WO1997008889A1

WO1997008889A1 - Caption moving

Info

Publication number: WO1997008889A1
Application number: PCT/IB1996/000862
Authority: WO
Inventors: Eiji Fujisaki; Kozo Fukumoto; Toshifumi Itoh
Original assignee: Philips Electronics N.V.; Philips Norden Ab
Priority date: 1995-08-28
Filing date: 1996-08-26
Publication date: 1997-03-06
Also published as: JPH0965241A

Abstract

It is an object of the invention to provide a caption moving device for realizing to move only captions and for improving an identification level of captions after expanding. An image signal inputted to an input (1) is separated to a luminance signal and a color signal by a Y/C separating part (2). In the case of a colored condition, namely, when the color signal includes color information, a pulse signal generating part (4) generates, for example, a high level pulse signal. A first gate (3) outputs the luminance signal from the Y/C separating part (2) only when a low level pulse signal is outputted from the pulse signal generating part (4). A caption judging part (5) compares a luminance level of this luminance signal with a reference level and generates, for example, a high level judgement signal only when the luminance level exceeds the reference level. The judgement signal is inverted by an inverter (6). A second gate (7) outputs the luminance signal from the Y/C separating part (2) only when a high level inversion signal is outputted from the inverter (6). An adder (10) adds the judgement signal through a memory (8) to the luminance signal from the second gate (7) to generate a luminance signal for displaying.

Description

Caption moving.

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

Further, the present invention relates to a caption moving device for improving an identification level of the captions after moving the captions and performing the expanding process are performed as described above.

When an image of a cinema scope type made for a 4:3 television and comprising captions is displayed in a 16:9 television, a first caption line shown by is displayed in an image region in which an image is displayed, for example, as shown in Fig. 4. On the other hand, a second caption line shown by is displayed in a region, which is usually black, of the image region. In Fig. 4, a region indicated by X is an 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 the regions X and Y, they also will be same in following figures. When an image of a telecine made for a 4:3 television and comprising captions is displayed in a 16:9 television, both a first caption line shown by and a second caption line shown by are displayed in the image region in which an image is displayed, for example, as shown in Fig. 5.

Generally, the 16:9 television is provided with a function for expanding said image to the whole of the screen. When this image is merely expanded, the first caption line is still displayed in the image region after the expanding process, but the second caption line is missed from the screen (the image region), as shown in Fig. 6.

For preventing the captions from missing when the image is expanded, i.e. for realizing an image in which the captions of both the first line and the second line are displayed as shown in Fig. 7, a caption moving device, for example, as illustrated by a block diagram in Fig. 8 is used in a prior art. The operating function will be explained as follows. In Fig. 8, 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 image information corresponding to this image signal. This image information is written into a memory 64. The memory 64 has a capacity enough to at least store a signal which constructs the caption region, for example, indicated by X in Fig. 4. A control signal generating part 65 is connected to the memory 64. The control signal generating part 65 generates a control signal used for controlling a write/read position of the image information inputted to the memory 64. Based on the control signal generated by the control signal generating part 65, the memory 64 writes 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 the image signal reaches to the caption insertion region, for example, indicated by Y of a next field and writes 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 input image information is judged a caption, for example, a high level control signal 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, for example, a low level control signal 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, the image/caption changing part 68 set the switch to a position 68b-68c. As a result of 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 the expanding process 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 by the caption judging part 67 will be described in more detail. Generally, a caption is consist of a high level luminance signal. The caption judging part 67 is aimed at this point, which is provided with a predetermined reference level for judging whether the input 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 cinema scope type as shown in

Fig. 9 is inputted to the image signal input 61. A signal part indicated by a of the image signal S in Fig. 9 represents captions. On the other hand, signal parts of a high luminance level as indicated by the signal part b in Fig. 9 generally exist in an 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 this level, not only the signal part a representing captions but also the signal parts b representing an image is judged captions. As a result of this, a control signal P shown in Fig. 9 is outputted 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 at the caption judging part 67, an image of a high luminance level which is substantially same as that of captions is also judged captions and then moved.

Further, as, for example, a part of the screen after performing the caption moving process (not performing the expanding process) is illustrated in Fig. 10, the above caption moving device performs the moving process as if the second caption line overlaps with the original first caption line present in the caption insertion region.

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 this moved image overlaps with an image present in the caption insertion region. Further, as a result of the caption moving process and the expanding process, an identification level of the captions are very low because there are portions which the captions after moving overlaps with the original captions. In view of the above problem, it is an object of the invention to provide a caption moving device for moving only captions and for improving the identification level of the captions after expanding. To this end, a first aspect of the invention provides a caption moving device as defined in claim 1. The present invention notices that a caption is white (an achromatic color) and as regards a TV signal an image signal representing white, does not include a chroma signal (a color signal).

Claims 2 and 3 define advantageous embodiments. Claim 4 defines a caption moving method in accordance with a second aspect of the invention. These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

In the drawings: Fig. IA is a block diagram of an embodiment of a caption moving device according to the invention, and Fig. IB is a principle of a signal of this device;

Fig. 2 is an illustration displaying a luminance signal of which a luminance level of a caption part outputted from a second gate is inverted;

Fig. 3 is an illustration displaying a luminance signal for displaying; Fig. 4 is a screen of a 16:9 television on which an image of a cinema scope type for a 4:3 television comprising captions is displayed;

Fig. 5 is a screen of a 16:9 television on which an image of a telecine for a 4:3 television comprising captions is displayed;

Fig. 6 is a screen of a 16:9 television in the case that the image shown in Fig. 4 or Fig. 5 is expanded by an expanding function of the 16:9 television without performing a caption moving process;

Fig. 7 is a screen of a 16:9 television in the case that the image shown in Fig. 4 or Fig. 5 is expanded by an expanding function of the 16:9 television after performing a caption moving process; Fig. 8 is a block diagram of an embodiment of a conventional caption moving device;

Fig. 9 is an example of an image signal inputted to a caption moving device; and

Fig. 10 is an illustration displaying an output signal after performing the caption moving process (but not performing an expanding process) in the conventional caption moving device.

Fig. IA shows a block diagram of an embodiment of a caption moving device according to the invention and Fig. IB shows a principle of a signal of this device. Reference numeral 1 designates an image signal input. The image signal input 1 is connected to a Y/C separating part 2. A luminance signal output 2a of the Y/C separating part 2 is connected to a first gate 3 and a second gate 7. A chroma signal output 2b of the Y/C separating part 2 is connected to the first gate 3 through a pulse signal generating part 4. The first gate 3 is connected to a caption judging part 5. The caption judging part 5 is connected to an inverter 6 and a memory 8. The inverter 6 is connected to the second gate 7. The memory 8 is connected to a control signal generating part 9, which generates a control signal for controlling a write/read position of a signal inputted to this memory 8. Also, the memory 8 is connected to an adder 10. The adder 10 is connected to the second gate 7 and a luminance signal for displaying output 11.

An image signal inputted to the image signal input 1 (see a in Fig. IB) is inputted to the Y/C separating part 2. At the Y/C separating part 2, a Y/C separation in accordance with the input image signal is performed, whereby a luminance signal and a chroma signal corresponding to the input image signal are generated. Y of the Y/C separating part 2 represents a luminance and C thereof represents a chroma (a color). The luminance signal and the chroma signal are outputted from the luminance signal output 2a and the chroma signal output 2b of the Y/C separating part 2, respectively. The luminance signal outputted from the output 2a of the Y/C separating part 2 (see b in Fig. IB) is inputted to the first gate 3 and the second gate 7. Also, the chroma signal outputted from the output 2b of the Y/C separating part 2 (see c in Fig. IB) is inputted to the pulse signal generating part 4. The pulse signal generating part 4 is a so-called flip-flop circuit, generating a pulse signal corresponding to the input chroma signal. Namely, the pulse signal generating part 4 generates, for example, a high level pulse signal when there is a colored condition that color information is included in the input chroma signal. Also, the pulse signal generating part 4 generates, for example, a low level pulse signal when there is an achromatic colored condition that color information is not included therein (see d in Fig. IB). This pulse signal is inputted to the first gate 3. The first gate 3 performs an output control of the luminance signal from the Y/C separating part 2 in accordance with the input pulse signal from the pulse signal generating part 4. Then, the first gate 3 outputs the luminance signal from the Y/C separating part 2 only when the low level pulse signal representing the achromatic colored condition is inputted thereto. Therefore, only a luminance signal in the case that the input image signal represents an achromatic color is outputted from the first gate 3 (see e in Fig. IB).

The luminance signal outputted from the first gate 3 is inputted to the caption judging part 5. The caption judging part 5 is a so-called comparator, comparing a luminance level of the input luminance signal with the predetermined reference level. Based on this comparison result, the caption judging part 5 judges whether that signal represents a caption or an image (see e in Fig. IB) . Namely, when the luminance level of the input luminance signal exceeds the reference level, the caption judging part 5 judges that this luminance signal represents a caption, and generates, for example, a high level judgment signal representing valid. On the other hand, when the luminance level of the input luminance signal does not exceed the reference level, the caption judging part 5 judges that the luminance signal represents an image, and generates, for example, a low level judgment signal representing invalid. This judgment signal is written into the memory 8. The memory 8 has a capacity enough to at least store a signal which constructs the caption region, for example, indicated by X in Fig. 4. The memory 8 is connected to the control signal generating part 9, which generates a control signal used for controlling a write/read position of the input judgment signal. Based on the control signal generated by the control signal generating part 9, the memory 8 writes the judgment signal at a point of time when the image signal reaches to the caption region X of a certain field, reads the stored judgment signal 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 judgment signal again at a point of time when the image signal reaches to the caption region X of this field. Subsequently, the judgment signal is read from the memory 8 and outputted toward the adder 10.

On the other hand, the judgment signal outputted from the caption judging part 5 is input to the inverter 6. The inverter 6 inverts a level of the inputted judgment signal. Namely, the inverter 6 generates, for example, a low level inversion signal when the high level judgment signal representing a caption (valid) is inputted. On the other hand, the inverter 6 generates, for example, a high level inversion signal when the low level judgment signal representing an image (invalid) is inputted. This inversion signal is inputted to the second gate 7. The second gate 7 performs an output control of the luminance signal from the Y/C separating part 2 in accordance with the inversion signal outputted from the inverter 6. Then, the second gate 7 outputs the luminance signal from the Y/C separating part 2 only when the high level pulse signal representing invalid is inputted. Therefore, a luminance signal such that a level corresponding to the caption part is inverted from high (a white color) to low (a black color), i.e. a luminance signal representing an image as shown in Fig.

5 2 is outputted from the second gate 7 to the adder 10. The adder 10 adds the luminance signal outputted from the second gate 7 to the judgment signal, for example, one field before read from the memory 8 to generate a luminance signal for displaying. The luminance signal for displaying represents an image such that captions are moved into the caption insertion region, as shown in Fig. 3. Subsequently, this luminance signal for displaying is outputted

10 from the luminance signal output 11. The luminance signal for displaying outputted from the luminance signal output 11 is recovered together with the chroma signal and then displayed on the screen after the expanding process by an image expanding device (not shown). Although the process such that the original caption is inverted to black is performed for improving a caption identification after moving captions as described above in

15 the invention, for example, it is also possible to improve the caption identification by adding a known interpolating means to the second gate 7. In this case, in accordance with the content of the judgment signal outputted from the caption judging part 5 (the inverter 6), for example, when the signal representing invalid is inputted, the second gate 7 outputs the luminance signal from the Y/C separating part 2. When the judgment signal representing

20 valid is inputted, the inteφolating means is activated and a luminance signal such that the luminance signal outputted from the Y/C separating part 2 is inteφolated is outputted from the second gate 7. Consequently, because the color of the original caption displayed after expanding the image is inteφolated to be same as the ambient color, the caption identification after moving captions is more improved. As regards the inteφolation of the

25 luminance signal of the original caption, it will be obvious that it is necessary that the chroma signal is similarly inteφolated and this chroma signal and said luminance signal are recovered.

* As described above, the caption moving device of the present invention is 30 constructed such that a high luminance level signal is not merely judged a caption, but, an image signal having a high luminance level and not including a chroma signal is judged a caption. Consequently, when an image, such that a telecine and a cinema scope type is expanded in a 16:9 television, it is realized that only captions are moved. Further, the caption moving device of the present invention is constructed such that the original caption before moving captions is inverted to black or inteφolated. Consequently, an caption identification after moving captions and expanding the image is improved.

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:

Y/C separating means (2) for generating a luminance signal (Y) and a color signal (C) in response to an input image signal representing an image comprising a caption region (X) on which captions are displayed; condition signal generating means (4) for generating a condition signal representing a colored condition if the color signal (C) includes color information, and an achromatic colored condition if the color signal (C) does not include color information; first gate means (3) for furnishing a gated luminance signal in response to the luminance signal (Y) only when the condition signal represents the achromatic colored condition; judging means (5) for comparing the gated luminance signal with a predetermined reference level, to obtain a judgment signal indicating an achromatic image signal having a high luminance level; and means (10) for furnishing the luminance signal (Y) in dependence upon the judgment signal to generate a luminance signal for displaying.

2. A caption moving device, comprising:

Y/C separating means (2) for generating a luminance signal (Y) and a color signal (C) corresponding to an input image signal which represents an image comprising a caption region (X) on which captions are displayed; pulse signal generating means (4) for generating a pulse signal which represents a colored condition that the color signal (C) outputted from the Y/C separating means (2) includes color information, and an achromatic colored condition that the color signal (C) therefrom does not include color information; first gate means (3) for outputting the luminance signal (Y), which is separately inputted thereto, only when the pulse signal represents the achromatic colored condition; judging means (5) for comparing a luminance level of the luminance signal (Y) outputted from the first gate means (3) with a predetermined reference level, and for setting a judgment signal, which represents the comparison result, to invalid when the luminance level does not exceed the reference level; storage means (8) for storing the judgment signal outputted from the judging means (5); control signal generating means (9) for performing a writing control for writing the judgment signal corresponding to the image of the caption region to the storage means (8), and a reading control for reading the judgment signal from the storage means (8); second gate means (7) for outputting the luminance signal (Y), which is separately inputted thereto, from the Y/C separating means (2), only when the judgment signal is invalid; and adding means (10) for adding the luminance signal outputted from the second gate means (7) to the judgment signal read from the storage means (8) to generate a luminance signal for displaying; wherein the reading control is performed when the luminance signal for displaying corresponding to a caption insertion region in the image, which consists of the luminance signal for displaying, is generated.

3. A caption moving device as claimed in Claim 2, wherein the second gate means (7) comprise inteφolating means, wherein the inteφolating means is activated when the judgment signal is valid and a luminance signal such that the luminance signal outputted from the Y/C separating means (2) is inteφolated, is outputted from the second gate means (7).

4. A caption moving method, comprising the steps of: generating (2) a luminance signal (Y) and a color signal (C) in response to an input image signal representing an image comprising a caption region (X) on which captions are displayed; generating (4) a condition signal representing a colored condition if the color signal (C) includes color information, and an achromatic colored condition if the color signal (C) does not include color information; furnishing (3) a gated luminance signal in response to the luminance signal (Y) only when the condition signal represents the achromatic colored condition; comparing (5) the gated luminance signal with a predetermined reference level, to obtain a judgment signal indicating an achromatic image signal having a high luminance level; and furnishing (10) the luminance signal (Y) in dependence upon the judgment signal to generate a luminance signal for displaying.