JP2015118283A - Video display device, method for controlling video display device, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a phenomenon in which a moire pattern of an animal body is emphasized by a time base and visible as noise when geometrical correction and motion blur improvement processing are performed.SOLUTION: A video display device includes: a moire determination section for determining the degree of moire generation of a display video on the basis of an input video; a control section for controlling the degree of reduction processing of the blur visible in accordance with the input video on the basis of the degree of moire generation determined by the moire determination section; and a processing section for performing processing of reducing the blur in accordance with control by the control section.

Description

  The present invention relates to a video display device, a video display device control method, and a program.

  In recent years, video display apparatuses including various display devices such as liquid crystal display devices such as TV receivers and PC monitors have been put into practical use. Also, in these video display devices, so-called geometric correction is performed for the purpose of resolution conversion for performing enlargement / reduction processing of the input video and correction of trapezoidal distortion in a projection type video display device such as a projector. .

  In general, when geometric correction is performed, signal aliasing distortion occurs depending on the processing contents of the interpolation processing. In particular, when correction is performed on an image in which a periodic pattern exists uniformly, the image is visually recognized as moire, and image quality is deteriorated. On the other hand, a technique for performing a blurring process to suppress moire has been disclosed (Patent Document 1).

  On the other hand, in a hold-type display device typified by a liquid crystal display device, motion blur according to the light output period is observed when the moving object is viewed (following the moving object with a line of sight in moving image display). . As a technique for reducing such motion blur, a “spatial frequency separation method” has been proposed. The “spatial frequency separation method” is a method in which a spatial high-frequency component of an image involved in motion blur is concentrated on one of the subframes and the other is reduced and displayed. As a result, spatial high-frequency components are localized in one subframe in the output image, and motion blur can be improved (Patent Document 2).

JP 2001-78039 A JP 2009-042481 A

  However, a moire pattern generated by image geometric correction such as resolution conversion and trapezoidal distortion correction may be easily visible in a moving image even if it is not noticeable in a still image. This is because the moire pattern varies depending on the display position, so that the change in the moire pattern of the moving object is visually recognized as noise on the time axis. In particular, the motion blur improvement process improves the sharpness of the moving image, so that the change in the moire pattern of the moving object may be further emphasized and viewed.

  On the other hand, it is possible to suppress the moiré that is visible when the moving object is displayed by using the conventional technique and increasing the intensity of the blurring process, but the sharpness is reduced when the still image is displayed. There is a problem.

  In view of the above problems, an object of the present invention is to improve a phenomenon in which a moire pattern of a moving object is emphasized on a time axis and is recognized as noise when geometric correction or motion blur improvement processing is performed. To do.

A video display device according to the present invention that achieves the above-described object is as follows.
Moire determination means for determining the degree of moire occurrence in the display video based on the input video;
Control means for controlling the reduction processing degree of blurring visually recognized according to the movement of the input video, based on the moire occurrence degree determined by the moire determination means;
Processing means for performing processing for reducing the blur according to control by the control means.

  According to the present invention, it is possible to improve a phenomenon in which a moire pattern of a moving object is visually recognized as noise on the time axis when geometric correction or motion blur improvement processing is performed.

The block diagram which shows the function structural example of the video display apparatus which concerns on embodiment of this invention. The block diagram which shows the function structural example of the video processing part which concerns on 1st Embodiment. The figure which shows an example of operation | movement of the motion blur reduction degree control part which concerns on 1st Embodiment. The flowchart which shows the procedure of the process which the video display apparatus concerning 1st Embodiment implements. The block diagram which shows the function structural example of the video processing part which concerns on 2nd Embodiment. The block diagram which shows the function structural example of the video processing part which concerns on 3rd Embodiment.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. The embodiment described below shows an example when the present invention is specifically implemented, and is one of the specific examples of the configurations described in the claims.

(First embodiment)
FIG. 1 is a block diagram showing a functional configuration example of a video display apparatus according to the present invention. The video display device includes a video processing unit 101 that processes and outputs an input video, a display element 106 that displays the video, and a driver 105 that drives the display element 106. In recent years, various display elements 106 are being used as display devices 106, such as CRTs, so-called liquid crystal displays, plasma displays, FED displays, and the like as video display devices such as televisions. In the present embodiment, the display element 106 will be described as a liquid crystal display element.

  The video processing unit 101 includes a motion blur reduction processing unit 102, a moire determination unit 103, and a motion blur reduction degree control unit 104. The video processing unit 101 may have a color correction function and a gamma adjustment function that are not shown. Hereinafter, the function of each processing unit will be described.

<Motion blur reduction processing unit 102>
The motion blur reduction processing unit 102 performs a process of improving the sharpness of a moving image that is visually recognized when a video is displayed. For example, in a hold-type display element typified by a liquid crystal display element, motion blur according to the light output period is observed when the moving object is viewed (following the moving object with a line of sight in moving image display). . Several processes have been proposed for reducing motion blur and improving the sharpness of moving images.

  For example, the frame frequency of the input video signal is multiplied by N (one frame is divided into N subframes), and the video of each subframe is converted to video interpolated in the time axis direction using motion vector information or the like. There is known a technique for reducing motion blur by displaying a replacement. Further, for example, a technique for reducing motion blur by a so-called “spatial frequency separation method” in which a spatial high-frequency component of an image related to motion blur is displayed on one subframe while the other is reduced. It has been known.

<Moire determination unit 103>
The video processing unit 101 performs geometric enlargement and reduction processing represented by resolution conversion, lens distortion correction in a projector, so-called trapezoidal correction for correcting the shape of a projected video, and special effects for video. Correction may be performed. In some cases, an image having undergone geometric correction is input. In general, when geometric correction is performed on an image, the aliasing distortion of the signal is visually recognized as moire depending on the processing content of the interpolation processing. Moire is a heterogeneous pattern that does not exist in the input video, and is particularly easily visible in a screen region where a periodic pattern with high contrast exists uniformly.

  In a moving image such as scroll display, since the pixel value of a periodic pattern changes according to the screen position, there is a phenomenon that it is visually recognized as noise such as flicker. Even if it is not a periodic pattern, when the moving object is viewed, the pixel value of the moving object changes according to the screen position, so that it is visually recognized as noise. This phenomenon is particularly noticeable in high-frequency thin wires.

  The moiré determination unit 103 has a function of determining the degree of the moiré pattern that is visually recognized when an image is displayed.

<Video processing unit 101 according to the first embodiment>
FIG. 2 is a block diagram illustrating a functional configuration example of the video processing unit 101 according to the first embodiment. Elements having the same functions as those in the block diagram shown in FIG. In the following description, it is assumed that an image divided into two subframes (N = 2) is input.

<Motion Blur Reduction Processing Unit 102 According to the First Embodiment>
The motion blur reduction processing unit 102 first generates spatial low-frequency component image data L using the LPF 202 from input image data A input in subframe units from a resolution conversion unit 201 described later. The LPF 202 is a two-dimensional low-pass filter. This filter does not specify a function. For example, a Gaussian function, a moving average or a weighted moving average may be used. The LPF 202 performs a filter operation using a predetermined coefficient from the input image data A to cut off (filter) the upper limit spatial frequency, and generate the spatial low-frequency component image data L. Spatial low-frequency component image data L is represented by Expression (1).

L = LPF (A) Formula (1)
The subtractor 203 calculates the spatial high-frequency component data H by subtracting the spatial low-frequency component image data L generated by the LPF 202 from the input image data A according to the equation (2).

H = AL Formula (2)
The distributor 204 distributes the spatial high-frequency component data H to the first data H1 and the second data H2 according to a predetermined coefficient α (0.0 ≦ α ≦ 1.0), and each of the data H1. Is output to the adder 205, and H2 is output to the adder 206. H1 and H2 are calculated by Expression (3) and Expression (4), respectively.

H1 = H × α Formula (3)
H2 = H × (1−α) Formula (4)
The adder 205 adds the spatial high frequency component data H1 to the input image data A, and calculates output image data S1. The output image data S1 is calculated based on the equation (5).

S1 = A + H1 Formula (5)
The adder 206 adds the spatial high-frequency component data H2 to the spatial low-frequency component image data L to calculate output image data S2. The output image data S2 is calculated based on the equation (6).

S2 = L + H2 Formula (6)
The changeover switch unit 207 switches and outputs the output image data S1 and the output image data S2 so as to be in a predetermined order in units of subframes. Here, since the speed is doubled (two subframes), the output image data S1 and the output image data S2 may be output alternately in units of subframes.

  If the value of the coefficient α is large (for example, α = 1.0), most of the spatial high-frequency components are added to the output image data S1 and output, and most of the spatial high-frequency components of the image data S2 are subtracted. Is output. By alternately outputting these, it is possible to concentrate the spatial high-frequency component of the image involved in motion blur on one of the subframes and reduce the other, thereby improving motion blur. Can do.

  On the other hand, for example, when the coefficient α is the smallest, α = 0.0, S1 = S2 = A, and the motion blur improvement effect in the “spatial frequency separation method” cannot be expected. By adjusting the value of the coefficient α in the range (0.0 ≦ α ≦ 1.0), the degree of improvement in motion blur can be controlled. The coefficient α in the present embodiment is calculated and set by the motion blur reduction degree control unit 104 based on the determination result of the moire determination unit 103.

<Resolution Conversion Unit 201 According to the First Embodiment>
The resolution conversion unit 201 enlarges or reduces the video size of the input video at a predetermined rate, and inputs the video size to the video processing unit 101. The resolution conversion unit 201 may be an enlargement / reduction process of the entire screen, or may be a partial conversion process. Further, it may be a trapezoidal distortion correction in a projection type video display device such as a projector. Here, the enlargement ratio and the reduction ratio are collectively referred to as a deformation ratio, and a deformation ratio of 1.0 indicates a state in which there is no deformation. Indicates the state of A large deformation rate indicates that the degree of deformation is large before and after the deformation.

  In the resolution conversion unit 201, first, in order to suppress aliasing distortion that occurs particularly when the sampling interval is coarse, band limitation is performed and smoothing is performed. For example, a filter coefficient may be generated according to the deformation rate and a filtering process may be performed. Next, based on the parameter information indicating the coordinate relationship before and after deformation, coordinate conversion is performed based on a conversion method such as affine conversion to generate a deformed image.

<Moire determination unit 103 according to the first embodiment>
The moiré determination unit 103 determines or estimates the degree of occurrence of moire in the displayed video. In particular, the degree of occurrence of moire generated in the deformation process in the resolution conversion unit 201 is determined. For example, the determination is made according to the presence / absence of deformation in the resolution conversion unit 201 and the degree of deformation rate. If there is no deformation, it can be determined that moire has not occurred. If there is deformation, it is determined that the moire that is visible when the moving object is displayed is more visible, for example, the larger the deformation rate, the greater the deformation rate. To do.

<Motion blur reduction degree control unit 104>
FIG. 3 is a diagram showing an example of the operation of the motion blur reduction degree control unit 104, and shows a formula for generating the coefficient α. In FIG. 3, the vertical axis is the coefficient α, the horizontal axis is the degree of deformation, and the degree of deformation is d, the degree of deformation can be expressed by Equation (7).

Degree of deformation = | 1.0−d | Formula (7)
When the degree of deformation is 0.0, that is, when there is no deformation, the coefficient α is set to the second value (1.0) to improve motion blur. When the degree of deformation is 0.5, the coefficient α is set to the first value (0). .5), control is performed so that the degree of improvement in motion blur is gradually weakened. This suppresses moiré that is visually recognized when the moving object is displayed.

  In FIG. 3, for example, when the degree of deformation changes from 0.0, the change amount of the coefficient α is slightly increased. When the degree of deformation is greater than a predetermined value (0.5 in this example), the coefficient α is set to 0.5. It is fixed at. The purpose of this is to increase the degree of improvement with respect to moire that is easily visible with or without deformation, while maintaining the degree of improvement in motion blur at a constant level when the degree of deformation is greater than a predetermined level. Note that the value of α may be from the first value to the second value, but is not necessarily limited to 0.5 or more and 1.0 or less. Other ranges of values may be used.

  However, the moire determination method and the control method of the motion blur reduction degree according to the degree of occurrence of moire are not limited to the above-described methods. For example, the spatial frequency component information of the input video is acquired, and the sampling after deformation is performed. The determination may be made according to the degree of the frequency component higher than the frequency. Also, by recognizing the pattern of the input video, it is possible to recognize a pattern in which moire is difficult to be visually recognized at the time of standing still but moire is easily visible in the moving image, for example, high-frequency characters and fine lines, and make a determination according to the degree. Further, it may be determined by having a photo sensor (not shown) and sensing the output video. Further, moire determination and motion blur reduction degree control may be applied to each image area or each object such as a character.

  Since the moire pattern generated by geometric correction such as resolution conversion changes depending on the display position, the degree of motion blur reduction processing is controlled for issues that appear as noise such as flicker when the moving object is displayed. By doing so, noise can be suppressed. In addition, in order to control the motion blur reduction processing degree rather than controlling the degree of smoothing in the resolution conversion unit 201 described above, even if the input video is a still image, the sharpness in the still image is reduced. There is no end to it.

<Processing Flow in First Embodiment>
With reference to the flowchart of FIG. 4, a sequence of the above video processing will be described. First, in step S1, the video processing unit 101 receives video input. In step S <b> 2, the moire determination unit 103 determines the degree of moire occurrence. For example, as described above, the determination is made according to the presence / absence of deformation, the degree of deformation rate, and the spatial frequency component information of the input video. Any of these pieces of information may be used in combination for determination.

  In step S <b> 3, the motion blur reduction degree control unit 104 determines the presence / absence of moire generation based on the determination result of the moire generation degree. When it is determined that moiré has occurred (S3; YES). Proceed to step S4. On the other hand, when it is determined that no moire has occurred (S3; NO). Proceed to step S5.

  In step S4, the motion blur reduction degree control unit 104 calculates the motion blur reduction degree according to the determination result of the moire occurrence degree, and performs control so as to weaken the processing degree of the motion blur reduction process. The processing contents of steps S2 to S4 may be performed for each pixel, for each screen area, or for each object present in the video.

  After determining the processing degree of the motion blur reduction process in step S4, in step S5, the motion blur reduction processing unit 102 performs the motion blur reduction process on the video data. In step S6, the video processing unit 101 outputs video data.

  As described above, it is desirable to perform a series of image processing every frame. Also good.

  As described above, in the present embodiment, application to the “spatial frequency separation method” has been shown as an example of the motion blur reduction process. According to the present embodiment, motion blur reduction is performed for a problem that is recognized as noise such as flicker when a moving object is displayed by changing a moire pattern generated by geometric correction according to a display position. Noise can be suppressed by controlling the processing degree. Further, since only the degree of motion blur reduction processing is controlled, the sharpness of the still image area can be maintained when the input video is a still image.

(Second Embodiment)
In the first embodiment, application to the “spatial frequency separation method” is shown as an example of the motion blur reduction process. On the other hand, the liquid crystal display element may generate an afterimage when displaying a moving image because the response speed of the liquid crystal is not sufficiently high with respect to a change in the video signal. In order to improve the liquid crystal response speed, the video signal displayed in the next frame is compared with the video signal displayed in the previous frame, and the video signal displayed in the next frame is corrected according to the comparison result. A so-called overdrive process (OD process) for driving a liquid crystal is known.

  In the present embodiment, application to “overdrive processing” will be described as an example of motion blur reduction processing. FIG. 5 is a block diagram illustrating a functional configuration example of the video processing unit 101 in the second embodiment. Elements having the same functions as those in the block diagrams shown in FIGS. 1 and 2 are denoted by the same reference numerals.

  The frame memory unit 501 stores video signal data (frame data included therein). The frame memory unit 501 can be realized by, for example, a DDR-SDRAM (Double Data Rate-Synchronous DRAM) or an SDRSDRAM (Single Data Rate-Synchronous DRAM). The memory controller 502 controls reading and writing processing of the frame memory unit 501. The memory controller 502 reads the video signal data of the previous frame stored in the frame memory unit 501 and outputs it to the OD correction amount calculation unit 503. The OD correction amount calculation unit 503 compares the video signal data of the previous frame with the video signal data displayed in the next frame for each pixel, and calculates the overdrive correction amount for each pixel.

  The overdrive correction amount indicates a correction value to be added to or subtracted from the video signal data to be displayed in the next frame in order to improve the liquid crystal response speed. This is determined according to, for example, a combination of the video signal data of the previous frame and the video signal data to be displayed in the next frame, or the amount of change using a lookup table. Since the overdrive correction amount is intended to improve the liquid crystal response speed, when the video signal data of the previous frame and the video signal data displayed in the next frame are the same, the overdrive correction amount is , “0” is generally used.

  The gain adjustment unit 504 multiplies (gain adjustment) the coefficient α generated by the motion blur reduction degree control unit 104 and the overdrive correction amount. The coefficient α is determined as described with reference to FIG. 3 in the first embodiment, for example. The overdrive correction amount after the gain adjustment is added to or subtracted from the video signal data to be displayed in the next frame by the OD correction unit 505, and the overdrive processing is completed.

  With the above processing, the overdrive correction amount can be adjusted according to the degree of occurrence of moire. Specifically, when moire is easily visible in a moving image, the amount of overdrive correction is reduced and the responsiveness of the liquid crystal is reduced, thereby suppressing the moire visible when the moving object is displayed. It becomes possible. Note that the reverse correction may be performed so as to further delay the response of the liquid crystal as compared with the case where the overdrive process is not performed.

  As described above, in the present embodiment, application to the “overdrive process” has been shown as an example of the motion blur reduction process. According to this embodiment, the moire pattern generated by the geometric correction changes according to the display position, thereby overdrive correction for a problem that is visually recognized as noise such as flicker when the moving object is displayed. Noise can be suppressed by controlling the amount. Also, since only the overdrive correction amount is controlled, the sharpness of the still image area can be maintained even when the input video is a still image.

(Third embodiment)
In the third embodiment, application to “black image insertion processing” is shown as an example of motion blur reduction processing. The “black image insertion process” is, for example, a part of the output subframe period or a part of the output video signal when the frame frequency of the input video signal is multiplied by N (one frame is divided into N subframes). The area is masked with a black level signal. As a result, it is possible to generate and display a pseudo display image when impulse driving is performed, and to reduce motion blur in a hold type display element typified by a liquid crystal display element. The longer the mask processing period, the lower the integrated luminance level of the output video, but it is possible to reduce the motion blur caused by the hold type display element.

  FIG. 6 is a block diagram illustrating a functional configuration example of the video processing unit 101 according to the third embodiment. Elements having the same functions as those in the block diagrams shown in FIGS. 1 and 2 are denoted by the same reference numerals. The mask processing unit 601 performs a predetermined video signal level (for example, black level signal) replacement (mask processing) on a part or all of the video and outputs the result. The changeover switch unit 602 selects whether or not to perform mask processing according to the output of the motion blur reduction degree control unit 104. Specifically, control is performed so that the mask processing period is shortened when moire is easily visible in a moving image. As a result, it is possible to control the effect of reducing motion blur by pseudo impulse driving, and it is possible to suppress moire that is visually recognized when a moving object is displayed.

  In addition, although the control method of the mask processing period was shown, you may control the black signal level applied by mask processing area size and mask processing. In addition, when the image is divided into N subframes, an interpolation image is generated in the time direction with reference to the motion vector, and each subframe is replaced and displayed to reduce motion blur (“interpolation image insertion processing”). It can be applied to the same manner. Specifically, when moire is easily visible in a moving image, the interpolated image may be generated so that the interpolated image approaches the input image (motion vector = “0”).

  As described above, in this embodiment, application to the “black image insertion process” or the “interpolated image insertion process” has been shown as an example of the motion blur reduction process. That is, in this embodiment, the moire pattern generated by the geometric correction changes according to the display position, so that the problem of being visually recognized as noise such as flicker when the moving object is displayed is “black”. In the “image insertion process”, the black image insertion period and the insertion area are controlled. On the other hand, in the “interpolation image insertion process”, the generation method of the interpolation image is controlled. This makes it possible to suppress noise.

(Other embodiments)
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

Claims (17)

Moire determination means for determining the degree of moire occurrence in the display video based on the input video;
Control means for controlling the reduction processing degree of blurring visually recognized according to the movement of the input video, based on the moire occurrence degree determined by the moire determination means;
A video display device comprising: processing means for performing processing for reducing the blur according to control by the control means.   The video display apparatus according to claim 1, wherein the moire determination unit determines the moire occurrence degree based on frequency component information of the input video. Further comprising resolution conversion means for enlarging or reducing the video size of the input video,
The video display apparatus according to claim 1, wherein the moire determination unit determines the moire occurrence degree based on a deformation rate indicating an enlargement rate or a reduction rate by the resolution conversion unit. The processing means includes
Low-pass filter means for generating low-frequency component image data based on input image data input in units of subframes from the resolution conversion means;
A subtractor for subtracting the low frequency component image data from the input image data to calculate high frequency component data;
A distributor for distributing the high-frequency component data into first data and second data according to a predetermined coefficient;
A first adder that calculates the first output image data by adding the first data to the input image data;
A second adder for calculating the second output image data by adding the second data to the low-frequency component image data;
4. The video display according to claim 3, further comprising: a selector switch that switches and outputs the first output image data and the second output image data in a predetermined order in subframe units. apparatus.   The video display apparatus according to claim 4, wherein the control unit sets the value of the predetermined coefficient based on a determination result by the moire determination unit.   6. The control means according to claim 5, wherein the coefficient value is set to be larger as the degree of deformation of the input image is smaller, and the coefficient value is set to be smaller as the degree of deformation of the input image is larger. Video display device.   The video display device according to claim 6, wherein a value of the coefficient is not less than a first value and not more than a second value.   8. The video display device according to claim 7, wherein when the degree of deformation is larger than a predetermined value, the value of the coefficient is fixed to the first value. The processing means includes
A frame memory section for storing video signal data;
A memory controller that controls read processing and write processing of the frame memory unit;
A video signal to be displayed in the next frame for each pixel by comparing the video signal data of the previous frame read from the frame memory unit by the memory controller with the video signal data to be displayed in the next frame. The video processing apparatus according to claim 1, further comprising: a correction amount calculating unit that calculates an overdrive correction amount to be added to or subtracted from the data. The control means sets a predetermined coefficient value based on the determination result by the moire determination means,
The processing means further includes gain adjustment means for performing gain adjustment by multiplying the coefficient set by the control means and the overdrive correction amount calculated by the correction amount calculation means. The video processing apparatus according to claim 9.   11. The overdrive correction means for adding / subtracting the overdrive correction amount gain-adjusted by the gain adjustment means to / from video signal data to be displayed in the next frame. The video processing apparatus described. The processing means includes
Mask processing means for performing mask processing for replacing a part or all of the input video signal with a predetermined video signal level;
The video processing apparatus according to claim 1, further comprising: a changeover switch that selects whether or not to perform the masking process according to an output of the control unit. The control means controls the blur reduction processing degree to be higher as the moire occurrence degree determined by the moire determination means is higher.
The video processing apparatus according to claim 12, wherein the change-over switch performs selection so that the period of the mask processing is shortened as the degree of reduction processing is higher.   The processing means divides one frame into N subframes by multiplying the frame frequency of the input video signal by N, and video obtained by interpolating the video of each subframe in the time axis direction using motion vector information The video display apparatus according to claim 1, wherein motion blur is reduced by replacing the display with the display.   The video display apparatus according to claim 1, wherein the processing unit reduces motion blur by a spatial frequency separation method. A method of controlling a video display device,
Moire determination means for determining the degree of moiré in the displayed video based on the input video;
A control step of controlling a blur reduction processing degree visually recognized according to the movement of the input video based on the moire occurrence degree determined by the moire determination step;
And a processing step of performing processing for reducing the blur according to control by the control step.   The program for making a computer perform each process of the control method of the video display apparatus of Claim 16.

Images