JP2785179B2 - Interference removal apparatus and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing interference components generated in a decoded image when a predetermined image is superimposed on an encoded image of the second generation EDTV system (hereinafter referred to as EDTV-II). It relates to a removing device.

[0002]

2. Description of the Related Art Recently, EDTV-II has attracted attention.
Has a screen aspect ratio of 16: 9 as shown in FIG. On the other hand, the current television system has a screen aspect ratio of 4: 3. So, EDTV
In order to achieve compatibility between the -II system and the current television system, a so-called letterbox format has been proposed for the EDTV-II system.

In the letter box format, when a screen having an aspect ratio of 16: 9 is reproduced on a screen having an aspect ratio of 4: 3, as shown in FIG. , The main image area), and the upper and lower screen areas of the main image area are screenless areas (hereinafter, referred to as non-image areas).
Is displayed as Therefore, by multiplexing the vertical temporal high-frequency component and the vertical luminance high-frequency component in the non-image portion, the EDT
High resolution, which is one of the features of the V-II system, is achieved.

On the other hand, when only the main picture portion is transmitted in the letterbox format, the decoded image has a horizontal spatial resolution reduced to about ／ of that of the current system when compared at the same screen size. I do. Therefore, in order to prevent this, the horizontal luminance high frequency component (HH) of the horizontal band of 4.2 to about 6 MHz of the luminance signal is carrier-suppressed amplitude-modulated to about 2 to 4 M
Hz frequency-shifted horizontal resolution enhancement signal (H
H ′) are multiplexed in the main picture section.

FIG. 9 shows a signal spectrum in this case.
The horizontal resolution augmentation signal (HH ') is multiplexed in the first and third quadrant holes conjugate to the color signal C in the vertical-time frequency domain. For this reason, a signal in which the polarity of the color is inverted for each feed is obtained, and multiplex transmission can be performed with little interference with the current receiver.

[0006]

However, the EDTV-I
When an image signal such as a character is superimposed on an I-system encoded image signal, a vertical high-frequency component of a color signal generated at a boundary between the encoded image and the image signal such as a character is originally included in the image signal such as a character. The vertical high-frequency component of the color crosstalks with the horizontal resolution reinforcement signal (HH '),
Interference occurs in the decoded image.

Therefore, as one method for preventing such interference, when superimposing is performed, the encoded image signal is decoded once, returned to a sequential scanning signal of 525 scanning lines, and then superimposed. And then encode it again. However, in the above-described method, decoding and encoding must be repeated every time superimposing is performed, resulting in extremely low work efficiency and deterioration of image quality.

Further, even if, for example, it is desired to use the superimposed encoded image again at another station, once the interference has occurred, it cannot be removed.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a technique for solving the above-mentioned problems, which eliminates interference that occurs in a decoded image when a predetermined image is superimposed on an EDTV encoded image. Is to do. An object of the present invention is to provide an interference removal apparatus for removing interference generated in a decoded image when a predetermined image is superimposed on an EDTV encoded image, wherein the predetermined image is a superimposed encoded image. Among them, the predetermined image specifies an area in which a superimposed image is obtained, and the area is enlarged by a predetermined range to obtain an area in which a disturbing component is present.From the superimposed encoded image, Means for removing a horizontal resolution enhancement signal in an area where the interference component exists.

The means for determining the area where the interference component exists is based on a super key signal used when superimposing a predetermined image on the encoded image.
It is preferable that the superimposed area is specified and the area is enlarged by a predetermined range. Further, a means for determining an area where the interference component exists is extracted by extracting a color signal from an encoded image signal in which a predetermined image signal is superimposed to determine a difference between lines of the color signal. If a superimposed area is specified from and the area is enlarged by a predetermined range, interference can be removed even if the encoded image has been superimposed once.

It is an object of the present invention to provide an interference removal method for removing interference generated in a decoded image when a predetermined image is superimposed on an EDTV encoded image, wherein the predetermined image is superimposed. Among the encoded images, the area where the predetermined image is superimposed is specified, and the area where the interference component is present is specified by enlarging the area by a predetermined range.
Removing a horizontal resolution augmentation signal in an area where the interference component exists from the superimposed encoded image.

In the step of determining the area where the interference component exists, the super key signal used when superimposing a predetermined image on the encoded image is used.
It is preferable to specify the superimposed area, or the predetermined image may be used to specify the superimposed area from the difference between the color signal lines in the already superimposed encoded image. .

[0013]

According to the present invention, as shown in FIG.
The superimposed area of the encoded image is identified by the super key, and the boundary of the area is enlarged by a predetermined range. On the other hand, the horizontal resolution enhancement signal extraction circuit 3 extracts a horizontal resolution enhancement signal from the encoded image.

The extracted horizontal resolution augmentation signal is multiplied by the output of the area enlargement circuit 2 to obtain a horizontal resolution augmentation signal in the enlarged area, and the horizontal resolution augmentation signal in the area is subtracted from the encoded image. That is, the horizontal resolution enhancement signal in the area is removed and output.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described. The first embodiment is a method of removing an interference after specifying an area using a super key signal used when performing superimposition. FIG. 1 is a block diagram of the first embodiment.

In FIG. 1, reference numeral 1 denotes a superimposing device which inputs an encoded image signal of the EDTV system and an image signal of characters and the like, and superimposes characters and the like on a predetermined area of the encoded image. The area to be superimposed is specified by a preset super key signal. 2 is an area enlargement circuit. The area expanding circuit 2 expands the range of the superimposed area specified based on the super key signal by two scanning lines above and below this area. Then, the pixels inside the enlarged area are set to “1”, and the pixels outside the area are set to “1”.
The digital signal is output by expressing it as "0". The reason for enlarging the area is that interference mainly occurs at the boundary between superimposed characters and the like and the encoded image.

Reference numeral 3 denotes a horizontal resolution enhancement signal (HH ') extraction circuit for extracting a horizontal resolution enhancement signal (HH') from the superimposed encoded image. This horizontal resolution enhancement signal (HH ') extraction circuit 3
As shown in FIGS. 2 and 3, in order to calculate the horizontal resolution enhancement signal (HH ′) of the black circle pixel on the C field, the calculation is also performed using the white circle pixels on the A and B fields. That is,
In order to calculate the horizontal resolution enhancement signal (HH ') of the C field, the calculation is performed using this C field and the past A and B fields.

Hereinafter, the configuration of the horizontal resolution enhancement signal (HH ') extraction circuit 3 will be described in detail. FIG. 4 is a block diagram of the horizontal resolution enhancement signal (HH ′) extraction circuit 3. FIG.
Among them, 11 to 13 are delay units, 14 to 18 are multipliers, and 19 is an adder. First, when the signal of the pixel a in the A field is input, the signal of the pixel a is delayed by 262 lines by the delay unit 11, delayed by one line by the delay unit 12, and delayed by 262 lines by the delay unit 13. .

Next, when the signal of the pixel b in the B field is input while the signal of the pixel a is delayed as described above, the signal of the pixel b is delayed by the delay unit 11 by 262 lines. At 12 the delay is one line. Subsequently, while the signals of the pixels a and b are delayed as described above, B
When the signal of the pixel c in the field is input, the signal of the pixel c is delayed by the delay unit 11 by 262 lines.

Further, while the signals of the pixels a, b and c are delayed as described above, the signal of the pixel d in the C field is input. The signals of the pixels b and d are input to the adder 19 via the multipliers 14 and 16, and the signals of the pixels a and c are inverted in sign by the multipliers 15 and 17 and input to the adder 19. You.

In the adder 19, the signals of the pixels a, b, c and d are added, and the added signal is quartered in the multiplier 18 and output, that is, the horizontal resolution enhancement signal of the pixel d ( HH ′) is output. A multiplier 4 multiplies the horizontal resolution augmentation signal (HH ′) from the horizontal resolution augmentation signal (HH ′) extraction circuit 3 by the digital signal from the area enlargement circuit 2. That is, the horizontal resolution augmentation signal (HH ') in the enlarged area includes "
The expanded horizontal resolution enhancement signal (HH ') outside the area is multiplied by "0." As a result, the multiplier 4 outputs the horizontal resolution enhancement signal (HH') in the enlarged area. HH ′) is output.

An adder 5 subtracts the output of the multiplier 4 from the superimposed encoded image. That is, the output of the adder 5 is the horizontal resolution enhancement signal (H) in the area of the encoded image that has been enlarged as described above.
H ′). According to the first embodiment, since the horizontal resolution augmentation signal (HH ') causing the disturbance is extracted only from the area where the disturbance exists from the encoded image, the occurrence of the disturbance in the decoded image is prevented. I can do it.

Next, a second embodiment will be described. FIG. 5 is a block diagram of the second embodiment. The same components as those in the first embodiment are denoted by the same reference numerals. The second embodiment is a case where interference is removed from an encoded image in which characters or the like have already been superimposed, and a case where a superimposed area cannot be specified by a super key.

Therefore, in order to specify the superimposed area, the color signal is extracted from the encoded image by the color vertical edge detection circuit 6, and the superimposed area is specified by the difference between the color signal lines. FIG. 6 is a block diagram of the color vertical edge detection circuit 6. In FIG. 6,
21 is a color signal extraction circuit, 22, 23 are delay circuits, 24,
25 is an adder, 26 and 27 are absolute value circuits, 28 and 29 are comparators, and 30 is an OR gate.

First, a color signal is extracted from the encoded image signal superimposed by the color signal extraction circuit 21. The extracted color signals are converted into 1 by delay circuits 22 and 23.
Delayed line by line. Then, the difference between the color signals of the upper and lower lines is obtained by the adders 24 and 25. That is, each output of the adders 24 and 25 is a line-to-line difference of the color signal for each of the three lines.

The absolute value circuits 26 and 27 calculate the absolute value of the difference between the lines of each color signal. Next, the absolute value of the difference between the lines of each color signal is compared with a predetermined threshold value (about 30%) by the comparators 28 and 29. If the absolute value is larger than the threshold value, "1" is output. , "0" if smaller
Is output.

The output from each of the comparators 28 and 29 is input to the OR gate 30, and if at least one of them is "1", "1" is output. Therefore, in the superimposed area of the encoded image,
1 is output, and "0" is output outside the area, thereby specifying the superimposed area in the encoded image, and, as in the first embodiment, the area enlarging circuit. In step 2, the area is enlarged, and the horizontal resolution enhancement signal (HH ') in the enlarged area is removed.

The second embodiment is useful when an encoded image in which characters and the like have been superimposed once is reused in another station.

[0029]

According to the present invention, a vertical high-frequency component of a color signal generated at a boundary between an encoded image and an image signal such as a character from an area where an interference exists in the encoded image and an image signal such as a character are originally included. The horizontal resolution augmentation signal which crosstalks with the vertical high frequency component of the color which is being removed is removed.

Therefore, even if superimposing is performed on an EDTV-II system encoded image using a conventional superimposing device, there is an excellent effect that no interference occurs in the decoded image. Also, by specifying the area where the interference is present by the difference between the color signal lines and removing the interference, it is possible to provide a decoded image without interference even if the encoded image is already superimposed. There is also an effect.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment.

FIG. 2 is a diagram for explaining a horizontal resolution enhancement signal extraction circuit 3;

FIG. 3 is a diagram for explaining a horizontal resolution enhancement signal extraction circuit 3;

FIG. 4 is a block diagram of a horizontal resolution enhancement signal extraction circuit 3;

FIG. 5 is a block diagram of a second embodiment.

FIG. 6 is a block diagram of a color vertical edge detection circuit 6.

FIG. 7 is a diagram of an EDTV-II type screen.

FIG. 8 is a diagram for explaining a letter box format.

FIG. 9 is a diagram of a signal spectrum.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Superimpose device 2 Area expansion circuit 3 Horizontal resolution reinforcement signal extraction circuit 4 Multiplier 5 Adder 6 Color vertical edge detection circuit

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hidehiko Kikuchi 14th station, Nibancho, Chiyoda-ku, Tokyo Japan Television Broadcasting Network Co., Ltd. Technology Development Center (58) Fields surveyed (Int. Cl. ⁶ , (DB name) H04N 7/015

Claims (6)

(57) [Claims] An interference removing device for removing interference generated in a decoded image when a predetermined image is superimposed on an EDTV encoded image, wherein the predetermined image is included in the superimposed encoded image. Means for identifying an area in which the predetermined image is superimposed, expanding the area by a predetermined range to determine an area in which an interference component is present, and, based on the superimposed encoded image, Means for removing the horizontal resolution enhancement signal in the area where the component exists. 2. The method according to claim 1, wherein the means for determining an area in which the interference component is present specifies a superimposed area by using a super key signal used when superimposing a predetermined image on the encoded image. 2. The interference removal device according to claim 1, wherein the device is a means for enlarging a predetermined range. 3. A means for determining an area in which an interference component exists includes extracting a color signal from an encoded image signal in which a predetermined image signal is superimposed to determine a difference between color signal lines. 2. The interference removal apparatus according to claim 1, further comprising means for specifying a superimposed area from the difference and expanding the area by a predetermined range. 4. An interference elimination method for removing interference generated in a decoded image when a predetermined image is superimposed on an EDTV encoded image, wherein the predetermined image is included in the superimposed encoded image. A step of specifying an area in which the predetermined image is superimposed, specifying an area in which an interference component is present by enlarging the area by a predetermined range, and, from the superimposed encoded image, Removing the horizontal resolution enhancement signal in the area where the interference component exists. 5. The method according to claim 1, wherein the step of determining the area in which the interference component exists includes identifying a superimposed area using a super key signal used when superimposing a predetermined image on the encoded image. The interference removal method according to claim 4, wherein 6. The step of specifying an area where an interference component exists is characterized by specifying a superimposed area from a difference between lines of color signals in a superimposed encoded image of a predetermined image. 5. The method of claim 4, wherein the interference is removed.