JP2002311937A - Color display device and color display method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color display device which can sufficiently lessen color breakup. SOLUTION: The color breakup disturbance is ameliorated by compensating the display positions of two colors among three primary colors to position relatively shifted with respect to the remaining one color according to the movement of images in displaying the images.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color display device, and more particularly, to a display device that performs color display by sequentially displaying three primary colors during a scan of one field for one display cell.

[0002]

2. Description of the Related Art A liquid crystal display LCD (Liquid crystal display) using a shadow mask type CRT (Cathode-ray tube) or a color filter is typically used as a color display device.
ystal display). A color display device using these uses a space division type color display method in which a red display cell, a green display cell, and a blue display cell are combined into one pixel.

Unlike the color display device using the space division type color display method described above, recently, three primary colors are sequentially displayed in one display cell at a time of scanning one field, so that color display is performed. field sequential color display method for displaying (F ield- s equential C olor D is
play method), some projection display devices and direct-view LC
Attention has been paid as a method for colorizing D, and development is proceeding. Examples of these are described in the following documents, for example. (1) V. Markandy, RJ Gove, SMPTE Journal, Oct. 1995, p
p.680-685. (2) T.Takahashi, et al., Proc. IDW'98, ALC4-4, pp.84
5-846 (Dec. 1998). (3) N. Koma, et al., SID'00DIGEST, P-28, pp. 632-635
(May 2000). The feature of the FSCD method described above is that it is not necessary to combine three display cells into one pixel as in a space-division type color display method, and one display cell is made into one pixel. Accordingly, high definition of the display device can be achieved. Further, if the definition is the same, the cost can be reduced.

FIG. 6 shows an example of a display sequence by the FSCD method. In FIG. 6, the horizontal axis represents time (t), and the vertical direction represents three displayed primary colors (R (red),
G (green), B (blue)). In FIG. 6, R1, G1, and B1 indicate each primary color in the first field. Similarly, R2, G
2, B2 indicates each primary color in the second field. In FIG. 6, the field frequency (fv) of the image signal indicating the image to be displayed is 60 Hz. Therefore, the time for scanning one field is 1/60 second. The display time of each primary color is 1/180 second, which is the time obtained by equally dividing the time for scanning one field. As described above, in the FSCD method, three primary colors are sequentially displayed one by one.

[0005]

However, in the FSCD method, since three primary colors are displayed in one display cell in a time-division manner, a color which is peculiar to the FSCD method is displayed on a displayed image. ) There was a problem that interference occurred.

[0006] Coloring refers to, for example, as shown in FIG. 7, a plurality of bright colors (blue, cyan, yellow, and red in FIG. 7) different from white at the boundary between an image that should be white and the background. It is a phenomenon that is viewed, and interferes with the original image display, and is a main cause of significantly deteriorating the image quality of the displayed image. FIG. 7 shows, by way of example, how a color image appears when a rectangular white image moves at a constant speed from left to right in front of a black background screen.

[0007] In FIG. 7, a vivid color (blue, cyan, yellow, red) different from white is visually observed at a boundary portion between the background and the forward and backward direction with respect to the traveling direction of the rectangular white image. This is a false color that should not be present in an original white image, and is perceived as remarkable image quality deterioration in a general image. For example, the image quality deteriorates such that the outline of the moving human face displayed on the display device appears to be colored red or blue.

The appearance of the color varies depending on the movement of the viewpoint of the viewer (referred to as a viewer) or the content of the displayed image, and the moment when the viewer blinks even in a still image. Occurs. In particular, the color is clearly viewed when a moving image is displayed. When a moving image is displayed, the color is constantly viewed, so that the influence on the image quality is increased.

Therefore, when the FSCD method is used for a moving image display device for television or the like, a countermeasure for preventing discoloration is indispensable.

Here, the mechanism of the occurrence of color shift will be described with reference to FIG. FIG. 8 is a diagram showing an image displayed using the FSCD method in a two-dimensional manner using one spatial axis and a time axis. The rectangular white image shown in FIG. It is a figure showing a state of moving to the right from.

When such an image is displayed, as a human visual property, a moving rectangular white image follows the eye, and the trajectory of the viewpoint viewing the rectangular white image is indicated by an arrow in FIG. . This characteristic has little individual difference as long as a human is looking at a displayed rectangular white image.

Also, due to the temporal characteristics of human vision, the display light displayed within the time required to scan one field is almost completely integrated in the human visual system. That is, the color viewed by a human is a color obtained by adding (integrating) the display light on the locus of the arrow in FIG. 8, and a false color is colored instead of white at the end of the rectangular white image. Occurs.

For example, in FIG. 8, in a region immediately to the right of a region that looks white, blue (B) is not added, and green (G) and red (R) are added. . Further, in the area on the right side, only red (R) is added, so that it is viewed as red.

Such a false color depends on the moving direction of the image and the R
Although it changes depending on the display order of GB, in any case, a color different from the original color is displayed, and remarkable image quality deterioration occurs. As for the image quality deterioration, the larger the area where the above-mentioned coloring occurs is, the larger the image quality deterioration is felt. If the display sequence is constant, the faster the movement of the image, the larger the area where coloration occurs and the greater the degree of image quality degradation.

As described above, in the display device using the FSCD method, there is a problem that the image quality is deteriorated due to coloring.

Although a method for improving coloration is described in, for example, the above-mentioned document (1), in the conventional method,
There has been a problem that the discoloration cannot be sufficiently improved.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a color display device capable of sufficiently reducing color blur.

[0018]

To achieve the above object, a color display device according to the present invention comprises a color signal input section for inputting color signals corresponding to each of the three primary colors. What is claimed is: 1. A color display device for displaying an image by sequentially displaying colors indicated by input color signals in respective fields, and a motion estimating unit for estimating a motion of the image based on a color signal input from the color signal input unit And a display position control unit that controls the display positions of the colors indicated by the color signals corresponding to each of the three primary colors based on the result estimated by the motion estimation unit.

With this configuration, it is possible to provide a color display device capable of sufficiently reducing color shift.

Further, the display position control unit sets the display position of the color indicated by the color signal corresponding to each of the two colors among the color signals corresponding to each of the three primary colors to the remaining one color. The present invention is characterized in that control is performed to relatively shift the display position of the color indicated by the color signal.

With this configuration, the configuration of the display position control unit can be simplified.

Further, the color signals corresponding to the two colors are color signals corresponding to two colors other than the color having the highest visibility among the three primary colors.

With this configuration, even if the estimation result in the motion estimation unit does not reflect the actual motion of the image, the display position is shifted for the color having the highest visibility. Therefore, image quality degradation due to estimation errors can be minimized.

Further, the motion estimating section converts a color signal input from the color signal input section into a luminance signal indicating luminance, and a luminance signal converting section based on the luminance signal converted by the luminance signal converting section. And a motion vector detecting unit for detecting a motion vector indicating a moving direction of the image.

With this configuration, the detection of the motion vector by the motion estimating unit can be performed based on the luminance at which human visibility is higher than the color.

The color display method according to the present invention comprises
A color signal input step of inputting a color signal corresponding to each of the primary colors, and a color display method of displaying an image by sequentially displaying colors indicated by the color signals input in the color signal input step in each field. A motion estimation step of estimating the motion of the image based on the color signal input in the color signal input step,
Based on the result estimated by the motion estimation step,
A display position control step of performing control to shift display positions of colors indicated by color signals corresponding to the three primary colors, respectively.

According to such a method, it is possible to provide a color display method capable of sufficiently reducing color shift.

In the display position control step, among the color signals corresponding to the three primary colors, the display position of the color indicated by the color signal corresponding to each of the two colors corresponds to the remaining one color. The present invention is characterized in that control is performed to relatively shift the display position of the color indicated by the color signal.

According to such a method, the configuration of the display position control step can be simplified.

Further, the color signals corresponding to each of the two colors are color signals corresponding to two colors other than the color having the highest luminosity factor among the three primary colors.

With such a method, even if the estimation result in the motion estimation step does not reflect the actual motion of the image, control is performed to shift the display position for the color having the highest visibility. Therefore, image quality degradation due to estimation errors can be minimized.

The motion estimating step includes a luminance signal converting step of converting the color signal input in the color signal input step into a luminance signal indicating luminance, and a luminance signal converted in the luminance signal converting step. ,
A motion vector detecting step of detecting a motion vector indicating a moving direction of the image.

According to such a method, the detection of the motion vector in the motion estimation step can be performed based on the luminance with high human visibility.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an outline will be given of a method of improving the color interference caused by using the FSCD method according to the present invention, particularly the color interference in a moving image display.

According to the present invention, the display position of two of the three primary colors is compensated for and displayed at a position shifted relative to the remaining one color in accordance with the motion of the image, thereby preventing color interference. It will improve.

In general, a motion compensation technique based on the motion of an image is used in fields such as MPEG coding and television system conversion, which are image compression techniques. By using this motion compensation technique, it is possible to improve the color hindrance of the moving image display by the FSCD method.

Next, an embodiment of the color display device according to the present invention will be described with reference to the drawings. FIG.
1 is a diagram showing a configuration of a color display device according to an embodiment. In FIG. 1, the color display device according to the embodiment includes a color signal input unit 1, a motion estimation unit 2, a display position control unit 3, and a display unit 4. It is assumed that the display sequence of the color display device according to the embodiment is as shown in FIG.

The color signal input unit 1 is configured to externally input a color signal corresponding to R (red), a color signal corresponding to G (green), and a color signal corresponding to B (blue). .

Next, the motion estimating section 2 is configured to estimate the motion of a moving image based on the color signal input from the color signal input section 1, and includes a luminance signal converting section 5, a motion vector detecting section. 6.

The luminance signal conversion unit 5 is configured to convert a color signal corresponding to each of the three primary colors input by the color signal input unit 1 into a luminance signal. For example, the luminance signal Y is converted using the following conversion equation.

Y = 0.7152 × G + 0.0722 × B
+ 0.2126 × R Here, G indicates the value of the color signal corresponding to green, B indicates the value of the color signal corresponding to blue, and R indicates the value of the color signal corresponding to red.

As is apparent from this equation, the three primary colors are RG
When B is selected, since the coefficient of 0.7152 is larger than the other two, the color with the highest visibility is G (green).
It turns out that it is.

The motion vector detector 6 calculates the motion vector V (Vx, Vy) for each pixel of the image or for each block of an appropriate size such as 8 × 8 pixels from the luminance signal converted by the luminance signal converter 5. ) Can be detected. When detecting a motion vector, it is assumed that a luminance signal indicating the luminance of a past image to be used is stored.

Here, the motion vector V is represented by a horizontal component Vx
And the signal of the vertical component Vy, which indicate the number of pixels (unit: pixel / field) that the image moves in the horizontal and vertical directions in one field scanning time, respectively. As a method of detecting a motion vector, for example, a block matching method or the like can be used.

The reason why a motion vector is detected from a luminance signal in this way is that visibility is generally higher for luminance than for color.

Next, the display position controller 3 comprises a vector allocator 7, a motion compensation buffer memory circuit 8, a buffer memory circuit 9, a motion compensation buffer memory circuit 10, and a changeover switch 11.

The vector allocator 7 assigns 1 to the motion vector V (Vx, Vy) detected by the motion vector detector 6.
Vector + V / 3 (Vx /
3, Vy / 3), -V / 3 (-Vx / 3, -Vy / 3)
Is output to the motion compensation buffer memory circuit 10 and the motion compensation buffer memory circuit 8, respectively.

The motion compensation buffer memory circuit 8 is configured to store the color signal corresponding to the red color input from the color signal input unit 1, and the motion compensation buffer memory circuit 1
0 is configured to store a color signal corresponding to blue inputted from the color signal input unit 1. The buffer memory circuit 9 is configured to store a color signal corresponding to green input from the color signal input unit 1.

The above-mentioned memory circuit and changeover switch 1
6, the color signals corresponding to the three primary colors are respectively shown in FIG.
Is converted into a signal having a display period of 1/180 second (field color sequential signal). In FIG. 1, these signals are represented by R ', G', and B '. That is, this conversion can be realized by storing the chrominance signals in the motion compensation buffer memory circuits 8 and 10 and the buffer memory circuit 9 and reading out the stored signal at an appropriate timing at a clock frequency three times as high as the storage time.

The changeover switch 11 includes R ', G', B
The operation is performed in synchronization with the operation of the motion compensation buffer memory circuits 8, 10, and the buffer memory circuit 9.

The motion compensation buffer memory circuits 8, 1
0 is configured to perform motion compensation based on the motion vector input from the vector allocating unit 7. For example, the motion compensation buffer memory circuit 8 sends the motion vector −V / 3 (−Vx / 3, −Vy /
When 3) is input, the color signal is changed to a color signal obtained by shifting the red display position by −Vx / 3 pixels in the horizontal direction and −Vy / 3 pixels in the vertical direction. means.). Similarly, the motion compensation buffer memory 10
Is also configured.

Next, the display unit 4 is configured to display an image based on the field color sequential signal output from the display position control unit 3. The display unit 4 includes a drive circuit 12, a display device 13, and a backlight 14. It is configured.

The drive circuit 12 is configured to convert the field color sequential signal output from the display position control unit 3 into a format suitable for driving the display device 13 and drive the display device 13.

The display device 13 displays an image, and is composed of, for example, a transmission type liquid crystal device.
In this case, the display device displays an image by changing the transmittance of light emitted from the backlight 14. It is assumed that the backlight 14 can switch the emission color to any one of R (red), G (green), and B (blue). For example, the light emitting diodes of R (red), G (green), and B (blue) may be alternately turned on / off. The emission color is synchronized with the color signal selected by the changeover switch 11. For example, R
If (red) is selected, the light emitting diode that emits red light is turned on.

The color display device according to the embodiment is configured as described above, and the operation and function will be described below with reference to FIGS.

First, color signals corresponding to R (red), G (green), and B (blue) of the same pixel are input by the color signal input unit 1 (color signal input step) (S101).

The input color signal corresponding to R (red) is input to the motion compensation buffer memory circuit 8, the color signal corresponding to G (green) is input to the buffer memory circuit 9, and the color signal corresponding to B (blue) is input. Each is stored in the motion compensation buffer memory circuit 10 (S102).

Further, R, which is input from the color signal input unit 1,
The color signals corresponding to G and B are converted into a luminance signal in the luminance signal conversion unit 5 (luminance signal conversion step).
(S103). Then, the motion vector detection unit 6 detects a motion vector V based on the converted luminance signal (motion vector detection step) (S104).

Next, the vector allocating section 7 receives the motion vector V detected by the motion vector detecting section 6 and sends the motion vector V / 3 to the motion compensation buffer memory circuit 10.
The motion vector −V / 3 is stored in the motion compensation buffer memory circuit 8.
Output to

The motion compensation buffer memory circuit 10 converts the stored color signal corresponding to blue into a color signal whose display position is shifted by the motion vector V / 3 based on the input motion vector V / 3. Similarly, based on the input motion vector -V / 3, the motion compensation buffer memory circuit 8 converts the stored color signal corresponding to red into the motion vector -V /
A color signal for shifting the display position by 3 (display position control step) (S105).

Next, the color signals from the motion compensation buffer memory circuit 8, the buffer memory circuit 9, and the motion compensation buffer memory circuit 10 are converted into serialized field color sequential signals by a changeover switch 11 for switching at a period of 1/180 second. Output to the display unit 4, and in the display unit 4,
Red is displayed at the position shifted by the motion vector −V / 3, green is displayed at the original display position after 1/180 second, and blue is displayed at the position shifted by the motion vector V / 3 after 1/180 second. Is displayed (S106).

As described above, if the motion vector is correctly detected by the motion vector detecting section 6, a moving image free from color disturbance can be displayed on the color display device using the field color sequential display method. it can.

The color display device according to the embodiment has an F
This is an application of a motion compensation technique to a color display device using an SCD. As described above, it is not necessary to apply the motion compensation to all three primary colors. If the motion compensation is applied to two of the three primary colors, an effect of improving color interference can be obtained. By applying only two colors in this manner, one motion compensation buffer memory circuit having a large circuit scale can be saved.

In order to perform motion compensation, it is necessary to detect a motion vector of each part of the image from the image. However, the current motion estimation technology cannot accurately detect a motion vector in various images. For this reason, when using the motion compensation technique, consideration must be given to the case where a motion vector is erroneously detected. As described above, in the color display device according to the embodiment, the motion compensation is applied only to two of the three primary colors having low visibility.

Therefore, even if a motion vector is erroneously detected, motion compensation is not performed on a color having the highest visibility, so that image quality deterioration due to erroneous detection of a motion vector can be minimized. it can.

Next, the mechanism by which the color display device of the embodiment can improve the color hindrance will be described with reference to FIG.

The moving speed of the image is Vx (pixels / field) in the right direction (the direction in which x increases), and 0 (V
y = 0), and the motion vector is assumed to be correctly detected.

As shown in FIG. 3, as a result of the motion compensation, R
(Red) is shifted leftward by Vx / 3 pixels from G (green), and B (blue) is shifted rightward by Vx / 3.
The display is shifted by the pixel. As a result, the positions of the three primary colors displayed as evident from FIG. 3 are aligned with the movement of the image, that is, the movement of the viewpoint. Therefore, it can be seen that even if these display lights are integrated in the visual system of the observer, they are not colored and do not interfere.

FIG. 4 is a diagram showing a second example of the configuration of the display position control unit 3. As shown in FIG. That is, this example is an example in which G (green), B (blue), and R (red) are displayed in this order, as is clear from FIG.

The vector allocating section 21 receives the motion vector V, converts the motion vector V / 3 to a motion compensation buffer memory circuit 23 for storing a color signal corresponding to B (blue), and converts the motion vector 2V / 3 to R ( The color signal corresponding to (red) is output to the motion compensation buffer memory circuit 24 that stores the color signal.

The buffer memory circuit 22, the motion compensation buffer memory circuits 23 and 24, the changeover switch 2
5. The color signal input unit 30 is the same as that described in FIG. As described above, even when the display control unit 3 is configured, the color disturbance can be improved in the same manner as the configuration described with reference to FIG.

Although not shown, motion compensation may be performed on all three primary colors for display. For example, GBR
, The motion vector V is -V / 6
To G (green), V / 6 to B (blue), and V / 2 to R
(Red).

FIG. 5 shows a second configuration example of the color display device according to the present invention. General TV image signals use the interlaced scanning method,
When this is displayed on the LCD, it is necessary to convert from the interlaced scanning method to the progressive scanning method. Also in the case of conversion to this progressive scanning, the converted image quality can be improved by using motion compensation.

The color display device having the configuration shown in FIG. 5 applies the motion vector V detected by the motion estimating unit 1 to both the motion-compensated progressive scanning conversion unit 31 and the display position control unit 3 to perform field color sequential scanning. An image is displayed on the display unit based on the signal. With this configuration, a high-quality television signal can be displayed.

As described above, according to the color display device of the embodiment, at least two of the three primary colors are used.
By compensating and displaying two colors with particularly low luminosity at positions along the movement of the image, it is possible to reduce the color interference, which is a problem of the FSCD, particularly the color interference in displaying a moving image.

Therefore, according to the color display device of the embodiment, the FSC which is advantageous for high definition and low cost
It can contribute to the practical use and spread of D.

[0077]

According to the present invention, it is possible to provide a color display device capable of sufficiently reducing color shift.

[0078]

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a color display device according to an embodiment.

FIG. 2 is a flowchart illustrating an operation of the color display device according to the embodiment.

FIG. 3 is a diagram showing a mechanism for improving color disturbance by the color display device according to the embodiment;

FIG. 4 is a diagram illustrating a second configuration example of the display position control unit.

FIG. 5 is a diagram showing a second configuration example of the color display device according to the present invention.

FIG. 6 is a diagram showing an example of a display sequence of the FSCD method.

FIG. 7 is a diagram schematically illustrating an example in which coloring occurs.

FIG. 8 is a diagram showing a mechanism of coloring caused by using the FSCD method.

[Description of Signs] 1 Color signal input unit 2 Motion estimation unit 3 Display position control unit 4 Display unit 5 Luminance signal conversion unit 6 Motion vector detection unit 7 Vector allocation unit 8 Motion compensation buffer memory circuit 9 Buffer memory circuit 10 Motion compensation buffer Memory circuit 11 Changeover switch 12 Drive circuit 13 Display device 14 Backlight 21 Vector allocation unit 22 Buffer memory circuit 23 Motion compensation buffer memory circuit 24 Motion compensation buffer memory circuit 25 Changeover switch 30 Color signal input unit 31 Motion compensated progressive scan conversion unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) G09G 5/00 G09G 5/00 550X 550 H04N 9/12 A H04N 9/12 9/64 F 9/64 G09G 5/00 520Z F-term (reference) 5C006 AA01 AA22 AF19 BB11 BF02 FA29 5C060 BC01 BE05 BE10 DB00 GA02 HB26 5C066 AA03 AA11 CA06 CA09 GA01 GB01 KE01 KM13 KM14 5C080 AA10 CC03 DD30 EE32 FF09 BB01 BB01

Claims (8)

[Claims] 1. A color signal input section for inputting color signals corresponding to each of three primary colors, and an image is displayed by sequentially displaying colors indicated by the color signals input from the color signal input section in each field. A color estimating unit for estimating the motion of an image based on the color signal input from the color signal input unit; and a color estimating unit based on a result estimated by the motion estimating unit.
A color display device comprising: a display position control unit that controls a display position of a color indicated by a color signal corresponding to each of primary colors to be shifted from each other. 2. The display position control unit determines a display position of a color indicated by a color signal corresponding to each of two colors among color signals corresponding to each of the three primary colors.
2. The color display device according to claim 1, wherein control is performed to relatively shift the display position of the color indicated by the color signal corresponding to the color. 3. The color signal according to claim 2, wherein the color signals corresponding to each of the two colors are color signals corresponding to two colors other than the color having the highest luminosity factor among the three primary colors. Display device. 4. A luminance signal conversion unit for converting a color signal input from the color signal input unit into a luminance signal indicating luminance, based on the luminance signal converted by the luminance signal conversion unit. The color display device according to any one of claims 1 to 3, further comprising: a motion vector detection unit that detects a motion vector indicating a direction in which the image moves. 5. A color signal input step for inputting color signals corresponding to each of the three primary colors, and an image is displayed by sequentially displaying colors indicated by the color signals input in the color signal input step in each field. A color display method, comprising: a motion estimation step of estimating the motion of an image based on the color signal input in the color signal input step; and a result estimated by the motion estimation step.
A display position control step of controlling a display position of a color indicated by a color signal corresponding to each of the three primary colors to be shifted from each other. 6. The display position control step according to claim 1, wherein the display position of the color indicated by the color signal corresponding to each of the two primary colors among the color signals corresponding to each of the three primary colors corresponds to the remaining one color. 6. The color display method according to claim 5, wherein control is performed to relatively shift the display position of the color indicated by the color signal. 7. A color signal according to claim 6, wherein the color signals corresponding to each of the two colors are color signals corresponding to two colors other than the color having the highest luminosity factor among the three primary colors. Display method. 8. The motion estimation step comprises the steps of: converting a color signal input in the color signal input step into a luminance signal indicating luminance; and a luminance signal converted in the luminance signal conversion step. 8. A color display method according to claim 5, further comprising: a motion vector detecting step of detecting a motion vector indicating a moving direction of the image.