val of each RGB channel using the histogram and saturation threshold of each RGB channel;

6. Calculate and output a new voltage using sth_val for each RGB channel;

7. Pixel compensation using a compensated LUT for the transformed image;

8. SSIM calculation;

9. if SSIM> = 0.9800 & P_current <= P_opt

10. h_opt = h;

11. sth_opt = saturation threshold;

12. P_opt = P_current;

13. end

14. end

15. end

16. Store the number of each category and the optimal value pair of the category into an array (category number, h_opt, sth_opt);

17. end

// pseudo code 2

Input: image, low power direction vector, h

Output: The converted image

1. Convert RGB colors (R, G, B) to CIELab colors (L, a, b);

2. Convert CIELab colors to low-power colors (L ', a', b ') that satisfy HVS using low power direction vectors and h;

3. Reconvert low-power color (L ', a', b ') satisfying HVS to RGB color (R', G ', B')

4. end

Lines 1 to 16 of the above pseudo code 1 are repeated for each representative image for each category, lines 2 to 14 are repeated for each of a plurality of candidate saturation limits, and lines 3 to 13 are repeated for a plurality of candidate color conversion distances Is repeated for each. Also, sth_val represents a pixel value corresponding to the candidate saturation limit, the initial P_opt is set to the power consumption when the basic panel voltage is input, and P_current represents the power consumption when the voltage calculated on the line 6 is input.

Referring back to FIG. 3, in step S320, the controller 200 determines a category to which an input image belongs among a plurality of categories. The controller 200 can determine the category according to the average luminance of the input image.

In step S330, the controller 200 color-converts the input image based on the optimum color conversion distance set for the determined category. For example, the color of the pixels of the input image is converted from the RGB color space to the CIELab color space, the color of the pixels is converted according to the optimum color conversion distance in the CIELab color space, and the converted color of the pixels is converted into RGB It can be reconverted to a color space.

In step S340, the controller 200 determines the pixel value corresponding to the optimal saturation limit set for the determined category among the pixel values of the pixels of the color-converted input image. The controller 200 may use the histogram of the input image to determine the pixel value corresponding to the optimal saturation limit.

In step S350, the controller 200 determines the panel voltage among a plurality of effective voltages capable of pixel compensation without saturation of pixels having pixel values below the determined pixel value. The controller 200 determines the panel voltage to be supplied to the panel in accordance with the input image instead of the basic panel voltage of the display device.

The controller 200 sets the pixels having pixel values that are equal to or smaller than the pixel value determined for each of the R channel, the G channel, and the B channel, similarly to the simulation panel voltage determination process in the simulation test described with reference to Fig. The lowest voltage among the compensating voltages may be determined as the effective voltage, and the panel voltage may be determined as the largest effective voltage among the effective voltages determined for the respective channels.

Although not shown in FIG. 3, in step S350, the controller 200 may control the converting unit (refer to 23 in FIG. 2) so that the determined panel voltage is supplied to the panel, The pixel value of the pixels of the input image can be compensated.

Thereby, the pixel-compensated input image corresponding to the color conversion and the adjusted panel voltage can be outputted as the final image to the panel portion (see 21 in Fig. 2) of the display device (see 20 in Fig. 2).

The following pseudo code 3 shows a method of applying a color conversion based DVS to an input image by a control method according to the technical idea of the present invention shown in FIG.

// pseudo code 3

Input: input image, low power direction vector, basic panel voltage, optimum value pair (sth_opt, h_opt) of each category, compensation LUT

Output: Final image, panel voltage

1. Calculate the average luminance of the input image;

2. category classification according to the average luminance of the input image;

3. Set the h and saturation thresholds to h_opt and sth_opt for that category;

4. Low power color conversion function call;

6. Calculate and output the panel voltage using sth_val for each RGB channel;

7. Pixel compensation using a compensated LUT for the transformed image;

8. Final image output;

9. end

9 is a view schematically showing a part of a configuration of a controller 900 according to an embodiment of the present invention.

Referring to FIG. 9, a controller 900 according to an embodiment of the present invention may include a category determination unit 910, a color conversion unit 930, and a panel voltage control unit 950.

The category determination unit 910 can determine a category to which an input image belongs among a plurality of categories.

The color conversion unit 930 can color-convert the input image based on the optimal color conversion distance set for the determined category. The color conversion unit 730 converts the colors of the pixels of the input image into CIELab color spaces in the RGB color space, converts the colors of the pixels according to the optimal color conversion distance in the CIELab color space, And can be reconverted from the color space to the RGB color space.

The panel voltage control unit 950 may determine a pixel value corresponding to the optimal saturation limit set for the determined category among the pixel values of the pixels of the color-converted input image. In addition, the panel voltage controller 950 can determine the panel voltage among a plurality of effective voltages capable of pixel-compensating pixels having pixel values below the determined pixel value without saturation, and converts the determined panel voltage to be supplied to the panel (Refer to 23 in Fig. 2).

More specifically, the panel voltage controller 950 can determine a pixel value corresponding to an optimal saturation limit for each of the R, G, and B channels of the color-converted input image, and outputs the R, The most effective voltage among the effective voltages for each channel is determined as a valid voltage by determining the lowest voltage among the voltages capable of pixel compensation without saturation for the pixels having the pixel value less than the determined pixel value for each of the G channel and the B channel, Can be determined by the voltage.

The optimum color conversion distance and the optimal saturation limit may be stored in advance in the controller 900. However, the present invention is not limited to this, and depending on the implementation, the variable setting unit 970 of the controller 900 may set itself.

For example, when a plurality of reference images are classified into a plurality of categories by the category determination unit 910, and a representative image of each of a plurality of categories is selected, the variable setting unit 970 sets an optimal color conversion The distance and the optimal saturation limit can be determined. The method of determining the optimal color conversion distance and the optimal saturation limit for the representative image has been described above, and a detailed description thereof will be omitted.

9, the controller 900 may further include a pixel compensation unit. The pixel compensation unit may compensate the pixel values of the pixels of the input image that are color-converted by the color conversion unit 930 according to the panel voltage determined by the panel voltage control unit 950, (Refer to 21 in Fig. 2). The pixel compensation unit may compensate the pixel value of the pixels of the color-converted input image based on, for example, pixel compensation information corresponding to the determined panel voltage. The pixel compensation information may indicate a maximum compensation value of pixels not saturated by the magnitude of the panel voltage, and may be stored in a storage means (not shown) of the controller 900 as a LUT.

10 (a) to 10 (d) are diagrams for comparing an original image with an image to which a control method according to an exemplary embodiment of the present invention is applied.

10 (a) and 10 (c) are original images, and FIGS. 10 (b) and 10 (d) are views for explaining an example of a control method according to the technical idea of the present invention, And the results of comparison between them are shown in Table 1 below.

The original image of Lenna (Fig. 10 (a)) and the original image of Baboon (Fig. 10 (c)) show the output image when the panel voltage is 9V. When the color conversion distance h is set to 3 and the saturation limit is set to 85%, the power consumption is reduced by 29.5% and the color conversion distance h is set to 4, When the saturation limit is set to 85%, it can be seen that the power consumption is reduced by 29.8% in outputting Baboon's transformed image (FIG. 10 (d)). In addition, since the degree of similarity at this time is more than 0.98, it can be seen that the degree of similarity with the original image is very high.

That is, according to the embodiments of the present invention, the image quality of the image is maintained at a level that does not affect the human visual system, and the power consumption of the display device can be greatly reduced, It is possible to reduce the power consumption of a mobile device such as a smart phone.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, This is possible.

20: Display device
200, 900: controller
910:
930: Color conversion unit
950:
970: variable setting section

Claims

As a control method for the panel voltage supplied to the panel of the display device,
Determining a category to which an input image belongs among a plurality of categories;
Color transforming the input image based on a preset optimal color conversion distance for the determined category;
Determining a pixel value corresponding to a predetermined optimal saturation threshold for the determined category among pixel values of pixels of the color-converted input image; And
Determining the panel voltage from a plurality of valid voltages capable of compensating for pixels having pixel values below the determined pixel value without saturation;
&Lt; / RTI >

The method according to claim 1,
Before the step of determining the category,
Classifying the plurality of reference images into the plurality of categories according to an average luminance of the pixels;
Selecting a representative image for each of the plurality of categories; And
And setting an optimal color conversion distance and an optimal saturation limit for each of the plurality of categories using the selected representative images.

3. The method of claim 2,
Wherein setting the optimal color conversion distance and the optimal saturation limit comprises:
A power saving amount of the display device when the plurality of candidate pairs are applied by performing at least one simulation test on the representative image based on a plurality of candidate pairs each consisting of a candidate color conversion distance and a candidate saturation limit, Obtaining a similarity between the original image of the representative image and the color-converted representative image displayed on the panel; And
Based on the obtained power consumption amounts and similarities, sets a candidate color conversion distance and a candidate saturation limit of a pair of the plurality of candidate pairs to an optimal color conversion distance and an optimal saturation limit of a category to which the representative image belongs The method comprising the steps of:

The method of claim 3,
In the simulation test,
Color converting the representative image according to one candidate color conversion distance;
Determining a mock pixel value corresponding to a candidate saturation limit of one of the pixel values of the pixels of the color-converted representative image;
Determining a simulated panel voltage from among a plurality of simulated valid voltages capable of compensating for pixels having pixel values below the determined simulated pixel value without saturation;
Compensating a pixel value of pixels of the color-converted representative image according to the determined simulated panel voltage;
Calculating power consumption of the display device according to the determined simulated panel voltage; And
And calculating the similarity between the pixel-compensated representative image displayed on the panel and the original image of the representative image when the determined simulated panel voltage is supplied to the display device.

The method of claim 3,
Wherein the step of setting the candidate color conversion distance and the candidate saturation limit of the pair of the plurality of candidate pairs to the optimal color conversion distance and the optimal saturation limit of the category to which the representative image belongs,
A pair of candidate color conversion distances and a candidate saturation limit satisfying the condition that the power consumption is the smallest among the obtained power consumption amounts and the similarity is equal to or greater than a preset reference value is set as an optimal color conversion distance and optimal saturation range of the category to which the representative image belongs To the limit.

The method according to claim 1,
The color conversion may include:
Converting a color of pixels of the input image from an RGB color space to a CIELab color space;
Converting the color of the pixels according to the optimal color conversion distance in the CIELab color space; And
And re-converting the converted color of the pixels from the CIELab color space to the RGB color space.

The method according to claim 1,
Wherein determining the panel voltage comprises:
Determining a pixel value corresponding to the optimal saturation limit for each of the red (R), green (G), and blue (B) channels of the color-converted input image;
Determining a valid voltage capable of compensating for pixels having a pixel value less than or equal to a pixel value determined for the channel for each of the R, G, and B channels of the color-converted input image without saturation; And
And determining the highest effective voltage among the effective voltages of the R, G, and B channels as the panel voltage.

8. The method of claim 7,
Wherein determining the effective voltage for each of the R, G, and B channels comprises:
The method of claim 1, wherein each of the R, G, and B channels compensates for pixels having a pixel value less than a pixel value determined for the corresponding channel without saturation, And determining the voltage as a valid voltage.

A computer readable medium having stored thereon at least one program for controlling a panel voltage supplied to a panel of a display device,
When the program is executed,
Determining a category to which an input image belongs among a plurality of categories;
Color-converting the input image based on a preset optimal color conversion distance for the determined category;
Determining a pixel value corresponding to a predetermined optimal saturation threshold for the determined category among pixel values of pixels of the color-converted input image; And
Determining the panel voltage from a plurality of valid voltages capable of compensating for pixels having pixel values below the determined pixel value without saturation.

A controller for controlling a panel voltage supplied to a panel of a display device,
A category determination unit that determines a category to which an input image belongs among a plurality of categories;
A color conversion unit for performing color conversion on the input image based on an optimal color conversion distance set in advance for the determined category; And
A pixel value corresponding to a predetermined optimal saturation limit for the determined category among pixel values of pixels of the color-converted input image, and a plurality of pixels capable of compensating for pixels having pixel values below the determined pixel value without saturation A panel voltage controller for determining the panel voltage among effective voltages of the panel;
&Lt; / RTI >

11. The method of claim 10,
Wherein the category determination unit comprises:
Classifying the plurality of reference images into the plurality of categories according to the average luminance of the pixels, selecting representative images of each of the plurality of categories,
The controller comprising:
And a variable setting unit for setting an optimal color conversion distance and an optimal saturation limit for each of the plurality of categories using the selected representative images.

12. The method of claim 11,
Wherein the variable setting unit comprises:
A power saving amount of the display device when the plurality of candidate pairs are applied by performing at least one simulation test on the representative image based on a plurality of candidate pairs each consisting of a candidate color conversion distance and a candidate saturation limit, The degree of similarity between the original image of the representative image and the color-converted representative image displayed on the panel is obtained,
Based on the obtained power consumption amounts and similarities, sets a candidate color conversion distance and a candidate saturation limit of a pair of the plurality of candidate pairs to an optimal color conversion distance and an optimal saturation limit of a category to which the representative image belongs And a controller.

13. The method of claim 12,
In the simulation test,
Wherein the variable setting unit color-converts the representative image according to the one candidate color conversion distance,
Wherein the variable setting unit determines a mock pixel value corresponding to a candidate saturation limit of one of pixel values of the pixels of the color-converted representative image, and compensates the pixels having pixel values below the determined mock pixel value without saturation Determining a simulated panel voltage from a plurality of simulated effective voltages,
Wherein the variable setting unit compensates the pixel value of the pixels of the color-converted representative image according to the determined simulated panel voltage,
Wherein the variable setting unit calculates power consumption of the display device according to the determined simulated panel voltage,
Wherein the variable setting unit is configured to calculate the similarity between the pixel-compensated representative image displayed on the panel and the original image of the representative image when the determined simulated panel voltage is supplied to the display device.

14. The method of claim 13,
Wherein the variable setting unit comprises:
A pair of candidate color conversion distances and a candidate saturation limit satisfying the condition that the power consumption is the smallest among the obtained power consumption amounts and the similarity is equal to or greater than a preset reference value is set as an optimal color conversion distance and optimal saturation range of the category to which the representative image belongs And the limit is set to the limit.

11. The method of claim 10,
Wherein the color conversion unit comprises:
Converting the colors of the pixels of the input image from the RGB color space to the CIELab color space, converting the colors of the pixels according to the optimal color conversion distance in the CIELab color space, and converting the converted colors of the pixels from the CIELab color space Converted into an RGB color space.

11. The method of claim 10,
Wherein the panel voltage controller comprises:
A pixel value corresponding to the optimal saturation limit is determined for each of the R, G, and B channels of the color-converted input image, and a pixel value corresponding to the R, G, and B channels of the color- Determining a valid voltage capable of compensating for pixels having a pixel value equal to or less than the determined pixel value without saturation and determining a maximum effective voltage among the R, G, and B channel effective voltages as the panel voltage, Controller.

17. The method of claim 16,
Wherein the panel voltage controller comprises:
The method of claim 1, wherein each of the R, G, and B channels compensates for pixels having a pixel value less than a pixel value determined for the corresponding channel without saturation, And determines it as an effective voltage.

11. The method of claim 10,
Wherein the display device includes a conversion unit for supplying a predetermined voltage to the panel,
Wherein the panel voltage controller comprises:
And controls the converting unit so that the determined panel voltage is supplied to the panel.