JP2010008535A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device capable of determining change of scene with high precision and performing proper FRC processing when performing the FRC processing of movement compensation type. <P>SOLUTION: This image display device is provided with an FRC part 16 for converting the number of frames or the number of fields of an input image signal by inserting the image signal on which movement compensation processing is applied between the frames or the fields of the input image signal internally and outputting it into a display panel and a scene change detection part 6 for detecting whether scene is changed or not based on the histogram of the input image signal. The FRC part 16 initializes movement vector when the change of scene is detected by the scene change detection part 6. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a video display device, and more particularly to a video display device having a function of converting a frame rate or a field rate.

  Conventionally, a technique for converting a frame rate (the number of frames) by interpolating an image between frames in order to improve motion blur in a hold-type display method such as a liquid crystal display device is known. This technique is called FRC (Frame Rate Converter) and is put into practical use in liquid crystal display devices and the like.

  For example, Patent Document 1 describes a technique for improving a decrease in spatial frequency characteristics that causes motion blur by increasing the frame frequency of a display image by generating an interpolation frame adaptively in motion. ing. In this method, at least one interpolated image signal to be interpolated between frames of a display image is formed in a motion adaptive manner from the preceding and following frames, and the formed interpolated image signal is interpolated between frames and sequentially displayed. ing.

  On the other hand, in recent video display devices, particularly in liquid crystal display devices, not only gain control of the input video signal, but also by modulating the luminance of the backlight light source in conjunction with the gain control of the input video signal, Techniques have been proposed for reducing power and enhancing contrast.

  For example, in Patent Documents 2 and 3, when the histogram of the video signal is equal to or less than a predetermined ratio of the displayable band (when the luminance distribution is dark), the backlight luminance is decreased and the gain of the input video signal is increased. Further, it is described to improve the contrast while maintaining the video display luminance. In particular, Patent Document 3 describes that non-linear correction is performed on a high gradation region so as not to cause whitening caused by increasing the gain of an input video signal.

  Furthermore, Patent Document 4 describes that the gain of an input signal is increased to the dynamic range width and the luminance of the backlight is adjusted according to the maximum luminance level, minimum luminance level, and average luminance level of the video signal. .

As described above, according to the techniques described in Patent Documents 2 to 4, when a dark image is input as a whole, the backlight luminance is decreased and the gain of the input image signal is increased. While maintaining the same luminance, it is possible to achieve power saving and improve contrast.
Japanese Patent No. 3295437 JP 2006-276677 A US Patent Application Publication No. 2006/0274026 Japanese Patent Laid-Open No. 2001-27890

  In the FRC process described above, a motion vector is initialized when there is a scene change. This is because when the scene changes, there is little correlation between the current screen and the previous screen, and therefore, when motion compensation is performed between the current screen and the previous screen, an unnatural image is obtained. As one means for detecting such a scene change, APL (average luminance level) of a video signal is generally used. This APL can be calculated relatively easily by adding the luminance values of the video. In the conventional video display device, if the change in APL is large, it is determined that there is a scene change, and the motion vector is initialized during the FRC process.

  However, when the above APL is used as a means for detecting a scene change, even if the scene changes, if the APL happens to be the same, the video display device determines that there is no scene change and moves There is a problem that the image quality is deteriorated without initializing the vector.

  In the luminance modulation processing described in Patent Documents 2 to 4, the APL after the luminance modulation processing changes greatly depending on the presence or absence of a white peak such as caption. In the case of a video including a white peak such as caption, the video signal has a value from 0 to 255, and thus the gain of the video signal is not changed. On the other hand, in the case of a dark image that does not include a white peak, the gain of the image signal is changed and extended from 0 to 255, and the backlight luminance is controlled to be reduced accordingly. For this reason, even in a similar scene, the APL greatly changes depending on the presence or absence of a white peak such as a caption.

  When the FRC process is performed together with the luminance modulation process, a scene change is detected based on the APL of the video signal after the luminance modulation process in the FRC circuit. Therefore, even if the scene is similar, if the APL after the luminance modulation processing changes greatly due to the presence or absence of a white peak, the video display apparatus determines that there is a scene change based on the change in the APL, and performs FRC processing. Sometimes the motion vector was initialized.

  The present invention has been made in view of the above circumstances, and provides a video display device capable of accurately determining a scene change and performing appropriate FRC processing when performing motion compensation type FRC processing. With the goal.

  In order to solve the above-mentioned problem, the first technical means of the present invention interpolates a video signal subjected to motion compensation processing between frames or fields of an input video signal, so that a frame of the input video signal is obtained. A video display device comprising rate conversion means for converting the number or number of fields and outputting to the display panel, comprising scene change detection means for detecting whether or not a scene change is based on a histogram of the input video signal, The rate conversion means initializes a motion vector when a scene change is detected by the scene change detection means.

  According to a second technical means, in the first technical means, the scene change detecting means determines a scene change when the amount of change of the histogram between frames or fields of the input video signal is larger than a predetermined value. It is characterized by that.

  According to a third technical means, in the first or second technical means, the rate conversion means detects a motion vector information between successive frames or fields included in the input video signal, and Based on the detected motion vector information, an interpolation vector allocating unit that allocates an interpolation vector between the frames or between the fields, and an interpolation video generating unit that generates an interpolation video signal from the allocated interpolation vector; And a video interpolating unit for interpolating the generated interpolated video signal between the frames or the fields.

  According to a fourth technical means, in any one of the first to third technical means, there is provided luminance modulation means for controlling the light emission luminance of the backlight and the gain of the input video signal in conjunction with each other. Is.

  According to the present invention, when a motion compensation type FRC process is performed, a scene change can be accurately determined based on a histogram of an input video signal, so that an appropriate FRC process can be performed.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments according to a video display device of the invention will be described with reference to the accompanying drawings. The video display device in this embodiment (hereinafter represented by a liquid crystal display device) includes a luminance modulation unit that controls the emission luminance level of a backlight light source and the gain of an input video signal in conjunction with each other, a frame rate or An FRC unit that converts a field rate is provided. Although the present invention can be applied to any of a field signal, an interpolated field signal, a frame signal, and an interpolated frame signal, both (field and frame) are in a similar relationship with each other, so A signal and an interpolated frame signal will be described as representative examples.

<Outline of Luminance Modulation Processing According to the Present Invention>
Ideally, the amount of light emitted from the liquid crystal display device faithfully reproduces the level of the video signal to be displayed. That is, when displaying a black screen, the amount of light emitted from the screen should ideally be zero. However, in an actual liquid crystal display device, there is some light leakage, and even when a black screen is displayed, gray display is performed instead of black.

  One important performance of a liquid crystal display device is a contrast ratio (hereinafter also referred to as CR). In the liquid crystal display device, CR is a ratio between the maximum luminance and the minimum luminance on the display panel. In the case of a liquid crystal display device, the maximum luminance is determined by the maximum light emission luminance of the light source, and the minimum luminance is determined by the amount of light leakage during black display. Therefore, when the light emission luminance of the light source is constant, the contrast ratio is constant in the same liquid crystal panel.

  FIG. 1 is a graph showing the relationship between the input gradation (video signal level) and the luminance value on the liquid crystal panel for liquid crystal panels with CR of 3000 and 6000. The maximum brightness is the same 450 cd, but the display brightness (minimum brightness) on the liquid crystal panel at the input gradation (pixel value) 0 is 0.15 cd in the case of CR3000 and 0.075 cd in the case of CR6000. There is a difference.

  Here, when the light emission luminance of the light source is reduced to 50% and the input video signal is amplified by a predetermined amount when the CR3000 liquid crystal panel is used, the relationship between the pixel value of the input video signal and the display luminance value of the liquid crystal panel is The relationship is as shown by the dotted line in FIG. 1, and a luminance expression close to that of a CR6000 liquid crystal panel can be obtained with pixel values of 0 to 128. However, an image with a pixel value greater than 128 cannot be expressed in gradation, and so-called whitening occurs. Therefore, it is necessary to adjust the light emission luminance of the backlight and set the gain according to the feature amount of the input video signal.

  For example, when the luminance histogram of the input video signal indicates a luminance distribution with a pixel value of 128 or less, the backlight luminance is reduced to 50% as shown in FIG. Control that allows quantitative amplification may be performed. By controlling the backlight emission luminance and setting the gain in accordance with the feature amount of the input video signal in this way, it is possible to increase the contrast feeling and at the same time to save power by lowering the backlight emission luminance. It becomes possible.

  In the above description, the case where the luminance histogram of the input video signal shows a luminance distribution with a pixel value of 128 or less has been described as an example. However, other than the above example, for example, when the white portion in the video is extremely small, The degree of importance can be lowered and black expression can be improved in the same manner. At this time, the unsharp portions of the white area may be ignored, or the gain in the white area may be determined so that the white area can be reduced by the gain setting for realizing the target CR.

In addition, in the luminance modulation processing according to the present invention, in order to save power, processing for dynamically suppressing the light emission luminance of the light source according to the feature amount such as APL of the video obtained from the video signal as described later is also performed. And execute.
In other words, the reference emission luminance level for setting the gain setting and the emission luminance level of the backlight light source is first set in accordance with the video feature amount (APL, peak (maximum luminance value), histogram information, etc.), thereby saving power. In addition, a process for producing a contrast feeling as described above (that is, setting the light emission luminance level to an appropriate value equal to or lower than the reference light emission luminance level) is performed on the reference light emission luminance level. Thus, the CR is improved and further power saving is performed, and the gain of the video signal is set in conjunction with the processing so as to maintain the visual luminance.

<System configuration example of a liquid crystal display device that performs luminance modulation processing according to the present invention>
FIG. 2 is a block diagram showing a system configuration example of the liquid crystal display device according to the present invention. The liquid crystal display device illustrated in FIG. 2 includes a scaling unit 1, a Y histogram detection unit 2, an APL detection unit 3, a BL (backlight) luminance level setting unit 8, a CPU (Central Processing Unit) / CPLD (Complex Programmable Logic Device). 11, a BL adjustment unit 12, an image quality correction unit 14, an RGBγ / WB (White Balance) adjustment unit 15, an FRC (Frame Rate Control) unit 16, and a video output unit 17.

  The liquid crystal display device illustrated in FIG. 2 further includes an advanced luminance modulation unit 20 that executes the main part of the luminance modulation processing according to the present invention. The advanced luminance modulation unit 20 corresponds to the luminance modulation unit of the present invention, and includes a histogram stretching unit 4, a distortion module 5, a scene change detection unit 6, a first temporary filter 7, a second temporary filter 9, and a variable delay 10. The configuration design unit 13 is included. Note that, as described above, the luminance modulation processing according to the present invention is determined not only by dynamic light emission luminance control according to a feature quantity such as APL but also by a predetermined condition of the video feature quantity. This is an advanced luminance modulation process in which a light emission luminance level BLreduced that gives a sense of contrast to the light emission reference light emission luminance level BLref is selected and the gain of the video signal is also set. Therefore, the part that executes this process is called an “advanced” luminance modulation unit 20.

First, the outline of each block in the liquid crystal display device of FIG. 2 will be described.
The video output unit 17 includes a liquid crystal panel that displays video based on the video signal, and a liquid crystal control circuit that converts the video signal into a signal for driving the liquid crystal panel and outputs the signal to the liquid crystal panel. Although the details will be described later, the video signal is converted using the gain set by the advanced luminance modulation unit 20 and then input to the video output unit 17. That is, in the luminance modulation processing according to the present invention, a video signal indicating a video to be displayed by the video output unit 17 is a processing target. The gain and its setting will be described later.

  The BL adjustment unit 12 includes a lamp composed of a fluorescent tube and a lamp driving circuit that drives the lamp, and a light source that irradiates the liquid crystal panel from the back and side surfaces (also referred to as a backlight light source or simply a backlight). Configure. In the luminance modulation processing according to the present invention, this lamp is a target of emission luminance control.

  The BL adjustment unit 12 is controlled by the CPU / CPLD 11. The CPU / CPLD 11 is a signal for actually dimming by the lamp driving circuit (for example, an inverter circuit) of the BL adjustment unit 12 in accordance with a signal (for example, a duty signal) indicating the light emission luminance level BL reduced output from the advanced luminance modulation unit 20. It is converted into (for example, a signal suitable for driving such as pulse width modulation) and output to the BL adjustment unit 12. The backlight dimming value is converted into a signal for actual backlight dimming. Further, as the lamp, for example, a lamp composed of an LED (Light Emitting Diode) or a combination of an LED and a fluorescent tube may be adopted, and at the same time, a lamp driving circuit corresponding to the lamp may be provided. Good.

  The parts for processing the video signal output to the video output unit 17 and controlling the BL adjustment unit 12 via the CPU / CPLD 11 are the scaling unit 1, the Y histogram detection unit 2, the APL detection unit 3, and the BL luminance level setting unit. 8, an image quality correction unit 14, an RGBγ / WB adjustment unit 15, an FRC unit 16, and an advanced luminance modulation unit 20.

  First, the scaling unit 1 changes the number of pixels of the video frame indicated by the input video signal (input video signal) or the aspect ratio of the video frame by calculation according to the resolution of the liquid crystal panel and the like.

  Here, as the input video signal, for example, a signal obtained by demodulating a video signal received as a broadcast wave, a video signal received via a communication network, a signal obtained by reading a video signal stored in an internal storage device, various recorders and various players This corresponds to a video signal received from an external device such as a tuner device or a tuner device, or a video signal obtained by performing various video processes on the video signal. Although not shown, the liquid crystal display device of FIG. 2 may be configured to be able to acquire any of such video signals.

  The image quality correction unit 14 changes the contrast, color, and the like of the video with respect to the video signal output from the scaling unit 1 according to user settings and the like.

  The RGB γ / WB adjustment unit 15 adjusts γ, WB (white balance) / CT (color temperature), etc., of the video signal output from the image quality correction unit 14. Further, the RGBγ / WB adjustment unit 15 changes the gain of the signal by a gain setting signal from the advanced luminance modulation unit 20 (actually the configuration design unit 13). Here, the gain for the video signal output from the image quality correction unit 14 is changed, or the gain for the video signal after γ adjustment in the RGB γ / WB adjustment unit 15 is changed. Then, the RGBγ / WB adjustment unit 15 performs conversion of the video signal based on the gain, and compensates for the luminance reduction by the gain with respect to the control for reducing the light emission luminance level by the advanced luminance modulation unit 20 as described later. Here, in order to suppress noise in the low gradation part, this conversion is performed after γ adjustment and before WB adjustment.

  The gain setting signal from the advanced luminance modulation unit 20 is a signal indicating a conversion coefficient for converting the pixel value (video signal level) of the video signal to be output to the liquid crystal panel. This gain setting signal is a common conversion coefficient for multiplying each video signal level (in this example, a value of 0 to 255) as shown in the following example, and gaining a peak by gaining as described later. The gain may be corrected by the RGBγ / WB adjustment unit 15 for a certain video signal level range obtained based on the video signal level range.

  The FRC unit 16 is a frame rate converter corresponding to the rate conversion means of the present invention, and detects the motion vector of the video from the adjusted video signal output from the RGBγ / WB adjustment unit 15 and generates an interpolated video. Thus, the display frequency is usually converted from the display frequency of 60 Hz to the display frequency of 120 Hz. Of course, the display frequency to be processed in the FRC unit 16 and the display frequency after processing are not limited to this. In the example of FIG. 2, the liquid crystal driving circuit of the video output unit 17 converts the video signal output from the FRC unit 16 into a signal for driving the liquid crystal panel and outputs the signal to the liquid crystal panel.

  The Y histogram detection unit 2 divides the video frame into pixel units and generates a histogram representing the frequency of occurrence of the luminance value of each pixel. The histogram generated by the Y histogram detection unit 2 has a frequency value for each of luminance values (Y) 0 to 255, for example. The APL detection unit 3 calculates the average luminance level of the video signal for each video frame. The value calculated by the APL detection unit 3 is a value indicating 0% when the entire screen is black, and a value indicating 100% when the entire screen is white.

  The histogram stretching unit 4 sets a range to be used by the advanced luminance modulation unit 20 from the histogram generated by the Y histogram detection unit 2. For example, it is assumed that the distortion module 5 is a module that performs an operation with a minimum value 0 to a maximum value 255, and the input video signal is originally a signal having a minimum value 10 to a maximum value 235. In such a case, the histogram stretching unit 4 sets the frequency value for each of the minimum value 10 to the maximum value 235 to the frequency for each of the minimum value 0 to the maximum value 255 in order to match the calculation in the distortion module 5. It stretches to fit the value.

  The distortion module 5 is actually set from the histogram input from the histogram stretching unit 4 and a reference emission luminance level (also referred to as a backlight target value) BLref set by a BL luminance level setting unit 8 described later. The light emission luminance level (also referred to as the backlight value) BLreduced, that is, the light emission luminance level used for backlight control is selected (determined). The selection is performed within a range that does not exceed the reference emission luminance level BLref set by the BL luminance level setting unit 8 from a plurality of predetermined emission luminance levels. Also, here, a backlight value BLreduced that can realize a display image closer to the liquid crystal panel having the target CR is selected. The distortion parameters such as the target CR may be set from a main CPU (not shown).

  The scene change detection unit 6 detects the presence or absence of a scene change from the degree of change between the histogram one frame before and the current histogram. For example, the cumulative value of the frequency change of each luminance value is calculated, and if it is larger than a specific value, it is determined that the scene has changed.

  The first temporary filter 7 is provided to prevent visual discomfort caused when the above-described light emission luminance level BLreduced actually set selected by the distortion module 5 changes suddenly. After the amount of change in the light emission luminance level BLreduced is slow, it is output to the subsequent stage as the light emission luminance level BLreduced that is actually set. At the time of a scene change, since a slow change in the light emission luminance level BLreduced is returned, the user feels uncomfortable. Allow change.

  The BL luminance level setting unit 8 is a video feature amount such as an APL value output from the APL detection unit 3 or histogram information output from the Y histogram detection unit 2, and an OPC (Optical Picture Control) output from a main CPU (not shown). A maximum value of the light emission luminance level of the backlight is determined with reference to a value of the brightness sensor) or a user set value. For example, when the APL is high, the maximum value of the light emission luminance level of the backlight is set to a low value so that an image without feeling dazzling can be obtained. The maximum value of the light emission luminance level of the backlight is the reference light emission luminance level (backlight target value) BLref for the advanced luminance modulation executed by the advanced luminance modulation unit 20. As the video feature amount for determining the light emission luminance level BLref for reference, APL or histogram information can be used as described above, and the feature amount to be used is selected according to the embodiment. For the histogram information, the peak value (maximum luminance value) of the video, the ratio of the video signal included between the predetermined luminances smaller than the maximum luminance, and the like are used.

  Since the selection by the distortion module 5 is performed within a range that does not exceed the reference emission luminance level BLref set by the BL luminance level setting unit 8, the BL luminance level setting unit 8 selects the reference emission luminance level BLref. As described above, the maximum value of the light emission luminance level of the backlight is set. In the example of FIG. 2, the reference light emission luminance level that has passed through the second temporary filter 9 is BLref.

  The second temporary filter 9 is a filter having a function equivalent to that of the first temporary filter 7. In brief, when the APL changes rapidly and the change does not affect the selection in the distortion module 5, the emission luminance level BLreduced output from the first temporary filter 7 is temporal. Change has been mitigated. However, since the gain setting is calculated based on the reference emission luminance level output from the BL luminance level setting unit 8, the gain changes and the display luminance on the liquid crystal panel changes abruptly. In order to eliminate or alleviate such a sudden change in display luminance, a second temporary filter 9 is provided.

  The variable delay 10 is a delay unit for timing the video output from the video output unit 17 and the backlight dimming in the BL adjustment unit 12. In backlight dimming, backlight luminance control is performed after a relatively small amount of processing if the dimming value is determined. On the other hand, the video signal gain is determined by advanced luminance modulation, the frame rate is controlled by the FRC unit 16 and converted to the panel control signal by the liquid crystal control circuit after the luminance level of the video signal is changed. Since many processes are performed, a time delay occurs. Then, the timing of the backlight dimming control and the video gain control that should be performed at the same time is shifted, and the balance between the backlight and the video is lost. Therefore, the backlight dimming is intentionally delayed by the variable delay 10 to match the timing of the backlight dimming control and the video gain control.

  The configuration design unit 13 determines the gain of the video signal based on the reference emission luminance level BLref determined by the BL luminance level setting unit 8 and the emission luminance level BLreduced selected by the distortion module 5. In the example of FIG. 2, the levels BLreduced and BLref are used after passing through the temporary filters 7 and 9, respectively. If the reference light emission luminance level (backlight target value) BLref and the selected light emission luminance level (backlight value) BLreduced are the same, there is no need to change the luminance level of the video signal, and the gain is 1. Further, when the selected light emission luminance level is lower than the reference light emission luminance level, the gain is set in a direction to increase the luminance level of the video signal according to the value.

<Detailed Description of Main Blocks for Performing Luminance Modulation Processing According to the Present Invention>
The BL brightness level setting unit 8, the scene change detection unit 6, the distortion module 5, the configuration design unit 13, and the RGBγ / WB adjustment unit 15 will be described in this order as main blocks in the liquid crystal display device of FIG.

<< BL brightness level setting section 8 >>
The BL luminance level setting unit 8 receives the APL of the video signal detected by the APL detection unit 3 and controls based on detection information from a brightness sensor (not shown) that measures the ambient brightness (ambient illuminance). A signal and a control signal based on a user setting for setting the brightness of the liquid crystal panel are input. In addition, when information such as the frequency that cannot be expressed when the video signal is expanded or information such as the minimum luminance and the maximum luminance of the video signal is used as the video feature amount, the Y histogram detection unit 2 uses the screen unit of the video signal. These pieces of information (referred to as histogram information) required in units of frames are input. When both APL and histogram information are used, each information is input to the BL luminance level setting unit 8.

  Then, the BL luminance level setting unit 8 outputs a reference light emission luminance level BLref based on these control signals and APL. More specifically, a method of dynamically adjusting the backlight luminance according to the APL of the input video signal that changes in screen units (frame units) is applied, and the light emission luminance level obtained thereby is used for reference light emission. Output as the brightness level BLref.

  In order to generate the reference light emission luminance level BLref, a luminance control table (lookup table) held in the BL luminance level setting unit 8 is used. The luminance control table defines the relationship of the light emission luminance level of the backlight according to the video feature amount (APL in this case) of the input video signal, that is, the luminance control characteristic. A plurality of selectable brightness control tables are prepared and held in a table storage memory such as a ROM (Read Only Memory) provided in the BL brightness level setting unit 8.

  For example, a photodiode is applied to a brightness sensor that measures the brightness around the liquid crystal display device. The brightness sensor generates a DC voltage signal corresponding to the detected ambient light and outputs it to a main CPU (not shown). The main CPU outputs a control signal for selecting the brightness control table to the BL brightness level setting unit 8 according to the DC voltage signal corresponding to the ambient light.

  Further, the main CPU outputs a luminance adjustment coefficient for adjusting the luminance control value of the luminance control table as a control signal based on a user setting for setting the brightness of the liquid crystal panel. The brightness adjustment coefficient is used for setting the brightness of the entire screen in accordance with a user operation. For example, screen brightness adjustment items are set on a menu screen held by the liquid crystal display device. The user can set an arbitrary screen brightness by operating the setting item. The main CPU recognizes the brightness setting and outputs a brightness adjustment coefficient to the BL brightness level setting unit 8 according to the set brightness.

  The BL luminance level setting unit 8 selects a luminance control table by designating a table No. according to a control signal output from the main CPU according to the detection information of the brightness sensor. Alternatively, the luminance control table to be selected may be generated by calculation. Then, the brightness conversion value of the selected brightness control table is multiplied by the brightness adjustment coefficient obtained as a control signal based on the user setting, and the slope of the brightness control characteristic of the brightness control table is changed, and finally, for reference A brightness control table used to generate the light emission brightness level BLref is determined. Then, the BL luminance level setting unit 8 uses the luminance control characteristic of the determined luminance control table to generate and output a reference emission luminance level BLref according to the APL output from the APL detection unit 3.

  As described above, the luminance control table defines the relationship between the APL that is the feature amount of the input video signal and the light emission luminance level of the backlight. For example, when the APL is large, the light emission luminance level of the backlight is small. By setting so as to be, the luminance of the backlight is suppressed so as not to feel dazzling in the case of a high-luminance image. In accordance with the luminance control characteristics of the luminance control table, the light emission luminance level BLref dynamically changes according to the change in the APL of the video signal. The brightness control characteristics in the brightness control table are not particularly limited, and those that specify characteristics that dynamically change the light emission brightness level of the backlight according to the feature amount of the input video signal can be applied as appropriate. .

  The reference emission luminance level BLref output from the BL luminance level setting unit 8 in this manner is delayed by the action of the first temporary filter 7 and then input to the configuration design unit 13 for calculating the video gain. In addition to being used, it is input to the distortion module 5 and used to determine the emission luminance level BLreduced according to the histogram.

<< Scene Change Detection Unit 6 >>
3A and 3B are diagrams for explaining the Y histogram of the video signal and its transition. FIG. 3A shows an example of the Y histogram of the previous frame, and FIG. 3B shows the current histogram following FIG. 3A. FIG. 3C is a diagram showing an example of the Y histogram of a frame, and FIG. 3C is a diagram showing a frequency change portion by integrating the histograms of the respective frames shown in FIGS. 3A and 3B. FIG. 4 is a block diagram illustrating a configuration example of the scene change detection unit 6 in the liquid crystal display device of FIG.

  When the video scene changes, the content of the video changes greatly, so the luminance distribution of the video signal is considered to change significantly. The scene change detection unit 6 uses this to detect a scene change. Specifically, the scene change detection unit 6 detects the presence / absence of a scene change from the histogram of the previous frame of the video signal and the degree of change in the current histogram.

  The scene change detection unit 6 corresponds to the scene change detection unit of the present invention, and includes a histogram buffer 61 and a histogram change detection unit 62. The histogram buffer 61 stores histogram data of the previous frame. The histogram change detection unit 62 compares the histogram data of the current frame and the previous frame, calculates a cumulative value of the frequency change, and determines a scene change when it is larger than a specific value. When it is determined that the scene change has occurred, the histogram change detection unit 62 outputs the inter-frame scene change detection signal to the first temporary filter 7 and the FRC unit 16.

  As a specific example, consider a case where the image of the previous frame is a histogram as shown in FIG. 3A and the image of the current frame is a histogram as shown in FIG. In this case, the histogram data of FIG. 3A is stored in the histogram buffer 61. The histogram change detector 62 compares the data in the histogram buffer 61 with the histogram data of the current frame, and detects the frequency change. The hatched portion in FIG. 3C is the frequency change portion. The histogram change detection unit 62 calculates the accumulated value of the frequency change portion, in other words, the area, and determines that a scene change has occurred if it is larger than a predetermined value. Then, the histogram change detection unit 62 outputs a scene change detection signal for only the frame determined to be a scene change.

<< Distortion Module 5 >>
FIG. 5 is a diagram for explaining an example of the light emission luminance level selection process executed by the distortion module in the liquid crystal display device of FIG. h1 represents a Y histogram of the video signal. Here, the horizontal axis represents the input gradation of the video signal (also referred to as a pixel value or video signal level that can be taken as the video signal), and the vertical axis represents the frequency of each video signal level.

  For such a video histogram h1, A is a video luminance range that can be displayed when the light emission luminance level of the backlight is 100% in the liquid crystal panel to be used. Also, let B be the video luminance range that can be displayed on the liquid crystal panel of the target CR. Also, let C be an image luminance range that can be displayed at a specific light emission luminance level among the light emission luminance levels that can be selected by the distortion module 5. In the histogram h1, the portions that overlap the video luminance range B on both sides of the video luminance range C are the portions to be subjected to the above-mentioned numericalization, and are evaluation value calculation portions. Of the evaluation value calculation portion, the low luminance portion is D1 and the high luminance portion is D2.

The evaluation value (Distortion) is calculated by the following equation (1) based on the frequency and weighting with respect to the selectable light emission luminance level.
Distortion = Σ {(frequency of image luminance range D1 + D2) × (distance weight)} (1)

  As the weight, a distance weight that increases as the distance from the image luminance range C that can be displayed at the light emission luminance level that is an evaluation value calculation target increases. Here, the distance weight of the low luminance portion D1 is E1, and the distance weight of the high luminance portion D2 is E2. Therefore, even if the frequency value is the same, the evaluation value becomes larger as it is far from the range that can be expressed. This is because the farther from the range that can be expressed, the greater the influence that cannot be expressed as video. The values calculated by the frequency and the weight are F1 (low luminance part) and F2 (high luminance part). The evaluation value is the sum of the areas (cumulative total) of F1 and F2.

  The distortion module 5 selects the light emission luminance level corresponding to the video luminance range C having the lowest evaluation value among the evaluation values calculated for each light emission luminance level as the output light emission luminance level BLreduced. At this time, the distortion module 5 corresponds to the video luminance range C having the lowest evaluation value in a range not exceeding the light emission luminance level BLref set by the BL luminance level setting unit 8 and relaxed by the second temporary filter 9. The light emission luminance level BLreduced is selected.

  Ideally, the evaluation value is calculated for all selectable light emission luminance levels in the distortion module 5. However, since there is a limitation on the processing time or the like, the luminance control range of selectable light emission luminance levels may be equally divided, and for example, the light emission luminance level may be calculated for about 10%.

  That is, the video luminance range that can be displayed at the specific light emission luminance level of the above equation (1) is set as C, and the selectable light emission luminance levels are sequentially applied to calculate the evaluation value for each light emission luminance level. The light emission luminance level having the lowest evaluation value among the calculated evaluation values is set as the selected light emission luminance level BLreduced, and this value is output to the first temporary filter 7 to be used for backlight dimming control. And output to the configuration design unit 13 for use in setting (calculating) video gain.

  The selection processing in the distortion module 5 will be described with specific numerical values with reference to FIGS. FIG. 6 is a diagram for explaining a specific example of the luminance modulation processing in the liquid crystal display device according to the present invention, and is a diagram showing an example of the relationship between the panel CR and the target CR in the video histogram. Here, the maximum luminance of the liquid crystal panel is 450 cd when the CR (panel CR) of the liquid crystal panel to be used is 2000, the target CR is 3500, the luminance control range of the backlight is 20 to 100%, and the backlight luminance is 100%. To do. Moreover, each alphabet symbol in FIG. 6 is based on FIG.

  In this example, the video luminance range A that can be displayed on the liquid crystal panel to be used is 450 cd to 0.225 cd. In addition, the target image luminance range B that can be displayed on the liquid crystal panel is 450 cd to 0.128 cd. Then, the frequency for each video signal level 0 to 255 is assigned so as to match the video luminance range B. In this case, the difference between the video luminance range A and the video luminance range B is about 5 digits.

  If there is an image in the difference between the image luminance range B and the image luminance range A in the histogram h1, the luminance expression closer to the target CR can be expressed by lowering the light emission luminance level of the backlight. However, if an image is distributed on the high luminance side, a portion that cannot be expressed by reducing the light emission luminance level of the backlight occurs. Therefore, as described above, the evaluation value is calculated to obtain the optimum light emission luminance level BLreduced.

  FIG. 7 is a diagram showing a video luminance range C when the light emission luminance level is 100%, which is one of the selection targets, and FIG. 8 is a video luminance range when the light emission luminance level is about 70%, which is one of the selection targets. FIG. 9 is a diagram showing a video luminance range C at a light emission luminance level of about 50%, which is one of the selection targets. Each alphabet symbol in FIGS. 7-9 is based on FIG.

  As shown in FIG. 7, when the emission luminance level indicates 100%, the evaluation value F1 for the low luminance portion has a certain value, and the evaluation value F2 for the high luminance portion has no value. . Further, as shown in FIG. 8, when the emission luminance level is lowered to about 70%, both the low luminance portion evaluation value F1 and the high luminance portion evaluation value F2 have low values. As shown in FIG. 9, when the emission luminance level is lowered to about 50%, the evaluation value F1 for the low luminance portion has no value, and the evaluation value F2 for the high luminance portion has a large value. Comparing the areas (cumulative) of the evaluation value calculation results at the respective light emission luminance levels exemplified in FIGS. 7 to 9, the light emission luminance level is the lowest when it is 70%. Therefore, the distortion module 5 selects and outputs a light emission luminance level of 70%.

<< Configuration Design Section 13 >>
A basic model showing the relationship between the pixel value input to the liquid crystal panel and the display brightness on the liquid crystal panel is expressed by the following equation (2). Here, Y is the display luminance on the liquid crystal panel, BL is the light emission luminance level of the backlight (backlight DUTY), and CV (Code Value) is the pixel value input to the liquid crystal panel. In this example, it is assumed that the gradation of the video signal is quantized from 0 to 255.
Y = BL (CV / 255) ^γ (2)

The configuration design unit 13 adjusts the video gain so as to increase the brightness on the screen when the light emission brightness of the backlight is reduced by the light emission brightness level BLreduced selected by the distortion module 5. When the pixel value to which the gain is applied is CV reduced, the screen brightness (display luminance on the liquid crystal panel) when the emission luminance level is lowered is BL reduced (CV reduced / 255) ^γ . On the other hand, the brightness of the screen when the backlight is controlled at the reference light emission luminance level BLref is BLref (CVref / 255) ^γ . The pixel values may be determined so as to make these values equal and compensate for the decrease in the light emission luminance of the backlight caused by the light emission luminance level BLreduced. That is, the configuration design unit 13 may perform a gain setting that satisfies the following expression (3).
Y = BLreduced (CVreduced / 255) ^γ = BLref (CVref / 255) ^γ (3)

  Therefore, the gain (G) is expressed by the following equation (4). For example, when the reference light emission luminance level BLref is 100%, the following equation (5) is obtained. It is preferable to store the relationship between BLref and BLreduced as a look-up table in the ROM of the configuration design unit 13 or the like so that the arithmetic processing of the following expression (4) is executed at high speed.

G = CVreduced / CVref = (BLref / BLreduced) ^{1 / γ} (4)
G = (1 / BLreduced) ^{1 / γ} (5)

  FIG. 10 is a diagram illustrating an example of the video signal gain set by the RGBγ / WB adjustment unit based on the gain setting signal output from the advanced luminance modulation unit in the liquid crystal display device of FIG.

  With reference to FIG. 10, the relationship between the input gain setting value (conversion coefficient) and the gain curve obtained therefrom will be described. As shown in FIG. 10A, when the gain setting of the video signal output from the advanced luminance modulation unit 20 is 1.0, there is no problem with a linear gain curve for all luminances. However, when the gain is 1.0 or more, as shown in FIG. 10B, the high luminance portion has a uniform value of 255, and so-called whitening occurs. In advanced luminance modulation processing, for example, the gain may be set so that the black portion is tightened at the expense of white-out of a small number of white luminance portions. The quality will be greatly reduced.

  Therefore, it is preferable to reduce the gradation of the high-brightness part by performing signal expansion according to the gain setting for low and medium brightness and making the gain curve non-linear for high brightness. To prevent). This method has a trade-off relationship between brightness and whiteout. If the non-linear region is narrowed, the region in which normal brightness can be expressed increases, but the high luminance gradation is lowered. Conversely, if the non-linear region is widened, the region where normal brightness can be expressed decreases, but the high luminance gradation is maintained to some extent. In practice, the non-linear luminance may be made non-linear only in the portion affected by the white-out, for example, by setting the output by the gain setting to 90% or more or 95% or more. FIG. 10C shows a gain curve corrected so that a portion of 90% or more becomes non-linear when the gain setting is 1.2. FIG. 10D shows a gain curve that is corrected so that a portion of 90% or more becomes non-linear when the gain setting is 1.6.

  Further, as described above, in order to avoid whiteout in a high luminance portion that occurs when the gain setting exceeds 1.0, it is necessary to make the high gradation region of the gain curve partly non-linear. However, since the RGBγ / WB adjustment unit 15 simply performs proportional calculation based on the gain setting, such a gain curve cannot be calculated. Therefore, the gain curve may be stored in the memory for each gain setting, or the linear portion of the gain curve is simply proportionally calculated from the gain setting value and exemplified in FIGS. 10 (C) and 10 (D). As described above, the non-linear portion may be calculated by interpolation or the like for the portion of 90% or more. Note that the gain setting may be calculated for each frame or may be calculated in units of a plurality of frames in accordance with a change in luminance of the backlight.

  FIG. 11 is a block diagram illustrating a configuration example of a motion compensation type FRC unit included in the liquid crystal display device of the present invention. The FRC unit 16 is roughly divided into a vector detection unit 161 that detects a motion vector between two consecutive frames included in the input video signal, and an interpolation frame (interpolated video) based on the detected motion vector. It is comprised with the flame | frame production | generation part 162 to produce | generate. In addition, although the vector detection part 161 shows about the example at the time of using an iterative gradient method for motion vector detection, it is not limited to this iterative gradient method, A block matching method etc. may be used.

  Here, the feature of the iterative gradient method is that a motion vector can be detected in units of blocks, so that several types of motion amounts can be detected, and a motion vector can be detected even in a small-sized moving object. Also, the circuit configuration can be realized on a small scale as compared with other methods (block matching method or the like). In this iterative gradient method, a method is used in which the gradient method is repeated for the detected block, using the motion vector of a nearby block that has already been detected as an initial displacement vector, and starting from this. According to this method, it is possible to obtain an almost accurate motion amount by repeating the gradient method about twice.

In FIG. 11, a vector detection unit 161 limits a high frequency band by applying a LPF to the luminance signal extraction unit 161 a that extracts a luminance signal (Y signal) from an input video signal (RGB signal), and the extracted Y signal. A preprocessing filter 161b for detecting the motion, a frame memory for motion detection 161c, an initial vector memory 161d for storing initial vector candidates, and a motion vector detection unit 161e for detecting a motion vector between frames using an iterative gradient method. And an interpolation vector evaluation unit 161f that allocates an interpolation vector between frames based on the detected motion vector.
The motion vector detection unit 11e corresponds to the motion vector detection unit of the present invention, and the interpolation vector evaluation unit 11f corresponds to the interpolation vector allocation unit of the present invention.

  Since the calculation of the iterative gradient method uses the differential component of the pixel, it is easily affected by noise, and the calculation error increases if the gradient change amount in the detection block is large. To limit the high-frequency band. In the initial vector memory 161d, motion vectors (initial vector candidates) already detected in the previous frame are stored as initial vector candidates.

  The motion vector detection unit 161e selects a motion vector closest to the motion vector of the detected block from the initial vector candidates stored in the initial vector memory 161d as an initial vector. That is, the initial vector is selected by the block matching method from the already detected motion vectors (initial vector candidates) in the blocks near the detected block. Then, the motion vector detection unit 161e detects a motion vector between the previous frame and the current frame by a gradient method calculation using the selected initial vector as a starting point.

  The interpolation vector evaluation unit 161f evaluates the motion vector detected by the motion vector detection unit 161e, assigns an optimal interpolation vector to an inter-frame interpolation block based on the evaluation result, and sends it to the frame generation unit 162. Output.

The frame generation unit 162 includes an interpolation frame memory 162a for accumulating two input frames (previous frame and current frame), two input frames from the interpolation frame memory 162a, and an interpolation vector evaluation unit 161f. An interpolation frame generation unit 162b that generates an interpolation frame based on the interpolation vector of time, a time base conversion frame memory 162c for storing input frames (previous frame and current frame), and a time base conversion frame A time base conversion unit 162d for inserting the interpolation frame from the interpolation frame generation unit 162b into the input frame from the memory 162c.
The interpolation frame generation unit 162b corresponds to the interpolation video generation unit of the present invention, and the time base conversion unit 162d corresponds to the video interpolation unit of the present invention.

  FIG. 12 is a diagram for explaining an example of the interpolation frame generation process by the frame generation unit 162. The interpolation frame generation unit 162b extends the interpolation vector V assigned to the interpolation block to the previous frame and the current frame, and interpolates each pixel in the interpolation block using pixels near the intersection with each frame. . For example, in the previous frame, the luminance of point A is calculated from three points in the vicinity. In the current frame, the luminance of point B is calculated from the three neighboring points. In the interpolated frame, the luminance at point P is interpolated from the luminance at points A and B. The brightness at point P may be the average of the brightness at point A and the brightness at point B, for example.

  The interpolated frame generated as described above is sent to the time base conversion unit 162d. The time base conversion unit 162d performs a process of converting the frame rate by inserting an interpolation frame between the previous frame and the current frame. As described above, the FRC unit 16 can convert the input video signal (60 frames / second) into the motion compensated output video signal (120 frames / second), and output this to the display panel, thereby reducing motion blur. It is possible to reduce and improve the video quality. Here, a case where the frame rate conversion of an input video signal of 60 frames / second to an output video signal of 120 frames / second is described, but for example, output video signals of 90 frames / second and 180 frames / second are obtained. Needless to say, it may be applied to a case.

  The main characteristic part of the video display device according to the present invention is to accurately determine a scene change and perform an appropriate FRC process when performing a motion compensation type FRC process. As a configuration for this, a motion compensation process is performed between a scene change detection unit 6 corresponding to a scene change detection means for detecting whether or not a scene change is based on a histogram of an input video signal, and a frame of the input video signal. An FRC unit 16 corresponding to rate conversion means for converting the number of frames of the input video signal by interpolating the video signal and outputting it to a display panel (not shown) is provided. The FRC unit 16 initializes a motion vector when a scene change is detected by the scene change detection unit 6.

  In FIG. 11, when a scene change detection signal is output from the scene change detection unit 6 and input to the FRC unit 16, the motion vector detection unit 161e initializes the motion vector, that is, is stored in the initial vector memory 161d. Initialize initial vector candidates. The initial vector memory 161d stores motion vectors that have already been detected in the previous frame as initial vector candidates, but these initial vector candidates are reset as the motion vector is detected by the motion vector detection unit 161e. Then, the motion vector is detected between the frames after the scene change, and the initial vector candidates are stored again in the initial vector memory 161d.

  FIG. 13 is a diagram for explaining an example of changes in the histogram and APL after advanced luminance modulation when there is a caption. FIG. 14 is a diagram for explaining an example of changes in the histogram and APL after advanced luminance modulation when there is no caption. In the figure, 30 is a video frame, 31 is a caption, 32 is a histogram of the video frame 30, 33 is a histogram of the caption 31, and 34 is a histogram after luminance modulation processing. Here, a case where a video with subtitles and a similar video without subtitles are continuously input will be described.

  A video frame 30 shown in FIG. 13A includes a caption 31, and a histogram as shown in FIG. 13B is input to the scene change detection unit 6. The APL at this time is 27%. When the advanced luminance modulation processing is performed on the video frame 30, the video frame 30 includes the white peak of the caption 31, and the video signal has a value from 0 to 255. Does not change the gain from 0 to 255 as shown in FIG. In this case, of course, APL does not change and becomes 27%.

  On the other hand, when the video frame 30 shown in FIG. 14A is input as the next frame, the video frame 30 does not include subtitles. Therefore, the histogram as shown in FIG. Is input. The APL at this time is 25%. When advanced luminance modulation processing is performed on the video frame 30, the video frame 30 is a dark video with no white peak such as subtitles. Therefore, as shown in FIG. It is controlled so that the dynamic range (for example, 0 to 255) is fully used. In this case, APL greatly changes to 50%.

  13 and 14, in the case of the conventional example in which the motion vector is initialized based on the change in APL, the APL after the luminance modulation processing is changed from 27% in FIG. 13C to that in FIG. Since it has changed to 50%, the FRC unit 16 determines that the scene has changed even though it is a similar scene, and the motion vector is initialized.

  In other words, when the FRC process is performed together with the luminance modulation process, the APL changes greatly depending on the presence or absence of the white peak even in the same scene, so the liquid crystal display device is based on the change of the APL. It was determined that there was a scene change, and the motion vector was initialized during FRC processing.

  On the other hand, in the case of the present invention in which the motion vector is initialized based on the change of the histogram, the histogram input to the scene change detection unit 6 changes from FIG. 13 (B) to FIG. 14 (B). The amount of change corresponds to the portion indicated by the oblique lines in FIG. 14B (that is, the histogram 33 of the caption 31). Since the amount of change in the histogram is smaller than a predetermined value, the scene change detection unit 6 does not determine that it is a scene change and does not output a scene change detection signal. For this reason, the FRC unit 16 does not unnecessarily initialize the motion vector.

  FIG. 15 is a diagram illustrating an example of the relationship between the APL and the histogram in the video. FIG. 16 is a diagram illustrating another example of the relationship between the APL and the histogram in the video. In the figure, 40 is a video frame of a general landscape, 41 is a histogram of the video frame 40, 50 is a video frame 50 of a black and white block, and 51 is a histogram of the video frame 50. Here, a case will be described in which images having the same APL and a changed scene are continuously input.

  When APL is used as means for detecting a scene change, the APL happens to be the same (in this example, even if the scene changes from the general landscape in FIG. 15A to the black and white block in FIG. 16A). 50%), it was determined that there was no scene change in the liquid crystal display device, the motion vector was not initialized, and the image quality was deteriorated.

  On the other hand, in the case of the present invention in which the motion vector is initialized based on the change in the histogram, the histogram input to the scene change detection unit 6 changes from FIG. 15B to FIG. The amount of change corresponds to the portion indicated by the oblique lines in FIG. Since the amount of change in the histogram is larger than a predetermined value, the scene change detector 6 determines that the scene has changed and outputs a scene change detection signal. For this reason, the FRC part 16 can initialize a motion vector appropriately.

  The predetermined value may be determined in advance by analyzing the degree of image quality deterioration according to whether or not to initialize the FRC process with respect to the amount of change in the histogram of various contents. That is, rather than continuing the FRC process without determining the scene change, the predetermined value may be determined so that the image quality degradation is smaller when the FRC process is determined and the FRC process is initialized.

  From the above, it can be seen that the scene change detection by the histogram is more accurate than in the case of APL. As in the example shown in FIGS. 15 and 16, even if the scene change cannot be detected well by the APL, the scene change can be detected accurately by the histogram.

  Here, in order to perform the advanced luminance modulation process, it is necessary to know the luminance distribution in the video, and for this reason, the most reasonable histogram is used. As a secondary use of the histogram, it can be used to detect a scene change, and can be used as a criterion for determining whether or not to initialize a motion vector during FRC processing.

  As described above, when the motion compensation type FRC process is performed, the scene change can be accurately determined based on the histogram of the input video signal, so that the appropriate FRC process can be performed.

It is a graph which shows the relationship between an input gradation (video signal level) and the luminance value on a liquid crystal panel about CR and 3000 and 6000 liquid crystal panels. It is a block diagram which shows the system structural example of the liquid crystal display device which concerns on this invention. It is a figure for demonstrating the Y histogram of a video signal, and its transition. It is a block diagram which shows the structural example of the scene change detection part in the liquid crystal display device of FIG. It is a figure for demonstrating an example of the light emission luminance level selection process performed with the distortion module in the liquid crystal display device of FIG. It is a figure for demonstrating the specific example of the luminance modulation process in the liquid crystal display device which concerns on this invention. It is a figure which shows the video-luminance range C in the case of the light emission luminance level 100% which is one of the selection objects. It is a figure which shows the image luminance range C when the light emission luminance level which is one of the selection objects is about 70%. It is a figure which shows the image luminance range C when the light emission luminance level which is one of the selection objects is about 50%. FIG. 3 is a diagram illustrating an example of a video signal gain set by an RGB γ / WB adjustment unit based on a gain setting signal output from an advanced luminance modulation unit in the liquid crystal display device of FIG. 2. It is a block diagram which shows the structural example of the motion compensation type | mold FRC part with which the liquid crystal display device of this invention is provided. It is a figure for demonstrating an example of the interpolation frame production | generation process by a frame production | generation part. It is a figure for demonstrating the example of a change of the histogram after advanced luminance modulation, and APL when there exists a caption. It is a figure for demonstrating the example of a change of the histogram after advanced luminance modulation, and APL when there is no closed caption. It is a figure which shows an example of the relationship between APL and a histogram in an image | video. It is a figure which shows the other example of the relationship between APL and a histogram in an image | video.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Scaling part, 2 ... Y histogram detection part, 3 ... APL detection part, 4 ... Histogram stretching part, 5 ... Distortion module, 6 ... Scene change detection part, 7 ... 1st temporary filter, 8 ... BL brightness level Setting unit, 9 ... second temporary filter, 10 ... variable delay, 11 ... CPU / CPLD, 12 ... BL adjustment unit, 13 ... configuration design unit, 14 ... image quality correction unit, 15 ... RGB γ / WB adjustment unit, 16 DESCRIPTION OF SYMBOLS ... FRC part, 17 ... Video output part, 20 ... Advanced luminance modulation part, 161 ... Histogram buffer, 162 ... Histogram change detection part, 161 ... Vector detection part, 161a ... Luminance signal extraction part, 161b ... Preprocessing filter, 161c ... Frame memory for motion detection, 161d ... initial vector memory, 161e ... Vector detection unit, 161f ... interpolation vector evaluation unit, 162 ... frame generation unit, 162a ... frame memory for interpolation, 162b ... frame generation unit for interpolation, 162c ... frame memory for time base conversion, 162d ... time base conversion unit .

Claims (4)

Rate conversion means for converting the number of frames or fields of the input video signal and outputting it to the display panel by interpolating the video signal subjected to motion compensation between frames or fields of the input video signal A video display device,
Scene change detection means for detecting whether or not a scene change based on a histogram of the input video signal;
The video display device, wherein the rate conversion means initializes a motion vector when a scene change is detected by the scene change detection means.   2. The video display device according to claim 1, wherein the scene change detecting means determines that a scene change occurs when a change amount of a histogram between frames or fields of the input video signal is larger than a predetermined value. A video display device.   3. The video display device according to claim 1, wherein the rate conversion means detects a motion vector information between consecutive frames or fields included in the input video signal, and the detected motion. Based on vector information, an interpolation vector allocating unit that allocates an interpolation vector between the frames or between the fields, an interpolation video generating unit that generates an interpolation video signal from the allocated interpolation vector, and the generated A video display device comprising: a video interpolation unit for interpolating an interpolated video signal between the frames or the fields.   4. The video display device according to claim 1, further comprising luminance modulation means for controlling the light emission luminance of the backlight and the gain of the input video signal in conjunction with each other. .

Images