JPS63182984A - Television signal demodulator - Google Patents

Abstract

PURPOSE:To maintain a clear image in a block having no block boundary, in an insignificant block, and an area between insignificant blocks by providing a circuit that judges whether to apply a post-processing filter or not in the unit of picture element, and applying said filter only to the peripheral picture elements of a significant block. CONSTITUTION:A significant/insignificant information outputted from a buffer 319 for significant/insignificant block information is transmitted to a prediction decoding circuit 306 and a filter on/off decision circuit 101 through a line. The decision circuit 101 informs a post-processing filter on/off switch 104 of filter-on/off information in the unit of picture element so that the post-processing filter is applied only to the peripheral picture elements of a significant block and not applied to an insignificant block. The switch 104 receives through lines 102 and 103 the output of an image reproduction circuit 308 and the output of the post-processing filter circuit 310 to which an output from the circuit 308 is inputted, and switches between the output of the image reproduction circuit and that of the post-processing filter in accordance with an on/off information, to output either output to an inter-frame compensation circuit 312.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a television signal decoding device used in video conference systems, video telephones, monitoring systems, and the like.

Prior Art FIG. 3 shows the configuration of a conventional television signal decoding device. In FIG. 3, 302 is a reception buffer, and when it receives a compressed television signal from an encoding device (not shown) through a line 301, it temporarily stores it and then sends it to an entropy decoding circuit 304 through a line 303. . The entropy decoding circuit 304 decodes the frame drop information, significant/insignificant block information, motion vector information, and prediction error information of the current frame from the compressed television signal, and performs interframe interpolation through a line 314, respectively. It is transmitted to circuit 312 , to buffer 319 for significant/insignificant block information through line 318 , to buffer 312 for motion vector information through line 311 , and to predictive decoding circuit 306 through line 305 . Here, the dropped frame information is information regarding whether the target frame is a dropped frame or a coded frame, and interpolation is performed by the interframe interpolation circuit 312 only for dropped frames. Also significant/
Determination of non-significant blocks is performed on a block-by-block basis, which is a set of a plurality of pixels, and information on motion vectors and prediction error information only for pixels in significant blocks are transmitted to the encoding device and the decoding device.

Note that here, a block refers to a set of pixels that partially constitute a frame, a significant block refers to a portion that has moved, and a non-significant block refers to a portion that does not move and to which the previous value is applied.

The motion vector information buffer 312 stores motion vector information. Further, the significant/non-significant block information buffer stores significant/non-significant block information.

The predictive decoding circuit 306 uses a prediction function predetermined between the encoding device and the decoding device, for example, as shown in FIG.
, 91, and the reproduced pixel value of the corresponding current target frame is A
, B, C, S, the prediction function p=s1+I: (A-A1)/3]+[(day-day1
)/3] + [(c-C1)/3'] By calculating the prediction function P according to Decode the value S. In this case, a motion vector is input to the predictive decoding circuit 306 from the motion vector information buffer 312 through a line 313.

In the image reproduction path 308, significant/non-significant block information is obtained from the buffer 319 for significant/non-significant block information through line 310, and based on this, the reproduced pixel values of the significant blocks are also output from the predictive decoding circuit 306. The reproduced pixel value of a block is appropriated from the pixel value of the corresponding block in the previous frame, thereby reproducing an image for one frame.

The temporary processing filter 310 obtains the reproduced image for one frame from the image reproduction circuit through the line 309, and performs the above-mentioned significant/
Apply a filter to make the block boundaries of non-significant blocks less noticeable. This filter is applied to all pixels of one frame. As a filter at this time, for example, a low-pass filter as shown in FIG. 5 is used.

In FIG. 5, X represents the pixel value of the current target pixel before being filtered, and AD represents the pixel value of each position before being filtered.

At this time, let X be the pixel value of the current target pixel after applying the filter.

The inter-frame interpolation circuit 312 is connected to the post-processing filter 310 through a line 311 and to the entropy decoding circuit 304 through a line 314, and according to the frame-drop information transmitted through the line 314, the frame-drop frame repeats the previous frame. , the encoded frame is line 311
Outputs the playback frame transmitted through the .

The NTSC signal synthesis circuit 315 is an interframe interpolation circuit 31
2, the 30 frames per second signal generated by line 313
and its signal (e.g. Y.

1, Q signal) into an NTSC signal. The NTSC signal synthesized here is transmitted through line 315 to D/A conversion circuit 316, where it is converted into an analog signal and then output through line 317.

In this way, even in the above-mentioned conventional television signal/decoding apparatus, by inserting the post-processing filter as described above, it is possible to eliminate the boundaries between significant blocks and non-significant blocks, and between significant blocks and significant blocks. Borders can be made less noticeable.

Problems to be Solved by the Invention However, in the above-mentioned conventional television signal decoding device, the boundaries between significant blocks and the boundaries between significant blocks and non-significant blocks are made inconspicuous for all pixels. Because a low-pass filter is applied to the block, the low-pass filter is also applied within blocks and between non-significant blocks that originally have no block boundaries, and the entire high frequency component is removed. However, there was a problem in that the reproduced image was blurred.

The present invention solves these conventional problems, and makes it possible to make the boundaries between significant blocks and between significant blocks and non-significant blocks less noticeable, and to make it possible to make the boundaries between significant blocks and non-significant blocks inconspicuous. It is an object of the present invention to provide a television signal decoding device using a post-processing filter that can maintain a clear image between non-significant blocks.

Means for Solving the Problems In order to achieve the above object, the present invention provides a circuit that determines whether or not to apply a post-processing filter on a pixel-by-pixel basis, and applies the post-processing filter only to pixels surrounding a significant block. The configuration is such that the post-processing filter is not applied to other pixels.

Therefore, according to the present invention, the block boundaries between significant blocks and between significant blocks and non-significant blocks can be made inconspicuous, and the image can be kept clear in areas other than the above. It has the effect of being able to do something.

Embodiment FIG. 1 shows the configuration of an embodiment of the present invention. In FIG. 1, the same reference numerals as in FIG. 3 indicate the same components as in FIG. The configuration and operation of the parts in FIG. 1 that are different from the conventional configuration example shown in FIG. 3 will be explained below.

In FIG. 1, the significant/non-significant information output from the buffer for significant/non-significant block information at 319 is on line 310.
The signal is transmitted to the filter on/off determination circuit 101 along with a predictive decoding circuit 308 through the filter. Filter on
As shown in FIG. 2, the off determination circuit 101 applies a pixel-by-pixel filter so that the post-processing filter is applied only to the peripheral pixels of the significant block (a) and not to the non-significant block (b). On/off information on line 10
3 through the post-processing filter on/off switch 104
tell. Post-processing filter on/off switch 104
receives the output from the image reproducing circuit 308 and the output from the image reproducing circuit 308 passed through the post-processing filter circuit 310 through lines 102 and 103, respectively, and reproduces the image pixel by pixel according to the above-mentioned filter on/off information. The circuit output and the post-processing filter output are transmitted to the interframe interpolation circuit 312 through the switching line 106.

In this way, according to the above embodiment, since the post-processing filter is applied only to the peripheral pixels of significant blocks, the block boundaries between significant blocks or between significant blocks and non-significant blocks can be made inconspicuous. Moreover, it has the effect that the image can be kept clear within blocks without block boundaries or between non-significant blocks.

Effects of the Invention As is clear from the above embodiment, the present invention applies a post-processing filter that makes block boundaries less noticeable only to pixels surrounding significant blocks, and between significant blocks or between significant blocks. This method has the advantage that the block boundaries between and non-significant blocks can be made inconspicuous, and the image can be kept clear within blocks without block boundaries or between non-significant blocks.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of a television signal decoding device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram for explaining pixels that turn on and off in post-processing fill in the same device, and FIG. 3 is a professional example showing a conventional example. 4 is an explanatory diagram for explaining the prediction function of the predictive decoding circuit in the television signal decoding device, and FIG. 5 is an explanatory diagram for explaining post-processing fill. 101...Filter on/off determination circuit, 1
04... Post-processing filter on/off switch, 304... Entropy decoding circuit, 306
. . . Predictive decoding circuit, 308 . . . Image reproduction circuit, 310 . . . Post-processing fill, 312.
. . . Interframe interpolation circuit, 312 . . . Motion vector) Buffer for Az information, 319 . . . Buffer for significant/insignificant block information. Figure 2 (σ) Yes! 0 in case of block (processing filter? or 1 pixel O edge processing filter? or 1 fJ and 1 pixel o o
−”' ■ Chen Tuu

Claims (1)

[Claims] After decoding a plurality of blocks constituting a frame of an image formed by a transmitted image signal, a post-processing filter for making boundaries between the blocks inconspicuous and use or non-use of the post-processing filter are controlled. A switch circuit is provided, and a judgment circuit individually judges whether each block is a significant block accompanied by movement or a non-significant block without movement, and based on the judgment result, pixels surrounding the significant block are A television signal decoding device that controls the switch circuit so that the post-processing filter is inserted only when the post-processing filter is inserted.