JP2958646B2 - Image decoding device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image decoding device in an image receiving device that simultaneously displays a plurality of images.

(Prior art)

There is a method of simultaneously displaying a plurality of images on a screen of one image display device in order to simultaneously watch a plurality of channels on a television (TV) image or simultaneously view a plurality of ground images in a multipoint video conference. At this time, in order to display a plurality of images on a limited screen space of the image display device, a part or all of the plurality of images are superimposed and combined to simultaneously display the plurality of images on a screen. There is an image receiving device.

FIG. 3 is a diagram for explaining a display screen of the image receiving apparatus, and is an example of a case where three images, image 1, image 2, and image 3, are simultaneously displayed on the display screen.

In FIG. 3, image 2 is displayed on image 3 and image 1 is displayed on image 2. Therefore, image 3 has an area that is hidden by image 2 and image 1 and is not displayed on the screen, and image 2 also has an area that is hidden by image 1 and is not displayed on the screen.

In such a case, conventionally, an image for which decoding processing is performed uniformly regardless of whether a received image signal is a signal corresponding to a display area on a screen or a signal corresponding to a non-display area. A decoding device was used.

FIG. 4 is a diagram for explaining a configuration of an image receiving apparatus for simultaneously displaying a plurality of images decoded by using such an image decoding apparatus on a screen. Takes an example.

In FIG. 4, 1, 2 and 3 are signal receiving devices, 4, 5, and 6 are image decoding devices, 7 is an image synthesizing device, and 8 is an image display device. The signal receiving device 1 and the image decoding device 4 are devices assigned to the image 1, and the signal receiving device 2 and the image decoding device 5 are devices assigned to the image 2.
Further, the signal receiving device 3 and the image decoding device 6
This is the device assigned to.

The image signal transmitted after the encoding by the image encoding device on the transmission side is received by the signal receiving device assigned to each. The received image signals are respectively decoded by the image decoding device. Then, in the image synthesizing device, a part or all of the images are superimposed and synthesized as necessary so that the plurality of decoded images fit within one screen, and the synthesized image is displayed on the image display device. .

As described above, the image signal transmitted from the image using the conventional image decoding device after being encoded by the image encoding device is received by the signal receiving device assigned to each. The received image signals are respectively decoded by the image decoding device. Then, in the image synthesizing device, a part or all of the images are superimposed and synthesized as necessary so that the plurality of decoded images fit within one screen, and the synthesized image is displayed on the image display device. .

[Problems to be solved by the invention]

As described above, in the image receiving apparatus using the conventional image decoding apparatus, decoding is performed irrespective of the display state on the screen. Also performs a decoding process equivalent to that of the displayed region, and there is a problem that there is a useless decoding process for a region that is hidden in another image and is not displayed on the screen.

The present invention has been made to solve the above problems.

An object of the present invention is to provide an apparatus for efficiently decoding a plurality of images by using information on overlapping of a plurality of images on a display screen of an image display device.

The above and other objects and novel features of the present invention are as follows.
It will become apparent from the description of the present specification and the accompanying drawings.

[Means for solving the problem]

To achieve the above object, the present invention provides a receiving unit for receiving a plurality of image signals encoded by an image encoding device, and an image decoding device for decoding each image signal received by the receiving unit. And management means for managing position / size / overlapping order information of each image simultaneously displayed on a screen; and receiving the position / size / overlapping order information of each image from the management means, and And a synthesizing unit for arranging and synthesizing the images on a single screen while allowing overlapping of the images. Position / size / overlapping order information, and the received image signal is an image signal corresponding to the display area displayed on the screen, or is not displayed hidden by another image. A display unit that performs a decoding process required and sufficient for display by an identification unit that identifies whether the image signal corresponds to a non-display region and a decoding unit that is applied to the image signal corresponding to the display region Decoding means and decoding means applied to an image signal corresponding to the non-display area, wherein only a part of the decoding processing in the display decoding means is performed or no decoding processing is performed at all. A partial decoding unit, based on a result of the identification performed by the identifying unit, when the input image signal is an image signal corresponding to a display area, inputting the input image signal to the display unit decoding unit; And switching means for inputting the input image signal to the non-display section decoding means when is an image signal corresponding to the non-display area.

[Action]

According to the above-described means, the information on the overlapping of a plurality of images on the display screen of the image display device is used, that is, the received image signal is an image signal corresponding to the display area or an image corresponding to the non-display area. It discriminates whether the signal is a signal, and switches the decoding means between a display area displayed on the screen and a non-display area that is hidden and not displayed by another image, thereby restoring an image to the display area. In addition, since the decoding process necessary to perform the above-described processing can be performed and unnecessary processing can be omitted for the non-display area, the amount of decoding processing of the entire apparatus can be reduced.

Also, by applying different decoding means for the area displayed on the screen of the image display device and the area not displayed, decoding processing is performed on the display area, and the non-display area is decoded. In other words, it is possible to take a measure of not performing the decoding process. If an area that is not displayed on the screen is not displayed at all, there is no need to decode the area.

Also, even when the region is displayed, if the received image signal is an image signal encoded by an encoding method that does not use the correlation between frames, it is difficult to decode one frame in the past. The transmitted signal is not used, and the decoding process of the area need not be performed while the signal is not displayed on the screen.

Also, when a received image signal is encoded using the correlation between frames, if a request for retransmission of an image is made when trying to display an area that has not been displayed on the screen until now, There is no need to perform decoding processing on the area.

Also, by using different decoding means for an area displayed on a screen of an image display device and an area not displayed, a received image signal is encoded using a correlation between frames and a frame. If the image signal is an image signal encoded by the image encoding means using both of the encoding methods that do not use the correlation between the image components, a signal component representing an inter-frame difference for the image signal corresponding to the display area on the screen It is possible to take a measure of performing a decoding process including signal components other than the above, and performing a process of only a signal component representing an inter-frame difference on an image signal corresponding to a non-display area. When the image encoding means uses both the encoding method using the correlation between frames and the encoding method not using the correlation between frames, the received image signal has a signal component representing an inter-frame difference and an inter-frame difference. Although it is composed of signal components resulting from the encoding method that does not use correlation,
In order to display an image of an area that has been hidden by another image on the screen, an integration operation is performed on the inter-frame difference signal component even when the area is not displayed on the screen. Must be. On the other hand, a signal component caused by an encoding method that does not use correlation between frames is unnecessary for restoring another frame. Therefore, in a region not displayed on the screen, it is not necessary to process signal components other than the inter-frame difference signal component, and it is sufficient to process only the inter-frame difference signal component, and the region is displayed. In some cases, the image in the area can be restored without requesting the transmitting side to retransmit the image signal.

As described above, by not performing the decoding process on the area not displayed on the screen of the image display device or by simplifying the process, the scale of the storage device of the decoding device is reduced, and the decoding process speed is improved. It becomes possible to do.

(Example of the invention)

Hereinafter, an embodiment of the present invention will be specifically described with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of an embodiment of an image decoding apparatus according to the present invention.

An image is encoded in units of pixels or in units of blocks made up of several pixels, and this unit is hereinafter referred to as an encoding unit. Therefore, the term "coding unit" is to be read as a pixel or a block depending on the coding method.

In the figure, 11, 12, 13 are synchronization control circuits, 14, 15, 16 are scanning circuits, 17, 18, 19 are decoding means storage circuits, 20, 21, 22 are decoding means switching circuits, 23, 24, 25 is a display section decoding means, 26,2
7, 28 are non-display section decoding means, 29, 30, 31 are delay circuits, 32, 3
Reference numerals 3 and 34 denote image signal output switching circuits, 35, 36 and 37 are decoding means determination circuits, and 38 is a display screen management device.

This embodiment is an example in which three images are displayed on a display screen, and 11, 14, 17, 20, 23, 26, 29, 32, and 35 constitute an image decoding device for image 1. Equipment group, 12, 15, 18, 2
1,24,27,30,33,36 are a group of devices constituting an image decoding device for image 2, and 13,16,19,22,25,28,31,34,37 are Device group constituting an image decoding device for
Reference numeral 38 denotes a display screen management device shared by three images.

As shown in FIG. 2, the decoding means storage circuits 17, 18, and 19 are composed of storage units of the same number as the total number of coding units constituting one frame of an image. And have a one-to-one correspondence. The value stored in this storage unit indicates whether the corresponding coding unit is displayed on the display screen.

In this embodiment, when the value of the storage unit is "0", it indicates that the corresponding coding unit is not displayed on the screen, and when "1", the corresponding coding unit is displayed on the screen. And

In the display screen management device 38 that manages the display state of a plurality of images on the screen of the image display device, the position of the image, the size of the image, and the overlapping order of the images are managed. , 37, referring to these data,
The presence / absence of display is determined for each coding unit, and which of the two decoding means is applied is written in the decoding means storage circuits 17, 18, and 19.

In the present embodiment, “1” is written in the storage unit corresponding to the coding unit determined to be displayed on the screen, and “0” is written in the storage unit corresponding to the area not displayed.

FIG. 2 shows a determination method of the decoding means determination circuits 35, 36, and 37;
FIG. 3 is a diagram for explaining the relationship between decoding means storage circuits 17, 18, and 19 and a display screen.

When the coding unit is a block, the boundary between the display area and the non-display area does not match the boundary of the coding unit,
It is possible that both a display area and a non-display area exist in one coding unit. In such a case, such a coding unit is treated as a coding unit to be displayed. In FIG. 2, such a coding unit exists in the image 3. Second
In the case of the display screen shown in the figure, values are written in the decoding means storage circuits 17, 18, and 19 as shown in FIG.

The synchronization control circuits 11, 12, and 13 detect a synchronization signal indicating the start of a frame from the received image signal, and scan circuits 14, 15, and
The scanning circuit 1 starts scanning at 16 or generates an operation reference clock for the scanning circuits 14, 15, 16 from an image signal, and
By synchronizing the scanning at 4,15,16 with the image signal,
Adjustment is performed such that switching based on the values read from the decoding unit storage circuits 17, 18, and 19 is performed for the corresponding coding unit.

The scanning circuits 14, 15, and 16 start scanning the decoding means storage circuits 17, 18, and 19 when receiving the synchronization signal indicating the start of the frame from the synchronization control circuits 11, 12, and 13. Scanning circuits 14, 15, 16
Each time the operation reference clock is received from the synchronization control circuits 11, 12, and 13, while increasing the read address value for the decoding means storage circuits 17, 18, and 19 by one unit, the decoding means storage circuits 17, 18, and The value of the storage unit of the address of 19 is read and given to the decryption means switching circuits 20, 21, 22.

In the decoding means switching circuits 20, 21, and 22, if the value read from the decoding means storage circuits 17, 18, and 19 is "0", the non-display section decoding means 26, 27, and 28 output the image signal. If the read value is “1”, the image signal is passed to the display unit decoding means 23, 24, 25.

Non-display unit decoding means 26, 27, 28 are means for decoding coding units not displayed on the display screen, and display unit decoding means 23, 24, 25 convert coding units displayed on the screen. It is means for decoding. Here, the non-display section decoding means 26, 27, 28
Can be realized by an image decoding device that always outputs a black image signal without decoding a coding unit, or an image decoding device that only processes an inter-frame difference signal component of a coding unit.

In the image signal output switching circuits 32, 33, 34, the scanning circuit 1
The output of the selected decoding means is output from the image decoding device by the signal obtained by delaying the decoding means selection signal from the delay circuits 29, 30, and 31 by the time required for decoding the image signal from 4, 15 and 16. And sends the image signal processed by the decoding means to the image display device.

In the present embodiment, a synchronization control circuit, a scanning circuit, a decoding unit storage circuit, a decoding unit switching circuit, a display unit decoding unit, a non-display unit decoding unit, a delay circuit, a decoding unit determination circuit, and image signal output switching Although one circuit is prepared for each of the three images, it is also possible to share the three images by preparing only one of them and using it in a time-division manner. In the present embodiment, three images are displayed on the screen of the image display device. However, the present embodiment can be similarly executed when the number of images is not three.

As mentioned above, although the present invention was explained concretely based on an example, the present invention is not limited to the above-mentioned example.
It goes without saying that various changes can be made without departing from the scope of the invention.

〔The invention's effect〕

As described above, according to the present invention, when a plurality of images are simultaneously displayed on a screen, the information on the overlap of the plurality of images on the screen of the image display device is used to display the plurality of images on the screen. The image decoding means is switched between the area and the non-display area. Therefore, efficient image decoding can be performed without unnecessary decoding processing for the non-display area, and reduction in the storage device scale of the decoding apparatus and improvement in decoding processing speed can be expected.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an embodiment of an image decoding apparatus according to the present invention. FIG. 2 is a diagram showing a judgment method in a decoding means judgment circuit and a decoding means storage circuit shown in FIG. FIG. 3 is a diagram for explaining a relationship with a screen. FIG. 3 is a diagram for explaining a display screen of an image receiving device that simultaneously displays a plurality of images on a screen. FIG. 4 is an image receiving device that simultaneously displays a plurality of images. FIG. 3 is a diagram illustrating a configuration when a conventional image decoding device is used in FIG. In the figure, 11, 12, 13 ... synchronization control circuit, 14, 15, 16 ... scanning circuit,
17, 18, 19 ... decoding means storage circuit, 20, 21, 22 ... decoding means switching circuit, 23, 24, 25 ... display section decoding means, 26, 27, 28
... Decoding means for non-display part, 29, 30, 31 ... Delay circuits, 32, 33, 34
... an image signal output switching circuit, 35, 36, 37 ... a decoding means determination circuit, 38 ... a display screen management device.

Continuation of front page (58) Fields surveyed (Int.Cl. ⁶ , DB name) H04N 7/24-7/68 G09G 5/00-5/40 H04N 5/38-5/46

Claims (1)

(57) [Claims] 1. A receiving means for receiving a plurality of image signals encoded by an image encoding device; an image decoding device for decoding each image signal received by said receiving means; A management unit that manages position, size, and overlap order information of each image to be received, and receives the position, size, and overlap order information of each image from the management unit, and allows one or more images to overlap. An image decoding apparatus in an image receiving apparatus for simultaneously displaying a plurality of images on a screen, the image decoding apparatus comprising: Upon receiving the order information, the received image signal is an image signal corresponding to a display area displayed on the screen or an image signal corresponding to a non-display area which is hidden and not displayed by another image. An identification unit for identifying whether the image signal is an image signal; a display unit decoding unit for performing a decoding process necessary and sufficient for display by a decoding unit applied to an image signal corresponding to the display area; Non-display unit decoding means that performs only a part of the decoding process in the display unit decoding unit or performs no decoding process at all in the decoding unit applied to the image signal corresponding to the display area, When the input image signal is an image signal corresponding to the display area, the input image signal is input to the display decoding means based on the identification result by the identification means, and the input image signal corresponds to the non-display area. Switching means for inputting an input image signal to a non-display section decoding means when the image signal is an image signal to be decoded.