JPH0340583A - Picture decoder - Google Patents

Abstract

PURPOSE:To obtain an efficient picture decoder whose decoding processing quantity is reduced as the entire device by decreasing the processing quantity of a non-display area decoding circuit more than the processing quantity of a display area decoding circuit. CONSTITUTION:A synchronizing control circuit 1, a scanning circuit 2, a decoding means storage circuit 3 and a decoding means deciding circuit 9 utilize the information controlled by a picture display control circuit 10 so as to identify an input picture signal is a picture signal corresponding to an area display area displayed by a picture or a picture signal corresponding to a non display area not displayed on the screen. A decoding means switching circuit 4, a delay circuit 7 and a picture signal output changeover circuit 8 changes over the decoding circuit applied to an input picture signal based on the result of identification, the display area decoding circuit 5 applies the decoding processing of the picture signal and the non display area decoding circuit 6 reduce the decoding processing quantity of the picture signal. Thus, the efficient picture decoder reducing the decoding processing quantity is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to image decoding #A@ in an image receiving system that displays only a portion of a received image frame.

[Prior art]

FIG. 7 is a diagram illustrating the flow of image signals to the image encoding and decoding apparatus.

In FIG. 7, 201 is an image encoding device, 202 is an image decoding device, 203 is an original image, and 204 is an image signal 20.
? , 205 is an image signal corresponding to the original image 203, 206 is an image signal obtained by encoding the image signal 205 by the image encoding device 201, and 207 is the image signal obtained by decoding the image signal 206 by the image decoding device E 202. The image signal 208 is a transmission path. Usually, image encoding device 2
01 is installed on the image sending side and is an image decoding device! 202
is left on the H image receiving side.

A conventional image decoding device 202 converts an image signal 207 having the highest possible degree of similarity to an image signal 205 into an image signal 206.
A restored image 204 that is faithful to the original image 203 is displayed on a display screen by supplying an image signal 207 to an image display device.

In addition, in single-image communication/broadcasting, based on the sender's intention, the receiver's intention, or the intention of a third party, only a part (display area) of the image frame received by the receiver is displayed, and other areas (non-image frame) are displayed. There is an image receiving method that does not display the display area). FIG. 8 is a diagram illustrating such an image receiving method.

In FIG. 8, 301 is the original image on the transmitting side, 302 is the image obtained when the received image signal is completely decoded, and 303 is the image actually displayed on the display screen. In the case of FIG. 8, the transmitting side transmits an image of the upper body, the receiving side receives the image, and only the peripheral part of the face is displayed on the display screen.

In such a case, the conventional image decoding device is capable of faithfully restoring and displaying the entire frame area of the yKw image on the screen of the image display device, regardless of the display state of the image on one display screen. Decoding is performed by uniformly handling both the image signal corresponding to the display area and the image signal corresponding to the non-display area, without using information about which area in the image frame is displayed on the display screen.

[Problem to be solved by the invention]

However, in conventional image decoding devices, as mentioned above, applying the same decoding means to the non-display area as for the display area and decoding it to a level that can be displayed on the screen is difficult. The problem was that it was wasteful from a quantity standpoint.

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

An object of the present invention is to provide an efficient image decoding device that reduces the amount of processing required for decoding in a single image encoding device.

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

[Means to solve the problem]

To achieve the above object, the present invention provides an image decoding system used in an image receiving system that receives an image signal encoded by an image encoding device and displays only a part of the image frame on a screen. In the image display device, the input image signal is converted into an image by using an image display management means for managing which part of the image frame is displayed on the screen of the image display device, and information managed by the image display management means. A display area identification means for identifying whether an image signal corresponds to a displayed area (display area) or an image signal corresponding to an area not displayed on the screen (non-display area), and an image corresponding to the display area. display image decoding means for decoding the signal; non-display image decoding means for decoding the image signal corresponding to the non-display area; and application to the input ** signal based on the identification result by the display area identification means. a decoding means switching means for switching the decoding means to be used; the display image decoding means performs image signal decoding processing; and the non-display image decoding means reduces the amount of image signal decoding processing. The most important feature is that it is equipped with a control means.

Furthermore, in the non-display image decoding means, the control means for reducing the amount of image signal decoding processing includes a method in which the image signal is not decoded at all and a method in which only a part of the image signal is decoded. For example, for an image signal encoded by an image encoding means that uses both an encoding method that uses correlation between frames and an encoding method that does not utilize correlation between frames, the display image decoding means The non-display image decoding means performs decoding processing for both signal components resulting from the encoding method that utilizes the correlation between frames and signal components resulting from the encoding method that does not utilize the correlation between the frames. A control means is provided that performs decoding processing of signal components resulting from an encoding method that utilizes correlation between frames without performing decoding processing of signal components resulting from an encoding method that does not utilize correlation between frames. Features.

[Effect]

According to the above-mentioned means, the display area identifying means identifies whether the input image signal is an image signal corresponding to a display area or a non-display area, and decoding is performed based on the identification result. Switching the decoding means applied to the input image signal by the means switching means, that is, when the identification result is an image signal corresponding to the display area, the display image decoding means is applied, and the display image decoding means is applied to correspond to the non-display area. the decoding means is switched to apply the non-display image decoding means when the image signal is an image signal that By reducing the amount of decoding processing for image signals, it is possible to provide an efficient image decoding device that requires less processing amount for decoding than conventional techniques.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be specifically described using the drawings.

In addition, in all the figures for explaining an example.

Components having the same function are given the same reference numerals, and the explanation of the weaving is omitted.

An image frame is encoded and decoded pixel by pixel or block consisting of several pixels, and this unit is referred to as a coding unit in this text.

FIG. 1 is a diagram for explaining an embodiment of an image decoding device of the present invention.

In FIG. 1, 1 is a synchronous control circuit, 2 is a scanning circuit, and 3 is a synchronous control circuit.
4 is a decoding means storage circuit, 4 is a decoding means switching circuit, 5 is a display area decoding circuit, 6 is a non-display area decoding circuit, 7 is a delay circuit, 8 is an image signal output switching circuit, and 9 is a decoding means The determination circuit 10 is a display area management circuit.

The synchronous control circuit 1. The scanning circuit 2, the decoding means storage circuit 3, and the decoding means determining circuit 9 are connected to an image display management circuit 10.
Using information managed by This is to identify the The display image area decoding circuit S is for decoding the image signal corresponding to the display area, and the non-display area decoding circuit 6 is for decoding the image signal corresponding to the non-display area. It is something. The decoding means switching circuit 4, the delay circuit 7, and the image signal output switching circuit 8 are for switching the decoding means applied to the input image signal based on the identification result by the display area identification means.

The sender, the receiver, or a third party instructs which part of the received image frame to display on the screen, and the display area management circuit 1O determines which part of the received image frame Manages which part of the image is displayed on the screen of the image display device.

FIG. 2 is a diagram showing an example of the structure of an image frame when encoding and decoding are performed using blocks as encoding units. In this case, one image frame PF is 48 in total, 8 horizontally and 6 vertically.
It is composed of N encoding units.

FIG. 3 is a diagram for explaining the method of specifying the display area within the image frame PF. , expressed as coordinate values in a coordinate system with an axis in the vertical direction.

In Figure 3, the horizontal direction is the X axis and the vertical direction is the y axis, and the position of point A in the figure is expressed by the coordinates (Ax, Ay) 1
If the display area PFA in the image frame PF is a rectangle,
Since the display area PFA can be specified by the coordinates of the point A in the upper left corner and the coordinates of the point B in the lower right corner, the display area PFA can be specified by four numerical values A representing the coordinates of the points A and B.
Specify by x + AV *BX, By.

As shown in FIG. 4 (a block diagram showing a schematic configuration of the display area management circuit), the display area management circuit 10 includes an input interface 11101 for receiving and receiving instructions for the display area, and an input interface 11101 for receiving and receiving instructions for the display area, and an input interface 11101 for receiving and receiving instructions for the display area. numeric values Ax, Ay, Bx
, By, and an output interface circuit 103 that outputs the stored contents in response to a request from the decoding means determination circuit 9.

As shown in FIG. 5 (block diagram showing the internal configuration of the decoding means storage circuit), the decoding means storage circuit 3 has a number of storage units equal to the total number of encoding units Q constituting one frame of an image. The storage unit M and the encoding unit N have a one-to-one correspondence. That is, when the image frame PF is composed of 48 encoding units N as shown in FIG. 5, the decoding means storage circuit 3 is also composed of 48 storage units M. The value stored in such a storage unit M represents whether or not the corresponding coding unit N is displayed.

In this embodiment, when the value of the storage unit M is "O", it indicates that the corresponding encoding unit is not displayed on the screen.
11 #l indicates that the corresponding coding unit Q is displayed on the screen.

The decoding means determination circuit 9 receives the coordinate values of the upper left corner and the coordinate values of the lower right corner of the display area PFA from the display area management circuit IO, determines whether or not each encoding unit N is displayed, and performs two decoding operations. Which decoding means to apply is written in the decoding means storage circuit 3.

In this embodiment, "1" is set in the storage unit M corresponding to the encoding unit N determined to be displayed on the screen.

"0" is written in the storage unit M corresponding to the non-displayed area.

Then, as shown in FIG. 6 (a diagram for explaining the determination method of the decoding means determination circuit), the coordinates of the point A at the upper left corner of the display area PFA in the image frame PF are expressed as (A x e
A y ) - The coordinates of point B in the lower right corner are (B x + B
y ), the coordinates of the point P at the upper left corner of the coding unit that is the target of determination are (P x r P y ), and the coordinates of the point Q at the lower right corner are (Qx, Qy), then Qx≦ Ax
, Bx≦P x * Q y≦A yp B y≦py
When either of the following holds true, it is determined that the encoding unit belongs to the non-display area. (Note that when the encoding unit is a pixel, Px = Qx and Py = Qy hold.)
For example, focusing on encoding unit 2, the coordinates of point P2 in the upper left corner are (Px,,Py2), and the coordinates of point Q2 in the lower right corner are (
qxa+Qy2), since Q x a≦Ax holds true, it is determined that the encoding unit 2 belongs to the non-display area. Also, focusing on the encoding unit 14,
The coordinates of point P14 in the upper left corner are (P XLat P yi4
) - the lower right corner point Q coordinates (Q x s.Q)'t*)
When, Q xi, ≦Ax, Bx≦Px,. Qy,
, ≦Any, By, and 4≦py do not hold, so it is determined that the encoding unit 14 belongs to the display area PFA. Similar determinations can be made for other encoding units N, and the values are written into the decoding means storage circuit 3 as shown in FIG.

The synchronization control circuit 1 detects a synchronization signal indicating the start of an image frame PF from an input image signal and starts scanning in the scanning circuit 2, or starts scanning in the scanning circuit 2 from an image signal.
The decoding means storage circuit 3 generates an operation reference clock to synchronize the scanning in the scanning circuit 2 and the image signal.
Adjustment is made so that switching based on the value read from is performed for the corresponding encoding unit N.

When the scanning circuit 2 receives a synchronization signal indicating the start of the image frame PF from the synchronization control circuit 1, it starts scanning the decoding means storage circuit 3. Each time the scanning circuit 2 receives the operation reference clock from the synchronization control circuit 1, the scanning circuit 2 increases the value of the read address for the decoding means storage circuit 8 by one unit, and reads the value of the storage unit of the address in the decoding means storage circuit 3. is read out and applied to the decoding means switching circuit 4.

In the decoding means switching circuit 4, the decoding means storage circuit 3
If the value read from is “0”.

The image signal is passed to the non-display area decoding circuit 6, and if the read value is "1", the image signal is passed to the display area decoding circuit 5.

The display area decoding circuit S is a means for decoding the image signal of the coding unit displayed on the screen, and the non-display area decoding circuit 6 is a means for decoding the image signal of the coding unit that is not displayed on the screen. It is a means to do so.

Both circuits input image signals for each encoding unit,
The display area decoding circuit 5 outputs an image signal such as pixel data, but the display area decoding circuit 5 outputs an image signal obtained by decoding the input image signal, and the non-display area decoding circuit 6 outputs a dummy image signal unrelated to the input image signal. (for example, a black burst signal). The reason why the image signal is also output from the non-display area decoding circuit 6 is to enable synchronization in the subsequent circuit.

There are the following methods for reducing the amount of processing in the non-display area decoding circuit 6.

First, 5 is a method in which the input image signal is not decoded at all, and the second is a method in which only the inter-frame difference signal of the input image signal is processed and no other decoding is performed. .

For example, for an image signal encoded by an image encoding means that uses both an encoding method that uses correlation between frames and an encoding method that does not utilize correlation between frames, the display image decoding means The non-display image decoding means performs decoding processing for both signal components resulting from the encoding method that utilizes the correlation between frames and signal components resulting from the encoding method that does not utilize the correlation between the frames. A signal component resulting from an encoding method that uses correlation between frames is not decoded, but a signal component resulting from an encoding method that uses correlation between frames is decoded.

The former method described above does not perform any decoding processing that requires complicated processing, so it is possible to greatly reduce the amount of processing.

Furthermore, in the latter method, only the interframe difference signal is processed, so the amount of processing can be reduced compared to the case where complete decoding including other signal components is performed.

The delay circuit 7 delays the decoding means selection signal from the scanning circuit 2 by the time required to decode the image signal.

The image signal output switching circuit 8 connects the output of the decoding circuit selected by the decoding means selection signal delayed by the delay circuit 7 to the output of the image decoding device, and outputs the image signal processed by the decoding means. is sent to the image display device.

As can be seen from the above description, according to this embodiment, the processing amount in the non-display area decoding circuit 6 is reduced by the display area decoding time v1.
By reducing the amount of processing required in 5, the amount of processing required for decoding can be reduced when looking at the entire image encoding device. Accordingly, it is possible to provide an image decoding device.

In this embodiment, the display area decoding means and the non-display area decoding means are realized by independent circuits, but the function of the non-display area decoding means is a subset of the function of the display area decoding means. Since the display area decoding means and the non-display area decoding means share a circuit and some of the functions of the display area decoding means are stopped, the non-display area decoding is possible. It is clear that the means can be realized.

The present invention has been specifically explained above based on examples, but
It goes without saying that the present invention is not limited to the embodiments described above, and can be modified in various ways without departing from the spirit thereof.

〔Effect of the invention〕

As described above, according to the present invention, in an image receiving system that receives an image signal encoded by a single image encoding device and displays only a part of the image frame obtained from the image signal on the screen, The display area identifying means identifies whether the input image signal is an image signal corresponding to the display area or a non-display area, and based on this identification result, the image signal corresponding to the display area is identified. When the display image decoding means is applied, the decoding means is switched so that the display image decoding means is applied when the image signal corresponds to a non-display area, and the non-display image decoding means is applied. By performing image signal decoding processing and reducing the amount of image signal decoding processing in the non-display image decoding means, the amount of processing required for decoding can be reduced compared to conventional image decoding devices. Therefore, it is possible to reduce the scale of the apparatus and improve the processing capacity of the apparatus.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the schematic configuration of an embodiment of an image decoding device of the present invention. Figure 2 shows the image frame diagram when encoding and decoding is performed using two blocks as a unit of encoding. 4. Diagrams showing examples. FIG. 3 is a diagram for explaining a method of specifying a display area within the difference between image frames. FIG. 4 is a block diagram showing the schematic configuration of the display area management circuit, FIG. 5 is a block diagram showing the internal configuration of the decoding means storage circuit, and FIG. 6 explains the determination method of the decoding means determining circuit. 7 is a diagram for explaining the flow of image signals to the image encoding and decoding device. FIG. 8 is a diagram for explaining an image reception method that displays only a part of the received image frame. This is a diagram for In the figure, 1... synchronous control circuit, 2... scanning circuit, 3...
...Decoding means storage circuit, 4...Decoding means switching circuit.

Claims (1)

[Claims] (1) In an image decoding device used in an image receiving system that receives an image signal encoded by an image encoding device and displays only a portion of the image frame on the screen, An image display management means that manages whether a portion is displayed on the screen of an image display device, and information managed by the image display management means is used to display an input image signal in an area where the input image signal is displayed on the screen (display area). display area identification means for identifying whether the signal corresponds to a corresponding signal or a signal corresponding to an area not displayed on a screen (non-display area); and display image decoding means for decoding an image signal corresponding to the display area. , a non-display image decoding means for decoding an image signal corresponding to the non-display area, and a decoding means switching means for switching the decoding means applied to the input image signal based on the identification result by the display area identification means. and an image decoding device characterized in that the display image decoding means performs image signal decoding processing, and the non-display image decoding means includes control means for reducing the amount of image signal decoding processing. Device.