JP2001255842A - Image display method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a well-balanced image by making boundary of display objects clear when displaying an image by line sequential scanning. SOLUTION: A display device and a display method therefor for obtaining a clear display by automatically recognizing a boundary of an image, and correcting signals in an area only in the neighborhood of the boundary, or between the boundary and other boundaries, in the display device for displaying the image by line sequential scanning.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct-type television receiver, a projection type display device, a computer image output device and a display method using a CRT, a liquid crystal device, a plasma device, an electroluminescence device, an electrochromic device and the like. Is proposed.

[0002]

2. Description of the Related Art Conventionally, in the case of performing color display with a plurality of dots, for example, for an arbitrary display content, an area of A color,
The display is performed separately for the B color area, the C color area, and the D color area. Similarly, in both monochrome display and color display, display may be performed separately in areas having different brightness.

[0003]

However, there has been a situation in which color mixing occurs at the boundaries of these areas, and clear display is difficult. In the case of color shading (brightness), color blurring sometimes occurred. This is not only a problem with the performance of the display device, but also because the high-frequency component was cut in the processing stage of the video signal before reaching the display device,
This was also caused by the dull signal waveform. In particular, it is difficult to see when displaying for OA, which requires high definition. Therefore, as shown in FIG.
On the other hand, a method has been proposed in which data 2 subjected to contour processing is subjected to arithmetic processing and the composite screen data 3 is actually displayed.

However, when using this method,
The calculation speed per screen must be extremely high, which is not suitable for displaying a moving image of 60 screens or more per second.

[0005]

Accordingly, the present invention proposes several alternatives to such a method. One of them is that when an apparatus that performs color display with a plurality of dots in a matrix configuration including a plurality of X axes and a plurality of Y axes is displayed by dot-sequential or line-sequential scanning, image data for an arbitrary row of the X-axis When a plurality of adjacent data of the same color are arranged, a means for performing information conversion of the end color data to black is provided.

Further, when a plurality of adjacent data of the same color are lined up simultaneously in one line of image data of an arbitrary Y axis,
It is characterized in that it has means for performing information conversion of the end color data into black.

By doing so, a clear display as shown by the data in FIG. 3 can be obtained without performing a high-speed display as in the related art.

In the above description, when a plurality of adjacent data of the same color are arranged, a clear display is obtained by converting the end color data into black. For example, when performing gradation display, when a plurality of adjacent data of the same light intensity are arranged, a sharper display is obtained by increasing or decreasing the light intensity of the end data. be able to.
This means that if you are trying to show a display that emits more intense (more stimulating the retina) light against a background that emits weak light,
By emphasizing the periphery of the display having the strong light, that is, the display that is more recognizable (ie, increasing the intensity of the light), it is possible to display an image to be displayed (for example, a white character on a white background) on a screen having the same color. ) Emerges from the background and can be displayed clearly.

By utilizing this, in the present invention,
When a plurality of adjacent data of the same color are arranged, not only the extreme end color data is made black, but also the light intensity may be changed.

[0010] Further, in a specific color combination, a clearer display can be obtained by setting the endmost color of a plurality of data of the same color to a color other than black. In this case, display other than black may be performed.

The following method is a mathematically generalized version of such an idea. One of them is to calculate the average value of a specific section of the input display data, and further divide the section into a region having a value equal to or larger than the average value and a region having a value equal to or smaller than the average value. Then, the maximum value (substantially the maximum value of the area) and the minimum value (substantially the minimum value of the area) of each area are represented by data (output data) to be displayed in the area.
Is used as In this case, the maximum value and the minimum value of each area may be output discontinuously, but in that case, the color tone and brightness between the respective parts change so rapidly that the unnaturalness is visually felt. In some cases. In order to avoid such a situation, a transition section may be provided between the maximum value and the minimum value by any method, and continuous display may be performed in that section. For example, the slope of the input display data at the point where the input display data intersects with the average value may be determined, and the transition data may be determined as a straight line passing through the intersection and having the slope.

Alternatively, the absolute value of the derivative of the input display data is calculated, and the output display data of the section sandwiched by the points where the absolute value is an arbitrary maximum is defined as the minimum of the absolute value of the derivative of the section. Input display data at a certain point may be used as output display data. In this case as well, as in the former method, the output display data becomes discontinuous. To avoid such a problem, the same processing as in the former method may be performed.

Further, the absolute value of the derivative of the input display data may be calculated, and data obtained by enhancing only the vicinity of the point where the absolute value is maximum may be used as the output display data. That is, at the point where the absolute value of the derivative is maximal, the color tone of the image,
Since there is a transition between light and dark, the existence of the transition region can be emphasized by emphasizing the edges.

As described above, when there are adjacent areas having different brightness and color tone, each method is effective in emphasizing the boundary of each area. That is, all of the above methods are common in that the display device determines the boundary by some mechanical or automatic means and corrects the screen in accordance with the boundary. A display device having such a system is effective not only for ordinary OA equipment but also for display devices for amusement purposes.

For example, in an NTSC television broadcast, the number of scanning lines is 525, but the horizontal length is 1.5 times the vertical length, and the horizontal resolution is 1.5 times the 525 lines.
In the case of 0 lines, a wide band carrier of at least 30 MHz is required, but only a few MHz is actually allocated, and therefore a fine image cannot be transmitted. In particular, the display may be blurred or blurred in the horizontal direction despite high definition in the vertical direction. This is because the high-frequency component is cut by cutting the band of the image carrier as described above, which means that the video signal is rounded.

Such image blurring has not been recognized so much by the CRT system. This is because CRT is a point-sequential scan to restore high-definition images.
This is because a special high-frequency circuit was required for signal processing, including an electron beam with a high frequency of 30 MHz.

However, the situation is different in a display device adopting a line-sequential scanning method such as an LCD or a PDP. For example, in the 800 × 525 matrix described above, the parallel processing of the image signal for each column results in an 80
There is a time margin of 0 times. Therefore, it is considered that the image processing as described above is particularly suitable for LCDs and PDPs. A detailed description will be given by a plurality of the following embodiments.

[0018]

[Embodiment 1] In this embodiment, 640 × 400
An explanation using a liquid crystal display device having dots will be added. FIG.
1 shows the configuration of the device according to the present invention. The liquid crystal display device comprises an X-axis driver and a Y-axis driver (in the dotted line in the figure). These drivers are composed of a liquid crystal matrix (LC in the figure).
D), and a signal line for sending data to the Y-axis driver is provided.

It is assumed that the data processing device * A sequentially processes the input data and sends the processed data to the Y-axis driver (in the dotted line in the figure) according to the flowchart shown in FIG. The data processing device * B is shown in FIG.
It is assumed that the input data is sequentially processed and the processed data is sent to the Y-axis electrode according to the flowchart shown in FIG.

FIG. 2C will be further described using actual data. G (green) after R (red) lasts 3 times
The third R is converted into BL (black) by the processing of the data processing device. Similarly, from left 10
The Gth is converted into BL, and the 13th B from the left is converted into BL. However, the second B from the right and R at the right end are not continuous colors and are not converted as shown in the figure.

Although a liquid crystal display using a ferroelectric liquid crystal is used in this embodiment, it is understood that the present invention is also applicable to STN, TN, dispersion type liquid crystal display, EL, plasma display, and the like. Was.

[0022] In "Example 2" This embodiment shows an example of an image processing section of a line in the image, from the X _i in X _j. Although the number of pixels included in this section is required to be three or more, the number is preferably 20 or more from the viewpoint of mathematical processing. Alternatively, the whole one screen may be targeted. The data to be input in this section is shown in FIG. First, the average value of the brightness of the input data in this section is calculated. As a result, the obtained average value is indicated by a dotted line in the figure. Next, as shown in FIG depending data in this section is greater than or less than the average value, (X ₁ from X _i) areas a,
b (X ₁ to X ₂ ), c (X ₂ to X ₃ ) and d (X
Split from ₃ to X _d ). Then, the maximum value of the area a, the minimum value of the area b, the maximum value of the area c, and the minimum value of the area d are set as display data to be output in each section. An example is shown by a chain line in FIG.

However, in such a process, the output data has discontinuous values, which tends to give a visually unnatural impression. Therefore, in order to eliminate the discontinuity, the output values of each area are connected by a straight line having an appropriate slope,
Provide continuity. As the slope, the slope of the input data at points X ₁ , X ₂ , and X ₃ , which are the boundary points of the respective regions, is appropriate. Specifically, a straight line having an inclination at each point and passing through each point was adopted. Then, by connecting this straight line to the above-mentioned maximum value and minimum value, data as shown by a solid line in FIG. 4B was created, and this was used as output display data.

[Embodiment 3] In this embodiment, a process of calculating a derivative of input image data and calculating output image data based on the derivative will be described. The section from the pixel X _i of rows in the same manner as in Example 2 to X _j, 5
The data shown in (A) is input. The derivative of this data is immediately obtained by differentiation or an equivalent operation. The absolute value of the derivative thus obtained is shown in FIG. The simplest way to calculate the derivative is to calculate the difference between the input image data of adjacent pixels X _k and X _{k + 1} and the difference between f (X _k ) and f (X _{k + 1} ).

In FIG. 5B, the absolute value of the derivative takes a maximum value at points X ₂ , X ₄ , X ₆ and points X ₁ , X ₃ , X ₃
Take the local minimum. Therefore, based on the maximum values obtained in this way, a region sandwiched between these maximum values, for example, between points X ₂ and X ₄ is defined as a group of regions, and a (point X ₂ up), b (from point X ₂ to X _4), c
(From point X ₄ to X _6), and d (the point X ₆ or later). Then, as output data of these regions, data of points at which the absolute value of the derivative of each region is minimum is used. For example, in the area a, the input data f (X ₁ ) of the point X ₁ , and in the area b, the data f (X ₃ ) of the point X ₃ . At these points, the absolute value of the derivative becomes 0, that is, the maximum value and the minimum value of each section. On the other hand, in the section c, the data f (X ₃ ) of the point X ₅ is adopted, but in this case, it is noted that f (X ₃ ) is neither the maximum value nor the minimum value of the area. Should. The output display data processed as described above is as shown in FIG.

In this embodiment, there is no need to divide input pixel data into appropriate sections as in the case of the second embodiment.
In the case of the second embodiment, if the section to be set is too large,
For example, when one row of data is regarded as one section, if the average value is different from that of the next row, the displayed signal may have little difference as an input signal, but may have a large output. is there. Conversely, if the section to be set is narrow, the object of the present invention of giving sharpness to an image cannot be sufficiently achieved. For example, in the example of FIG. 4, the region c has a very complicated structure, but these structures are ignored due to the mechanical judgment that the average value is equal to or greater than the average value in the set section.

In this embodiment, since the procedure of calculating the average value after setting the section is not performed, it is possible to capture even a special structure of a portion that is sufficiently smaller than the set section, and the image becomes unnatural. Less.

Embodiment 4 This embodiment is shown in FIG. For example, in television broadcasting, it is difficult to transmit an extremely steep boundary. This is because, as described above, there is a limit to the frequency band that can be used for broadcasting. When a signal has a sharp boundary, it contains a very large number of high-frequency components. Therefore, the original signal is shown in FIG.
6A, the actually received and processed video signal is as shown by the solid line in FIG. 6A.

When such a signal is displayed as it is, an image with no blurred border is obtained. Therefore, it is required to restore a signal close to the original signal by some method. In the present embodiment, an example will be described in which a signal close to the original signal is output by specifying such a boundary portion and performing enhancement processing on the image signal of that portion.

As a method of specifying the boundary, a derivative of the input signal is calculated, and a point at which the absolute value becomes a maximum is set as the boundary. That is, a portion where the signal value changes rapidly may be considered as a boundary. However, in this method, the absolute value of the derivative may be maximized even when the signal changes very smoothly. It is not always considered that there is a sharp image at a place where such a gentle change occurs. Therefore, a threshold value may be set for the absolute value of the derivative, and a boundary may be determined only when a value equal to or greater than the threshold value is obtained.

After the boundary is determined in this way, a process for clarifying the boundary is performed based on the value of the input signal at the boundary point (indicated by a in FIG. 6). For example, if the input signal at an arbitrary point X near the boundary is f
(X), the output signal g (X) is expressed as g (X) = f (a) + [f (X) -f (a)] exp
The value given by [1 / (X−a) ² ] may be adopted. However, X ≠ a. In general terms, g (X) = f (a) + [f (X) −f (a)] h (X−
a) (X ≠ a) Here, the function h (x) converges to 1 when x is infinity or infinity, and takes infinity or a finite positive value when x = 0.

In practice, the calculation is not performed each time, and the difference [f (X) -f (a)] is multiplied by a specific value every time the pixel is separated from the pixel recognized as the boundary by the above-described method, and f (a) is calculated. )
, An operation of adding an output signal may be employed. For example, if the boundary is X _k , X
_{The k + 1} pixel is multiplied by 2.72, and X _{k + 2} is 1.28.
, X _{k + 3} is 1.12, X _{k + 4} is 1.06, X
_{k + 5} is multiplied by 1.04, X _{k + 6} is multiplied by 1.03, and X _{k + 7} to X _{k + 8} is multiplied by 1.02. You just need to avoid it. Pixels in the opposite direction X _k−1 , X _k−2 , X _k−3 , X _k−4 , X _k−5 , X
_The same processing is performed for _k-6 , _{Xk-7, and Xk-8} . This processing is based on the above equation, h (x) = exp
This is substantially the same as the case of (1 / x ² ).

Alternatively, without such mathematically strict correction, the pixel next to the boundary pixel is simply 10 times, the second pixel is 5 times, the third pixel is 3 times, and the fourth pixel is 2 times, 5th pixel is 1.5 times, 6th pixel is 1.2
It is only necessary to execute a flowchart such that the processing is not performed on the pixels which are twice as long and the seventh pixel is 1.1 times, and the pixels farther than it are 1.1 times.

The technical idea of this embodiment is the same as that of the first embodiment. The method of identifying a boundary is mathematically performed.
It is characterized in that processing is performed on pixels near the boundary of a specific area. Therefore, unlike Embodiments 2 and 3, there is no one who uniformly defines the signal in the region other than the boundary portion, so that a continuous change in subtle hue and a continuous change in brightness are maintained. .

[0035]

As described above, a region having the same color or the same brightness having a plurality of dots is automatically identified, and a black outline is provided at the end, or the boundary is emphasized by arithmetic processing. By eliminating an intermediate transition region, color mixing with other colors does not occur, and a sharp display can be realized.

In the case of the first embodiment, processing is performed at the stage of transferring data from an LCD to an image display device such as a PDP, so that the processing speed does not decrease and realization is possible even on a high-speed operation screen. It is now possible. In the other embodiments, the processing takes a little time, but there is no particular problem as long as the display method allows parallel processing for each column of the screen, such as an LCD or PDP.

[Brief description of the drawings]

FIG. 1 shows a configuration of a display device according to the present invention.

FIG. 2 shows a flow chart of a system according to the invention and an example of data processing according to the invention.

FIG. 3 shows an image processing method according to a conventional example.

FIG. 4 shows an example of processing of an image signal according to the present invention.

FIG. 5 shows an example of processing an image signal according to the present invention.

FIG. 6 shows an example of processing an image signal according to the present invention.

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[Procedure amendment]

[Submission date] February 28, 2001 (2001.2.2
8)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 9/68 103 G09G 5/36 520C (72) Inventor Yasuhiko Takemura 398 Hase, Atsugi-shi, Kanagawa Pref. Conductor Energy Laboratory

Claims (9)

[Claims] 1. A method for displaying an image having a gradation by a plurality of dots arranged in a matrix consisting of a plurality of X axes and a plurality of Y axes using a line sequential scanning method.
The slope of the input signal for one axis is obtained, and the point where the absolute value of the slope is the maximum is set as a boundary, and the display of the plurality of dots near the boundary is corrected by the output signal obtained by performing the input signal enhancement processing. An image display method. 2. A method for displaying an image having a gradation by a plurality of dots arranged in a matrix consisting of a plurality of X axes and a plurality of Y axes using a line sequential scanning method.
Calculate the derivative of the input signal for one axis, set a threshold to the absolute value of the local maximum of the derivative, and set the input image boundary when the absolute value of the local maximum exceeds the threshold. An image display method, wherein display of the plurality of dots near the boundary is corrected by an output signal having undergone signal enhancement processing. 3. The emphasizing process of the input signal is performed by input signal f
(X), the output signal g (x) converges to 1 at infinity or infinity, and at x = 0, a function taking an infinity or a finite positive value is defined as h (x), and g (x) = f (a) ) + [F (x) −f (a)] h (x−
3. The image display method according to claim 1, wherein: a) (x ≠ a). 4. The image display method according to claim 3, wherein the function h (is exp [1 / x ² ]. 5. The emphasizing process of the input signal is such that a pixel at the boundary is X _k , an input signal of an n-th (n is a positive number) pixel X _{k ± n} is f (X _{k ± n} ), and n ( (n is a positive number), the output signal of the pixel X _{k ± n} is g (X _{k ± n} ), and Z ₁ >
_{Z 2> ... Z n-1} > using a constant _{Z n} satisfying _{Z n g (X k ± n} ) = [f (X k ± n)] - f (X k)] Z
_{2. The method according} to claim 1, wherein the calculation is performed by an expression represented by _n + f ( _Xk ).
Or the image display method according to 2. Wherein said _{Z n} is an image display method according to claim 5, characterized in that the ^{_{Z n = exp [1 / n}} 2]. 7. The input signal emphasizing process is described as follows: the boundary pixel is X _k , the input signal of an n-th (n is a positive number) pixel X _{k ± n} is f (X _{k ± n} ), and n ( (n is a positive number), and _let the output signal of the pixel X _{k ± n be} g (X _{k ± n} ), where Z ₁ > Z
_2> ... and _{Z n-1> Z n} using a constant _{Z n} satisfying _{g (X k ± n) =} f (X k ± n) , characterized in that is carried out by expression represented as _{Z n} Claim 1
Or the image display method according to 2. 8. The image display method according to claim 1, wherein the image is displayed by a liquid crystal display device. 9. The image display method according to claim 1, wherein the image is displayed by a light-emitting display device.