JPH06351007A - In-loop filter circuit for dynamic image encoding device - Google Patents

Abstract

PURPOSE:To reduce a noise stored in a prediction loop by inserting an in-loop filter into a prediction loop in a dynamic image encoding device used for broadcasting. CONSTITUTION:The timing of the right and left picture elements of a picture element under consideration is matched by a delay part 1 and a delay part 2, and the data of those picture elements are inputted to ROM 3 and 4 in which the arithmetic result of a filter is preliminarily stored. Thus, the filter in a horizontal direction is operated, and noise components stored in the prediction loop can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-loop filter circuit in a moving picture coding apparatus, and more particularly to an in-loop filter arranged in a prediction loop in a moving picture coding apparatus of high bit rate used for broadcasting. Regarding the circuit.

[0002]

2. Description of the Related Art As one of high-efficiency coding of moving images, a filter is provided in a local decoding prediction loop to prevent noise from accumulating in the prediction loop, and to reduce accumulated noise to improve coding efficiency. There are known methods for improving That is,
For example, the filter is operated as a low-pass type two-dimensional filter to attenuate high frequency components of the signal and noise included in the prediction loop.

However, this system is used for an image encoding device in moving picture transmission such as a video conference and a videophone, and in a high bit rate moving image encoding device used for broadcasting, the encoding is performed. No filter was used in the prediction loop because the data was converted into a block-like scan.

[0004]

As described above, as described above,
The in-loop filter has not been used in the moving picture coding apparatus used for broadcasting. In such an apparatus, since the data in the prediction loop is converted into a block-shaped scan instead of the normal scan line direction scan, even if an in-loop filter is inserted, a normal two-dimensional filter or the like is used. I couldn't.

The present invention has been made to solve the above-mentioned problems, and in a moving picture coding apparatus used for broadcasting, a noise is accumulated in the prediction loop by inserting a filter in the prediction loop. An object of the present invention is to provide an in-loop filter circuit in a moving picture coding device that can be reduced.

[0006]

A filter circuit according to the present invention comprises first delay means for delaying an input pixel signal N + 8 by 8 pixels and outputting the delayed pixel signal N + 8 as a first delayed pixel signal N.
Second delay means for further delaying the output of the first delay part by 8 pixels and outputting as the second delayed pixel signal N-8;
The input pixel signal N + 8 and the first and second delayed pixel signals N and N-8 are subjected to arithmetic processing, and the filter coefficient is set to K.
, The output pixel signal N ′ is N ′ = (N−8) × K +
And N = (1-2K) + (N + 8) × K.

[0007]

According to the present invention, the delay pixel signal output from the first and second delay sections has the same timing as the input pixel signal. Then, a predetermined filter coefficient is read from the storage circuit for the delayed pixel signal and the input pixel signal and subjected to arithmetic processing, whereby the pixel of interest can be filtered in the horizontal direction.

[0008]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. As shown in the figure, this circuit has a first delay section 1 and a second delay section 2. The delay unit 1 delays the input pixel data by 8 pixels. The output of the delay unit 1 is connected to the input of the delay unit 2. The delay unit 2 further delays the data output from the delay unit 1 by 8 pixels.

The input of the ROM 3 is connected to the output of the delay unit 2, and the same pixel data as that of the delay unit 1 is input. The ROM 3 performs a predetermined calculation based on the input pixel data and the value of the data output from the delay unit 2, stores the result, and outputs the set value. ROM4
Has its input connected to the output of the ROM 3 and the output of the delay unit 1. The ROM 4 performs a predetermined calculation based on the values of the data output from the ROM 3 and the data output from the delay unit 1, stores the result, and outputs the set value.

Next, the operation will be described. The input pixel data D1 is input in advance in a unit of a block in advance from the normal order in the scanning line direction, as shown in FIG.
Here, the block unit is 8 × 8 pixels. A case where the pixel signal N in FIG. 2 is filtered in the horizontal direction as shown in the following equation will be described. N ′ = (N−8) × K + N × (1-2K) + (N + 8) × K (1) where N ′ is the filtered data and K is the filter coefficient (0 ≦ K <1).

The input pixel signal (N + 8) is input to the delay unit 1 and delayed by eight pixels. Further, it is input to the delay unit 2 and delayed by 8 pixels. The pixel signal (N-8) delayed by a total of 16 pixels has the same timing as the input pixel signal (N + 8), and is input to the ROM 3. Here, predetermined data is stored so that the calculation result represented by the following equation can be obtained. S1 = (N-8) × K + (N + 8) × K (2)

The output timing of the output signal S1 coincides with the timing of the delayed pixel signal N output from the delay unit 1. The two pixel signals are input to the ROM 4. The ROM 4 stores predetermined data so as to obtain the calculation result represented by the following equation. N ′ = S1 + N × (1-2K) (3)

Therefore, by substituting the equation (2) into the equation (3), the equation (1) is obtained, and the pixel N of interest can be filtered in the horizontal direction.

As described above, according to this apparatus, the noise component accumulated in the prediction loop can be suppressed with a simple structure. In particular, it is possible to reduce the noise generated at the edge portion on the screen.

[0015]

As described above, the present invention can be implemented with a relatively simple circuit structure, and is therefore effective in reducing the load on the hardware and suppressing the noise component accumulated in the prediction loop. .

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation of FIG.

[Explanation of symbols]

 1, 2 Delay section 3, 4 ROM

Claims (2)

[Claims] 1. A first delay means for delaying an input pixel signal N + 8 by 8 pixels and outputting it as a first delay pixel signal N, and further delaying an output of the first delay section by 8 pixels. Second delay means for outputting the second delayed pixel signal N-8 as a second delayed pixel signal N-8, and arithmetic processing on the input pixel signal N + 8 and the first and second delayed pixel signals N, N-8 When the filter coefficient is K, the output pixel signal N ′ is N ′ = (N−
8) × K + N × (1-2K) + (N + 8) × K, and an in-loop filter circuit in the moving picture coding device. 2. The arithmetic means receives the input pixel signal N + 8 and the second delayed pixel signal N-8 as input, performs arithmetic processing, and outputs S = (N-8) as an output pixel signal S. ) × K + (N + 8) × K
And a first ROM storing an operation for giving the operation to give the first delayed pixel signal N and the output pixel signal S as inputs, and N '= S + (1- 2. The in-loop filter circuit in the moving picture coding apparatus according to claim 1, further comprising a second ROM which stores an operation for giving 2K) * N.