KR20000004900A - Television system with provisions for displaying an auxiliary image of variable size - Google Patents

Abstract

PURPOSE: A television system with provisions for displaying an auxiliary image of variable size is provided to selectively reduce the size of an auxiliary image without changing the compression ratio of the compressed auxiliary video signal. CONSTITUTION: An auxiliary image can be displayed within main image during "picture-in-picture" or "PIP" mode of operation of a television system. Provisions for displaying an auxiliary image of variable size selectively crop a fixed amount of the auxiliary image, in response to a command signal which a user inputs, in order to selectively change area of the auxiliary image as a fixed size from a first area to a smaller fixed second area without changing the compression ratio of the compressed auxiliary video signal.

Description

Television system having apparatus for displaying sub-sized images of variable size

Many modern television systems are equipped with devices for displaying not only a main picture corresponding to the main video signal source but also a sub picture corresponding to the auxiliary video signal source. Such devices allow viewers to watch another program while watching one program. The auxiliary picture may be displayed in the main picture in the form of a so-called "PICTURE-IN-PICTURE" or "PIP". The auxiliary picture can also be displayed next to the main picture in the form of a so-called "PICTURE-OUTSIDE-PICTURE" or "POP".

The auxiliary picture converts an analog video signal from an auxiliary signal source into a digital video signal, "subsamples" the digital video signal by removing pixel samples and lines from the digital video signal, and compresses the digital video in memory. And storing the signal and restoring the stored digital signal from the memory in synchronization with the horizontal and vertical synchronization components of the video signal from the main video signal source. A so-called anti-aliasing filter is used to reduce the bandwidth of the digital signal before compression to avoid artifacts in the secondary image following subsampling. The digital signal recovered from the memory is converted into an analog signal. The converted analog video signal corresponding to the auxiliary picture is combined with the analog signal corresponding to the main picture to form a synthesized analog video signal. The synthesized analog video signal is supplied to a display device. The compositing operation is performed by a " multiplexer " or switching unit that selectively separates the main video signal from the display device during the predetermined portion of the predetermined horizontal scanning lines of the main video signal and instead couples the auxiliary video signal to the display device. do.

The auxiliary picture is generally formed smaller than the main picture. For example, the auxiliary picture may be 1/3 of the main picture size. However, it is desirable that such an auxiliary image not be obscured by the main image, such that its size can be selectively reduced to a smaller size, such as 1/3 to 1/4 size. One way to achieve this is to change the compression rate of the secondary picture. Changing the subsample rate and associated anti-aliasing filtering and changing the management of memory to store subsampled digital signals requires a relatively large and complex circuit. Moreover, additional compression tends to make it more difficult to see in detail the graphics and text and the subpictures embedded in the subpicture.

The present invention relates to a television system having a device for displaying an auxiliary picture together with a main picture, and more particularly to a television system having a device capable of changing the size of an auxiliary picture.

Embodiments of the present invention are described in detail with reference to the following drawings.

1A and 1B show screens of a television system for operation of various PIP modes.

2 is a block diagram of a television system having a PIP processing unit constructed according to the present invention;

3 is a graphical representation of a method of reducing the size of an auxiliary image in accordance with the present invention.

4 is a waveform diagram of various signals that also indicate a method by which an auxiliary picture can be reduced in size in accordance with the present invention;

Fig. 5 is a block diagram showing the execution of a portion of the PIP processing section of the television system of Fig. 2 constructed in accordance with the present invention.

The present invention is to reduce the size of the auxiliary picture selectively by cutting out a predetermined amount of the auxiliary picture from the auxiliary picture without changing the compression ratio of the compressed auxiliary video signal inducing the auxiliary picture.

FIG. 1A shows a screen of a typical 4: 3 aspect ratio television receiver having a relatively small auxiliary picture corresponding to 1/3 of the video compression ratio inserted in the main full size main picture during the PIP mode of operation.

The auxiliary picture of 1/3 size tends to cover the main picture. Therefore, it is desirable to allow the user to selectively reduce the size of the auxiliary picture to, for example, a quarter size auxiliary picture. FIG. 1B shows what happens if the reduction in size is performed by increasing the image compression rate to 1/4. The main picture becomes more visible but the sub picture is compressed to the point where the details in the sub picture become less divergent. In addition, any graphics or characters inserted into the auxiliary image of the studio such as a closed caption text (CLOSED CAPTION TEXT) such as a channel number, such as the receiver itself, will be significantly reduced.

Reduction of the size of the auxiliary image according to the present invention can be performed by cutting out a predetermined portion of the first auxiliary image without changing the image compression ratio. Such results are indicated in FIG. 1A by a quarter size secondary image labeled “CROPPED”. The main image is more visible due to the reduction in size. Part of the auxiliary picture is lost, but the details and text or graphics of the picture look relatively good because the picture is not compressed.

The circuit that reduces the size of the secondary image by adopting the cropping method is much less complicated than the circuit employing the compressed method. Compression circuits require a significant number of complex circuits to change the compression subsampling rate and associated anti-aliasing filtering and to change the management of the memory for storing subsampled digital signals.

Hereinafter, the configuration of the present invention will be described with reference to FIG.

Briefly, in the PIP processing unit of the television system shown in FIG. 2, a composite video signal corresponding to an auxiliary image including a chrominance signal component and a luminance component is a baseband component such as a luminance signal and two color difference signals or three color difference signals. Carry out processing to form them. Each of the component signals is compressed, synchronized with the video signal corresponding to the main picture, and synthesized with the corresponding component of the main video signal to form a synthesized component signal. The synthesized component signals are coupled to a display device such as an image tube. At least, in the context of the present invention, only one PIP processing channel is shown in FIG. 2 because the PIP processing channels DL for the various components are similar to each other. In the following description, the terms "secondary video signal" and "main video signal" correspond to one of the component signals.

As shown in FIG. 2, the analog auxiliary video signal received at the input terminal 1 is converted into a digital video signal by the D / A converter 3. The digital auxiliary video signal is subsampled in the compression unit 5 to remove the predetermined number of pixels and the predetermined number of lines per line. The compression unit 5 is provided with an anti-aging filter for reducing the bandwidth of the auxiliary video signal in preference to the subsampling in order to reduce artifacts in the auxiliary picture reproduced by the subsampling process. The compressed auxiliary video signal is also stored in a memory provided in the compression unit 5 and is read out from the memory in synchronization with the vertical and horizontal synchronous components of the main video signal and restored. The digital video signal read out from the memory of the compression unit 5 is connected to a digital multiplexer ("MUX") or a switch 7. The function of the multiplexer 7 and the associated "BORDER" unit 9 will be described below. First, when the multiplexer 7 connects the digital video signal read out from the memory to the D / A converter 11, the D / A converter 11 converts the digital video signal into an analog signal. The resulting compressed auxiliary analog signal is synthesized with the main analog video signal input to terminal 13 by analog multiplexer or switch 15. The resulting composite video signal is connected to the display device 17 to be displayed as a screen including the auxiliary picture in the main picture.

The clock unit 19 generates clock signals for various parts of the PIP processing section, and the control unit 21 generates various control signals for the PIP processing section. The control unit 21 responds to the horizontal (H) and vertical (V) synchronous signal components of the main video signal and also to the user's initial PIP and CROP command signals. The PIP command signal executes the PIP operation mode. The cutting command signal performs a cutting operation by reducing the size of the auxiliary image.

The multiplexer 15 operates to replace the main video signal with a compressed sub video signal at a desired position of the sub picture in response to the switching signal. The multiplexer 15 is also called an "overlay switch" because it combines the main video signals and the compressed auxiliary video signals (even if one signal is replaced by another). The switching control signal for the multiplexer 15 is also blunted by "fast switching" or "FSW" due to the speed at which the multiplexer 15 operates.

In particular, the multiplexer 1 comprises a predetermined horizontal line corresponding to the upper edge of the auxiliary picture and ending at another predetermined line corresponding to the lower edge of the auxiliary picture, and during the predetermined portion of each field and the left edge of the auxiliary picture. The secondary video signal is outputted during the preset portion of each horizontal scanning line within the preset portion of each field starting from the preset pixel corresponding to the position of and ending at the other preset pixel corresponding to the position of the right edge of the auxiliary image. It is operated to replace with a signal. This operation is shown in FIG. The contents of the memory of the compression unit 5 are read during the period in which the main video signal is replaced with the auxiliary video signal in response to the address signals.

The multiplexer 7 and its associated "boundary" unit 9 provide a boundary for the secondary image. The boundary unit 9 is a register which stores digital values corresponding to the color level in the case of color components and the shade of the boundary in the case of luminance signal components. If only a gray-scale boundary is desired, the digital boundary value for the color component may correspond to the blanking level. The multiplexer 7 is operated in response to the switching control signal to separate the output signal of the compression unit 5 from the D / A converter 11 and replace the output signal with a digital threshold at the desired position of the boundary. The multiplexer 7 operates to synthesize the compressed auxiliary video signal and a signal representing a boundary thereof. Therefore, the multiplexer 7 is also referred to as a "border insert" switch, and its switching control signal is also referred to as a "BORDER INSERT" switching control signal.

Looking in more detail with respect to the creation of the boundary, in a predetermined manual of a predetermined number (for example three) of horizontal lines on the upper edge of the auxiliary image, the boundary insertion multiplexer 7 has the widths of the left and right boundaries, For example, the boundary value provided by the boundary unit 9 is connected to the D / A converter 11 for a predetermined portion of the lines corresponding to the sum of the widths of the three pixels and the auxiliary image. In this way, the upper side of the boundary portion is formed. During each of the predetermined number of horizontal lines corresponding to the height of the auxiliary image, the boundary insertion multiplexer 7 sets the boundary value D / D for a predetermined number of pixels, for example, before the left edge and after the right edge. It is connected to the A converter (11). In this way, left and right boundary portions are formed as shown in FIG. Finally, during a predetermined number (eg, 3) horizontal lines of the lower edge of the auxiliary image, the boundary inserting multiplexer 7 is the width of the left and right boundary portions (eg, three pixels) and the width of the auxiliary image. The boundary value is connected to the D / A converter 11 for each predetermined portion of the lines corresponding to this sum. In this way, the lower side of the boundary portion is formed.

The " overlay " multiplexer 15 recognizes that the boundary signal having the main video signal is exactly provided to synthesize the compressed auxiliary video signal plus the added edge signal. Referring to Fig. 4, while the auxiliary image is displayed, the period of the HIGH logic level of the FSW control signal for the horizontal line corresponds exactly to the width of the auxiliary image plus the widths of the left and right sides of the boundary. Thus, the boundary insertion switching control signal is generated in association with the FSW control signal.

Hereinafter, an operation of the PIP processing unit for selectively reducing the size of the auxiliary image by cropping the predetermined portion of the auxiliary image will be described with reference to FIG. 3.

3 shows an auxiliary image of a predetermined size, for example 1/3, including a circle CIRCLE, as can be seen in the example. In order to reduce the size of the auxiliary image, for example, when reducing from 1/3 size to 1/4 size, the auxiliary image is cut by removing approximately 12.5% of the auxiliary image from both upper and lower sides and left and right sides. You lose. This means that although the secondary image looks smaller, the object (e.g. the circle) contained in the secondary image is the same position and size for both sides of the secondary image of size 1/4 and size 1/3.

Cropping is performed by controlling the overlay multiplexer 15 to remove the additional number of pixels per line and the additional number of lines from the compressed auxiliary signal. The compressed auxiliary signal is not changed and is continuously generated as in the 1/3 size mode. In another manner, the multiplexer 15 considered considers the period of the high logic level of the FSW control signal so that the compressed auxiliary video signal extends beyond the time interval corresponding to the region of the subpicture being truncated. By changing, the time for connecting to the display unit 17 instead of the main video signal is reduced. As shown in Fig. 4, there is a corresponding change in the BORDER INSERT switching control signal so that the boundary is inserted into the corrected position in proportion to the subsidiary image that has been cut.

Thus, in a typical embodiment, the use of the cropping method to reduce the size of the auxiliary picture only involves changing two signals, and does not need to change the other signal. In addition, in the PIP processing section in which no boundary is provided, the cutting method includes only changing the FSW control signal, which is only one signal. The operation of this method avoids the need to complicate or expand the circuit since there is very little need to change in the system to perform the scaling.

5 shows a BORDER INSERT switching control signals for cutting an auxiliary image and a circuit for changing the FSW. Basically, the contents of the registers for determining the positions of the top, bottom, left and right edges of the auxiliary image are selectively changed in response to the user's initial cropping (CROP) signal. In particular, the sizes of the two auxiliary pictures, for example, the positions of the top, bottom, left, and right edges for sizes of 1/3 and 1/4, for example, digital words comprising 8 bits are represented by four digital multiplexers (21- 21). 1), 21-3, 21-5, and 21-21, respectively. For example, in Fig. 5, "HP" indicates the position of the left edge portion of the 1/3 sized auxiliary image which is not cut off, and "VP" indicates the upper edge of the 1/3 sized auxiliary image which is not cut off. Indicates the position of the negative. The multiplexers 21-1 and 21-3 select digital values for the positions of the left and right edges, respectively, and the multiplexers 21-5 and 21-7 position the upper and lower edges. To select each digital value for. The outputs of the multiplexers 21-1, 21-3, 21-5, and 21-7 are registers 21-9, 21-11, 21-13, and 21-. Is connected to each of the 15). The contents of the registers 21-9 and 21-11 indicate the positions of the left and right edges of the auxiliary image and are thus related to the left and right borders BORDER. The contents of the registers 21-13 and 21-15 indicate the positions of the upper and lower edges of the auxiliary image, and thus are related to the upper and lower borders BORDER.

The switching control signal generating unit includes a pixel, line counters corresponding to the vertical (V) and horizontal (H) synchronous components of the clock signal and the main video signal, and a register counting the line count to generate the FSW control signal. 13) and (21-15) and comparators for comparing the contents of registers 21-9 and 21-11 for counting pixels. The BORDER INSERT switching control signal is generated in a similar manner.

In operation, if you want an unclipped 1/3 image, the CROP control signals have a low logic level, and left, right, top, and bottom for an uncropped image. The digital value representing the position of the edges is selected and connected to one of the registers 21-9, 21-11, 21-13 and 21-15, respectively. If you want a chopped quarter-size secondary image, the CROP control signals have a high logic level, and a digital value indicating the position of the left, right, top, and bottom edges for the cropped image. And are connected to one of registers 21-9, 21-11, 21-13 and 21-15, respectively.

Although the present invention has been described with reference to specific embodiments, modifications may be made by those skilled in the art. For example, it is not necessary to change all of the four edge portions to reduce the size of the auxiliary image. This is in some ways less desirable than the methods disclosed in detail. If you change only one edge, the aspect ratio of the screen will change. If only the sectors of the two orthogonal edges are changed, the center of the auxiliary picture will have to be changed. In addition, the shape of the object TOPOLOGY may be modified. For example, the analog level corresponding to the boundary may be inserted after the compressed auxiliary video signal is converted into an analog form. These and other modifications may be considered within the scope of the present invention as defined by the following claims.

Claims (15)

Means for providing a main video signal corresponding to the main image; Means for providing an auxiliary video signal; Means for compressing the auxiliary video signal according to a given compression ratio to produce a compressed auxiliary video signal comprising a plurality of pixels per scan line corresponding to the auxiliary image having a first size and a predetermined number of scan lines; Means for synthesizing the main video signal and the compressed sub video signal to generate a synthesized video signal corresponding to a screen in which the main picture and the sub picture are combined; Means for combining the synthesized video signal with a display device; In response to a command signal input by a user to selectively change an area of the auxiliary image from the first area to a second, smaller, fixed second area by a predetermined size without changing the compression ratio of the compressed auxiliary video signal. Thereby selectively removing an additional fixed number of lines from the predetermined number of lines of the compressed video signal while simultaneously adding an additional fixed number of pixels from the predetermined number of pixels per line of the compressed video signal. Means for selectively removing pixels per line; a television system having an apparatus for displaying a secondary image of a variable size. 2. The apparatus according to claim 1, wherein said synthesizing means comprises a switching device for selecting one of said main video signal or said compressed auxiliary video signal in response to a switching control signal, wherein said selectively removing means is said additional number. Means for controlling said switching control signal to remove said line of pixels and said additional number of pixels per line. 3. The apparatus of claim 2, wherein the switching control signal generating means comprises: means for storing a vertical edge position of the auxiliary image; Means for storing a horizontal edge position of the secondary image; Means for generating the switching control signal in response to contents of the vertical and horizontal edge position storing means; Means for selectively loading the first fixed vertical edge position value or a second fixed vertical edge position value into the vertical edge position storage means; Means for selectively loading said first fixed horizontal edge position value or a second fixed horizontal edge position value into said horizontal edge position storage means, Wherein the first vertical and horizontal edge position values correspond to a first size of the auxiliary image, and the second vertical and horizontal edge position values correspond to a second size of the auxiliary image. A television system having a device for displaying a light. 3. The apparatus of claim 2, wherein the switching control signal generating means comprises: means for storing a left edge position of the auxiliary image; Means for storing a right edge position of the auxiliary image; Means for storing an upper edge position of the auxiliary image; Means for storing a lower edge position of the auxiliary image; Means for generating the switching control signal in response to contents of the upper, lower, left, and right edge position storing means; Means for selectively loading a first fixed left edge position value or a second fixed left edge position value into the left edge position storing means; Means for selectively loading a first fixed right edge position value or a second fixed right edge position value into the right edge position storing means; Means for selectively loading a first fixed upper edge position value or a second fixed upper edge position value into the upper edge position storing means; Means for selectively loading a first fixed lower edge position value or a second fixed lower edge position value into the lower edge position storing means, The first left, right, top, and bottom edge position values correspond to the first size of the auxiliary image, and the second left, right, top, bottom edge position values correspond to the second size of the auxiliary image. And a device for displaying a secondary image of a variable size. 2. The apparatus of claim 1, further comprising means for generating a boundary signal corresponding to a boundary surrounding the auxiliary picture; The synthesizing means further comprises additional means for synthesizing the boundary signal and the compressed auxiliary video signal to produce an additional composite video signal corresponding to the auxiliary image surrounded by the boundary; And said synthesizing means synthesizes said additional synthesized video signal and said main video signal to produce said synthesized video signal. 6. The apparatus according to claim 5, wherein said synthesizing means includes a switching device for selecting one of said main video signal and said additional synthesized video signal in response to a switching control signal; And said selectively removing means comprises means for controlling said switching control signal to remove said additional number of lines and said additional number of pixels per line. Television system with a device. 7. The apparatus of claim 6, wherein the additional synthesizing means comprises: an additional switching device for selecting one of the boundary signal generating means and the compressed auxiliary video signal in response to an additional switching control signal; And means for inducing said additional switching control signal in response to said switching control signal. Means for providing a main video signal corresponding to the main picture; Means for providing an auxiliary video signal; Means for compressing the auxiliary video signal according to a given compression rate to produce a compressed auxiliary video signal containing a predetermined number of scan lines and a plurality of pixels per scan line corresponding to the auxiliary image having a first size; The main video signal or the compressed auxiliary video signal in response to a switching control signal to synthesize the main video signal and the compressed auxiliary video signal to generate a synthesized video signal corresponding to a screen on which the main and auxiliary pictures are synthesized. A switching device for selecting a signal; Means for coupling the synthesized video signal to a display device; In response to a command signal input by a user to selectively change an area of the auxiliary image from the first area to a second, smaller, fixed second area by a predetermined size without changing the compression ratio of the compressed auxiliary video signal. Thereby selectively removing an additional fixed number of lines from the predetermined number of lines of the compressed video signal while simultaneously adding an additional fixed number of pixels from the predetermined number of pixels per line of the compressed video signal. Means for selectively removing pixels per line; The switching control signal generating means comprises means for storing a vertical edge position of the auxiliary image; Means for storing a horizontal edge position of the secondary image; Means for generating the switching control signal in response to contents of the vertical and horizontal edge position storing means; Means for selectively loading the first fixed vertical edge position value or a second fixed vertical edge position value into the vertical edge position storage means; Means for selectively loading said first fixed horizontal edge position value or a second fixed horizontal edge position value into said horizontal edge position storage means, Wherein the first vertical and horizontal edge position values correspond to a first size of the auxiliary image, and the second vertical and horizontal edge position values correspond to a second size of the auxiliary image. A television system having a device for displaying a light. Means for providing a main video signal corresponding to the main picture; Means for providing an auxiliary video signal; Means for compressing the auxiliary video signal according to a given compression ratio to produce a compressed auxiliary video signal corresponding to the auxiliary picture having a first size; Means for synthesizing the main video signal and the compressed sub video signal to produce a synthesized video signal corresponding to a screen on which the main picture and the sub picture are synthesized; Means for coupling the synthesized video signal to a display device; In response to a command signal input by a user, to selectively change the area of the auxiliary image from the first area to a smaller second fixed area without changing the compression ratio of the compressed auxiliary video signal. Means for causing said secondary image of fixed size to be selectively cropped; a television system having an apparatus for displaying a secondary image of a variable size. 10. A television system according to claim 9, wherein said cutting means causes said secondary image to be cut vertically and horizontally. A method of displaying a main image corresponding to a main video signal and an auxiliary image corresponding to a sub video signal, Compressing the auxiliary video signal according to a given compression ratio to generate a predetermined number of scan lines corresponding to the auxiliary image having a first size and a compressed auxiliary video signal containing a plurality of pixels per scan line; Synthesizing the main video signal and the compressed auxiliary video signal to generate a synthesized video signal corresponding to a screen obtained by combining the main picture and the auxiliary picture; Coupling the synthesized video signal to a display device; In response to a command applied by a user, to selectively change the area of the auxiliary picture from the first area to a smaller, second, fixed area by a predetermined size without changing the compression ratio of the compressed auxiliary video signal. Selectively removing an additional fixed number of lines from the predetermined number of lines of the compressed video signal and an additional fixed number of lines per pixel from the predetermined number of lines per line of the compressed video signal And selectively removing the pixels. 12. The method of claim 11, wherein the synthesizing comprises selecting one of the main video signal and the compressed auxiliary video signal; And selectively removing the amount of time for which the main video signal is selected compared to the amount of time for which the compressed auxiliary video signal is selected. 12. The method of claim 11, wherein the synthesizing includes selecting one of the main video signal and the compressed auxiliary signal in response to a set of values corresponding to positions of vertical and horizontal edges of the auxiliary picture. and; And selectively removing the edge position values from the first set fixed values to a second set of fixed values. A method of displaying a main image corresponding to a main video signal and an auxiliary image corresponding to a sub video signal, Compressing the auxiliary video signal according to a given compression ratio to generate a predetermined number of scan lines corresponding to the auxiliary image having a first size and a compressed auxiliary video signal containing a plurality of pixels per scan line; Synthesizing the main video signal and the compressed auxiliary video signal to generate a synthesized video signal corresponding to a screen obtained by combining the main picture and the auxiliary picture; Coupling the synthesized video signal to a display device; Fixed in response to a command applied by a user to selectively change the area of the auxiliary picture from the first area to a smaller second fixed area by a predetermined size without changing the compression ratio of the compressed auxiliary video signal. And causing the auxiliary image of a predetermined size to be selectively cropped. The method of claim 14, wherein the auxiliary image is cropped vertically and horizontally.