JPH11313339A - Display controller and dynamic image/graphics composite display method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a color component of a chromakey color from appearing on a synthesis display image in the case of synthesis display between a graphics image signal having a background area in a chromakey color and a dynamic image signal. SOLUTION: An arithmetic system of filtering processing of horizontal filters 105N, 105C, 105P is changed depending on a chromakey color signal CKEY denoting whether or not pixel data of a graphics image are coincident with a chromakey color. Thus, the arithmetic method is selected for the case that pixel data of the chromakey color are included in pluralities of images being a filtering processing object or for other cases. For example, it is prevented that a color component of a chromakey color that is not to be visible is displayed with mixture by applying arithmetic processing excluding pixel data in the chromakey color at a border between a background area and a foreground area of the graphics image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a display control device for combining a graphics image signal and a moving image signal of a computer and displaying the combined signal on a TV, and a moving image / graphics combination display method applied to the device.

[0002]

2. Description of the Related Art In recent years, with the development of computer technology,
Various multimedia-compatible digital video players, set-top boxes, and the like that can be used by connecting to a home TV have been developed.

[0003] Such digital video players and set-top boxes are not only used for displaying computer graphics, but also for CDs (Compact Disks) and DVs.
D (Digital Versatile Disk)
It is possible to decode and reproduce the moving image data that has been digitally compressed and stored in the digital camera.

[0004] DVD is a new video disc standard that can record video information such as a movie with high image quality on an optical disc of the same size as a CD using moving picture coding called MPEG2. The DVD recording / reproducing method is based on the concept of variable rate coding from the viewpoint of securing both the image quality and the recording time for the capacity. The data amount of the variable rate coded data depends on the image quality of the original image, and the data amount increases in a scene with more intense motion. The moving image data stored on the DVD is created based on the same NTSC video signal as a home TV, and the image decoded and reproduced by the MPEG2 decoder becomes an interlaced scanning video signal.

Recently, advanced graphics processing such as three-dimensional graphics can be realized even in a home digital video player or set-top box by increasing the speed of a CPU and improving a graphics controller. The graphics data can interactively change the display image according to a user operation such as scrolling the screen freely. For this reason, it is desired to realize a new video with high entertainment properties by fusing graphics and a natural moving image of MPEG2 and displaying them in a composite manner.

In general, RGB used in a computer
When displaying a graphics image signal of a format on a TV, signal conversion for converting the signal format of the graphics image signal from RGB format to YUV format for TV display and filtering processing for removing flicker are required. .

Since the luminance band and color band of the graphics image signal are wider than those of the video signal defined by TV, the graphics image signal is
When displayed on V, a flicker phenomenon called flicker occurs. In the filtering process, an averaging operation between pixels adjacent in the horizontal or vertical direction is performed, whereby the signal band of the graphics image signal is adjusted to the signal band of the TV video signal.

As a method for synthesizing a filtered graphics image signal and a moving image signal input from an MPEG decoder or the like, a method using a chroma key is known.

In an image synthesizing method using a chroma key, a portion of a graphics image screen which is desired to be transparent,
That is, in a portion where the moving image signal side is desired to be displayed at the time of synthesis, a corresponding area (background area) of the graphics image is embedded with pixel data of a color called a chroma key color. Then, at the time of display processing, it is determined whether or not each pixel data of the graphics image matches the chroma key color, and the graphics image and the moving image are selected for each pixel in accordance with the determination, thereby displaying the graphics image on the background area. The moving image is composited and displayed.

[0010]

However, in the filtering process, as described above, since the averaging operation is performed between pixels adjacent in the horizontal or vertical direction, the filtering process is performed on a background area which is originally transparent and cannot be seen. Is mixed with the graphics image of the foreground area during the filtering operation. In this case, when the image of the synthesis result is displayed on the screen, the color component of the chroma key color is seen near the boundary with the moving image on the graphics image.

Although it is conceivable to use an inconspicuous color such as gray as the chroma key color, this will limit the colors that can be used as the chroma key color, and the application program for graphics display will be limited. This may cause problems such as incompatibility with the image, and restrictions on colors that can be used in the foreground area of the graphics image.

SUMMARY OF THE INVENTION The present invention has been made in view of such a point, and when a graphics image signal and a moving image signal are combined and displayed, the color components of the invisible chroma key color are not mixed and displayed. It is another object of the present invention to provide a display control device and a moving image / graphics composite display method capable of obtaining a high-quality composite display screen from which flicker has been removed.

[0013]

In order to solve the above-mentioned problems, the present invention sets a background area of a graphics image signal drawn in an image memory to a predetermined chroma key color, and designates a background area designated by the chroma key color. A display control device for synthesizing and displaying a moving image signal on a background area
Means for outputting a chroma key color signal indicating whether the color of the pixel data of the graphics image signal read from the image memory matches the chroma key color, and a plurality of pixel data adjacent to the graphics image signal A filtering unit for performing a predetermined arithmetic processing for filtering on the graphics image signal in units, wherein a color of pixel data of a foreground area of the graphics image signal is not affected by pixel data of a chroma key color of a background area Filtering means for changing an operation method for the filtering based on the chroma key color signal, and combining and displaying the moving image signal on a graphics image signal filtered by the filtering means. It is characterized by.

This display control device is configured so that the operation method of the filtering process is changed according to the chroma key color signal indicating whether or not the pixel data of the graphics image signal matches the chroma key color. As a result, it is possible to switch the operation method between a case where the pixel data of the chroma key color is included in a plurality of adjacent pixel data to be subjected to the filtering process and a case other than the above. Therefore, for example, at the boundary between the background region and the foreground region of the graphics image signal, by performing an arithmetic operation by excluding the chroma key color pixel data from the target of the filtering operation, the color component of the chroma key color that should not be seen can be obtained. Mixed display can be prevented. By performing the filtering process in consideration of the problem of mixing the color components of the chroma key color, it is possible to display a high-quality composite image in which flicker is removed and there is no color mixing with the chroma key color. .

The filtering means includes a plurality of multiplication circuits for multiplying each of the plurality of pixel data to be subjected to the arithmetic processing for the filtering by a coefficient value for weighting, and a multiplication result of each of the multiplication circuits. An adder circuit for calculating a weighted average of the plurality of pixel data by adding, so that the value of the weighted average is not affected by the pixel data of the chroma key color, based on the chroma key color signal, The coefficient value of the multiplication circuit to which the pixel data is input is changed.

In this manner, the weighted average (K1 · I1 + K2 · I2 +... + Kn · In) is used as the filtering means.
By using a circuit for calculating the arithmetic mean ((I
1 + I2 +... + In) / n), geometric mean ((I1 · I
Unlike the averaging operation such as (2 ... n) nth root), by changing the weighting coefficient values (K1, K2, ...), the chroma key color component can be easily excluded from the operation term. It is possible to do.

Further, instead of changing the coefficient value, the pixel data (I1, I2,.
, In) are exchanged, whereby a multiplication circuit to which chroma key color pixel data is input is
Pixel data input to another multiplication circuit may be input. By replacing the input pixel data in this manner, the chroma key color component can be excluded from the operation term. Further, it is not necessary to prepare a multiplication circuit having a variable coefficient value, and the circuit scale can be reduced.

A selection means for selecting one of pixel data input to a predetermined multiplication circuit in a plurality of multiplication circuits and an output of the addition circuit as a filtering result is provided.
A configuration in which the pixel data of interest other than the chroma key color is directly bypassed without performing the filtering operation may be used, so that the chroma key color component may be excluded from the operation term. With this configuration, only one multiplexer is provided as the selection means, and the circuit scale can be further reduced.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. First, a configuration of a display control device according to an embodiment of the present invention will be described with reference to FIG. This display control device is used for an image display system such as a digital video player, a set-top box, or a personal computer, and displays computer graphics, moving images, and composite images of these graphics and moving images on a home TV. Provide a function to display on. The image display system includes a display control device,
1, a system bus 1 such as a PCI bus, a CPU 2 for controlling the entire system and executing an application program, a main memory 3, a DVD drive 4, a DVD decoder 5, and the like are provided.

The DVD drive 4 reads contents stored in a DVD medium composed of an optical disk. This content is composed of moving image data (DVD video) or fusion data of moving image data and graphics data.

The moving image data includes main video (video), 16
Sub-pictures (sub-pictures) up to channels and audio (audio) up to eight channels can be included. In this case, these video, sub-picture, and audio are digitally compression-encoded and recorded according to the MPEG2 standard. In the MPEG2 standard, MPE
The data encoded by G2 can include other encoded data, and the encoded data is one MPEG
It is treated as two program streams. MPEG2 is used for encoding video, and run-length encoding and D
OLBY AC3 is used. The encoding processing of the MPEG2 standard is variable rate encoding, and the amount of information recorded / reproduced per unit time can be made different. Therefore, the higher the moving rate of the scene, the higher the transfer rate of the MPEG stream constituting the frame group corresponding to the scene, the higher the quality of the moving image can be reproduced.

MPEG read from DVD media
The two program streams are sent to the DVD decoder 5 via the memory 3 under the control of a DVD title reproduction application program executed by the CPU 2. The DVD decoder 5 separates the MPEG2 program stream into video data, sub-picture data, and audio data, decodes them, synchronizes them, and outputs them. After the decoded video data and sub-picture data are combined, they are sent to the display control device as YCrCb format video data.

On the other hand, read from the DVD media,
Alternatively, graphics data provided by an application program is written to an image memory (VRAM) 101 of the display control device. This graphics data is in the RGB format, and is used for display combined with moving image data. A background area is set in the graphics data by a chroma key color, and moving image data is synthesized and displayed on the background area.

As shown, the display control device includes a bus interface 100, an image memory (VRAM) 101,
Memory controller 102, matrix circuit 103, flip-flop group 104, three horizontal filter circuits 10
5, a vertical filter 106, a signal conversion circuit 107, a synthesizing circuit 108, an NTSC encoder 109, a chroma key signal CKEY generating circuit 200, a chroma key color designation register 201, and the like.

The memory controller 102 writes graphics data to the image memory (VRAM) 101 and reads the graphics data for display. in this case,
The memory controller 102 alternately reads the graphics data of three display lines (previous line, current line, next line) continuous in the vertical direction in a predetermined data size unit in a time-division manner. The image data at the same horizontal position in the next line order is output one pixel at a time.

The current line means a display target line (n) to be interlaced on the TV, the previous line is the display line (n-1) immediately before the previous line, and the next line is the next line after the current line. Display line (n +
1). Since graphics data is data for non-interlaced display, interlaced display is used for TV display. For example, when an odd field is displayed on a TV, the current lines are the display lines 1, 3, 5 , 7,... Are updated. In this case, the previous lines are display lines 0, 2, 4,.
6, next line is display line 2, 4, 6,
It changes like 8, ...

The matrix circuit 103 converts the color space of each pixel data of the graphics data read by the memory controller 102 from RGB to YCbCr444 format. This conversion is generally performed by the following equation (1).

Y = 0.257R + 0.504G + 0.098B + 16Cb = −0.148R−0.291G + 0.439B + 128 Cr = 0.439R−0.368G−0.071B + 128 ... (1) The pixel data subjected to the color space conversion by the matrix circuit 103 is output to the horizontal filters 105P, 105C, 105N,
., 105P, 105C, 105N,...

The horizontal filter 105C performs a filtering process for averaging the graphics data of the current line to be displayed in the horizontal direction in the horizontal direction. Here, as shown in FIG.
A three-tap configuration in which filtering operation is performed in units of three consecutive pixels (previous pixel P, current pixel C, next pixel N) on the current line by using a delay circuit composed of 04C1 and 104C2 is illustrated. . The current pixel C is a pixel to be displayed on the current line, the next pixel to the current pixel is the next pixel N, and the pixel immediately before the current pixel is the previous pixel P.

The horizontal filter 105N performs a filtering process for averaging the graphics data of the next line in the horizontal direction.
5C, the two flip-flops 104N1, 1
By using the delay circuit composed of 04N2, filtering calculation processing is performed in units of three consecutive pixels of the next line (previous pixel P, current pixel C, next pixel N).

The horizontal filter 105P performs a filtering process for averaging the graphics data of the previous line in the horizontal direction.
05C, two flip-flops 104P1,
By using a delay circuit composed of 104P2, filtering operation processing is performed in units of three consecutive pixels of a previous line (a previous pixel P, a current pixel C, and a next pixel N).

In each of these horizontal filters, arithmetic processing by weighted averaging is performed. Assuming that the weighting coefficients of each of the three taps are Kp, Kc, and Kn, the value of the current pixel C for which the weighted average is calculated is Kp P + Kc.C + Kn.N (2)

Each time new pixel data is input, the input pixel becomes a new next pixel C, the next pixel N becomes the current pixel C, the current pixel C becomes the previous pixel P, and so on. The filtering arithmetic processing by the weighted average is executed while shifting by one.

The horizontal filters 105P, 10P
The arithmetic processing of each of 5C and 105N is controlled by the CKEY signals 1, 2, and 3 from the CKEY signal generation circuit 200, and when the chroma key color pixel data is included in the three pixels to be processed, the chroma key is used. The operation method is changed so that the operation term for the color pixel data is excluded. CKEY signals 1, 2,
3 indicates that the pixel data read from the memory controller 102 is stored in the chroma key color designation register 201.
Is "1" when the color matches the chroma key color set in "1", and "0" otherwise.
The KEY signal 1 corresponds to the pixel data of the previous line, and the CKEY signals 2 and 3 correspond to the pixel data of the current line and the next line, respectively. That is, the CKEY signal generation circuit 200 performs a comparison with the chroma key color of the chroma key color designation register 201 for each pixel data input one pixel at a time in the order of the previous line, the current line, and the next line, and according to the comparison result, The chroma key color signal corresponding to the compared line is set to “1” or “0”. This is shown in FIG.

In FIG. 2, the background area of the graphics image to which the moving image data is synthesized is indicated by oblique lines. The chroma key color signal CKEY is "1" in the background area of the graphics image and "0" in the foreground area as shown in the figure. This is the same for any of CKEYs 1, 2, and 3. Considering the scanning direction of each line, when the pixel data read from the VRAM 101 moves from the background area to the foreground area, the chroma key color signal CKEY becomes "1". Changes from "0" to "0", and when moving from the foreground area to the background area, the chroma key color signal CKEY changes from "0" to "1".

The vertical filter 106 is provided for the horizontal filter 10.
This filter performs filtering processing for averaging in the vertical direction in units of three pixels at the same horizontal position filtered by 5P, 105C, and 105N, and is composed of a weighted average calculation processing circuit having a 3-tap configuration, like the horizontal filter. Have been. The weighting factor for each of the three taps is K
Assuming that p, Kc, and Kn, the value of the current pixel C from the horizontal filter 105C for which the weighted average value is to be calculated is Kp · P + Kc · C + Kn · N (3).

Such a vertical filtering operation by weighted averaging is sequentially executed each time three pixels at the same horizontal position subjected to horizontal filtering are newly arranged. FIG. 3 shows this vertical filtering process.

FIG. 3 shows an example of the vertical filtering process when the line L3 is the current line to be displayed. The line L2, the line L3, and the line L4 are sequentially shifted from the first pixel to the corresponding pixel position of the line L3.
Vertical filtering between pixels is sequentially performed. As a result, 1 to be displayed in the odd field of the TV
Graphics data for the line is generated. At the time of the next scan, the odd line next to the line L3, that is, the line L5, becomes the current line to be displayed, and vertical filtering is performed on three lines L4, L5, and L6.

The operation of the vertical filter 106 is as follows.
CKEY signal 1 from CKEY signal generation circuit 200
When the chroma key color pixel data is included in three pixels at the same horizontal position to be processed, the calculation method is controlled so that the calculation term for the chroma key color pixel data is excluded. Changes are made.

The signal conversion circuit 107 includes the vertical filter 10
The pixel data of YCbCr444 format output from 6 is converted into the same YCbCr422 format as the moving image data to be synthesized. Specifically, if the pixel data in YCbCr444 format output from the vertical filter 106 is represented by Y0, Y1, Y2, Y3,... Cb0, Cb1, Cb2, Cb3,. The image data output from the conversion circuit 107 is represented by Cb0, Y0, Cr0, Y1, Cb2, Y2, Cr2,
Y3,.

The combining circuit 108 combines the moving image data output from the DVD decoder 5 and the graphics image data output from the signal conversion circuit 107. As a first example of the synthesizing circuit 108, there is a multiplexer that selects moving image data when the graphics image data of the current line matches the chroma key color, and selects the graphics image data when the graphics image data does not match. . In this case, the moving image data and the graphics image data may be selected on a pixel-by-pixel basis based on the CKEY signal 2 described above.
As shown in (1), moving image data (video image) and a graphics image having a chroma key color as a background are synthesized. As a second example of the synthesizing circuit 108, there is an α blending circuit. The α blending circuit determines the degree of transmission of the graphics image for each pixel of the graphics image based on the α value,
Assuming that the graphics image data is G and the moving image data is V, α · G + α · V is the synthesis result. Therefore, for example, the graphics data is displayed for the pixel to which α = 1 is given, and the moving image data is not displayed.
Conversely, graphics data is not displayed for pixels for which α = 0 is given, and moving image data is displayed. When such an α blending circuit is used, for example, a plurality of sets of the chroma key color data and the α value are set in the chroma key color designation register 202, and the chroma key color data which is read by the memory controller 102 and matches the pixel data is set. The α value corresponding to
08. As a result, a plurality of colors having different transmittances can be used as the chroma key colors for specifying the background area of the graphics image data.

The NTSC encoder 109 converts a composite image of graphics and a moving image into a video signal for TV display such as NTSC. FIG. 5 shows an example of a specific configuration of each horizontal filter.

Here, as described above, a case of a three-tap configuration having three inputs of next pixel data N, current pixel data C, and previous pixel data P is shown. As shown in the figure, the three-tap horizontal filter has three multipliers 201, 202, and 203 for multiplying input pixel data by a predetermined coefficient value for weighting, and outputs of the multipliers 201, 202, and 203. And an adder 204 for adding. Multipliers 201, 202, 2
Assuming that the coefficient values of 03 are Kn, Kc, and Kp, Kn · N + Kc · C + Kp · P is calculated as the weighted average processing result of the current pixel data C.

The multipliers 201, 202, and 203 are configured so that their coefficient values can vary Kn, Kc, and Kp. The variable setting of the coefficient values Kn, Kc, Kp is controlled by the corresponding CKEY signal.

The operation of the horizontal filter shown in FIG. 5 will be described below. The left edge of the graphics image to be displayed in the foreground,
That is, in the portion where the CKEY signal changes from "1" to "0", as shown in FIG. 6A, chroma key color pixel data is input to the P input, and foreground display is input to the C input and the N input. Is input. At this time, the filter performs the calculation of Kn · N + Kc · C + Kp · P. In the term of Kp · P, the color component of the chroma key color is calculated, and as a result, the color of the chroma key color is used in the averaging calculation. Will be mixed. In order to avoid this, in this example, control is performed to dynamically change the coefficient value at the boundary portion, for example, as Kp = 0, Kc = 1/2, Kn = 1/2. This makes it possible to eliminate the influence of P input, which is a chroma key color.

At the right end boundary of the graphics image portion to be displayed in the foreground, that is, immediately before the CKEY signal changes from "0" to "1", as shown in FIG. , And pixel data for foreground display are input to the C input and the P input. At this time, the color components of the chroma key color are mixed by the term of Kn · N. In this example, the coefficient values at this boundary portion are, for example, Kp = 1/2, Kc = 1/2, Control is performed to dynamically change such as Kn = 0. This makes it possible to eliminate the influence of the N input which is a chroma key color.

FIG. 7 shows a second configuration example of each horizontal filter. The filter circuit of FIG. 7A performs arithmetic processing by weighted averaging similarly to the filter of FIG. 5, and includes three multipliers 301 and 302 for multiplying input pixel data by a predetermined coefficient value for weighting. , 303, an adder 304 for adding the outputs of the multipliers 301, 302, 303, and multiplexers 305, 306 provided before the multipliers 301, 303.

Coefficient K of multipliers 301, 302 and 303
n, Kc, and Kp are fixed. Therefore, for example, if the coefficient values Kn, Kc, and Kp are fixed to powers of two, the multipliers 301, 302, and 303 can be replaced with simple shift registers.

Kp = 1/4, Kc = 1/2, Kn = 1 /
Assuming that the number is 4, the arithmetic circuit performs an operation of P / 4 + C / 2 + N / 4.

The operation of the horizontal filter shown in FIG. 7A will be described below. At the left end boundary of the graphics image portion to be displayed in the foreground, that is, the portion where the CKEY signal changes from "1" to "0", chroma key color pixel data is input to the P input, and foreground display is input to the C input and the N input. Is input. At this time, the multiplexer 306 selects the C input instead of the P input of the chroma key color. As a result, the calculation of C / 4 + C / 2 + N / 4 is performed, and the output result is 3C / 4 + N / 4, so that the mixture of the chroma key colors of the P input can be eliminated.

At the right end boundary of the graphics image portion to be displayed in the foreground, that is, immediately before the CKEY signal changes from "0" to "1", chroma key color pixel data is input to the N input, and , P inputs pixel data for foreground display. At this time, the multiplexer 305 sets the chroma key color N
The C input is selected instead of the input. As a result, the calculation of P / 4 + C / 2 + C / 4 is performed, and the output result becomes P / 4 + 3C / 4, so that the mixture of the chroma key colors of N inputs can be eliminated.

Further, as shown in FIG. 7B, each of the multiplexers 305 and 306 may be configured to select one of the N input and the P input. In this case, in the portion where the CKEY signal changes from "1" to "0", the multiplexer 306 selects the N input instead of the P input of the chroma key color, and N / 4 + C / 2 + N / 4. An operation is performed.

In the portion immediately before the CKEY signal changes from “0” to “1”, the multiplexer 305
In the example, the P input is selected instead of the N input of the chroma key color, and the calculation of P / 4 + C / 2 + P / 4 is performed.

FIG. 8 shows a third configuration example of the horizontal filter. The filter circuit of FIG. 8 performs arithmetic processing by weighted averaging similarly to the filter of FIG. 7, and includes three multipliers 401, 402, and 403 that multiply input pixel data by a predetermined coefficient value for weighting. , An adder 40 that adds the outputs of the multipliers 401, 402, and 403.
4 and a multiplexer 405 provided at the output stage of the adder 404.

Coefficient K of multipliers 401, 402 and 403
n, Kc, and Kp are fixed. Therefore, for example, if the coefficient values Kn, Kc, and Kp are each fixed to a power of 2, the multipliers 401, 402, and 403 can be replaced with simple shift registers.

Kp = 1/4, Kc = 1/2, Kn = 1 /
Assuming that the number is 4, the arithmetic circuit performs an operation of P / 4 + C / 2 + N / 4.

At the left end boundary of the graphics image portion to be displayed in the foreground, that is, at the portion where the CKEY signal changes from "1" to "0", chroma key color pixel data is input to the P input, and Is input with pixel data for foreground display. At this time, in the multiplexer 406, the C input is selected instead of the output of the adder 404. As a result, the C input is bypassed as it is as the calculation result, so that the mixture of the chroma key colors of the P input can be eliminated.

Also at the right end boundary of the graphics image portion to be displayed in the foreground, that is, at the portion immediately before the CKEY signal changes from “0” to “1”, the multiplexer 406 outputs the C input instead of the output of the adder 404. Selected, thereby bypassing the C input as it is as the calculation result.

According to the configuration of FIG. 8, the number of multiplexers can be reduced as compared with FIG. 7, and the mixture of chroma key colors can be prevented with a simpler configuration. The configurations of the filter circuits shown in FIGS. 5, 7, and 8 can be applied to the vertical filter 106.

The upper boundary of the graphics image portion to be displayed in the foreground, that is, the CKEY signal (C
When KEY1) is “1” and the CKEY signal (CKEY2) of the current line is “0”, chroma key color pixel data is input to the P input of the vertical filter 106, and a graphics image to be displayed in the foreground is displayed. When the CKEY signal (CKEY3) of the next line is “1” and the CKEY of the current line is
When the Y signal (CKEY2) is “0”, chroma key color pixel data is input to the N input of the vertical filter 106.
By performing the same control as that of the filter circuit of FIG. 7 or FIG. 8, it is possible to prevent mixing of chroma key colors.

As described above, according to the present embodiment, the filtering of the horizontal filters 105N, 105C, and 105P is performed according to the chroma key color signal CKEY indicating whether the pixel data of the graphics image matches the chroma key color. The arithmetic method is configured to be changed, so that the arithmetic method can be switched between the case where the pixel data of the chroma key color is included in a plurality of images to be subjected to the filtering process and the other cases. . Therefore, for example, at the boundary between the background region and the foreground region of the graphics image, the chroma key color pixel components are excluded from the target of the filtering process. It can be prevented from being displayed.

[0062]

As described above, according to the present invention,
When a graphics image signal and a moving image signal are combined and displayed, it is possible to obtain a high-quality combined display screen from which flicker has been removed without mixing and displaying the invisible chroma key color components. .

[Brief description of the drawings]

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

FIG. 2 is an exemplary view showing a relationship between a graphics image and a chroma key color signal CKEY used in the display control device of the embodiment.

FIG. 3 is an exemplary view for explaining a vertical filtering operation in the display control device of the embodiment.

FIG. 4 is an exemplary view for explaining the operation of combining the graphics image and the moving image by the display control device of the embodiment.

FIG. 5 is an exemplary view showing a first configuration example of a filter circuit used as a horizontal / vertical filter of the display control device of the embodiment.

FIG. 6 is a diagram for explaining the operation of the filter circuit of FIG. 5;

FIG. 7 is an exemplary view showing a second configuration example of a filter circuit used as a horizontal / vertical filter of the display control device of the embodiment.

FIG. 8 is an exemplary view showing a third configuration example of a filter circuit used as a horizontal / vertical filter of the display control device of the embodiment.

[Explanation of symbols]

 2 CPU 3 Main memory 4 DVD drive 5 DVD decoder 101 VRAM 102 Memory controller 103 Matrix circuit 105N Next horizontal filter 105C Current horizontal filter 105P Previous horizontal filter 106 Vertical filter 107 Signal conversion circuit 108 synthesis circuit 109 NTSC encoder 200 CKEY signal generation circuit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04N 5/265 G06F 15/66 450

Claims (8)

[Claims] 1. A display control for setting a background area of a graphics image signal drawn in an image memory to a predetermined chroma key color, and combining and displaying a moving image signal on the background area specified by the chroma key color. In the apparatus, a unit that outputs a chroma key color signal indicating whether or not the color of the pixel data of the graphics image signal read from the image memory matches the chroma key color; A predetermined arithmetic process for filtering the graphics image signal in pixel data units, wherein the color of the pixel data of the foreground area of the graphics image signal is the pixel data of the chroma key color of the background area. Based on the chroma key color signal so as not to be affected by Display control device operation method comprising a filtering means for changing, characterized in that by combining the moving picture signal on a filtered graphics image signal to display by said filtering means for filtering. 2. A filtering device comprising: a plurality of multiplying circuits for multiplying each of a plurality of pixel data to be subjected to arithmetic processing for the filtering by a coefficient value for weighting; and a multiplication result of each of the multiplying circuits. An addition circuit for calculating a weighted average of the plurality of pixel data by adding, the chroma key color signal based on the chroma key color signal so that the weighted average value is not affected by the chroma key color pixel data. 2. The display control device according to claim 1, wherein a coefficient value of the multiplication circuit to which the pixel data is input is changed. 3. The filtering means includes: a plurality of multiplication circuits for multiplying each of a plurality of pixel data to be subjected to the arithmetic processing for the filtering by a coefficient value for weighting; and a multiplication result of each of the multiplication circuits. An adding circuit for calculating a weighted average of the plurality of pixel data by adding, and the plurality of multiplying circuits based on the chroma key color signal so that the value of the weighted average is not affected by the chroma key color pixel data. 2. A display control device according to claim 1, further comprising means for exchanging pixel data inputted to said multiplication circuit between said multiplication circuits. 4. The filtering means comprises: a plurality of multiplying circuits for multiplying each of the plurality of pixel data by a coefficient value for weighting; and adding a multiplication result of each of the multiplying circuits to weight the plurality of pixel data. An addition circuit for calculating an average; and a selection unit for selecting one of pixel data input to a predetermined multiplication circuit in the plurality of multiplication circuits and an output of the addition circuit as a filtering result, wherein the filtering result is the chroma key. 2. The display control device according to claim 1, wherein a selection operation of the selection unit is controlled based on the chroma key color signal so as not to be affected by color pixel data. 5. The filtering unit according to claim 1, wherein the filtering unit performs a filtering operation for each pixel data included in the same horizontal display line of the graphics image signal. 2. The display control device according to claim 1, further comprising: vertical filtering means for executing the arithmetic processing for the filtering for each pixel data at the same horizontal position in each display line. 6. A background area of a graphics image signal to be drawn in an image memory is set to a predetermined chroma key color, and a moving image signal is synthesized on a background area specified by the chroma key color to be displayed on a TV screen. Means for outputting a chroma key color signal indicating whether or not the color of the pixel data of the graphics image signal read from the image memory matches the chroma key color; and the graphics image signal. Filtering means for performing a filtering process for matching a signal band to a TV video signal in a plurality of adjacent pixel data units,
Based on the chroma key color signal, based on the chroma key color signal, the boundary between the background region and the foreground region, and the other portions, so that the color of the pixel data of the foreground region of the graphics image signal is not affected by the pixel data of the chroma key color of the background region. Filtering means for changing the operation method for the filtering with other parts, and combining the moving image signal with the graphics image signal filtered by the filtering means and displaying the combined signal on a TV screen. A display control device characterized by the above-mentioned. 7. A moving picture / video which sets a background area of a graphics image signal drawn in an image memory to a predetermined chroma key color, and combines and displays a moving image signal on the background area designated by the chroma key color. A graphics synthesis display method, comprising: determining whether a color of pixel data of the graphics image signal read from the image memory matches the chroma key color; and determining a plurality of adjacent pixels of the graphics image signal. Performing predetermined arithmetic processing for filtering on the graphics image signal in data units, so that the color of the pixel data of the foreground area of the graphics image signal is not affected by the pixel data of the chroma key color of the background area, According to a result of the determination, an arithmetic method for the filtering is changed. Video / graphics composite display method. 8. A background area of a graphics image signal to be drawn in an image memory is set to a predetermined chroma key color, and a moving image signal is synthesized on a background area specified by the chroma key color and displayed on a TV screen. A moving image / graphics composite display method to be displayed, comprising: determining whether a color of pixel data of the graphics image signal read from the image memory matches the chroma key color; A filtering operation for matching the signal band to the TV video signal in units of a plurality of pixel data, so that the color of the pixel data in the foreground area of the graphics image signal is not affected by the pixel data of the chroma key color in the background area A boundary portion between the background region and the foreground region, and other portions according to the determination result. A moving image / graphics synthesis display method, wherein the method of the filtering operation is changed by the following.