JPH0713497A - Image display device - Google Patents

Abstract

PURPOSE:To provide the image display device capable of displaying images with which an observer does not have an odd feel at all times even when looking at the same region. CONSTITUTION:The observer's head direction and visual line direction are detected by a head direction detecting section 6 and visual line detecting section 7. A region setting section 4 specifies the observer's observation direction on a screen 10. This region setting section 4 specifies the observation position with respect to the image information inputted from an image accumulation section 5 and determines the region where resolution is varied. A resolution varying section 3 changes the resolution of the resolution varying region so as to make the resolution adaptable to the human retina characteristic and thereafter, this section outputs the entire image information to a first projector 1 and outputs the local image information changed in the resolution to a second projector 2. The first projector 1 displays the entire image on the screen 10 and the second projector displays the local image in accordance with the image information outputted from the resolution varying section 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device for displaying an image corresponding to image information, and more particularly to an image display device for displaying an image adapted to human retina characteristics, for example, in the field of image communication and human. The present invention relates to an image display device used in a field using an interface.

[0002]

2. Description of the Related Art A conventional image display device will be described below with reference to the drawings. FIG. 6 is a block diagram showing the configuration of a conventional image display device.

In FIG. 6, the image display device includes a first projector 11, a second projector 12, a position setting unit 13, an image storage unit 14, a head direction detection unit 15, a line-of-sight direction detection unit 16, and a screen 10. Including.

The first projector 11 receives overall image information corresponding to the entire image output from the image storage unit 14 via the position setting unit 13, and the entire image (hereinafter, an image for peripheral vision) is displayed on the screen 10. Is displayed).

The head direction detecting section 15 and the line-of-sight direction detecting section 16 detect the head direction and the line-of-sight direction of an observer observing the screen 10, and send the head-direction detecting signal and the line-of-sight direction detecting signal to the position setting section 13. Output. Position setting unit 13
Specifies the observation position on the screen 10 of the observer based on the input head direction detection signal and line-of-sight direction detection signal. The position setting unit 13 determines a region in which the resolution of the image information is changed within a preset range centered on the specified observation position. The position setting unit 13 includes an image storage unit 14
Then, the resolution of a predetermined area determined from the entire image information input from is changed and output to the second projector 12. The second projector 12 displays the input image information having the changed resolution as a local image (hereinafter, referred to as an image for central vision) in a region within a circle of a broken line shown in FIG.

The change in resolution of the central vision image displayed as the local image is reduced based on the human retina characteristics (reference: Tasaki, Oyama, Hiwatari, "Visual Information Processing", Asakura Shoten, 1985). Image processing is being performed. FIG. 7 shows a diagram for explaining the retinal characteristics reported in the above document. FIG. 7A is a two-dimensional representation of a human visual acuity characteristic in which the distance from the fovea on the retina is a function, and FIG. 7B is a three-dimensional representation. As shown in FIG. 7, it can be seen that the human visual acuity characteristic is highest near the fovea centralis on the retina and decreases toward the periphery. This is because the density of cells in the human retina is concentrated near the fovea and becomes coarser toward the periphery.
The above-mentioned image display device sets the retinal characteristic in advance, increases the resolution of the image at the center of the observation position of the observer so as to conform to the set retinal characteristic, and performs image processing in which the resolution decreases toward the periphery. I am doing it. The above processing is performed by the position setting unit 13, and the outer edge of the local image displayed by the second projector 12 and the resolution of the entire image displayed by the first projector 11 are smoothly connected, and the second projector displays the image. The boundary perception between the central vision image and the peripheral vision image displayed by the first projector is reduced.

Further, since the position setting unit 13 moves the position of the image for central vision displayed by the second projector 12 according to the observation position of the observer, the observer can determine which position on the screen 10. Even if the above is observed, it is possible to observe an image whose resolution is changed based on the above-mentioned retinal characteristics.

[0008]

However, it has been confirmed by experiments that the visual acuity characteristics of humans differ depending on whether the image is presented to the peripheral vision or not. The experimental method projects a random dot pattern in the peripheral vision area while the examinee looks at the Landolt index near the center of the large screen. While changing the Landolt index, the size of the dot pattern presented in the peripheral vision area is also changed. The test subject's visual acuity at this time is measured. As a result of experiments, it has been found that the visual acuity in central vision decreases as the size of the peripheral vision stimulus increases.

Further, it has been reported that the visual acuity of peripheral vision increases in proportion to the time during which the same region is focused. Figure 8
The figure explaining the experiment method which measures the time change of a retinal characteristic is shown in FIG. In the experiment method shown in FIG. 8, a plurality of Landolt indices are arranged in the peripheral vision region, and the visual acuity in the peripheral vision is performed by the same method as the visual acuity measurement in the central vision. The test subject is taught to look at the Landolt index in the front direction in the central view. The distance from the central vision is discretely selected, and the Landolt index is arranged for each distance, that is, in the peripheral vision region. Simultaneously with the start of observation, the index of the peripheral vision area is presented. In order to obtain the relationship between the visual acuity recovery time in peripheral vision and the visual acuity, the degree of visual acuity recovery of the examinee is measured and measured every 3, 6 and 9 seconds after the start of observation. The head of the person to be tested is fixed to the chin rest.

FIG. 9 shows the results of measurement of changes in retinal characteristics over time by the above test method. The visual acuity of the test subject at this time was 1.0 according to the Landolt index. That is, this is the visual acuity value immediately after the start of observation in central vision. It was used to examine visual acuity with an upper limit of 1.0 and a lower limit of 0.6 in central vision. In addition, the Landolt index in central vision refers to the retinal characteristics and has an upper limit of 0.8.
To a lower limit of 0.06 was used to examine visual acuity. The visual acuity characteristics of peripheral vision were analyzed every 10 ° up to a viewing angle of 40 °. As shown in FIG. 9, it has been clarified that the visual acuity of central vision decreases with the passage of observation time, while the visual acuity of peripheral vision improves.

The above report result is a phenomenon that cannot be explained only by the conventional retinal characteristics. Therefore, in the conventional image display device, only by changing the resolution of the image on the display screen based on only the static retinal characteristics without considering the temporal change to the preset change state of the resolution, When gazing at the same region, the resolution is not changed by adapting to the retinal characteristics of a person that changes with the passage of time, so there is a problem that the observed image feels strange.

An object of the present invention is to solve the above problems, and it is an object of the present invention to provide an image display device for displaying an image that does not always cause a sense of discomfort even when an observer looks at the same area.

[0013]

An image display device according to the present invention comprises a changing means for arbitrarily changing the resolution of image information, and a display means for displaying an image corresponding to the image information whose resolution is changed by the changing means. including.

[0014]

In the image display device according to the present invention, since the resolution of the image information can be arbitrarily changed by the changing means, the display means can display an image adapted to the change of the human retina characteristics which changes with the passage of time. Can be displayed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image display apparatus according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an image display device according to an embodiment of the present invention.

In FIG. 1, the image display device includes a first projector 1, a second projector 2, a resolution varying unit 3, an area setting unit 4,
The image storage unit 5, the head direction detection unit 6, the line-of-sight direction detection unit 7,
Includes screen 10. The image storage unit 15 temporarily stores images to be displayed in advance. The image storage unit 5 stores predetermined image information from the stored image information in the area setting unit 4
Output to. Head direction detection unit 6 and line-of-sight direction detection unit 7
Detects the head direction and line-of-sight direction of the observer, and outputs the head-direction detection signal and the line-of-sight direction detection signal to the area setting unit 4. The area setting unit 4 specifies the observation position on the screen 10 of the observer based on the input head direction detection signal and the gaze direction detection signal, and determines the initial resolution variable area according to the observation position. The area setting unit 4 changes the initial resolution of the image information output from the image storage unit 5 and outputs a resolution variable area signal for instructing a resolution variable area to the resolution variable unit 3. The resolution variable unit 3 appropriately changes the resolution of the image information in consideration of the observation time and the like based on the input image information and the resolution variable region signal, and outputs the image information for central vision in which the resolution is changed to the second image information. In addition to outputting to the projector 2, the entire image information corresponding to the entire screen 10 is output to the first projector 1. The first projector 1 displays an entire image (image for peripheral vision) corresponding to the input entire image information on the screen 10. The second projector 2 displays the input image information for central vision at the observation position (the area inside the circle of the broken line) observed by the observer. Further, the resolution varying unit 3 varies the resolution of the image for central vision with time, based on the retina characteristics of the person described later.

Next, the resolution varying section 3 and the area setting section 4
Will be described in more detail. FIG. 2 is a block diagram showing a detailed configuration of the resolution varying unit 3 and the area setting unit 4 shown in FIG.

In FIG. 2, the area setting section 4 includes an observation center setting section 41 and a resolution variable area initial setting section 42. The observation center setting unit 41 specifies the observation position on the screen 10 of the observer based on the input head direction detection signal, line-of-sight direction detection signal, and image information, and presents the coordinate value of the observer in the physical space. Convert to the inside coordinate value. After the center for resolution conversion is determined, the resolution variable area initial setting unit 42 gives an initial degree of change in the resolution of the presentation screen from the central portion to the peripheral portion.

The resolution varying unit 3 includes a time-distance converting unit 31,
The resolution conversion function unit 32 and the image processing unit 33 are included. Time
In the distance conversion unit 31, firstly, the area for resolution conversion is changed according to the distance between the viewpoint of the observer and the observation position.
For that purpose, a preset distance and a parameter included in a function for performing conversion are associated with each other, the information is stored in advance, and referred to as necessary. Second,
Consider the observation time in a certain area of the observer. It is known that, when observing the same region, the target of interest extends to the peripheral portion with the passage of time. Therefore, by giving the size of the area for resolution conversion as a function of time, flexibility can be given to the system. Regarding the observation time, its average value is given as its initial value.

Next, the resolution conversion function unit 32 performs processing for actually variably controlling the resolution according to the position of the observer's viewpoint.

The resolution conversion area and its degree are determined,
The resolution of the input original image is subjected to nonlinear coordinate conversion by the image processing unit 33. After the above processing, the image information for central vision is output to the second projector 2 and the entire image information is output to the first image projector 1.

By the above-mentioned operations, the image display apparatus of the present invention changes the resolution variable region according to the distance between the observer's viewpoint and the observation position, and changes the image resolution according to a predetermined time function. It becomes possible. Therefore, the resolution of the image information can be arbitrarily changed to display an image that adapts to changes in human retina characteristics that change over time, and even if an observer looks at the same area, a sense of discomfort is always present. It is possible to display a screen that you do not feel.

Next, the method of changing the resolution of the image of the image display device will be described more specifically.

In order to change the conventional retinal characteristics shown in FIG. 7 with time, control conditions are required for parameters to be controlled. According to conventional knowledge (references: Tasaki, Oyama, Hiwatari, “Visual Information Processing”, Asakura Shoten, 1985),
Human visual information processing includes parallel processes, but it is known that the total processing amount is limited. As shown by the results of the visual psychology experiment, when the image is presented to the peripheral vision, the visual acuity of the central vision is reduced correspondingly, which suggests that the processing mechanism is shared. In other words, it can be inferred that the visual work amount is always kept constant. When modeled based on this, it is considered that the visual acuity characteristics of peripheral vision are improved as much as the visual acuity of the fovea centralis on the retina is reduced. Mathematically speaking, it is approximated by a three-dimensional function, and deformation is given so that the integral value becomes constant. FIG. 3 shows a model in which the retinal characteristics when the resolution is changed are functionalized. 3A and 3B show the initial state, and FIGS. 3C and 3D show the state after a lapse of time. In addition, (a) and (c) of FIG. 3 are models showing two-dimensionally the retinal characteristics, and (b) and (d) are models showing three-dimensionally. As shown in (c) and (d) of FIG. 3, it can be seen that the visual acuity of the central vision decreases and the visual acuity of the peripheral vision improves as time passes (t1 → t2 → t3).

Usually, the above retinal characteristics are approximated by a Gaussian distribution type function G (x, y).

[0026]

[Equation 1]

Here, σ is a standard deviation, and x and y are coordinate values from the gazing point. Also, σ = σ (t) is assumed to introduce a time variable. Since σ indicates the range of blur in the image on the display screen, as described above, the pattern can be approximated by a sigmoid function based on the experimental result shown in FIG. 9 according to the observation time of the observer. Can be expressed. FIG. 4 shows the relationship between the dispersion value approximated by the sigmoid function and the time. The measured time is
Since it was every 3, 6, and 9 seconds, from the change of the viewing angle shown in FIG. 9, the expression that the visual acuity of peripheral vision is improved can be considered equivalent to the increase of the variance value of the Gaussian distribution pattern. it can. Although it is not measured after 9 seconds, it is assumed that the perceived amount of blur is saturated after a certain time.

Next, let us consider a decrease in visual acuity in central vision and an improvement in peripheral vision. In this case, the 1 / (2πσ ² ) term, which is a constant of the Gaussian distribution type function G (x, y), is
Since 1 / {2π (σ (t)) ² }, σ
It can be seen that there is an inverse relationship with the value of (t). However, the change in the relative visual acuity between the central vision and the peripheral vision is not so remarkable as the change indicated by the value of 1 / {2π (σ (t)) ² }. Therefore, this term is replaced with g = g (t). Regarding this function, considering the two values of the visual acuity at the start of observation and the visual acuity of about 80% at that time from the results of the experiment, the temporal change of the maximum visual acuity in central vision from t = 0 to 9 seconds Can be approximated. In this way, the model in which the retina characteristics shown in FIG. 3 when the resolution is variable can be designed as a function of time. It should be noted that v1 and v2 shown in FIG. 3 represent values when the resolution is best in central vision. In addition, rx, ry, dx, and dy indicate the size of the processing area for the display image. As an example of the range of these variables, a viewing angle of 40 ° is set as an upper limit. In reality, up to about 60 ° is the range that can be seen by peripheral vision, but practically there is no problem even if 40 ° is set as one target.

Next, the state on the display screen when the resolution is changed by using the image display device configured as described above will be described. FIG. 5 is a diagram illustrating a change in resolution on the display screen. Each circle shown in FIG. 5 is a contour line showing the height difference of resolution, and circles of the same resolution are connected by a broken line. The elapsed time of the display screen shown in FIG. 5 is (a) →
The state where time has passed in the order of (b) → (c) is shown. As shown in FIG. 5, it can be seen that the resolution in peripheral vision gradually increases from the initial resolution according to the length of the observation time of the observer. On the other hand, it can be seen that the resolution in central vision is gradually decreasing. As described above, since the range of resolution and the degree of the resolution can be changed according to the time transition, it is possible to display an image that does not always feel discomfort even when the observer looks at the same region. .

In the above embodiment, the image to be displayed is stored in the image storage unit 5 in advance. However, by providing an image input unit instead of the image storage unit 5, it is possible to store image information input from the outside. The same can be applied.

[0031]

In the image display device according to the present invention,
Since the resolution of the image information is arbitrarily changed by the changing means, for example, the range of change in resolution and the degree of change in resolution can be easily controlled depending on the observation time of the observer. It is possible to display an image with a display resolution adapted to a human retina characteristic that changes with the passage of time. Therefore, it is possible to display an image in which the viewer does not feel a sense of discomfort even when he or she looks at the same region.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an image display device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a detailed configuration of a resolution varying unit and a region setting unit.

FIG. 3 is a diagram showing a model in which a retinal characteristic when a resolution is changed is made into a function.

FIG. 4 is a diagram showing a relationship between a variance value and time.

FIG. 5 is a diagram illustrating a change in resolution on a display screen.

FIG. 6 is a block diagram showing a configuration of a conventional image display device.

FIG. 7 is a diagram illustrating retinal characteristics that have been conventionally reported.

FIG. 8 is a diagram illustrating an experimental method for measuring a temporal change in retinal characteristics.

FIG. 9 is a diagram showing measurement results of temporal changes in retinal characteristics.

[Explanation of symbols]

 1 1st projector 2 2nd projector 3 Resolution variable part 4 Area setting part 5 Image storage part 6 Head direction detection part 7 Gaze direction detection part

Claims (4)

[Claims] 1. An image display device for displaying an image corresponding to image information, wherein the changing means arbitrarily changes the resolution of the image information, and the image corresponding to the image information whose resolution is changed by the changing means. And an image display device including display means for displaying. 2. The image display device according to claim 1, wherein the conversion means includes changing the resolution of the image information according to a predetermined time function. 3. The image display device according to claim 1, wherein the conversion means includes area setting means for setting an area for changing the resolution of the image information. 4. The image display device according to claim 3, wherein the area setting means includes detecting an observation position on the image of an observer who observes the image displayed by the display means.