WO1996038981A2

WO1996038981A2 - Caption moving

Info

Publication number: WO1996038981A2
Application number: PCT/IB1996/000344
Authority: WO
Inventors: Eiji Fujisaki
Original assignee: Philips Electronics N.V.; Philips Norden Ab
Priority date: 1995-05-31
Filing date: 1996-04-18
Publication date: 1996-12-05
Also published as: JPH08331456A; EP0793885A2; KR970705296A; WO1996038981A3

Abstract

It is an object of the invention to provide a caption moving device for realizing that only captions are moved so as to solve a distinct of picture due to a caption moving process accompanying an image expanding function of a 16:9 television. An input image signal from an input (1) is inputted to a motion detecting part (3)through an A/D converter (2) which generates an image information corresponding to the image signal. After performing a motion detecting process and a Y/C separating process of the image information, the motion detecting part (3) outputs a static luminance information to a memory (4) to which a control signal generating part (5) is connected. A D/A converter (6) generates a luminance signal corresponding to the static luminance information read from the memnory (4). A caption judging part (7) compares a luminance level of the static luminance information read from the memory (4) and a reference level and generates, for example, a high level when the luminance level exceeds the reference level, or for example, a low level when the luminance level does not exceeds the refference level. An image/caption switching part (8) selects either the input image signal or the luminance signal based on the control signal to output as an output image signal.

Description

Caption moving.

The present invention relates to a method and a device for moving captions, which are missed from a screen when an image made for a television with an aspect ratio of 4:3 and comprising captions, such as a telecine is displayed as expanded in a television with an aspect ratio of 16:9, into the screen (into an image region).

When an image of a telecine made for a 4:3 television and comprising captions is displayed in a 16:9 television, a caption line represented by _> is displayed in an image region, for example, as shown in Fig. 3. In Fig. 3, a region indicated by X is the image region in which captions are displayed and hereinafter will be referred as a caption region. Also, a region indicated by Y is an image region in which captions are inserted and hereinafter will be referred as a caption insertion region. As regards Y, it also will be same in following figures.

Generally, the 16:9 television is provided with a function for expanding said image to the whole of the screen. But, when this image is merely processed as expanded, the caption line is missed from the screen as shown in Fig. 4.

For preventing the captions from missing during the image expansion, i.e. for realizing an image in which the captions are displayed as shown in Fig. 5, a caption moving device as illustrated by a block diagram in Fig. 6 is used in a prior art. The operating function will be explained as follows. In Fig. 6, an input image signal from an image input 61 is inputted to an

A/D converter 62 and an input terminal 68a of an image/caption changing part 68. The A/D converter 62 performs an A/D conversion of the input image signal to generate an image information corresponding to this image signal. This image information is stored in a memory 64. The memory 64 has a capacity enough to at least store a data which constructs the caption region, for example, indicated by X in Fig. 3. A control signal generating part 65 is connected to the memory 64. The control signal generating part 65 generates a control signal which is used for controlling a write/read position of the inputted image information. Based on the control signal generated at the control signal generating part 65, the memory 64 writes an image information at a point of time when the image signal reaches to the caption region X in Fig. 3 of a certain field, reads the stored image information at a point of time when the image signal reaches to the caption insertion region, for example, indicated by Y in Fig. 3 of a next field and writes an image information again at a point of time when the image signal reaches to the caption region X of this field. Subsequently, the image information is read from the memory 64 and then inputted to a D/A converter 66 and a caption judging part 67. The D/A converter 66 performs a D/A conversion of the image information to generate an image signal corresponding to this image information. This image signal is inputted to an input terminal 68b of the image/caption changing part 68.

On the other hand, the image information inputted to the caption judging part 67 is judged whether this information represents a caption or an image. If the inputted image information is judged a caption, a control signal of, for example, a high level is outputted from the caption judging part 67 to the image/caption changing part 68. On the other hand, if the image information is judged an image, a control signal of, for example, a low level is outputted therefrom. The caption judging part 67 will be explained in detail later.

The image/caption changing part 68 changes a switch based on the control signal from the caption judging part 67. Namely, if the high level control signal is inputted from the caption judging part 67, the image/caption changing part 68 set the switch to a position 68b-68c. As a result oh this, an image signal, which represents a caption, for example, one field before, is outputted from an image signal output 69. Also, if the low level control signal is inputted therefrom, the image/caption changing part 68 set the switch to a position 68a-68c. As a result of this, an image signal, which represents a newest image, is outputted therefrom. The image signal outputted from the image signal output 69 is displayed on the screen after being processed as expanded by means of a conventional image expanding device (not shown). Thus, the captions does not miss from the screen (the image region) if the image expanding function which the 16:9 television comprises is performed.

The process performed at the caption judging part 67 will be explained in more detail. Generally, captions are white (an achromatic color). As regards a TV signal, a chroma signal (a color signal) is not included in an image signal which represents white and this image signal consists of only a luminance signal of a high level. The caption judging part 67 is aimed at this point, which is provided with a predetermined reference level for judging whether the image signal represents a caption or not. Namely, the caption judging part 67 judges that only the input image information of which a luminance level exceeds the reference level, i.e. only the image information of a high luminance level, represents a caption.

Now, it is assumed that an image signal S of a telecine as shown in Fig. 7A and B is inputted to the image signal input 61. A signal part indicated by a in Fig. 7 represents captions. On the other hand, signal parts of a high luminance level as indicated by b and c in Fig. 7 generally exist in the image signal. Now, it is assumed that a broken line R indicates the reference level set to the caption judging part 67. If the caption judgment of the image signal S is performed at that level, not only the signal part a but also the signal parts b and c which represent an image is judged that they are captions. As a result of this, a control signal P shown in Fig. 7A and B is inputted from the caption judging part 67 to the image/caption changing part 68 and consequently an image signal of a high luminance level other than captions is also outputted from the image signal output 69. Namely, when a luminance level of the image signal is merely compared, an image of a high luminance level which is substantially same as that of captions is also judged captions and then moved.

As the above description, an image of a high luminance level is also judged captions in the conventional 16:9 television. As a result of this, the screen during expanding is very distinct because such moved image and an image present in the caption insertion region are overlapped.

In view of the above problem, it is an object of the invention to provide a method and a device for moving only captions so as to solve the distinctness of the screen during expanding an image. The invention notices that captions are displayed on the screen for a few seconds, i.e. they are static. To this end, the caption moving device according to a first aspect of the invention is characterized by comprising: an A/D converting means which performs an A/D conversion of an input image signal which represents an image comprising a caption region on which captions are displayed to generate an image information corresponding to the image signal; a motion detecting means which performs a motion detection of the image and an extraction of a luminance information based on the image information outputted from the A/D converting means; a storage means which stores the luminance information corresponding to the caption region at least; a control signal generating means which performs a writing control such that the luminance information corresponding to the image of the caption region is written to the storage means and a reading control such that the luminance information is read from the storage means; a D/A converting means which performs a D/A conversion of the luminance information read from the storage means to generate a luminance signal corresponding to the image of the caption region; an image/caption switching means which selects either the input image signal or the luminance signal to output as an output image signal; and a caption judging means which generates a control signal such that when the luminance information exceeds a predetermined reference level, the image/caption switching means outputs the luminance signal as the output image signal and when the luminance information does not exceed the predetermined reference level, the image/caption switching means outputs the input image signal as the output image signal; wherein the reading control is performed when the output image signal corresponding to a caption insertion region set to the image is generated.

Further, a caption moving device according to a second aspect of the invention is characterized by comprising: an A/D converting means which performs an A/D conversion of an input image signal which represents an image comprising a caption region on which captions are displayed to generate an image information corresponding -to the image signal; a motion detecting means which performs a motion detection of the image based on the image information outputted from the A/D converting means and generates a motion detecting signal based on the motion detection; a storage means which stores the image information corresponding to the caption region at least; a control signal generating means which performs a writing control such that the image information corresponding to the image of the caption region is written to the storage means and a reading control such that the image information is read from the storage means; a D/A converting means which performs a D/A conversion of the image information read from the storage means to generate an image signal corresponding to the image of the caption region; an image/caption switching means which selects either the input image signal or the image signal to output as an output image signal; a caption judging means which judges that when the image information exceeds a predetermined reference level, the image information represents a caption and when the information does not exceed the predetermined reference level, the image information represents an image and generates a control signal based on the judging; and a switching signal generating means which generates a switching signal such that, based on the control signal outputted from the caption judging means, when the control signal corresponds to a caption and the motion detecting signal corresponds to a static image portion, the image/caption switching means outputs the image signal outputted from the D/A converting means as the output image signal, and that when the control signal corresponds to a caption and the motion detecting signal corresponds to a motion picture portion of the image, or the control signal corresponds to an image and the motion detecting signal corresponds to a static picture portion of the image, or the control signal corresponds to an image and the motion detecting signal corresponds to a motion picture portion of die image, the image/caption switching means outputs the input image signal as the output image signal; wherein the reading control is performed when the output image signal corresponding to a caption insertion region set to the image is generated.

Claims 3 and 4 define other favorable aspects of the invention.

According to the invention, it is realized that only captions are moved during expanding an image of, for example, a telecine in a 16:9 television because an image signal of a high luminance level is not merely judged a caption, but an image signal which has a high luminance level and is static is judged a caption.

Embodiments of the present invention will now be described with reference to the accompanying drawings, in which: Fig. 1 shows a block diagram of an embodiment of a caption moving device according to the invention;

Fig. 2 shows a block diagram of an another embodiment of a caption moving device according to the invention;

Fig. 3 shows a picture of a 16:9 television which shows an image of a telecine for a 4:3 television comprising captions;

Fig. 4 shows a picture of a 16:9 television in the case that the image shown in Fig. 3 is expanded by an expanding function which the 16:9 television comprises without performing a caption moving process; Fig. 5 shows a picture of a 16:9 television in that case that the image shown in Fig. 3 is expanded by an expanding function which the 16:9 television comprises with performing a caption moving process;

Fig. 6 shows a block diagram of an embodiment of a conventional caption moving device; and Fig. 7 shows an example of an image signal inputted to a caption moving device.

Fig. 1 shows a block diagram of an embodiment of a caption moving device according to the invention. An image signal input 1 is connected to an A/D converter 2 and an input terminal 8a of an image/caption changing part 8. The A/D converter 2 is connected to a motion detecting part 3. The motion detecting part 3 is connected to a memory 4. The memory 4 is connected to a control signal generating part 5, which generates a control signal for controlling a write/read position of an image information inputted to the memory 4. Also, the memory 4 is connected to a D/A converter 6 and a caption judging part 7. The D/A converter 6 is connected to an input terminal 8b of the image/caption changing part 8. The caption judging part 7 is connected to the image/caption changing part 8. An output 8c of the image/caption changing part 8 is connected to an image signal output 9. An input image signal from the image signal input 1 is inputted to the input terminal 8a of the image/caption changing part 8 and the A/D converter 2. At the A/D converter 2, an A/D conversion of the input image signal is performed to generate an image information corresponding to this image signal. This image information is inputted to the motion detecting part 3. At the motion detecting part 3, a motion of the image information, for example, per each field is detected and a Y/C separation of this information is performed. Now, Y means a luminance and C means a color. As a result of this motion detection and Y/C separation, a luminance information of a static part of the image information inputted (a static luminance information) is extracted and outputted from the motion detecting part 3. Subsequently, this static luminance information is inputted to the memory 4. The memory 4 has a capacity enough to at least store a data which constructs a caption region, for example, indicated by X in Fig. 3. Based on the control signal generated at the control signal generating part 5, the memory 4 writes the static luminance information at a point of time when the image signal reaches to the caption region X of a certain field, reads the stored static luminance information at a point of time when the image signal reaches to the caption insertion region, for example, indicated by Y of a next field and writes a static luminance information again at a point of time when the image signal reaches to the caption region X of this field. The static luminance information outputted from the memory 4 is inputted to the D/A converter 6 and the caption judging part 7. At the D/A converter 6, a D/A conversion of the static luminance information inputted is performed to generate a static luminance signal corresponding to this information. This static luminance signal is inputted to the input terminal 8b of the image/caption changing part 8.

The static luminance information is judged whether this information represents a caption or an image. For this judgment, the caption judging part 7 is provided with a predetermined reference level in the same manner as the conventional way. When a luminance level of the static luminance information inputted exceeds the reference level, this information is judged a caption and consequently a control signal of, for example, a high level is generated. On the other hand, when a luminance level thereof does not exceed the reference level, this information is judged an image and consequently a control signal of, for example, a low level is generated. The control signal is inputted to the image/caption changing part 8.

The image/caption changing part 8 change the switch based on the control signal from the caption judging part 7. When the high level control signal is inputted, the switch is set to a position 8b-8c. As a result of this, the static luminance signal of a high luminance level, i.e. a signal representing a caption is inputted through the input terminal 8b. On the other hand, the low level control signal is inputted, the switch is set to a position 8a- 8c. As a result of this, the input image signal from the image signal input 1 is inputted through the input terminal 8a. Consequently, an output image signal, which includes a signal referring to a caption to be moved, is outputted from the image signal output 9. The output image signal outputted from the image signal output 9 is displayed on the screen after being processed as expanded by means of a conventional image expanding device (not shown).

Although in the above embodiment, the white caption is represented with only the high level static luminance signal (i.e. a color signal is not especially assigned to the caption), a color signal representing white may be independently set to the static luminance signal by means of, for example, the motion detecting part 3 or the control signal generating part 5.

Fig. 2 shows a block diagram of an another embodiment of a caption moving device according to the invention. An image signal input 11 is connected to an A/D converter 12 and an input terminal 18a of an image/caption changing part 18. The A/D converter 12 is connected to a motion detecting part 13 and a memory 14. The motion detecting part 13 is connected to a switching signal generating part 20. The memory 14 is connected to a control signal generating part 15, which generates a control signal for controlling a write/read position of an image information inputted to the memory 14. Also, the memory 14 is connected to a D/A converter 16 and a caption judging part 17. The D/A converter 16 is connected to an input terminal 18b of the image/caption changing part 18. The caption judging part 17 is connected to the switching signal generating part 20. The switching signal generating part 20 is connected to the image/caption changing part 18. An output terminal 18c of the image/caption changing part 18 is connected to an image signal output 19.

An input image signal from the image signal input 11 is inputted to the input terminal 18a of the image/caption changing part 18 and the A/D converter 12. At the A/D converter 12, an A/D conversion of the image signal inputted is performed to generate an image information corresponding to this image signal. This image information is inputted to the motion detecting part 13 and the memory 14. At the motion detecting part 13, a motion detection of the image information inputted is performed, for example, between every fields. As a result of this motion detection, for example, when the image information represents a motion picture part of the image, a motion signal of a low level is outputted, while when the image information represent a static picture part thereof, a motion signal of a high level is outputted. The memory 14 has a capacity enough to at least store a data which constructs a caption region, for example, indicated by X in Fig. 3. Based on the control signal generated at the control signal generating part 15, the memory 14 writes an image information at a point of time when the image signal reaches to the caption region X of a certain field, reads the stored image information at a point of time when an image signal reaches to the caption insertion region, for example, indicated by Y of a next field and writes an image information again at a point of time when d e image signal reaches to the caption region X of this field. The image information outputted from the memory 14 is inputted to the D/A converter 16 and the caption judging part 17. At the D/A converter 16, a D/A conversion of the image information inputted is performed to generate an image signal corresponding to this image information. This image signal is inputted to the input terminal 18b of the image/caption changing part 18.

At the caption judging part 17, the image information is judged whether this information represents a caption or not. For the judgment, the caption judging part 17 is provided with a predetermined reference level in the same manner as the conventional way. When a luminance level of the image information inputted exceeds the reference level, this image information is judged a caption and consequently a control signal of, for example, a high level is generated. On the other hand, when a luminance level thereof does not exceed the reference level, this image information is judged an image and consequently a control signal of, for example, a low level is generated. The control signal is inputted to die switching signal generating part 20.

The switching signal generating part 20 generates a switching signal based on the motion signal from the motion detecting part 13 and the control signal from the caption judging part 17. When the motion signal is a high level and at the same time the control signal is a high level, the switching signal generating part 20 generates a switching signal of, for example, a high level. On the other hand, when the motion signal is a high level and at the same time the control signal is a low level, the motion signal is a low level and at the same time the control signal is a high level, or the motion signal is a low level and at the same time the control signal is a low level, the switching signal generating part 20 generates a switching signal of, for example, a low level. The switching signal is inputted to the image/caption changing part 18.

The image/caption changing part 18 changes the switch based on the switching signal from the switching signal generating part 20. When the high level switching signal is inputted, the switch is set to a position 18b-18c. As a result of this, an image signal representing a caption, for example, prior to one field is inputted through the input terminal 18b. On the other hand, when the low level switching signal is inputted, the switch is set to a position 18a- 18c. As a result of this, a newest input image signal from the image signal input 11 is inputted through the input terminal 18a. Consequently, an output image signal, which includes a signal referring to a caption to be moved, is outputted from the image signal output 19. The image signal outputted from the image signal output 19 is displayed on the screen after being processed as expanded by means of a conventional image expanding device (not shown).

When, for example, an image signal S indicated by A and B in Fig. 7 is inputted to the caption moving device in the both embodiments, a control signal P indicated by C in Fig. 7 is outputted from the caption judging part 7 and the switching signal generating part 20 to the image/caption changing part 8, 18. Consequently, an image signal representing a motion picture of a high luminance level is not outputted but an image signal representing a caption, for example, prior to one field is outputted from the image signal output 9, 19 and therefore displayed together with a newest image signal on the screen.

As described above, according to the caption moving device of the present invention, an image signal of an high luminance level is not merely judged a caption, but, as a result of that both the motion detection and Y/C separation of the image signal are performed between every fields, an image signal of a static picture part of a high luminance level is judged to be a caption. Therefore, an image of a motion picture part of a high luminance level is not moved into the image insertion region, but a caption is only moved accompanying the expansion of image.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The invention can be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer.

Claims

Claims:

1. A caption moving device comprising:

A/D converting means for performing an A/D conversion of an input image signal which represents an image comprising a caption region on which captions are displayed to generate an image information corresponding to the image signal; motion detecting means for performing a motion detection of the image and an extraction of a luminance information based on the image information outputted from the A/D converting means; storage means for storing the luminance information corresponding to the caption region at least; control signal generating means for performing a writing control such that the luminance information corresponding to the image of the caption region is written to the storage means and a reading control such that the luminance information is read from the storage means;

D/A converting means for performing a D/A conversion of the luminance information read from the storage means to generate a luminance signal corresponding to the image of the caption region; image/caption switching means for selecting either the input image signal or the luminance signal to output as an output image signal; and caption judging means for generating a control signal such that when the luminance information exceeds a predetermined reference level, the image/caption switching means outputs the luminance signal as the output image signal and when the luminance information does not exceed the predetermined reference level, the image/caption switching means outputs the input image signal as the output image signal; wherein the reading control is performed when the output image signal corresponding to a caption insertion region set to the image is generated.

2. A caption moving device comprising:

A/D converting means for performing an A/D conversion of an input image signal which represents an image comprising a caption region on which captions are displayed to generate an image information corresponding to the image signal; motion detecting means for performing a motion detection of the image based on the image information outputted from the A/D converting means and for generating a motion detecting signal based on the motion detection; storage means for storing the image information corresponding to the caption region at least; control signal generating means for performing a writing control such that the image information corresponding to the image of the caption region is written to the storage means and a reading control such that the image information is read from the storage means; D/A converting means for performing a D/A conversion of the image information read from the storage means to generate an image signal corresponding to the image of the caption region; image/caption switching means for selecting either the input image signal or the image signal to output as an output image signal; caption judging means for judging that when the image information exceeds a predetermined reference level, the image information represents a caption and when the information does not exceed the predetermined reference level, the image information represents an image, and for generating a control signal based on die judging; and switching signal generating means for generating a switching signal such that, based on the control signal outputted from the caption judging means, when the control signal corresponds to a caption and the motion detecting signal corresponds to a static image portion, the image/caption switching means outputs the image signal outputted from the D/A converting means as the output image signal, and mat when the control signal corresponds to a caption and the motion detecting signal corresponds to a motion picture portion of the image or the control signal corresponds to an image and the motion detecting signal corresponds to a static picture portion of the image or the control signal corresponds to an image and the motion detecting signal corresponds to a motion picture portion of the image, the image/caption switching means outputs the input image signal as the output image signal; wherein the reading control is performed when me output image signal corresponding to a caption insertion region set to the image is generated.

3. A method of moving captions from an input image signal which represents an image comprising a caption region on which captions are displayed to generate an image information corresponding to the image signal, the method comprising the steps of: performing a motion detection of the image and an extraction of a luminance information based on the image information; storing the luminance information corresponding to the caption region at least, to obtain a stored luminance signal; performing a writing control such that the luminance information corresponding to the image of the caption region is written in the storing step and a reading control such that the stored luminance information is read; selecting either the input image signal or the stored luminance signal to output as an output image signal; and generating a control signal such that when the luminance information exceeds a predetermined reference level, the luminance signal is furnished as the output image signal, and when the luminance information does not exceed the predetermined reference level, the input image signal is furnished as the output image signal.

4. A method of moving captions from an input image signal which represents an image comprising a caption region on which captions are displayed to generate an image information corresponding to the image signal, the method comprising the steps of: performing a motion detection of the image based on me image information and generating a motion detecting signal based on the motion detection; storing the image information corresponding to the caption region at least to obtain a stored image signal; performing a writing control such that the image information corresponding to me image of the caption region is written in the storing step and a reading control such that the image information is read; selecting either the input image signal or the stored image signal to output as an output image signal; judging that when the image information exceeds a predetermined reference level, the image information represents a caption, and when the information does not exceed the predetermined reference level, the image information represents an image, and generating a control signal based on the judging; and generating a switching signal such that when both the control signal corresponds to a caption and the motion detecting signal corresponds to a static image portion, the stored image signal is furnished as the output image signal, and that otherwise, the input image signal is furnished as the output image signal.