JP5586858B2 - Display control apparatus and display control method - Google Patents

Description

  The present invention relates to a moving image display control method.

  It is known that flicker (flickering of the display screen) can be reduced by increasing the drive frequency. The drive frequency indicates the number of times the display screen is rewritten per second, and corresponds to the vertical synchronization frequency, the refresh rate, and the like. For example, Patent Document 1 describes that flicker is reduced by increasing the drive frequency (refresh rate) when displaying a still image.

JP 2006-98765 A

  However, depending on the drive frequency, there is a risk that the degradation of the display image is perceived.

  For example, if the drive frequency is increased above the frame rate of the moving image content, flicker can be reduced, but jerkiness (outline blur of the moving area) may occur. On the other hand, if the drive frequency is set to be the same as the frame rate of the moving image content, a flicker problem may occur.

  Also, even if the same moving image is displayed at the same drive frequency, whether or not flicker or jerkiness is perceived varies depending on the user. Further, for example, even when images are displayed at the same drive frequency, the ease of perceiving flicker differs depending on the pixel value of the display image.

  The present invention has been made in view of the above problems, and an object thereof is to make it difficult for a user to perceive deterioration of a display image.

In order to solve the above problems, the display control apparatus of the present invention has the following configuration, for example. That is, a display control device capable of controlling the light emission interval of the display screen, the display control means for displaying an image in response to an input of an image signal, and whether or not the user perceives flicker from the displayed image. input means for inputting the evaluation information indicating, display a first image of the first pixel value in response to an input of the first image signal, and a second image of the second pixel value in the first light emission interval A memory for storing the first pixel value of the first image and the second pixel value of the second image when evaluation information indicating that the user perceives flickering is input. And the pixel value of the region in the third image among the third image and the fourth image that are sequentially displayed in response to the input of the second image signal and the second image signal is stored in the storage means the first corresponds to the pixel value, the pixel value of the region in said fourth image is, If corresponding to the stored previous SL second image pixel value to the serial storage means, lowering the brightness of the control and the area of the emission interval of the region a short second light-emitting interval than the first light emission interval Control means for performing at least one of the controls.

  According to the present invention, it is possible to make it difficult for a user to perceive deterioration of a display image.

1 is a block diagram of a display control device according to a first embodiment. FIG. 6 is a flowchart of display control processing according to the first embodiment. Conceptual diagram of moving area extraction Example of time variation of moving area Spatio-temporal display example of moving area Spatio-temporal spectrum display example of the visible moving region Flow chart of visual characteristic determination process Example of temporal change in luminance of test image for time response characteristics acquisition Example of test image of embodiment 2 FIG. 9 is a flowchart of display control processing according to the second embodiment. Block diagram of display control apparatus of embodiment 3 FIG. 9 is a flowchart of a display control method according to the third embodiment. Examples of time response characteristics and spatial response characteristics Examples of user visual characteristics Example of temporal change in pixel value of test image for time response characteristics acquisition Example of change in pixel value of test image for obtaining spatial response characteristics Examples of spatiotemporal spectra of moving regions Example of visual characteristics of user of embodiment 2 Flicker candidate area extraction example Spatio-temporal display example of flicker candidate area Example of spatio-temporal spectrum of flicker candidate region Example of time-frequency spectrum of flicker candidate region

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<Embodiment 1>
<About system configuration>
FIG. 1 is a block diagram illustrating a configuration example of a display control apparatus according to the present embodiment.

  The display control device 106 includes an input unit 101, a determination unit 102, an adjustment unit 103, an image processing unit 104, and a display unit 105. The display control device 106 according to the present embodiment includes the display unit 105 (for example, a display), but may be a device different from the display unit 105. Further, the display control device 106 can control the drive frequency in the range of 60 to 240 Hz. Here, the drive frequency indicates the number of times the display screen is rewritten per second, and corresponds to the vertical synchronization frequency, the refresh rate, and the like. That is, the display control device 106 is a display control device that can control the light emission interval of the display screen.

  The input unit 101 acquires the visual response characteristics of the user (viewer) via a remote controller operated by the user. And the input part 101 inputs a user's visual response characteristic. The visual response characteristic of this embodiment is acquired according to the user's evaluation value for the test image displayed on the display unit 105. That is, the input unit 101 inputs evaluation information for the display result of the test image. Details of the acquisition of the visual response characteristics will be described later with reference to FIG.

  The determination unit 102 determines the user's visual characteristics based on the user's visual response characteristics input by the input unit 101. That is, the determination unit 102 determines the visual characteristics of the user. A method for determining visual characteristics will be described later with reference to FIG.

  The adjustment unit 103 determines whether to convert the input moving image signal and / or change the parameter of the display unit 105 based on the visual characteristics of the user and the input moving image signal.

  The adjustment unit 103 determines, for example, whether or not flicker is perceived when an image corresponding to the input moving image signal is displayed based on the visual characteristics of the user and the input moving image signal. When the adjustment unit 103 determines that flicker is perceived, the adjustment unit 103 determines to convert the input moving image signal and / or change the parameter of the display unit 105. More specifically, when the adjustment unit 103 determines that flicker is perceived, the adjustment unit 103 increases the drive frequency of the display screen and / or the brightness value of the display image according to the input moving image signal. Decide to lower.

  The adjustment unit 103 determines, for example, whether jerkiness is perceived when an image corresponding to the input moving image signal is displayed based on the visual characteristics of the user and the input moving image signal. That is, the adjustment unit 103 determines whether or not a pseudo contour is perceived at the boundary between the moving area and the static area of the display image displayed at a driving frequency higher than the frame rate of the input moving image signal. When the adjustment unit 103 determines that jerkiness is perceived, the adjustment unit 103 determines to convert the input moving image signal and / or change the parameter of the display unit 105. More specifically, when the adjustment unit 103 determines that jerkiness is perceived, the adjustment unit 103 decreases the drive frequency of the display screen and / or sets the contrast ratio of the display image according to the input moving image signal. Decide to lower.

  Further, when the adjustment unit 103 determines to convert the input moving image signal, the adjustment unit 103 determines a parameter related to the conversion and outputs the determined parameter (adjustment data) to the image processing unit 104. Further, when the adjustment unit 103 determines to change the parameter of the display unit 105, the adjustment unit 103 determines a parameter related to the change and outputs the determined parameter (adjustment data) to the display unit 105.

  For example, when the adjustment unit 103 determines that the luminance of the display image is 5% lower than the luminance of the image corresponding to the input moving image signal, the adjustment unit 103 outputs adjustment data indicating the fact to the image processing unit 104. However, the adjustment unit 103 is not limited to the example of the luminance value as described above, and for example, the luminance values of a plurality of frame data (subframes) generated based on one frame data corresponding to the input moving image signal. Adjustment data for changing the distribution ratio may be output. For example, the adjustment unit 103 may output adjustment data for removing high-frequency components from some subframes to the image processing unit 104.

  For example, when the adjustment unit 103 determines to reduce the drive frequency in the display unit 105 from 120 Hz to 60 Hz, the adjustment unit 103 outputs adjustment data indicating the fact to the display unit 105. Note that the adjustment unit 103 may output adjustment data for reducing the luminance value of the display image to the display unit 105, and the display unit 105 may control the luminance value of the display screen.

  The image processing unit 104 converts the input moving image signal in accordance with the adjustment data output by the adjustment unit 103. Here, the input moving image signal is input from, for example, a video input device such as a digital video camera, a storage medium such as a hard disk drive, a server via the Internet, or the like. In this embodiment, a case where a moving image corresponding to an input moving image signal is displayed will be described. However, the present invention can also be applied to a case where a still image is displayed. The image processing unit 104 outputs the converted signal to the display unit 105.

  The display unit 105 displays an image corresponding to the image signal output from the image processing unit 104 according to the set parameters (drive frequency, contrast ratio, etc.).

<Determination process of visual characteristics>
Next, the acquisition of the visual response characteristic of the user by the input unit 101 and the determination process of the visual characteristic by the determination unit 102 will be described with reference to FIG. In this embodiment, the input unit 101 acquires time response characteristics and spatial response characteristics as the user's visual response characteristics (steps S701 to S710). Then, the determination unit 102 determines the visual characteristic of the user based on the time response characteristic and the spatial response characteristic acquired by the input unit 101 (step 711).

  FIG. 7 is a flowchart illustrating the process of acquiring the visual response characteristic of the user by the input unit 101 and the process of determining the visual characteristic of the user by the determination unit 102. Of the processes in FIG. 7, the processes from step S701 to step S705 are processes for obtaining a time response characteristic (time frequency response characteristic) among the visual response characteristics of the user. Further, the processing from step S706 to step S710 is processing for acquiring spatial response characteristics (spatial frequency response characteristics) among the user's visual response characteristics. In step S711, the determination unit 102 determines the visual characteristics of the user from the acquired time response characteristics and spatial response characteristics.

  Here, the time response characteristic indicates the relationship between the driving frequency and the contrast sensitivity of the user. An example of the acquired time response characteristic is shown in FIG. In FIG. 13A, when the user easily perceives screen flicker at a certain driving frequency (time frequency) (perceives flicker even when the brightness of the display image is low), the corresponding contrast sensitivity is increased. Is plotted. That is, the time response characteristic indicates the ease of perception of screen flicker at each drive frequency (time frequency).

  The spatial response characteristic indicates the relationship between the spatial frequency of the moving object in the display image and the contrast sensitivity of the user. An example of the acquired spatial response characteristic is shown in FIG. In FIG. 13B, when a user easily perceives contrast at a certain spatial frequency (perceives a difference in pixel value even if the contrast ratio in the display image is low), the corresponding contrast sensitivity is increased. It is plotted. That is, the spatial response characteristic indicates the ease of perception of contrast with respect to a moving object having each spatial frequency. In this embodiment, the spatial response characteristic is acquired for each moving speed of the moving object. The spatial response characteristic shown in FIG. 13B is an example of the spatial response characteristic at a certain moving speed. That is, the input unit 101 of the present embodiment acquires spatial response characteristics for each of a plurality of moving speeds.

  The processing in FIG. 7 is started when, for example, the visual characteristic registration mode is set by the user's operation of the remote control or the operation panel.

  In step S701, the input unit 101 causes the display unit 105 to display a test image for acquiring time response characteristics at a certain time frequency (for example, 10 [cycle / sec]). The test image displayed in step S701 is a test image (test image 1, test image 2) having the same pixel value throughout the frame. Note that the pixel values of the test image 1 and the test image 2 are different. An example of the brightness of the display screen when the test images 1 and 2 are alternately displayed is shown in FIG. As shown in FIG. 8, the test image 1 whose entire frame has a luminance value of Lmax and the test image 2 whose entire frame has a luminance value of Lmin are alternately displayed according to the time frequency. That is, for example, when the time frequency is 10 [cycle / sec], the test image 1 and the test image 2 are each displayed 10 times per second. Note that the test image is not limited to two types, and for example, the luminance value may gradually change. Further, the chromaticity may be changed instead of the luminance value. When an evaluation value is input from the user in step S701, the process proceeds to step S702.

  In step S702 (input procedure), the input unit 101 acquires an evaluation value input from the user from a remote controller or the like operated by the user. Here, the evaluation value input from the user is evaluation information indicating whether or not a change (flicker) of the display screen is perceived when the test images 1 and 2 are alternately displayed. When the user feels that the screen flickers, he presses a predetermined button on the remote control. In step S702, if an evaluation value indicating that the display screen flicker is perceived is acquired, the process proceeds to step S703. On the other hand, when the evaluation value indicating that the flicker of the display screen is perceived is not acquired, or when the evaluation value indicating that the flicker of the display screen is not perceived is obtained, the process returns to step S701, and the contrast of the test images 1 and 2 is obtained. Increase the ratio. Here, increasing the contrast ratio is performed, for example, by increasing the luminance Lmax of the test image 1 and not changing the luminance Lmin of the test image 2. However, the contrast ratio may be changed by other methods such as lowering Lmin without changing Lmax. That is, in step S702, the input unit 101 converts the first image (test image 1) and the second image (test image 2) to the first emission interval based on the first image signal (image signal of the test image). Enter the evaluation information for the display result when displayed in.

The input unit 101 according to the present embodiment first displays a test image with a sufficiently small difference between Lmax and Lmin, and gradually increases the contrast ratio when it is evaluated that the user does not perceive flicker. That is, if the input unit 101 evaluates that the user does not perceive flicker, the input unit 101 returns to step S701 to increase the contrast ratio. Then, the input unit 101 obtains Lmax and Lmin based on the boundary between the contrast ratio that perceives flicker and the contrast ratio that does not perceive flicker by continuing the process until the user perceives flicker.
When predetermined evaluation information (an evaluation value indicating that flicker is perceived) is input in step S702, the process proceeds to step S703.
In step S703 (storage procedure), the input unit 101 receives the pixel value (Lmax) of the first image (test image 1) to which predetermined evaluation information (evaluation value indicating perception of flicker) is input, and the first The pixel value (Lmin) of the second image (test image 2) is stored. Note that the input unit 101 of the present embodiment stores the luminance value as the pixel value of the test image when it is evaluated that the flicker is perceived, but the present invention is not limited to this. For example, when using test images having different chromaticities between the test image 1 and the test image 2, the chromaticity may be stored.

  Further, in step S703, the input unit 101 obtains the temporal contrast sensitivity m using the luminance values Lmax and Lmin when it is determined that flicker is perceived in step S702, and Expression (1).

  As shown in the equation (1), the user having a higher value of the temporal contrast sensitivity m perceives the flickering of the screen even if the luminance difference between the test image 1 and the test image 2 is small. In other words, it can be said that the user is likely to be concerned about flicker.

  Further, the temporal contrast sensitivity m may be obtained from Equation (2) using the average luminance Lmean and the amplitude ΔL of the test image.

  Further, as shown in FIG. 15, the test image may be such that only the chromaticity is changed with time so that the sum of the luminance values of the test image 1 and the test image 2 becomes constant. That is, the chromaticity C1 of the test image 1 and the chromaticity C2 of the test image 2 may be different. The contrast sensitivity m in this case is obtained from the following equation (3).

  In step S703, when the calculation of the temporal contrast sensitivity of a certain time frequency is finished, the process proceeds to step S704.

  In step S704, the input unit 101 determines whether the calculation of temporal contrast sensitivity at all time frequencies (drive frequencies) has been completed. If it is determined that the temporal contrast sensitivity has been calculated for all temporal frequencies, the process proceeds to step S705. On the other hand, if it is determined that there is a time frequency for which the temporal contrast sensitivity has not yet been calculated, the process returns to step S701 to change the time frequency (driving frequency) for displaying the test image to change the time contrast sensitivity. Continue the acquisition process. That is, for example, when calculating the temporal contrast sensitivity in the time frequency from 10 [cycle / sec] to 10 [cycle / sec] from the time frequency 10 [cycle / sec] to 120 [cycle / sec], the process of step S703 is performed 12 times. It will be.

  In step S705, the input unit 101 acquires the user's time response characteristics based on the temporal contrast sensitivity m at each time frequency obtained in step S703. The user's time response characteristic is, for example, as shown in FIG. When the input unit 101 outputs the acquired time response characteristic to the determination unit 102, the process proceeds to step S706.

  In step S706, the input unit 101 causes the display unit 105 to display a test image for acquiring spatial response characteristics. The test image displayed in step S706 is an image having regions with different pixel values in the frame. The input unit 101 sequentially displays a plurality of test images so that a region of a certain pixel value in the test image appears to move within the frame. An example of pixel values in the test image displayed in step S706 is shown in FIG. The test image shown in FIG. 16 has different luminance values depending on the position in the frame. That is, in step S706, the display unit 105 displays the moving image including the first pixel value region and the second pixel value region at the first light emission interval while moving the first pixel value region. . However, the test image is not limited to the example of FIG. The test image may have different chromaticity in the image.

  In this embodiment, the maximum luminance value in the test image is indicated as Lmax, and the minimum luminance value is indicated as Lmin. Further, the input unit 101 of this embodiment displays a test image as shown in FIG. 16 by moving it at a constant speed. Therefore, the sine wave of FIG. 16 corresponding to the test image 1 displayed first in step S706 and the sine wave corresponding to the test image 2 displayed next are shifted according to the moving speed. Examples of the moving speed to be set include 1 [pixel / frame] and 6.5 [pixel / frame].

  In step S707, the input unit 101 inputs an evaluation value input from the user. Here, the evaluation value input from the user is information indicating whether or not a difference (contrast) in pixel values in the test image can be perceived. That is, the user inputs evaluation information indicating whether there are regions having different pixel values in the test image or whether the pixel values in the test image all look the same.

  That is, in step S707, the input unit 101 displays a moving image including the first pixel value region and the second pixel value region at the first light emission interval while moving the first pixel value region. Enter the evaluation information for the display result. If an evaluation value indicating that the contrast is perceived is input in step S707, the process proceeds to step S708. On the other hand, if an evaluation value indicating that no contrast is perceived (all appear to be the same pixel value) is input, the process returns to step S706 to increase the contrast ratio of the test image. Increasing the contrast ratio is performed, for example, by increasing the maximum luminance value Lmax in the test image and not changing the minimum luminance value Lmin. However, the contrast ratio may be changed by other methods such as lowering Lmin without changing Lmax.

  The input unit 101 according to the present embodiment first displays a test image with a sufficiently small difference between Lmax and Lmin, and gradually increases the contrast ratio when it is evaluated that the user does not perceive contrast. The input unit 101 continues processing until the user perceives contrast, thereby acquiring Lmax and Lmin based on the contrast ratio when the contrast is perceived and the boundary between the contrast ratio when the contrast is not perceived.

  In step S707, the input unit 101 stores the first pixel value (Lmax) and the second pixel value (Lmin) to which predetermined evaluation information (an evaluation value indicating that a contrast is perceived) is input. .

  As described above, the input unit 101 allows the user to change the pixel value in the test image (contrast) at a certain spatial frequency (for example, 10 [cycle / deg]) at a certain moving speed (for example, 10 [pixel / sec]). Get the contrast ratio to perceive.

  Note that deg in this embodiment is an abbreviation for degree, and for example, 10 [cycle / deg] indicates that 10 cycles of the sine wave shown in FIG. 16 are displayed for a viewing angle of 1 degree. If the user evaluates that the display screen contrast is not perceived, the process proceeds to step S708.

  In step S708, the input unit 101 calculates the spatial contrast sensitivity m using the luminance values Lmax and Lmin when the contrast acquired in step S707 is perceived, and the above equation (1). As shown in Expression (1), a user having a higher spatial contrast sensitivity m can be said to be a user who perceives the contrast in the screen even if the difference in luminance value is small. It should be noted that the equations (2) and (3) can also be used for calculating the spatial contrast sensitivity m. When the calculation of the spatial contrast sensitivity at a certain spatial frequency and a certain moving speed is completed in step 708, the process proceeds to step S709.

  In step S709, the input unit 101 determines whether calculation of spatial contrast sensitivity at all spatial frequencies and all moving speeds has been completed. If it is determined that the calculation of spatial contrast sensitivity at all spatial frequencies and all moving speeds has been completed, the process proceeds to step S710. On the other hand, if it is determined that there is a spatial frequency or moving speed for which the spatial contrast sensitivity is not calculated, the process returns to step S706 to change the spatial frequency of the test image or the moving speed of the test image to change the spatial contrast. Continue the sensitivity acquisition process.

  In step S710, the input unit 101 acquires the user's spatial response characteristics based on the spatial contrast sensitivity m at each spatial frequency obtained in step S709. The spatial response characteristic of the user is, for example, as shown in FIG.

  The input unit 101 acquires the spatial response characteristics as shown in FIG. 13B for each moving speed in the test image and outputs the acquired spatial response characteristics to the determination unit 102. When the input unit 101 outputs the spatial response characteristics for each moving speed to the determination unit 102, the process proceeds to step S711.

  In step S711, the determination unit 102 determines the visual characteristics of the user by combining the time response characteristics and the spatial response characteristics acquired in steps S705 and S710.

  In step S711, the determination unit 102 normalizes the spatial contrast sensitivity obtained for each moving speed in step S710 using the maximum contrast sensitivity value. That is, as described above, the spatial response characteristic is acquired for each moving speed of the test image. Then, the determination unit 102 according to the present embodiment normalizes other spatial contrast sensitivities so that the highest spatial contrast sensitivity calculated is 1.

  In step S711, the determination unit 102 normalizes the time response characteristic obtained in step S705 using the maximum contrast sensitivity value. That is, the temporal contrast sensitivity obtained at other temporal frequencies is normalized so that the highest temporal contrast sensitivity is 1. The response characteristics shown in FIGS. 13A and 13B are normalized response characteristics.

  In step S711, the determination unit 102 determines the user's visual characteristics by integrating the temporal response characteristics shown in FIG. 13A and the spatial response characteristics shown in FIG. 13B on the spatio-temporal frequency plane. To do. For example, the vertical axis is the time frequency, the horizontal axis is the spatial frequency, the time response characteristics are arranged in parallel to the vertical axis, and the spatial response characteristics are arranged in parallel to the horizontal axis. The visual characteristics of the user determined in this way are as shown in FIG. 14, for example. The spectrum of the image actually perceived by the user can be obtained by accumulating the spatiotemporal spectrum of the image corresponding to the user's visual characteristics determined here and the input moving image signal.

  Note that the method of acquiring the user response characteristics is not limited to the above method. For example, instead of the test image as shown in FIGS. 8 and 16, the user response using the image corresponding to the input moving image signal is used. Characteristics may be acquired. In this case, for example, the user's visual characteristics are acquired in accordance with a change operation of parameters such as a drive frequency, a contrast ratio, and luminance performed while the user is viewing the image displayed on the display unit 105. Also good. The user can change the parameter, for example, by operating a button on a remote controller or operating a slide bar displayed on the display screen with an indicator such as a mouse.

<System-wide processing>
Next, display control processing performed by the display control apparatus 106 according to the present embodiment will be described. Note that the adjustment unit 103 according to the present embodiment generates an image corresponding to the input moving image signal based on the image corresponding to the input moving image signal and the visual characteristics of the user acquired by the method described with reference to FIG. A flicker evaluation value F indicating whether or not the user perceives flicker when displayed is calculated. In addition, the adjustment unit 103 according to the present exemplary embodiment determines whether the user perceives jerkiness when displaying an image according to the input moving image signal based on the image according to the input moving image signal and the visual characteristics of the user. A jerkiness evaluation value J indicating whether or not is calculated. When the flicker evaluation value F and the jerkiness evaluation value J are larger than the threshold values, the adjustment unit 103 converts the input moving image signal and / or changes the setting of the display unit.

  Hereinafter, the operation of this embodiment will be described in detail with reference to the flowchart of FIG.

  In step S <b> 201, the determination unit 102 determines the visual characteristics of the user by the procedure described above using the flowchart of FIG. 7, and outputs the determined visual characteristics to the adjustment unit 103.

  In step S <b> 202, the adjustment unit 103 acquires the input moving image signal from the image processing unit 104 together with the visual characteristics output from the determination unit 102. Here, the input moving image signal acquired by the adjusting unit 103 is a moving image signal corresponding to an image (frame) of a program that the user is currently viewing and to be displayed on the display unit 105 from now on. The adjustment unit 103 extracts a region (moving region) including the edge portion of the moving object from the image corresponding to the acquired input moving image signal. That is, the adjustment unit 103 according to the present embodiment extracts a region including the boundary between the moving object region and the non-moving region in the frame corresponding to the input moving image signal. As a method for detecting an edge portion of a moving object, for example, there is a method using a difference from a previously input frame, information on a motion vector, or the like.

  In step S202, the adjustment unit 103 extracts a flicker candidate region from an image corresponding to the input moving image signal. Details of the flicker candidate area extraction will be described later.

  In step S202, the adjustment unit 103 measures the luminance values of the extracted moving area and flicker candidate area for a certain period of time. That is, the adjustment unit 103 measures the luminance values of the blocks extracted as the moving area and the flicker candidate area for a plurality of frames. Then, based on the luminance values measured for a plurality of frames, the spatiotemporal spectra of the moving area and the flicker candidate area are acquired. A spatio-temporal spectrum is a spectrum obtained by two-dimensional Fourier transform of a change in luminance value within a region with respect to a spatial frequency and a temporal frequency. Details of the spatiotemporal spectrum acquisition process will be described later. When the adjustment unit 103 acquires the spatio-temporal spectrum of the moving region and the flicker candidate region, the process proceeds to step S203.

  In step S203, the adjustment unit 103 acquires the observation spectrum by filtering the acquired spatiotemporal spectrum with the visual characteristics of the user determined in step S201.

  That is, the adjustment unit 103 integrates the spatiotemporal spectrum of the moving region acquired in step S202 and the visual characteristics of the user determined in step S201, and the spatiotemporal region in the moving region of the image actually viewed by the user. A spectrum (moving region observation spectrum) is obtained. An example of the moving region observation spectrum is shown in FIG. Similarly, the adjustment unit 103 integrates the spatio-temporal spectrum of the flicker candidate area acquired in step S202 and the visual characteristics of the user determined in step S201, and the spatio-temporal spectrum in the flicker candidate area of the viewed image. (Flicker observation spectrum) is obtained.

  In other words, this process shows how the moving area and the flicker candidate area look when the user views a moving image corresponding to the input moving image signal. When the adjustment unit 103 acquires the moving region observation spectrum and the flicker observation spectrum, the process proceeds to step S204.

  In step S204, the adjustment unit 103 calculates the flicker evaluation value F and the jerkiness evaluation value J. The flicker evaluation value F is an evaluation value indicating the degree to which the user perceives flicker when a moving image corresponding to the input moving image signal acquired in step S202 is displayed. The jerkiness evaluation value J is an evaluation value indicating the degree to which the user perceives jerkiness when a moving image corresponding to the input moving image signal acquired in step S202 is displayed. That is, when these evaluation values are high, the user feels flicker and jerkiness more strongly. Processing for calculating the flicker evaluation value F and the jerkiness evaluation value J will be described later.

In step S205, the adjustment unit 103 determines whether or not the calculated flicker evaluation value F and jerkiness evaluation value J are each higher than a threshold value. Based on this result, it is determined whether flicker and jerkiness are anxious for the user. That is, the flicker evaluation value F is higher than the flicker threshold F _th, or jerkiness evaluation value J is higher than the threshold J _th of jerkiness (Yes in step S205), the image corresponding to the input video signal flicker or jerkiness is air, The process proceeds to step S206. If both evaluation values are equal to or less than the threshold value (No in step S205), it is determined that flicker and jerkiness are not anxious, and the input moving image signal is output to the display unit 105 as it is.

  In step S206 (control procedure), the adjustment unit 103 generates adjustment data according to the determination result in step S205 and the observation spectrum.

That is, in step S205, for example, when it is determined that the flicker evaluation value F is higher than the flicker threshold value _Fth , the adjustment unit 103 generates adjustment data for increasing the drive frequency. When the drive frequency is increased, the light emission interval is shortened, and the degree of flicker perception can be reduced. When the driving frequency is increased, the adjustment unit 103 determines the adjusted driving frequency so that the flicker evaluation value F after the driving frequency is increased is equal to or less than the flicker threshold _Fth .

However, the adjustment data generated when it is determined that the flicker evaluation value F is higher than the flicker threshold F _th is not limited to the adjustment data for increasing the drive frequency, but for example, the image data corresponding to the input moving image signal. It may be adjustment data for reducing the luminance. When the luminance of the image corresponding to the input moving image signal is lowered, the adjustment unit 103 adjusts the luminance after adjustment so that the flicker evaluation value F corresponding to the image after the luminance is lowered is equal to or less than the flicker threshold _Fth. decide.

  Further, the adjustment data generated by the adjustment unit 103 may be one or more of the above examples. The adjustment unit 103 outputs the generated adjustment data to the image processing unit 104 or the display unit 105 according to the content. That is, for example, the adjustment unit 103 outputs adjustment data including parameters for image processing performed to lower the luminance of the image according to the input moving image signal to the image processing unit 104, and the adjustment data for increasing the drive frequency is output. The data is output to the display unit 105. The adjustment unit 103 may output adjustment data for reducing the luminance of the display screen to the display unit 105.

Further, in step S205 of FIG. 2, the adjustment unit 103 is, for example, if the jerkiness evaluation value J is determined to be higher than the jerkiness threshold J _th, and generates the adjustment data for lowering the driving frequency. Decreasing the driving frequency can reduce the degree to which jerkiness is perceived. Adjustment unit 103, when lowering the driving frequency, jerkiness evaluation value J depending on the display image after lowering the driving frequency to be equal to or less than jerkiness threshold J _th, determines the driving frequency after adjustment.

However, adjustment data jerkiness evaluation value J is generated when it is determined to be higher than the jerkiness threshold J _th is not limited to the adjustment data for lowering the driving frequency, for example, to lower the contrast ratio of the display image The adjustment data may be used. Adjustment unit 103, to lower the contrast ratio, as jerkiness evaluation value J depending on the display image after lowering the contrast ratio becomes less jerkiness threshold J _th, to determine the contrast ratio after adjustment.

  As an example of the adjustment data other than the drive frequency and the contrast ratio, for example, the brightness of images (subframes) generated from one image (input frame) data corresponding to the input moving image signal is made different. Adjustment data may be used. This example will be described using an example in which an input moving image signal of 60 frames per second is displayed at 120 frames per second. In this case, two images (subframes) are generated from one image (input frame). If the luminance of one of the two subframes is lower than the luminance of the other subframe, Jerkness can be made inconspicuous. Therefore, for example, adjustment data for changing the distribution ratio of a plurality of subframes generated from one input frame may be generated so that the luminance of the subframes is different.

  Other examples of adjustment data include, for example, a low-pass filter for an instruction for emphasizing an edge of an image according to an input moving image signal or a part of a plurality of generated subframes. It may include instructions and parameters for making calls.

As will be described in detail later, in the moving region observation spectrum shown in FIG. 6, the main component is a spectral component indicating the natural movement of the moving region, and the other components (sub-components) are perceived by jerkiness. It is a component that causes That is, the jerkiness evaluation value J is calculated higher as the sub component is larger than the main component. The adjustment unit 103, if the jerkiness evaluation value J is determined to be higher than the jerkiness threshold J _th, leaving the main component, as the sub-component is reduced to generate an adjusted data.
Further, the adjustment data to be generated may be one or more of the above examples. The adjustment unit 103 outputs the generated adjustment data to the image processing unit 104 or the display unit 105 according to the content. For example, the adjustment unit 103 outputs adjustment data for reducing the contrast ratio of the image corresponding to the input moving image signal to the image processing unit 104. For example, the adjustment unit 103 outputs adjustment data for lowering the drive frequency to the display unit 105.

  If the adjustment unit 103 determines that flicker and jerkiness are not perceived even if the image corresponding to the input moving image signal is output as it is, adjustment data indicating that adjustment is not necessary is sent to the image processing unit 104, And output to the display unit 105. When the adjustment unit 103 outputs the adjustment data, the process proceeds to step S207.

  In step S <b> 207, the image processing unit 104 converts the input moving image signal in accordance with the adjustment data received from the adjustment unit 103. That is, the image processing unit 104 performs, for example, a change in the luminance or contrast ratio of an image according to an input moving image signal, edge enhancement, filtering processing using a low-pass filter, or the like. Then, the image processing unit 104 outputs the converted input moving image signal to the display unit 105, and proceeds to step S208.

  In step S <b> 208, the display unit 105 changes the setting of the display unit 105 according to the adjustment data received from the adjustment unit 103. That is, the display unit 105 changes the driving frequency, for example, according to the adjustment data. In addition, the display unit 105 changes, for example, the set values of brightness and contrast ratio set in the display unit 105 according to the adjustment data. When the display unit 105 changes the setting, the process ends.

<Calculation of jerkiness evaluation value J>
Next, calculation of the jerkiness evaluation value J performed by the adjustment unit 103 will be described. Here, the jerkiness evaluation value J is an evaluation value indicating the degree to which the user perceives jerkiness (motion blur) in an image actually viewed by the user. That is, the higher the jerkiness evaluation value J, the stronger the user feels jerkiness. The adjustment unit 103 can calculate the jerkiness evaluation value J from the input moving image signal and the visual characteristics of the user. The calculation method of the jerkiness evaluation value J is as follows.

  First, the adjustment unit 103 acquires visual characteristics from the determination unit 102. This corresponds to the process of step S201 in FIG.

  The adjustment unit 103 acquires an input moving image signal from the image processing unit 104. Here, the input moving image signal acquired by the adjustment unit 103 is an image signal corresponding to an image (frame) to be displayed on the display unit 105 from the program that the user is currently viewing. An example of the acquired image is shown in FIG. The adjustment unit 103 extracts a region (moving region) including the edge portion of the moving object from the image corresponding to the input moving image signal. That is, the adjustment unit 103 according to the present embodiment extracts a moving area (block 301) including a moving object area in the image corresponding to the input moving image signal and a boundary (edge part) between the non-moving area. As a method for detecting the edge portion of a moving object, for example, there is a method using a difference from a previously input image, information on a motion vector, or the like. Further, as illustrated in the example of FIG. 3, it is not necessary that the extracted moving area includes all areas of the moving object. When a plurality of moving objects are detected, the adjustment unit 103 according to this embodiment extracts a moving area of the moving object having a higher moving speed. However, for example, the entire frame may be extracted.

  Further, the adjustment unit 103 measures the luminance value of the block 301 determined as the moving region for a certain period of time. That is, the adjustment unit 103 measures the luminance value in the block 301 including the edge portion of the moving object for a plurality of frames. FIG. 4 shows the result of measuring the luminance value of the moving area for four frames by the adjustment unit 103. However, the number of frames to be measured is not limited to 4 frames. In this example, the moving object moves by Δx1 per frame time. In addition, the adjustment unit 103 converts the measured change in the luminance value in the block 301 into two-dimensional coordinates of time and space. The result of this conversion is as shown in FIG. Hereinafter, the display in the two-dimensional coordinates of time and space is referred to as spatiotemporal display, and the signal displayed in spatiotemporal space is referred to as a spatiotemporal signal.

  In this embodiment, the example of measuring the luminance value in the block 301 has been described. However, for example, the RGB value of the input moving image signal may be measured instead of the luminance value.

  In the spatio-temporal display shown in FIG. 5, the input moving image signals 1, 2, 3, and 4 correspond to the order displayed on the display unit 105. Further, the output signal interval in FIG. 5 corresponds to the drive frequency of the display unit 105. For example, when the drive frequency is 60 [Hz], the output signal interval is 1/60 [sec]. The light emission time in FIG. 5 is the light emission time of the display unit 105. At this time, the output signal interval and the light emission time can be acquired from the profile of the display unit 105. Alternatively, it is also possible to prepare a drive voltage measuring device or a light emission measuring device at an address on the display unit 105 and obtain it from there.

  The adjustment unit 103 obtains a spectrum of a time frequency and a space frequency by performing a two-dimensional Fourier transform on the space-time signal. Hereinafter, the spectrum obtained by the two-dimensional Fourier transform is referred to as a spatiotemporal spectrum. An example of the spatio-temporal spectrum in the moving region in this embodiment is shown in FIG. The spatiotemporal spectrum acquired in this embodiment has a direct current component removed.

  The process from when the adjustment unit 103 acquires the input moving image signal until it acquires the spatiotemporal spectrum of the moving region is performed on step S202 in FIG.

  The adjustment unit 103 acquires the moving region observation spectrum by filtering the spatiotemporal spectrum of the moving region with the visual characteristics of the user. In other words, the adjustment unit 103 integrates the spatiotemporal spectrum acquired in step S202 and the visual characteristics of the user determined in step S201, so that the spatiotemporal spectrum in the moving region of the image actually viewed by the user ( A moving region observation spectrum) is obtained. That is, by this process, it can be seen how the moving area looks when the user views the image corresponding to the input moving image signal.

  For example, when the user's visual characteristics (FIG. 14) at a certain moving speed are added to the spatiotemporal spectrum (FIG. 17) in the block 301 of the input moving image signal, the spatiotemporal spectrum of the moving region actually viewed by the user The (moving region observation spectrum) is as shown in FIG. That is, the adjustment unit 103 obtains the moving region observation spectrum by multiplying the user's visual characteristics and the spatio-temporal spectrum in the region (moving region) including the edge portion of the moving object of the image according to the input moving image signal. It is done.

  In FIG. 6, a spectrum surrounded by a white frame is a component (main component) in which a moving object appears to move smoothly. On the other hand, other spectra (sub-components) are noise components that cause jerkiness to be perceived. That is, in the moving region observation spectrum, as the amplitude of the sub component is smaller than the amplitude of the main component, an image in which the moving object is smoothly moving is perceived more clearly. Therefore, the adjustment unit 103 according to the present embodiment calculates the sum of the sub component spectra, and sets the value as the jerkiness evaluation value J.

  The process in which the adjustment unit 103 calculates the moving region observation spectrum corresponds to step S203 in FIG.

<Flicker evaluation value calculation process>
Next, calculation of the flicker evaluation value F performed by the adjustment unit 103 will be described. The flicker evaluation value F is an evaluation value indicating the degree to which flicker is perceived when the user views an image corresponding to the input moving image signal. That is, the higher the flicker evaluation value F, the stronger the user feels flicker. The flicker evaluation value F can be calculated from the input moving image signal and the visual characteristics of the user. The method for calculating the flicker evaluation value F is as follows.

  First, the adjustment unit 103 acquires visual characteristics from the determination unit 102. This corresponds to the process of step S201 in FIG.

  The adjustment unit 103 acquires an input moving image signal from the image processing unit 104. Here, the input moving image signal acquired by the adjustment unit 103 is an image signal corresponding to an image (frame) to be displayed on the display unit 105 from the program that the user is currently viewing. An example of the acquired image is shown in FIG. The adjustment unit 103 extracts a flicker candidate region from an image corresponding to the input moving image signal. The procedure for extracting the flicker candidate area is as follows.

  First, the adjustment unit 103 converts the RGB value of the input moving image signal into an XYZ value indicating a light stimulus value. When the RGB value of the input moving image signal is RGB, the gamma of the display unit 105 is γ, and the conversion matrix from the RGB value to the XYZ value is M, the relationship between the RGB value and the XYZ value is expressed by Equation (4).

  At this time, it is assumed that the display unit 105 holds the gamma and the conversion matrix of the display unit 105 in advance.

Next, among the converted signals to the XYZ stimulus values, the Y values representing the brightness, binarized using a threshold Y _th. That is, it is determined whether or not the luminance of each pixel of the image corresponding to the input moving image signal is higher than the threshold value _Yth . This threshold value _Yth can be set to, for example, half of the luminance value obtained by experiments and generally considered to cause human flicker. In this way, by binarizing the Y value using the threshold value Y _th , it is possible to divide into an area where flicker can be felt in an image corresponding to the input moving image signal and an area other than that.

For example, when an image as shown in FIG. 19A is displayed on the display, if the RGB value of the input moving image signal is converted into an XYZ value and the Y value is binarized with a threshold value _Yth , the display image is displayed. Is as shown in FIG. At this time, the area of a region having a Y value higher than the threshold value _Yth is S. When the area S is larger than the threshold value _Sth , a flicker candidate region is extracted from the region. That is, the adjustment unit 103 of the present embodiment, luminance is the area of the region of higher pixel than the threshold Y _th, it is larger than the threshold value S _th, and extracts the flicker candidate region from among the regions.

In this embodiment, the threshold value S _th is the area of a circle having a diameter corresponding to a viewing angle of 10 °. This is because flicker tends to be a concern when a high-luminance region extends over a viewing angle of 10 to 20 ° or more. On the contrary, even if there is a region with high luminance, if the region is less than 10 ° viewing angle, it is difficult for the user to perceive it as flicker. Therefore, in this embodiment, it is not used for calculating the flicker evaluation value F. The area with a viewing angle of 10 ° varies depending on the viewing distance (the distance between the user and the display screen). Therefore, the display control apparatus 106 according to the present embodiment causes the user to input the viewing distance, and sets the threshold value S _th based on the input viewing distance.

In this way, it is possible to set the threshold value S _th according to the usage environment of the display device, and to calculate the flicker evaluation value F with higher accuracy. However, the viewing distance may be acquired as a constant value. Here, a calculation method of the threshold value S _{th in} the case of 3H (distance that is three times the height of the display) that is a general viewing distance of a television will be described. Assuming that the display is full high-definition (1920 × 1080 pixels), the threshold value S _th can be obtained using, for example, Expression (5).

According to equation (5), S _th is approximately 250,000 pixels. Thus, Y values of the image corresponding to the input moving image signal, when high region than the threshold Y _th is above 250,000 pixel, and extracts the flicker candidate region from the region. An example of a region extracted as a flicker candidate region is shown in FIG. FIG. 19C shows an example in which the flicker candidate area is a rectangle, but the present invention is not limited to this. Further, the adjustment unit 103 according to the present embodiment determines the flicker candidate area so that the flicker candidate area includes an area having a viewing angle of 10 ° or more of the user.

  The adjustment unit 103 measures the luminance value of the area determined as the flicker candidate area for a certain period of time. That is, the adjustment unit 103 extracts the luminance value of the area determined as the flicker candidate area for a plurality of frames. Note that the luminance values extracted for a plurality of frames as flicker candidate areas are luminance values (Y values) obtained from XYZ values converted from RGB values, and are not binarized.

  Then, a spatio-temporal spectrum is acquired from the luminance values of the flicker candidate areas of a plurality of frames. FIG. 20 shows a result (time-space display) of measuring the luminance value of the flicker candidate area for four frames by the adjustment unit 103 and converting the change of the luminance value in the flicker candidate area into two-dimensional coordinates in time and space. FIG. 20 shows a spatio-temporal signal when the luminance values in the extracted flicker candidate region are all the same luminance values over four frames. When a plurality of flicker candidate areas can be taken, the adjustment unit 103 according to this embodiment extracts an area closer to the center of the display screen as a flicker candidate area. However, for example, the entire frame may be extracted. Further, the luminance value to be measured is not limited to 4 frames.

  The adjustment unit 103 performs a two-dimensional Fourier transform on the spatiotemporal signal, further removes a direct current component unrelated to flicker, and acquires a temporal frequency and a spatial frequency spectrum (spatiotemporal spectrum). An example of the spatio-temporal spectrum of the flicker candidate region in this embodiment is shown in FIG. The flicker evaluation value F can be obtained by integrating the user's visual characteristics to the spatio-temporal spectrum obtained here.

  FIG. 22A shows the spatio-temporal spectrum shown in FIG. 21 with a time frequency axis and an amplitude axis for explanation. When the adjustment unit 103 adds the user's visual characteristics to the spectrum of FIG. 22A, the result is as shown in FIG. The adjustment unit 103 according to the present embodiment sets the total sum of the spectrum obtained by integrating the spatiotemporal spectrum and the user's visual region as the flicker evaluation value F.

  The display control apparatus 106 of the present embodiment operates as follows with the above configuration. That is, the display control apparatus 106 stores, for example, Lmax and Lmin when it is determined that flicker is perceived in the stage of acquiring the response characteristics of the user. Then, when the stored Lmax and Lmin appear when the moving image corresponding to the input moving image signal is displayed, the input moving image signal is converted and / or the setting of the display screen is changed.

  That is, in step 701 in FIG. 7, the input unit 101 determines that the test image 1 (first image) and the test image 2 (second image) are based on the image signal (first image signal) of the test image. ) At the first drive frequency (first light emission interval).

  In step S <b> 702, the input unit 101 inputs an evaluation value (evaluation information) for the display result of the test images 1 and 2. Then, the input unit 101 stores the pixel value (Lmax) of the test image 1 and the pixel value (Lmin) of the test image 2 to which predetermined evaluation information (an evaluation value indicating flicker is perceived) is input. . As described above, the pixel values (Lmax and Lmin) stored in step S702 are pixel values based on the boundary between the contrast ratio at which the user perceives flicker and the contrast ratio at which the flicker is not perceived.

  Then, when the image based on the input moving image signal (second image signal) is displayed at the first light emission interval, the adjustment unit 103 displays the flicker candidate area as the pixel value (Lmax) of the stored test image 1. When the pixel values (Lmin) of the test image 2 are sequentially displayed, the following control is performed. In other words, the adjustment unit 103 performs control to shorten the light emission interval of the flicker candidate region to be shorter than the first light emission interval (increase the driving frequency) and / or control to decrease the luminance of the flicker candidate region. However, not only the flicker candidate area but also the light emission interval and brightness of the entire display screen may be controlled, for example.

  With such a configuration, it is possible to display an image with parameters (for example, a light emission interval and luminance) that are difficult for the user to perceive deterioration of the display image.

  Note that the input unit 101 of the present embodiment inputs evaluation values at each of a plurality of different light emission intervals (drive frequencies) in step S702. And the determination part 102 determines the visual characteristic based on the evaluation value in each of several different light emission intervals. Therefore, for example, the input unit 101 sequentially displays the first image (test image 1) and the second image (test image 2) at the first light emission interval, and the test image 1 at the third light emission interval. Test image 2 is displayed.

  Then, the input unit 101 sets the light emission interval in which predetermined evaluation information (evaluation value indicating that the screen flicker is perceived) out of the first light emission interval and the third light emission interval as the first image. And the pixel value of the second image. Then, when the adjustment unit 103 displays an image based on the input moving image signal at the light emission interval stored in the input unit 101, the pixel value of a predetermined region (flicker candidate region) in the image to be displayed is the first value. When the pixel value of the image corresponds to the pixel value of the second image, the following control is performed. That is, the adjustment unit 103 performs at least one of control for shortening the light emission interval of the flicker candidate area and control for reducing the luminance of the flicker candidate area.

  By doing so, it is possible to display an image with parameters (for example, a light emission interval and luminance) that are difficult for the user to perceive deterioration of the display image.

  In addition, the display control apparatus 106 of the present embodiment operates as follows with the above configuration.

  That is, in step 706 of FIG. 7, the display unit 105 moves the moving image including the first pixel value region and the second pixel value region in the first pixel value region while moving the first pixel value region. Displayed at (first emission interval). In step S707, the input unit 101 inputs an evaluation value (evaluation information) for the moving image display result. The input unit 101 stores the first pixel value and the second pixel value to which predetermined evaluation information (an evaluation value indicating that a contrast is perceived) is input.

  Then, the adjusting unit 103 moves the first pixel value area including the third pixel value area and the fourth pixel value area in the third pixel value area in accordance with the input moving image signal. In the case where the images are sequentially displayed at the first light emission interval, the following control is performed. That is, the adjustment unit 103 performs control and input moving image to make the light emission interval longer than the first light emission interval based on the third and fourth pixel values and the stored first and second pixel values. At least one of control for reducing the contrast ratio of the moving image displayed in accordance with the signal is performed. Note that increasing the light emission interval corresponds to lowering the drive frequency.

  That is, the adjustment unit 103 determines whether or not jerkiness generated according to the moving area in the display image is perceived by the user when the moving image corresponding to the input moving image signal is displayed. The determination is based on the pixel value of 2. Then, when it is determined that the user perceives jerkiness, the adjustment unit 103 performs at least one of processing for controlling the light emission interval and converting the input moving image signal.

  Note that the input unit 101 of this embodiment inputs evaluation values for a plurality of test images having different pixel values. That is, the input unit 101 displays a moving image including a region including the first pixel value and a region including the second pixel value at the first light emission interval while moving the region including the first pixel value. Enter evaluation information. In addition, the input unit 101 evaluates a moving image including a fifth pixel value region and a sixth pixel value region displayed at a first light emission interval while moving the fifth pixel value region. Enter information. The evaluation information input here is, for example, evaluation information indicating whether or not contrast can be perceived in the display screen. Then, the adjustment unit 103 performs the following control when sequentially displaying the image including the third pixel value region and the fourth pixel value region while moving the third region. That is, the adjustment unit 103 receives the pixel value to which predetermined evaluation information is input, and the third and fourth pixel values out of the first and second pixel values and the fifth and sixth pixel values. Based on the above, at least one of control for increasing the light emission interval and control for reducing the contrast ratio of the moving image is performed.

  In addition, the input unit 101 according to the present embodiment inputs evaluation values for a plurality of test images having different moving speeds in the moving area. In other words, the input unit 101 displays a moving image including the first pixel value region and the second pixel value region so that the first pixel value region moves at the first speed. Enter evaluation information. In addition, the input unit 101 displays a moving image including the first pixel value region and the second pixel value region so that the first pixel value region moves at the second speed. Enter evaluation information. Here, the input evaluation information is, for example, evaluation information indicating whether or not contrast can be perceived in the display screen. Then, the adjustment unit 103 determines the third pixel value region as the first image and the second image including the third pixel value region and the fourth pixel value region according to the input moving image signal. In the case where the images are sequentially displayed at the first light emission interval while moving at the speed, the following control is performed. That is, the adjustment unit 103 performs at least one of control for increasing the light emission interval and control for reducing the contrast ratio of the moving image based on the first, second, third, and fourth pixel values. The predetermined speed is a speed at which an evaluation indicating that jerkiness is perceived is input from the first speed and the second speed. The third and fourth pixel values are pixel values at the boundary between the moving area and the non-moving area of the image to be displayed.

  Note that the display control device 106 may determine whether jerkiness is perceived as follows. That is, the input unit 101 displays a test image and inputs an evaluation value as to whether or not the user perceives jerkiness. Then, the pixel values of the moving area and the non-moving area in the test image displayed when the evaluation for perceiving jerkiness is performed are stored. Then, the adjustment unit 103 determines that the user perceives jerkiness when the pixel values of the moving area and the non-moving area in the image corresponding to the input moving image signal correspond to the stored pixel values. When the adjustment unit 103 determines that the user perceives jerkiness, the adjustment unit 103 performs at least one of conversion of the input moving image signal and change of the display screen setting. Even in this case, it is possible to display an image with parameters (for example, a light emission interval and a contrast ratio) that are difficult for the user to perceive deterioration of the display image.

  As described above, the determination unit 102 of the present embodiment determines the visual characteristics of the user based on the evaluation regarding whether flicker or spatial contrast is perceived when a test image is displayed. .

  Then, the adjusting unit 103 obtains a spatiotemporal spectrum (moving region observation spectrum) of the moving region viewed by the user by integrating the spatiotemporal spectrum of the moving region in the image to be displayed and the visual characteristics of the user.

  Then, the adjustment unit 103 determines whether jerkiness is perceived when displaying an image corresponding to the input moving image signal based on the size of the main component and the sub component of the moving region observation spectrum. The value J is calculated. Then, when the jerkiness evaluation value J is higher than a predetermined value, at least one of changing the parameter (for example, driving frequency) of the display unit and converting the input moving image signal is performed so that the degree of jerkiness perception is lowered. Determine the adjustment data. Thereby, jerkiness can be made difficult to perceive.

  On the other hand, the adjustment unit 103 integrates the spatio-temporal spectrum of a predetermined area (flicker candidate area) in the image to be displayed and the visual characteristics of the user to thereby calculate the spatio-temporal spectrum (flicker of the flicker candidate area viewed by the user). (Observation spectrum) is obtained.

  Then, the adjustment unit 103 indicates a flicker evaluation value indicating whether flicker is perceived when an image corresponding to the input moving image signal is displayed based on the size of the main component and the sub component of the flicker observation spectrum. F is calculated. When the flicker evaluation value F is higher than a predetermined value, at least one of changing the parameter (for example, driving frequency) of the display unit and converting the input moving image signal is performed so that the degree of flicker perception is reduced. Determine the adjustment data. By doing so, flicker can be made difficult to perceive.

The adjustment unit 103 of the present embodiment, flicker evaluation value F is higher than the threshold F _th, and, if jerkiness evaluation value J is higher than the threshold J _th, for reducing the luminance value and the contrast ratio of the display image Generate adjustment data. This is because, for example, if the light emission interval is increased (the drive frequency is lowered), the degree of jerkiness perception can be reduced, but flicker is easily perceived. By doing so, both flicker and jerkiness can be made difficult to perceive.

In addition, the determination unit 102 according to the present embodiment corrects the visual characteristics determined based on the evaluation value for the test image in accordance with a display screen parameter change instruction input by the user. That is, when the moving image corresponding to the input moving image signal is displayed, for example, when the input for shortening the light emission interval of the display screen (increasing the driving frequency) is performed, the determination unit 102 is as follows. Correct the visual characteristics. That is, the determination unit 102 corrects the visual characteristic so that the contrast sensitivity is higher than the contrast sensitivity determined based on the test image.
This is because the input for shortening the light emission interval of the display screen is performed because it can be determined that there is a high possibility that flicker has been perceived. Similarly, the determination unit 102 corrects the visual characteristics according to an instruction to change the brightness or contrast ratio of the display screen. By doing in this way, a user's visual characteristic can be determined more accurately. However, the visual characteristics determined by using the test image may not be corrected.

  In the present embodiment, the case where a moving image corresponding to an input moving image signal is displayed has been described. However, the present invention can also be applied to a case where a still image is displayed. That is, for example, it is determined whether flicker is perceived according to the determined visual characteristics of the user and the display image, and display parameters such as the light emission interval (drive frequency) can be controlled according to the result. .

  In this embodiment, the visual characteristics are determined based on the input of the evaluation value for the display result of the test image. For example, the parameters input when the moving image corresponding to the input moving image signal is displayed are used. Based on this, the visual characteristics of the user can also be determined.

<Embodiment 2>
Next, the second embodiment will be described focusing on differences from the first embodiment. In the first embodiment, the visual characteristics are determined according to the evaluation value based on whether or not the temporal and spatial changes of the pixel value are perceived in the displayed test image. On the other hand, in the present embodiment, a case will be described in which the visual characteristics are determined based on the evaluation value of the appearance of the test image.

  FIG. 10 is a flowchart showing an operation performed by the display control apparatus of the second embodiment. Hereinafter, this embodiment will be described with reference to the block diagram of FIG. 1 and the flowchart of FIG.

  In step S <b> 1001, the determination unit 102 determines the user's visual characteristics based on the response characteristics acquired from the input unit 101. Acquisition of response characteristics by the input unit 101 and determination of the visual characteristics of the user are performed as follows.

  First, the input unit 101 displays a test image including a plurality of spatial frequency contrasts as shown in FIG. 9 on the display unit 105 while moving at a certain time frequency and a certain moving speed. In FIG. 9, three contrast sets each including 12 types of spatial frequency regions are displayed. In the present embodiment, the three contrast sets are displayed so as to move to the right side at a constant moving speed. When the rightmost contrast set disappears from the right end of the display screen, the contrast set is newly displayed from the left end of the display screen. Therefore, three contrast sets are always displayed on the display screen. However, the number of contrast sets on the display screen is not limited to three, and the types of spatial frequencies included in one contrast set are not limited to twelve.

  In other words, as illustrated in FIG. 9, the contrast set includes, for example, a plurality (12) of regions having different intervals between the white portion and the black portion. Then, the input unit 101 inputs an evaluation value indicating how the user looks in each area.

  The user inputs an evaluation value related to the appearance of contrast for each spatial frequency included in the contrast set. The evaluation value is set so that it can be evaluated, for example, on a 100-point scale. That is, for example, it moves at 5 [pixel / frame], and the appearance of the contrast displayed at the top of the contrast set displayed at a time frequency of 60 [cycle / sec] is input. Here, if the contrast (difference in pixel value) can be clearly perceived, it becomes 100 points, and if it cannot be perceived at all, it becomes 0 points. In the example of FIG. 9, 100 points are input if the four black regions arranged side by side according to the spatial frequency can be clearly perceived, and 0 points are input if they cannot be perceived at all. For example, when the black region appears to be three or five, a lower evaluation value is input than when the black region appears to be four. For example, if black areas that should be perceived as four are perceived as five, it can be determined that jerkiness is perceived.

  When the evaluation value of the contrast appearance displayed at the top is input, the evaluation value of the contrast appearance displayed below is sequentially input. When the input of all evaluation values of the contrast set is completed, the input unit 101 displays the contrast set moving speed or time frequency in the test image, and allows the user to evaluate the appearance of the contrast again.

  That is, for example, the moving speed is set from 1 [pixel / frame] to 50 [pixel / frame] in increments of 5 [pixel / frame], and at each moving speed, the time frequency is 60 [cycle / sec], The degree of appearance of each contrast in the contrast set in the case of 120 [cycle / sec] and 180 [cycle / sec] is evaluated. In the example of FIG. 9, 12 evaluation values are input for each contrast set. However, for example, when 0 point is input as the evaluation value, the evaluation value of the portion where contrast is less perceivable is automatically set to 0 point. The input unit 101 outputs the acquired evaluation value of the appearance of each contrast to the determination unit 102.

  Then, the determination unit 102 determines the user's visual characteristics by plotting the evaluation value output from the input unit 101 on three-dimensional coordinates with the vertical axis representing the time frequency and the horizontal axis representing the spatial frequency. An example of the plot result is shown in FIG. FIG. 18 is an example of the visual characteristics of the user at a certain moving speed. That is, as described above, when the appearance of contrast at each of the 11 types of movement speeds is evaluated, 11 diagrams as shown in FIG. 18 are created. In FIG. 18, evaluation values are plotted for six types of spatial frequencies of 1, 5, 10, 15, 20, and 25 Hz for easy viewing.

  In step S <b> 1001, the determination unit 102 outputs the determined visual characteristics of the user to the adjustment unit 103. The evaluation value may be determined for each moving speed and for each contrast in addition to each time frequency. In this way, it is possible to display an image more suitable for the visual characteristics of the user according to the contrast information of the image corresponding to the input moving image signal. When the adjustment unit 103 acquires the visual characteristics of the user, the process proceeds to step S1002.

  In step S1002, the adjustment unit 103 determines optimal adjustment data based on the visual characteristics of the user acquired in step S1001 and the input moving image signal. That is, the adjustment unit 103 acquires the input moving image signal via the image processing unit 104 in step S1002. This input moving image signal is an image signal of an image to be displayed in the future of the program being viewed by the user. Then, the adjustment unit 103 detects a moving object in the image corresponding to the input moving image signal, and acquires the moving speed.

Furthermore, the adjustment unit 103 performs a Fourier transform on the moving object and the surrounding area in the display image, thereby calculating the spatial frequency of the area.
Next, the visual characteristic of the user whose speed is closest to the calculated moving speed is selected. In the above-described example, one visual characteristic is selected from the visual characteristics of the user corresponding to the eleven types of movement speeds. Then, the adjustment unit 103 refers to the visual characteristic data of the selected user, and determines the drive frequency based on the time frequency value having the highest evaluation value in the calculated spatial frequency. The drive frequency determined in this manner is the drive frequency at which the moving object is most easily perceived by the user.

  For example, in the image according to the input moving image signal, when the moving speed of the moving object is 10 [pixel / frame] and the spatial frequency of the moving object and the surrounding area is 15 Hz, the driving frequency is To be determined. That is, when the visual characteristic of the user shown in FIG. 18 is the visual characteristic when the moving speed of the moving object is 10 [pixel / frame], the driving frequency for displaying an image according to the input moving image signal is 120 Hz is determined. This is due to the following reason. That is, according to FIG. 18, the score (evaluation value) when the drive frequency is 120 Hz is higher than the case of other drive frequencies (60, 240 Hz). This is because when the test image as shown in FIG. 9 is moved and displayed at 10 [pixel / frame], the drive frequency is 120 Hz rather than the drive frequency is 60 Hz or 240 Hz. It shows that four black areas can be clearly perceived in the area corresponding to the spatial frequency of 15 Hz.

  As described above, the adjusting unit 103 is a drive in which the contrast of the image according to the input moving image signal is most clearly perceived based on the moving speed of the image according to the input moving image signal and the spatial frequency in the image. Determine the frequency.

  In step S1004, the display unit 105 adjusts the drive frequency based on the adjustment data, and displays an image.

  As described above, the display control apparatus according to the present embodiment determines the visual characteristics of the user by evaluating the test image. Then, an optimum drive frequency is determined according to the speed of movement of the moving object in the display image, the spatial frequency of the display image, and the visual characteristics of the user. By doing so, it is possible to make it difficult to perceive deterioration of the display image.

<Embodiment 3>
Next, a third embodiment will be described focusing on differences from the first embodiment.

  In the first embodiment, at least one of the conversion of the input moving image signal in the image processing unit 104 and the setting change of the display unit 105 is performed according to the input moving image signal and the visual characteristics of the user. On the other hand, in the present embodiment, the input moving image signal is converted in the image input device that inputs the input moving image signal.

  FIG. 11 is a block diagram showing a system configuration example of a display control apparatus according to the third embodiment of the present invention. An image input device 107 is connected to the adjustment unit 103 and the image processing unit 104. The image input device 107 is a device for inputting an image, and is, for example, a digital video camera. This can also be used, for example, as a virtual reality camera that obtains an image that appears in the user's field of view within the virtual reality.

  FIG. 12 is a flowchart showing the processing of the display control apparatus according to the third embodiment of the present invention.

  In step S <b> 1201, the determination unit 102 determines the visual characteristic of the user based on the response characteristic acquired by the input unit 101. The process of determining the visual characteristics of the user is the same as in the first embodiment.

  In step S1202, the adjustment unit 103 generates adjustment data. The adjustment data generation procedure by the adjustment unit 103 is the same as that of the first embodiment. That is, the adjustment unit 103 acquires the luminance values of a region (moving region) including a moving object edge of the moving image corresponding to the input moving image signal for a plurality of frames. Then, a jerkiness evaluation value J is calculated based on the main component and the sub component of the moving region observation spectrum obtained by integrating the obtained spatiotemporal spectrum of the moving region and the visual characteristics of the user. If the jerkiness evaluation value J is equal to or greater than a predetermined value, adjustment data for changing the drive frequency and / or the brightness and contrast ratio settings of the display image is generated to reduce jerkiness.

  In step S1202, the adjustment unit 103 detects a region having a luminance value equal to or greater than a predetermined value in the moving image corresponding to the input moving image signal. If the area is larger than the predetermined area, a flicker candidate area is determined from the area, and the luminance values of the area are acquired for a plurality of frames. Then, the total of the spatio-temporal spectrum obtained by integrating the obtained spatio-temporal spectrum of the candidate flicker area and the visual characteristics of the user is calculated as the flicker evaluation value F. If the flicker evaluation value F is equal to or greater than a predetermined value, adjustment data for changing the drive frequency and / or the brightness and contrast ratio setting of the display image is generated to reduce flicker.

  The adjustment unit 103 outputs the generated adjustment data to the image input device 107, the image processing unit 104, and the display unit 105 as appropriate according to the content.

  In step S <b> 1203, the image processing unit 104 converts the input moving image signal based on the adjustment data and outputs the converted signal to the display unit 105.

  In step S1204, the display unit 105 adjusts the parameters of the display unit 105 based on the adjustment data, and displays an image.

  In step S <b> 1205, the image input device 107 converts the captured image signal based on the adjustment data, and sends the input moving image signal to the image processing unit 104.

  As described above, the adjustment unit 103 according to the present embodiment outputs the parameters (adjustment data) for converting the input moving image signal itself input to the display control device 106 to the image input device 107, and appropriately adjusts the image. Adjustment data is output to the processing unit 104 and the display unit 105. In this way, it is possible to make it difficult to perceive deterioration of the display image.

<Other embodiments>
The object of the present invention can also be achieved by the following embodiments. That is, a recording medium in which a program code of software that realizes the functions of the above-described embodiments is recorded is supplied to the system or apparatus. Then, the computer (or CPU or MPU) of the system or apparatus reads and executes the program code stored in the recording medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

  As a storage medium for supplying the program code, for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, a DVD, or the like is used. it can.

  The present invention is not limited to the form in which the functions of the above-described embodiments are realized by executing the program code read by the computer. That is, an operating system (OS) running on a computer performs part or all of actual processing based on an instruction of the program code, and the functions of the above-described embodiments may be realized by the processing. included.

  Further, the present invention includes the following forms. That is, the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. Thereafter, the CPU of the function expansion board or function expansion unit performs part or all of the actual processing based on the instruction of the program code, and the functions of the above-described embodiments are realized by the processing. .

DESCRIPTION OF SYMBOLS 101 Response characteristic input part 102 Visual characteristic determination part 103 Adjustment part 104 Image processing part 105 Display part

Claims (14)

A display control device capable of controlling a light emission interval of a display screen,
Display control means for displaying an image in response to an input of an image signal;
Input means for inputting evaluation information indicating whether or not the user perceives flicker from the displayed image;
The user perceives the flicker when the first image of the first pixel value in response to an input of the first image signal, and a second image of the second pixel value displayed in the first light emission interval Storage means for storing the first pixel value of the first image and the second pixel value of the second image when the evaluation information indicating is input,
Of the third image and the fourth image that are sequentially displayed in response to the input of the second image signal, the pixel value of the region in the third image is stored in the storage means. If the response to the pixel value, the pixel value of the region in said fourth image corresponds to the stored previous SL second image pixel value in the storage means,
A display control apparatus comprising: a control unit that performs at least one of control for setting a light emission interval of the region to a second light emission interval shorter than the first light emission interval and control for reducing luminance of the region. The control means specifies a region having a luminance of a threshold value or more and an area of a predetermined area or more from the third image, and among the third image and the fourth image, in the said pixel values of the specified the region in the 3 images the first image pixel value, and, the fourth of the pixel values of the specified the region before Symbol second field element in the image claims, characterized in that to carry out the value if at least one of the control to lower the brightness of the control which the emission interval of the region in a short second light-emitting interval than the first light emission interval the region The display control apparatus according to 1. When evaluation information indicating that the user has not perceived flicker when the first image and the second image are displayed at the first light emission interval according to the first image signal is input. The display control means outputs the fifth image having the fifth pixel value and the sixth image having the sixth pixel value, which have a larger luminance difference than the first image and the second image, to the first image. Display with the flash interval,
The storage means includes the fifth image when evaluation information indicating that the user perceives flickering when the fifth image and the sixth image are displayed at the first light emission interval is input. Storing the fifth pixel value of and the sixth pixel value of the sixth image;
Of the third image and the fourth image that are sequentially displayed according to the input of the second image signal, the pixel value of the region in the third image is stored in the storage means corresponding to the pixel value of the fifth, when the pixel value of the region in said fourth image corresponds to the pixel value of the 6 stored in the storage means, wherein the light emitting interval of the area first display control device according to claim 1, wherein the performing at least one of control to lower the brightness of the control and pre-Symbol area of the short has the second emission interval than the light emitting interval. The display control means indicates that the user has not perceived flicker when the first image and the second image are displayed at the first light emission interval according to the first image signal. The fifth image having a luminance that matches the first image and the sixth image having a luminance different from that of the second image are displayed in response to input of evaluation information. Item 4. The display control device according to Item 3. A display control device capable of controlling a light emission interval of a display screen,
Display control means for displaying an image in response to an input of an image signal;
Input means for inputting evaluation information indicating whether or not a user perceived an area having a different pixel value in the displayed image ;
When an image from the first pixel value to the second pixel value is displayed while moving the area of the first pixel value according to the first image signal, the user has a different pixel value in the image storage means for storing the first pixel value, and the second pixel value when the evaluation information indicating that the perception region is input,
The first area and the second area when an image including the first area and the second area is displayed at a first light emission interval while moving the first area in accordance with a second image signal. When the pixel value with respect to the region corresponds to the first pixel value and the second pixel value stored in the storage means, the second light emission is longer than the first light emission interval. display control apparatus characterized by a control means for performing at least one of a control of lowering the contrast ratio of images that will be displayed according to the control and the second image signal to the interval. Extracting means for extracting the moving region from an image based on the second image signal;
The control means has a pixel value of the first movement area and the second area having a higher movement speed among the first movement area and the second movement area extracted by the extraction means. When corresponding to the first pixel value and the second pixel value, the light emission interval is set to the second light emission interval longer than the first light emission interval, and display is performed according to the second image signal. The pixel value of the second moving area and the second area whose moving speed is lower than that of the first moving area is set to be the first pixel If the pixel values of the first moving area and the second area corresponding to the value and the second pixel value do not correspond to the first pixel value and the second pixel value, the control is not performed. The display control apparatus according to claim 5 . The first light emission interval while moving the first pixel value area in an image including the first pixel value area and the second pixel value area in response to the input of the first image signal. When the evaluation information indicating that the user did not perceive the difference between the first pixel value and the second pixel value in the image when being displayed, the display control means, An image including a region of a third pixel value and a region of a fourth pixel value having a larger pixel value difference than the first pixel value and the second pixel value is moved in the region of the third pixel value. While displaying at the first light emission interval,
When the user displays the image including the third pixel value area and the fourth pixel value area at the first light emission interval while moving the third pixel value area, the user performs the image display. When the evaluation information indicating that the difference between the third pixel value and the fourth pixel value is perceived is input, the third pixel value and the fourth pixel value are stored.
The control means includes
The image when the image including the first area and the second area is displayed at the first light emission interval while moving the first area in response to the input of the second image signal. When pixel values of the first region and the second region in the image correspond to the third pixel value and the fourth pixel value stored in the storage unit,
To perform at least one of control to lower the contrast ratio of a moving image to be displayed in response to a long said second control and the second image signal to the light emitting interval than the light emission interval of the first light emission interval 6. The display control apparatus according to claim 5, wherein The third pixel value of the image displayed when the evaluation information indicating that the difference between the first pixel value and the second pixel value is not perceived is input is the first pixel value. The display control apparatus according to claim 7, wherein the fourth pixel value is different from the second pixel value. 6. The first pixel value is a pixel value corresponding to a maximum luminance in the image, and the second pixel value is a pixel value corresponding to a minimum luminance in the image. The display control apparatus described. The display control apparatus according to claim 5, wherein the first pixel value and the second pixel value have the same luminance, but have different chromaticities. A display control method performed by a display control device capable of controlling a light emission interval of a display screen,
A display control step for displaying an image in response to an input of an image signal;
An input step for inputting evaluation information indicating whether or not the user perceives flicker from the displayed image;
The user perceives flicker when the first image having the first pixel value and the second image having the second pixel value are displayed at the first light emission interval in response to the input of the first image signal. A storage step of storing the first pixel value of the first image and the second pixel value of the second image when the evaluation information indicating
Of the third image and the fourth image that are sequentially displayed in response to the input of the second image signal, the pixel value of the region in the third image is stored in the storage step. If the response to the pixel value, the pixel value of the region in said fourth image corresponds to a pre-stored Symbol second image pixel value in the storing step,
A display control method comprising: a control step of performing at least one of a control for setting the light emission interval of the region to a second light emission interval shorter than the first light emission interval and a control for reducing the luminance of the region. To a computer that can control the light emission interval of the display screen,
A display control procedure for displaying an image in response to an input of an image signal;
An input procedure for inputting evaluation information indicating whether or not the user perceives flicker from the displayed image;
The user perceives flicker when the first image having the first pixel value and the second image having the second pixel value are displayed at the first light emission interval in response to the input of the first image signal. A storage procedure for storing the first pixel value of the first image and the second pixel value of the second image when the evaluation information indicating
Of the third image and the fourth image that are sequentially displayed in response to the input of the second image signal, the pixel value of the region in the third image is stored in the storage procedure. If the response to the pixel value, the pixel value of the region in said fourth image corresponds to a pre-stored Symbol second image pixel value in the storage procedure,
A program for executing a control procedure for performing at least one of control for setting the light emission interval of the region to a second light emission interval shorter than the first light emission interval and control for reducing the luminance of the region. A display control method performed by a display control device capable of controlling a light emission interval of a display screen,
A display control step for displaying an image in response to an input of an image signal;
An input step for inputting evaluation information indicating whether or not the user perceived an area having a different pixel value in the displayed image ;
When an image from the first pixel value to the second pixel value is displayed while moving the area of the first pixel value according to the first image signal, the user has a different pixel value in the image a storage step of storing the first pixel value, and the second pixel value when the evaluation information indicating that the perception region is input,
The first area and the second area when an image including the first area and the second area is displayed at a first light emission interval while moving the first area in accordance with a second image signal. When the pixel value with respect to the region corresponds to the first pixel value and the second pixel value stored in the storing step, the second light emission is longer than the first light emission interval. display control method characterized by a control step of performing at least one of control to lower the contrast ratio of images that will be displayed according to the control and the second image signal to the interval. To a computer that can control the light emission interval of the display screen,
A display control procedure for displaying an image in response to an input of an image signal;
An input procedure for inputting evaluation information indicating whether or not the user perceived an area having a different pixel value in the displayed image ;
When an image from the first pixel value to the second pixel value is displayed while moving the area of the first pixel value according to the first image signal, the user has a different pixel value in the image A storage procedure for storing the first pixel value and the second pixel value when evaluation information indicating that a region is perceived is input;
The first area and the second area when an image including the first area and the second area is displayed at a first light emission interval while moving the first area in accordance with a second image signal. When the pixel value with respect to the region corresponds to the first pixel value and the second pixel value stored in the storage procedure, the second light emission is longer than the first light emission interval. a program characterized by executing a control procedure for performing at least one of control to lower the contrast ratio of images that will be displayed according to the control and the second image signal to the interval.