JP2001186527A - Coding control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust the ratio of selection of an in-frame coding or an inter-frame coding, together with the characteristic of a coding processing unit and an image by comparing an activity of an input image signal with an activity of a prediction error signal after weighting the activities. SOLUTION: A coding control section 41 compares an activity of an input image signal 12 with an activity of a prediction error signal 15, after weighting the activities and outputs a coding control signal 42 that controls the selection of the in-frame coding or the inter-frame coding in a coding section 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image encoding device for encoding an image signal. In particular, the present invention relates to an inter-frame coding processing method for performing coding based on a difference signal between a frame of an input signal and a frame.

[0002]

2. Description of the Related Art In order to efficiently encode an image signal, means for removing a redundant component included in the image signal is used. In particular, as a typical technique for encoding a moving image, a so-called inter-frame encoding method that takes a difference between an already encoded image and an image to be newly encoded and encodes only difference information is well known. I have.

FIG. 40 shows, for example, Japanese Patent Application Laid-Open No. 63-20838.
FIG. 1 is a block diagram of an inter-frame encoding device disclosed in Japanese Patent Application Publication No. 2 (1993) -207, in which 1 is a frame memory for storing image information of a previous frame, 2 is a motion vector detecting unit,
Is a subtractor, 4 is an encoder, 5 is a local decoder, 6 is an adder, 7 is a filter, and 8 is a filter controller.

Next, the operation will be described. An image signal 11 of one frame before stored in the frame memory 1;
The input image signal 12 is subjected to block matching in the motion vector detection unit 2 and compared to generate a motion vector 13 indicating the amount of motion and its direction. Frame memory 1
Produces a motion compensated prediction signal 14 according to the motion vector 13. The subtracter 3 subtracts the motion compensated prediction signal 14 from the input image signal 12 to obtain a prediction error signal (also referred to as a difference signal) 1.
5 is generated.

[0005] The encoding unit 4 quantizes the prediction error signal 15 to generate encoded error information 16. Local decoding section 5 decodes encoded error information 16 and outputs local decoded error signal 17. The adder 6 outputs the motion compensation prediction signal 14
And a local decoding error signal 17 to generate a local decoding signal 18. The filter 7 removes high frequency components in the local decoded signal 18 and generates a smoothed local decoded signal 19. The filter control unit 8 outputs a control signal 20 for controlling insertion or non-insertion of the filter 7 according to the magnitude of the motion vector 13. The coded error signal 16 generated in this way and the motion vector 13 are transmitted via a transmission path. Generally, these processes are performed on the image signal in units of 16 × 16 pixels or in units of 8 × 8 pixels.

In the above-described conventional example, the filter 7 is provided at the subsequent stage of the adder 6, but a method of providing the filter 7 at the subsequent stage of the frame memory 1 is also known. Further, there are a method of performing search in units of integer pixels or less, a method of performing filter processing closed in units of blocks, and a method of performing filter processing including peripheral pixels in order to enhance the accuracy of motion detection. In any of these methods, noise is removed and the coding efficiency is improved by suppressing high-frequency components according to the amount of motion.

[0007] When intraframe encoding is performed by a conventional apparatus, the input image signal 12 is quantized by the encoding unit 4 as it is to generate encoded input information 16. The local decoding unit 5 decodes the encoded input information 16 and outputs a local decoding error signal 17 to the frame memory 1. The encoded input information 16 generated in this manner is transmitted via a transmission path.

[0008]

In the conventional interframe coding processing method, control is performed using information of a motion vector, so that a low-pass filter (LPF) is used in a static region as shown in FIG. By turning it off, a low-pass filter is inserted in the moving area without loss of resolution to remove noise although the resolution is reduced.

FIG. 41 is a diagram showing the relationship between the luminance intensity (I) of the signal and the frequency (f) of the signal. 14a shows the signal from the frame memory 1 when the low-pass filter is turned off, and 14b shows the low-pass filter. The signal from the frame memory 1 when the filter is turned on is shown.

[0010] As shown in FIG.
The case of F is a case where high resolution is maintained in a static region. Conversely, the case where the low-pass filter is turned on is the case where the resolution is reduced in the moving area. in this way,
By turning the low-pass filter from OFF to ON,
It becomes possible to remove the high frequency components shown by the oblique lines in FIG.

FIG. 42 shows a case where the difference signal 15 between the input signal 12 and the motion compensation prediction signal 14a from the frame memory is very small. That is, as shown in FIG. 42 (b), when the motion detection accuracy of the input signal 12 as shown in FIG. 42 (a) is very good and the motion compensation prediction signal 14a has almost the same characteristics. As shown in FIG. 42 (c), the difference signal 15 becomes very small. Therefore,
The amount of information encoded by the encoding unit 4 decreases, and the encoding efficiency improves.

However, there is a case where the filtering process is performed even though the motion detection accuracy in the moving area is good and the difference between the input signal and the motion compensation prediction signal from the frame memory is very small.

When the low-pass filter is turned on in the moving area as shown in FIG. 41, the high-frequency component of the motion compensation prediction signal 14 is cut off.
In this case, a high-frequency component remains in the difference signal between the result of the filtering process and the input signal, the information to be coded increases, the coding efficiency decreases, and the resolution of that portion decreases.

FIG. 43 is a diagram for explaining this problem. FIG. 43 (a) is similar to the input signal shown in FIG. 42 (a). Also, in FIG.
“b” indicates a characteristic in which the low-pass filter is turned on in the moving region and high-frequency components have been cut. That is, as compared with the motion compensated prediction signal 14a in FIG.
This indicates that high-frequency components (noise) are cut off and a motion-compensated prediction signal as shown in 14b is output. or,
In FIG. 43 (c), the input signal shown in FIG. 43 (a) and the motion-compensated prediction signal 1 shown in FIG.
The difference signal 15 of FIG. 4b is shown. As can be seen from the figure, since the high-frequency component remains, the information to be encoded by the encoding unit 4 increases, and the encoding efficiency decreases.

As described above, in the moving region, FIG.
Although the motion detection works with high precision as shown in FIG. 2 and there is no need to perform filter processing, since the filter processing is performed as shown in FIG. 43, the resolution of that part is reduced or encoding is required. There have been problems such as an increase in the amount of information.

Although the encoding unit 4 quantizes and encodes the prediction error signal 15, the signal input and encoded by the encoding unit 4 is limited to one type of prediction error signal. Even if the prediction error signal shows characteristics with poor coding efficiency, the prediction error signal is quantized and coded, so that a signal with good coding efficiency cannot always be obtained. was there.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides an inter-frame encoding processing method in which high-frequency components do not remain in a signal to be encoded and encoding efficiency is improved. With the goal.

Further, the present invention has been made to solve the above-mentioned problems, and a signal to be coded is a signal with high coding efficiency, and a coding control method in which coding efficiency is improved is obtained. The purpose is to:

[0019]

According to a first aspect of the present invention, there is provided an inter-frame encoding system which receives an input signal, determines whether or not the input signal has a characteristic that contains a large amount of high-frequency components, and If it is determined that the filter has a characteristic that contains many high-frequency components, a control signal for designating a filter coefficient is output so as to weaken the strength of the filter.

In the inter-frame encoding processing method according to the second invention, when it is determined whether or not the input signal has a characteristic of containing a large amount of high-frequency components, the determination is made using the activity of the input signal.

The interframe coding method according to the third invention uses a difference between a maximum value and a minimum value of the input signal or a sum of absolute differences or a square of the difference from the signal average value as the activity of the input signal.

The inter-frame encoding processing method according to the fourth invention further comprises the steps of:
When it is determined whether or not the input signal has a characteristic containing a large amount of high-frequency components, the activity of the input signal is used to normalize information corresponding to a difference between the input signal and a signal from the frame memory.

According to the fifth aspect of the present invention, the interframe coding method compares the activity of the input signal with a predetermined threshold value when determining whether or not the input signal has a characteristic containing a large amount of high frequency components. To determine.

In the inter-frame encoding method according to the sixth invention, the activity of the input signal is determined from the input signal and the frame memory when it is determined whether or not the input signal has a characteristic containing a large amount of high frequency components. Is used to normalize information corresponding to the difference between the signal and the signal, and the result of the normalization is compared with a predetermined threshold to make a determination.

In the interframe coding method according to a seventh aspect of the present invention, the filter control section generates a filter control signal for adaptively changing a binary or multi-valued filter coefficient value of the adaptive filter section.

In the interframe coding method according to the eighth invention, the adaptive filter section has one-dimensional or two-dimensional in a spatial direction and three-dimensional characteristics in which a temporal direction is added.

According to a ninth aspect of the present invention, in the inter-frame encoding method, the adaptive filter section is provided so as to perform a filtering process on a signal from the frame memory. Alternatively, the adaptive filter unit is provided so as to perform a filtering process on a locally decoded signal written in the frame memory.

According to a tenth aspect of the present invention, there is provided an inter-frame encoding processing method, wherein an input signal and a signal from the frame memory are input and information corresponding to a difference between the input signal and a signal from the frame memory is encoded. The encoding unit uses information corresponding to the difference between the input signal and the signal from the frame memory when encoding the input signal between frames.

The inter-frame encoding method according to the eleventh aspect of the present invention includes an encoding unit that performs encoding with an encoding error smaller than a value per pixel of information corresponding to the difference in the control unit.

[0030] In the inter-frame encoding processing method according to the twelfth aspect, a filter is provided in a decoding loop, and the control unit includes:
Further, a filter control signal is output based on information corresponding to the difference.

According to a thirteenth aspect of the present invention, there is provided an inter-frame coding processing system, wherein a control unit obtains a signal activity of an input signal or a signal from a frame memory, and a coding unit is provided which controls a coding error by the signal activity.

According to a fourteenth aspect of the present invention, there is provided an inter-frame encoding method, comprising the steps of: determining whether an input signal has a characteristic of containing a large amount of a high-frequency component; Outputting a control signal specifying a filter coefficient so as to weaken the strength of the filter, when it is determined that the filter has a characteristic including a large number of
A step of performing a filtering process based on the filter coefficient.

In the inter-frame coding processing method according to the fifteenth aspect, in the step of taking an input signal as an input and determining whether or not the input signal has a characteristic containing many high-frequency components, the activity of the input signal is used. To determine.

According to a sixteenth aspect of the present invention, there is provided an inter-frame encoding processing method comprising the steps of: inputting an input signal and a signal from a frame memory; obtaining information corresponding to the difference; And a step of performing encoding based on the changed quantization step size.

The interframe coding method according to the seventeenth aspect is a step of inputting an input signal or a signal from a frame memory and obtaining a relative characteristic signal, not an absolute strength, such as an activity signal. And a step of changing the quantization step size of the coding unit based on the characteristic signal, and a step of performing coding based on the changed quantization step size.

An encoding control method according to an eighteenth aspect of the present invention comprises:
An encoding control unit that outputs an encoding control signal to the encoding unit based on the activity of the input image signal or the signal from the frame memory is provided.

The encoding control method according to the nineteenth invention is as follows:
The activity of the inter-frame signal is compared with the activity of the intra-frame signal, and for example, the encoding of the encoding unit is controlled based on the activity of the signal having the smaller activity.

The encoding control method according to the twentieth invention is as follows:
When comparing the activity of the inter-frame signal and the activity of the intra-frame signal, at least one of the activities is weighted and compared.

The encoding control method according to the twenty-first invention is as follows:
The image processing apparatus further includes a filter for performing a filtering process, and a filter control unit that receives an input image signal and a signal from the frame memory and outputs a control signal of the filter.

The encoding control method according to the twenty-second invention is as follows:
At least two out of three activities of the activity of the prediction error signal subjected to the filtering process, the activity of the prediction error signal when the filtering process is not performed, and the activity of the input signal by the intra-frame prediction are compared. The encoding of the encoding unit is controlled based on the activity of a signal having a small activity.

The encoding control method according to the twenty-third invention is as follows:
When comparing the activity of the prediction error signal subjected to the filtering process, the activity of the prediction error signal when the filtering process is not performed, and the activity of the input signal by the intra-frame prediction, at least one of the activities is weighted. Is performed, and at least two or more of the three activities are compared.

The encoding control method according to the twenty-fourth invention is as follows:
The activity of the prediction error signal and the activity of the intra-frame signal that have been subjected to the filtering process control from the filter control unit in advance are compared, and the encoding of the encoding unit is performed based on the activity of the signal having the smallest activity. Control.

The encoding control method according to the twenty-fifth invention is as follows:
When comparing the activity of the prediction error signal, which has been subjected to the filtering process control by the filter control unit, with the activity of the intra-frame signal, at least one of the activities is weighted and compared.

The encoding control method according to the twenty-sixth invention is as follows:
An encoding control signal is output to an encoding unit based on an activity of an input image signal or a signal from the image memory, or encoding is performed to perform feedback control based on encoded data output from the encoding unit. And an encoding control unit that outputs an encoding control signal to the unit.

An encoding control method according to the twenty-seventh aspect of the present invention comprises:
As the activity, the difference between the maximum value and the minimum value of the signal or the sum of absolute differences or the sum of squares of the differences from the average value of the signal is used as the feature based on the signal.

[0046]

According to the inter-frame encoding processing method of the first to ninth aspects and the inter-frame encoding processing method of the fourteenth to fifteenth aspects, the filter control section is configured to determine the difference information between the input signal and the signal from the frame memory. The strength of the filter that cuts high-frequency components is changed based on the magnitude of the normalization result normalized by the input signal or the signal from the frame memory, or by comparing the difference information or the characteristics of the input signal with the threshold and comparing the results. In this way, high-frequency components do not always remain in the signal to be encoded, and the encoding efficiency is improved.
Even in the moving area, without reducing the visual resolution,
In addition, a visually good encoded image can be obtained.

Further, according to the tenth to thirteenth inventions, the interframe coding method according to the tenth to thirteenth inventions and the interframe coding method according to the sixteenth and seventeenth inventions provide a method for controlling the difference between an input signal and a signal from a frame memory in a control unit. Alternatively, since the quantization step size in the encoding unit is changed using the input signal or the signal from the frame memory, a signal having a small encoding error is generated.

The encoding control method according to the eighteenth to twenty-seventh aspects is based on a signal of a mode having an optimum feature (activity) among features (activity) obtained based on an input signal or a difference error signal. Since the encoding is controlled by the encoding control unit, the encoding efficiency can be improved.

[0049]

[Embodiment 1] FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG. Here, a case where encoding is performed using 8 × 8 pixels as a processing unit will be described. In FIG. 1, 21 is a filter control unit, and 22 is an adaptive filter unit. Other reference numerals are the same as those shown in FIG.

Next, the operation will be described with reference to FIG.
The motion vector detecting unit 2 detects the image signal 11 one frame before and the input image signal 12 stored in the frame memory 1.
Is the same as in the conventional example until the motion vector 13 is detected and the motion compensation prediction signal 14 corresponding to the motion vector 13 is generated. The filter control unit 21 generates a filter control signal 23 based on the input image signal 12 and the motion compensation prediction signal 14.

FIG. 2 shows the generation of the filter control signal 23.
It is explained based on. In FIG. 2, reference numeral 30 denotes an input image signal 1
A difference information calculation unit 31 for calculating difference information 32 between 2 and the motion compensation prediction signal 14, and 31 is a determination unit. The difference information calculation unit 30 calculates the absolute value of the difference or the square of the difference between the input image signal 12 and the motion compensation prediction signal 14 and calculates them for a plurality of pixels (8 × 8 pixels) in the filter processing unit of 8 × 8 pixels.
8 = 64 pixels) are accumulated, and the obtained result is referred to as difference information 32
Output as

FIG. 3 is a diagram for explaining the difference information 32. FIG. 3A shows an input image signal. In this embodiment, since the processing unit is 8 × 8 pixels, the input image signal is divided into S1 to S64 in one processing unit.
Up to 64 pixels exist. Next, FIG. 3B is a diagram illustrating a motion compensation prediction signal. The motion compensation prediction signal is also 8 × 8
A pixel is a unit of processing, and is composed of 64 pixels from Y1 to Y64. FIG. 3C illustrates the difference information calculation unit 3.
0 indicates a case where the result obtained by accumulating the absolute value of the difference between the input image signal 12 and the motion compensation prediction signal 14 for 64 pixels is used as difference information. FIG. 3D shows the difference information calculation unit 30.
Indicates a case where the square of the difference between the input image signal 12 and the motion compensation prediction signal 14 is taken and accumulated for 64 pixels, and the obtained result is used as the difference information 32.

The value of the difference information 32 becomes small when the prediction accuracy is high and the optimum prediction signal is obtained. However, when the prediction accuracy is low, when a completely different image is input, or when the frame memory 1 The value of the difference information 32 becomes large, for example, when the local decoding signal in the data includes many quantization errors.

The determination section 31 calculates the signal activity of the input image signal 12 corresponding to the plurality of pixels for which the difference information 32 has been obtained previously (hereinafter simply referred to as activity). For example, the signal activity is calculated as the difference between the maximum value and the minimum value of the signal as shown in FIG.

FIG. 4 is a diagram showing an example of a case where the signal activity is calculated from the difference between the maximum value and the minimum value of the pixel signal. The figure shows a case where signal activity is calculated for the first to eighth pixels for the sake of simplicity. In this example, since the luminance of the fourth pixel indicates the maximum value and the fifth pixel indicates the minimum luminance, the difference is defined as the signal activity.

Alternatively, the signal activity is obtained as a sum of absolute differences and a sum of squares of the differences from the signal average value as shown in FIG. FIG. 5 is a diagram illustrating an example of a case where signal activity is calculated using a difference absolute value or a difference square. As shown in FIG. 5A, assuming that the differences between the luminances of the first to eighth pixels and the average values of these eight luminances are X1 to X8, respectively, the absolute value of the difference from the signal average value is as shown in FIG. As shown in FIG. 5B, the value is obtained by adding the absolute values of X1 to X8. The square of the difference from the signal average value is a value obtained by squaring X1 to X8, respectively, as shown in FIG.

As shown in FIGS. 4 and 5, the signal activity does not indicate the absolute intensity of the image signal, but indicates a relative value. That is, the value X of the signal activity becomes small in the case of a signal that changes smoothly such that it contains a lot of low frequency components, and the value X of the signal activity becomes large in the case that it contains a lot of rapidly changing high frequency components.

The difference information 32 is normalized (divided) by the signal activity to obtain a normalized result, and outputs a filter control signal 23 for designating a filter strength for removing high-frequency components according to the magnitude of this value. That is, when the value of the normalization result is large (that is, in the case of a signal that changes smoothly such that the input image contains many low frequency components), the filter strength is increased. Also, when the value of the normalization result is small (that is, when the input image is a signal containing many rapidly changing high-frequency components).
Reduces the filter strength. In other words, the value of the normalization result specifies a multi-valued intensity specification in accordance with the number of a plurality of types of filters having different intensities in the adaptive filter unit 22.

For the sake of simplicity, when the insertion and non-insertion of a filter is designated by a binary value as the filter control signal 23, if the normalized information obtained before the predetermined value is larger, the filter is inserted to reduce the high frequency component. The filter control signal 23 is issued so as to remove the information to be coded by removing it, and if the normalized information is small, to insert a filter without using a filter and to use a prediction error signal that maintains the resolution.

FIG. 6 shows on / off of the filter control unit 21.
1 shows an embodiment of an f determination flow. This filter control unit 2
The operation 1 is based on the input image signal 12 and the motion-compensated prediction signal 14.
The on / off determination of the filter is performed by the above. First, in ST1, the filter is set to o as a default value.
ff. In ST2, the difference information calculation unit 30 calculates difference information N between the input image signal 12 and the motion compensation prediction signal 14. In ST3, the determination unit 31 calculates the value X of the signal activity of the input image signal 12. Next, in ST6, the difference information 32 is normalized (divided) by the value X of the signal activity. Divided by the value X of the signal activity this difference information N is smaller than the threshold value Th _NX, the filter to off. Divided by the value X of the difference information N signal activity, the threshold Th _NX at less than predicted is appropriate and the difference information 32 is small, or, it means a greater activity of the input image signal.
When the difference information 32 is small, it indicates that the prediction is appropriate, so that it is not necessary to turn on the filter. Also, when the activity of the input signal is large, the motion compensation prediction signal 14 often follows the input signal and contains many high-frequency components that change rapidly. Is output as is. Also, this difference information N is used as the signal activity value X.
In time divided by value is greater than the threshold value Th _NX is a filter to on. When the value obtained by dividing the value X of the signal activity this difference information N is larger than the threshold value Th _NX means that prediction is not adequate, a small activity difference information 32 is large or the input image signal. Difference information 3
When 2 is large, the prediction is not appropriate and the motion-compensated prediction signal 14 contains many high-frequency components. Therefore, by turning on the filter, the high-frequency component is removed from the motion-compensated prediction signal 14 to perform coding. Improve efficiency. When the activity of the input image signal is small, the filter is turned on similarly, but when the activity of the input image signal is large, the filter remains off. This is because, when the activity of the input image signal is large, the motion compensation prediction signal 14 is often a signal containing many high-frequency components that change rapidly. Therefore, the filter is turned off and the high frequency component of the motion compensation prediction signal 14 is left as it is. This improves the coding efficiency.

Next, FIG. 7 shows that the filter control unit 21 is turned on.
FIG. 14 is a diagram illustrating another example of the / off determination flow. 7, if the difference information N is greater than the threshold value Th _N, the filter to on. In this case the difference information N is larger than the threshold value Th _N, since the motion compensation prediction signal contains many high-frequency components, improve coding efficiency by removing high frequency components by the filter on Means that. Then, in ST5, signal activity X of the input image signal 12 is less than the threshold value Th _X, the filter to on. Signal activity X is threshold Th _X
A smaller input image signal hardly contains high frequency components. Therefore, even if the filter is turned on, there is almost no effect on the removal of the high frequency component, and the filter is turned off.
This is more effective in removing high-frequency noise than in the case of. Conversely, if signal activity X of the input image signal 12 is greater than the threshold value Th _X, and leaves the filter off. Signal activity X is the threshold Th _X is greater than the input image signal is considered to contain high frequency components. Therefore, it is considered that the motion compensation prediction signal 14 also includes a high frequency component corresponding to the input image signal 12. For this reason, the filter is kept off and the high-frequency component of the motion compensation signal 14 is output as it is.

FIG. 8 shows the on / off state of the filter control unit 21.
It is a figure which shows the other example of an off determination flow. The on / off determination flow shown in FIG. 8 is a combination of the flows shown in FIG. 6 and FIG. By using both the determination shown in FIG. 6 and the determination shown in FIG. 7, on / off of the filter can be determined using different threshold values, and the on / off control of the filter can be further finely controlled. Can be determined. Although not shown, it may be performed by comparing the signal activity and the threshold value Th _X to the on / off determination is calculated from the input image signal 12 of the filter control unit 21. That is, the difference information calculation process in ST2 from the on / off determination flow shown in FIG.
ST1 excluding process of comparison between h _N, ST3, ST5, S
The control of the filter may be performed using the on / off determination flow by T7.

When the value X of the signal activity is zero in ST6 of FIG. 6, since the signal activity cannot be divided by zero,
Although the result of the normalization is undefined, since the normalization operation is generally performed using a finite word length, the normalization operation has the maximum value in the word length. For example, in the case where the normalization operation is performed with a word length of 8 bits as one word, the normalization result is obtained by using the maximum value of the 8-bit value “FF”. this is,
This is the maximum value output by this normalization operation.

The adaptive filter section 22 performs a filtering process for removing high frequency components of the motion compensation prediction signal 14 according to the filter control signal 23. Fig. 9
As shown in FIG. 2, a filter having a one-dimensional or two-dimensional low-pass characteristic in the spatial direction or a three-dimensional filter having a filter coefficient value that changes with time can be applied.
3, the filter strength is changed.

FIG. 9 is a diagram for explaining a filter having one-dimensional, two-dimensional, and three-dimensional low-pass characteristics.
Indicates a filter having a low-pass characteristic in the one-dimensional direction. FIG. 9B shows a filter having a low-pass characteristic in a two-dimensional direction. FIG. 9C shows a filter having a low-pass characteristic in a three-dimensional direction by a processing unit of one-dimensional, two-dimensional, and frames at different times t1, t2, and t3. In FIG. 9, a black circle is a target pixel, and it is possible to perform a filtering process on the target pixel using pixels in one-dimensional, two-dimensional, or three-dimensional directions.

As shown in FIG. 10, the filtering process can be performed only on the pixels closed inside the processing unit of 8 × 8 pixels. However, the filtering process is performed on the pixels exceeding the processing unit of 8 × 8 pixels. The filtering process may be performed by using this. In FIG. 10, F1 indicates a case where a filtering process is performed on a pixel of interest over a processing unit of 8 × 8 pixels and using pixels of adjacent processing units. Similarly, F2 also shows a case where the pixel of interest is subjected to the filtering process using pixels in the processing unit of the adjacent 8 × 8 pixels.

Next, FIG. 11 is a diagram showing an example of the filtering process, and is a diagram for explaining the filtering process in the one-dimensional direction. Here, of the pixels S1 to S5, S3 is set as a target pixel. Also, K1 to K5 are coefficients, and the sum of K1 to K5 is assumed to be 1.0 as shown in FIG.

The filtering process is calculated by multiplying the luminance of each pixel by the coefficients K1 to K5 and taking the sum. If the values of the coefficients used for the filter use values as shown in FIG.
The target pixel S3 is affected by the brightness of the surrounding S1, S2, S4, and S5, and is averaged. On the other hand, when K3 = 1.0 and other coefficients are 0 as shown in FIG. 11D, the target pixel S3 has no effect on other pixels and is output as it is. , The filtering process is turned off.

FIG. 12 is a diagram showing a state where the strength of the filter changes by changing the coefficient in this way, and shows a case where the prediction signal 24 changes by the filtering process. According to the filter control signal 23, the coefficient of the filter changes, and as a result, the filter strength changes.
As shown in FIG. 2, the cut of the high frequency component of the prediction signal 24 can be controlled in multiple stages. That is, when the input signal contains many rapidly changing high-frequency components, the filter coefficient value changes and the prediction signal 24 changes in the direction of arrow A in FIG. If the input signal is a signal containing many low-frequency components, a filter is not inserted as shown by the arrow B in FIG.

The filtered prediction signal 24 is subtracted from the input image signal 12 by the subtractor 3 to generate a prediction error signal 15. The encoding unit 4 quantizes the prediction error signal 15 to generate encoded error information 16. Local decoding section 5 decodes encoded error information 16 and outputs local decoded error signal 17. The adder 6 outputs the prediction signal 24
And a local decoding error signal 17 to generate a local decoding signal 18, which is then written into the frame memory 1.

Embodiment 2 FIG. In the first embodiment, the motion vector detecting unit 2 is provided. However, due to simplification of the apparatus, for example, as shown in FIG. 13, the motion amount is always set to zero, and the motion vector detecting unit 2 shown in FIG. The same processing can be performed even when it is not provided.

Embodiment 3 FIG. In the first embodiment, the adaptive filter unit 22 is disposed after the frame memory 1.
Similar processing can be performed when the adaptive filter 22 is arranged downstream of the adder 6 as shown in FIG.

Embodiment 4 FIG. Also, as shown in FIG. 15, the motion amount is always set to 0 and the motion vector detecting unit 2 is not provided.
The adaptive filter 22 may be arranged after the adder 6.

Embodiment 5 FIG. Another embodiment of the present invention will be described with reference to FIG. The difference information 32 obtained by the filter control unit 21 is reduced by the number of pixels (8 × 8 = 64 pixels) and sent to the encoding unit 4 as difference information 25 per pixel.

FIG. 17 is a diagram showing the configuration of the filter control unit 21 in this embodiment. Reference numeral 33 denotes a per-pixel difference information calculation unit for calculating the per-pixel difference information 25. In the difference information calculation unit 30, as described above, the absolute value of the difference between the input image signal 12 and the motion-compensated prediction signal 14,
Alternatively, the difference square is calculated by taking the square of the difference and accumulating the difference square for a plurality of pixels (for 64 pixels) in a processing unit of 8 × 8 pixels.
Output as 2.

The fact that the per-pixel difference information calculator 33 divides this difference information 32 by 8 × 8 pixels, ie, 64 pixels, means that the average value of the difference information 32 per pixel is obtained. . In the encoding unit 4, the difference information 2 per pixel
5, the quantization step size is determined so that quantization is performed with a smaller encoding error.

FIG. 18 is a diagram for explaining the operation of the encoding unit 4 for determining the quantization step size. As shown in FIG. 18, the difference information 25 per pixel is the value of D1 for the first to eighth pixels, and the difference information 25 per pixel for the ninth to sixteenth pixels is the value of D2. , The difference information 25 per pixel for the 17th pixel to the 24th pixel is the value of D3. Then, it is assumed that the difference information D1, D2, and D3 per pixel are output from the filter control unit 21 in a relationship of D1>D2> D3 as shown in FIG.

When the encoding unit 4 receives such difference information 25 per pixel, the quantization step size of the first to eighth pixels is smaller than that of the difference information D1 per pixel. Select a step size SS1 that will be quantized. Similarly, for the ninth to sixteenth pixels, the step size SS quantized with a smaller encoding error based on the difference information D2 per pixel.
Select 2. For the 17th pixel to the 24th pixel,
A quantization step size SS3 that is quantized with a coding error smaller than the difference information D3 per pixel is selected. Accordingly, as shown in FIG. 18D, the quantization step size is selected by the encoding unit 4 in a relationship of SS1>SS2> SS3, and the input signal is quantized.

From the above, when the difference between the input image signal 12 and the motion compensated prediction signal 14 is large, the quantization step size becomes large, and when the difference between the input image signal 12 and the motion compensated prediction signal 14 is small. Reduces the quantization step size. Therefore, a decoded image with a small encoding error is generated.

However, the determination of the quantization step size in the encoding unit 4 is not determined only by the difference information 25 per pixel (also referred to as a control signal). For example, when the encoding amount is limited by the size of an output buffer for temporarily storing and outputting the encoded signal output from the encoding unit 4, the quantization step size is limited within the limitation. Select

Embodiment 6 FIG. In the fifth embodiment, the filter control unit 21 outputs the control signal 23 to the adaptive filter 22.
And the case where the control signal 25 is output to the encoding unit 4, there is no need to output these two control signals 23 and 25, and as shown in FIG. Alternatively, only the control signal 25 to 4 may be output. FIG. 20A is a diagram illustrating the configuration of the control unit 21 in this embodiment. The difference from FIG.
Is not present. In FIG. 20A, the operations of the difference information calculation unit 30 and the per-pixel difference information calculation unit 33 are the same as those described in the fifth embodiment, and a description thereof will not be repeated.

FIG. 20B is a diagram showing another configuration of the control section 21a in this embodiment.
Is characterized in that the signal activity is output as a control signal 25 from the. The determination unit 31a receives the input signal 12, and calculates the signal activity. The signal activity is calculated by a method as shown in FIG. 4 or FIG. As described above, the signal activity does not indicate the absolute intensity of the image signal, but indicates a relative value. That is, the value X of the signal activity becomes small in the case of a signal that changes smoothly such that it contains a lot of low frequency components, and the value X of the signal activity becomes large in the case that it contains a lot of rapidly changing high frequency components. Therefore, by inputting this signal activity as the control signal 25 and dynamically changing the quantization step size of the encoding unit 4, appropriate encoding can be performed.

FIG. 20C shows a configuration in which a motion compensation prediction signal 14 from a frame memory is input instead of the input signal 12 shown in FIG. 20B. Other operations are the same as those in FIG.

Embodiment 7 FIG. In the above embodiment, the case where the frame memory 1 stores the image frame as a unit has been described. However, the frame memory 1 may store the image frame in the field unit instead of the image frame unit. FIG. 21 shows the relationship between the frame and the field. FIG.
As shown in (a), one frame is composed of a first field and a second field, and the signal of the first field and the signal of the second field are displayed in the interlace mode as shown in FIG. By doing so, one image frame is configured.

Further, in the above-described embodiment, the case where the filter performs the filtering process in units of frames has been described, but the process may be performed in units of fields.

The same processing can be performed when the frame memory stores a plurality of frames. If there are multiple frames, the next frame or field that will be output after the current frame or field, such as a video that has already been shot, as well as having the previous frame or field May be stored.

Embodiment 8 FIG. In the above-described embodiment, the determination unit 31 obtains the signal activity of the input image signal 12 and normalizes the difference information 32. However, the determination unit 31 obtains the signal activity of the motion compensation prediction signal 14 and obtains the difference information 32.
The same processing can be performed by normalizing.

Embodiment 9 FIG. Hereinafter, an embodiment of the present invention will be described with reference to FIG. In FIG. 22, 41 is an encoding control unit, and 42 is an encoding control signal. Others are the same as FIG. However, FIG. 22 shows the adaptive filter 2 shown in FIG.
2. There is no filter control unit 21 and no motion vector detection unit 2.

Next, the operation will be described with reference to FIG. The image signal 11 of the previous frame stored in the frame memory 1 is used as a prediction signal. The subtractor 3 subtracts the image signal 11 from the input image signal 12 to generate a prediction error signal 15. The coding control unit 41 outputs a coding control signal 42 and a selection signal 150 to the coding unit 4 based on the activities of the input image signal 12 and the prediction error signal 15. The encoding unit 4 quantizes the selection signal 150 to generate encoded error information 16. Local decoding section 5 decodes encoded error information 16 and outputs local decoded error signal 17. After adding the image signal 11 and the local decoding error signal 17 by the adder 6 to generate a local decoding signal 18,
Write to frame memory 1. The coded error signal 16 generated in this way is transmitted via a transmission path.

The operation of the encoding control unit 41 will be described with reference to FIG. In the figure, 45 is an activity calculation unit, 46 is an activity comparison and selection unit, 12a is an activity obtained from the input image signal 12, 15a is an activity obtained from the prediction error signal 15, and 42
Is an encoding control signal for controlling the encoding unit, and 150 is a selection signal. In the coding control unit 41, the activity calculation unit 45 uses the input image signal 12 and the prediction error signal 1
5 are obtained and output to the activity comparison / selection unit 46.

Here, the signal activity means the difference between the maximum value and the minimum value of the signal or the sum of the absolute value of the difference from the signal average value or the sum of the square of the difference as described in the first embodiment. This activity is not the absolute intensity of the individual image signals, but a signal that changes smoothly over a plurality of pixels as a whole, that is, a signal that contains many low-frequency components, has a small signal activity value, and the high-frequency components that change rapidly , The value of the signal activity increases.

The activity comparison / selection section 46 compares the input activities and selects a mode that meets a predetermined condition. Here, the predetermined conditions include the following. (1) Select the mode that places the highest priority on the coding efficiency and maximizes the coding efficiency. (2) Emphasis is placed on improving the image quality, and a mode that improves the image quality is selected. (3) A considerable importance is given to the coding efficiency and the image quality, respectively, and if one of them increases the other importance, a mode having one of the importance is selected.

As described above, it is conceivable that the predetermined condition is to select a mode that matches the degree of importance with respect to the coding efficiency or the image quality. In addition, various conditions may be added depending on the system or apparatus. It is possible. For example, when selecting a mode that maximizes the above-described coding efficiency, a mode having a small signal activity is selected. On the other hand, when the mode for improving the image quality is selected, the input image signal 12 is selected. Also, when selecting a mode based on both the coding efficiency and the image quality, as a result of comparing the activities of the input image signal 12 and the prediction error signal 15, one of the signals may be selected if a certain relationship is satisfied. become. The activity comparison / selection unit 46 outputs a coding parameter such as a quantization step size based on the mode and the activity as the coding control signal 42,
The signal of the selected mode is output as the selection signal 150.

Next, the operation of the activity comparison and selection section 46 will be described with reference to FIG. In the figure, 46
a is a weighting circuit for weighting the activity 12a of the input image signal and / or the activity 15a of the prediction error signal 15, and 46b is a weighting circuit 4.
A comparator 46 for comparing the activities 12b and 15b of the input image signal and the prediction error signal output from 6a;
c is a control signal generator that selects either the input image signal 12 or the prediction error signal 15 and outputs it as a selection signal 150, and multiplexes a quantization step size and coding coefficients to output a coding control signal 42. It is. In this example, the weighting circuit 46a is not described for the sake of simplicity (the weighting circuit will be described later). Therefore, the comparator 46b has the activity 12a of the input image signal and the activity 15 of the prediction error signal.
a is input. The comparator outputs the result of comparing the two activities to the control signal generator as a mode signal 46m. The mode signal 46m is used for switching to select one of the input image signal 12 and the prediction error signal 15. Further, the mode signal 46m is multiplexed as a part of an encoding control signal together with encoding parameters such as a quantization step size and DCT (discrete cosine transform) coefficients in a control signal generator and output to the encoding unit 4. . The encoding unit 4 analyzes the signal multiplexed on the encoding control signal 42. For example, it is possible to know which of the input image signal 12 and the prediction error signal 15 is output as the selection signal from the mode signal. When the input image signal 12 is output as the selection signal 150, intra-frame encoding is performed. When the prediction error signal 15 is output as the selection signal 150, inter-frame coding is performed. These encoding processes are controlled by a quantization step size, a DCT coefficient, or the like.

Embodiment 10 FIG. An embodiment in which a filter control unit, an adaptive filter unit, and a motion vector detection unit are further incorporated in the ninth embodiment will be described with reference to FIG. 25, reference numeral 2 denotes a motion vector detection unit, 13 denotes a motion vector, 14 denotes a motion compensation prediction signal, 21 denotes a filter control unit, 22 denotes an adaptive filter unit, 23 denotes a filter control signal, 24 denotes a prediction signal, and the other in FIG. Is the same as The operation of each unit of the motion vector detection unit 2, the filter control unit 21, and the adaptive filter unit 22 is the same as that described in the first embodiment, and the description is omitted here.

In the ninth embodiment described above, the prediction error signal 15 is generated by subtracting this prediction signal from the image signal 11 of one frame before stored in the frame memory 1 as the prediction signal. On the other hand, Example 1
0 is that the prediction error signal 15 is obtained from the prediction signal 24 subjected to the filtering process from the filter control unit 21. That is, in this embodiment, the activity of the prediction error signal 15, which has been subjected to the filtering process control from the filter control unit 21 in advance, is compared with the activity of the intra-frame signal 12, and the coding control signal 42 is derived based on a predetermined condition. An example is shown.

As in this embodiment, the difference information between the input signal and the signal from the image memory is normalized by the filter control unit based on the activity of the input signal or the signal from the image memory. By changing the strength of the filter to be cut, high-frequency components do not always remain in the signal to be coded, and the coding control unit controls the activity of the prediction error signal and the input image signal that have been filtered in accordance with the filter strength. By deriving the coding control signal based on the signal of the mode having the least activity from the inside, the coding efficiency is improved.

Embodiment 11 FIG. In the ninth and tenth embodiments, the activities input by the activity comparison / selection unit 46 are compared to select a mode that meets the conditions, and the encoding parameters such as the quantization step size based on the mode and the activity are encoded. Although the mode was output as the control signal 42, the mode in which the minimum activity was output is selected from the activities input by the activity comparison / selection unit 46, and the encoding parameters such as the quantization step size based on the mode and the activity are encoded. It may be output as the conversion control signal 42. As described above, by selecting the one having the smallest activity, the encoding efficiency in the encoding unit is most improved.

Embodiment 12 FIG. In the ninth and tenth embodiments, when comparing the activities input by the activity comparison / selection unit 46, at least one of the activities may be weighted. FIG. 24 described above.
Is a circuit for weighting the activities in this embodiment. FIG. 26 is a diagram for explaining the operation of the weighting circuit 46a. FIG.
6A shows a case where the weighting circuit 46a does not weight any of the activities 12a and 15a of the input image signal 12 and the prediction error signal 15 for any of the activities. FIG. 26B shows that the weighting circuit 46a does not weight the activity 12a of the input image signal 12, and the prediction error signal 1
In the case of the activity 15a of No. 5, the value shown in FIG. 26A is weighted twice.

If the activity comparison / selection unit 46 selects the mode in which the smallest activity is output among the activities input, the activity 12a of the input image signal 12 is changed to the prediction error signal 15 in the case shown in FIG. The activity comparison / selection unit 46 outputs the prediction error signal 15 to the selection signal 1
Output as 50.

On the other hand, in the case of FIG. 26B, since the activity 15a of the prediction error signal 15 is weighted twice, the input image signal 12
Of the activity 12a. Therefore, the activity comparison and selection unit 46 sets the time t0 to the time t
During 1, the prediction error signal 15 is selected as the selection signal 150, and between time t1 and t2, the input image signal 12 is output as the selection signal 150.

FIG. 27 shows an embodiment of the processing flow of the weighting circuit 46a. The weighting circuit 46a calculates the activities 12a, 1a and 1b of the input image signal 12 and the prediction error signal 15.
5a, and then read out preset weighting coefficients W1 and W2. Then, the activity 12a of the input image signal 12 is multiplied by W1, the activity 15a of the prediction error signal is multiplied by W2, and the activity 12axW1 of the input image signal is weighted as the activity 12b of the input image signal. It outputs the activity 15axW2 of the prediction error signal as the activity 15b obtained by weighting the activity 15a of the prediction error signal (the difference signal between the input signal and the prediction signal read from the frame memory). In this example, both inputs are weighted, but either one may be used. In this embodiment, the input is the activity 12a of the input image signal and the activity 15a of the prediction error signal. However, three inputs may be used as in the embodiment described later, and the number of inputs is not limited. (See Example 15 described later).
FIG. 28 shows a specific processing flow of the weighting circuit described above. The operation of the weighting circuit is based on the activity 12a of the input image signal and the activity 15a of the prediction error signal.
a is input, the activity 12a of the input image signal is output as the activity 12b without weighting, and the activity 15a of the prediction error signal is weighted by doubling the activity 15a, and the result is used as the activity 1
Output as 5b.

Next, FIG. 29 shows an embodiment of the processing flow of the comparator 46b. The operation of the comparator 46b is to determine the coding mode by comparing the magnitudes of the two input signal activities. Activity 12b weighting activity 12a of the input image signal
And an activity 15b in which the activities of the prediction error signal (the difference signal between the input signal and the prediction signal read from the frame memory) are weighted, and if the activity 12b is smaller than the activity 15b,
The mode is set to the NTRA (intra-frame coding) mode, and if larger, the mode is set to the INTER (inter-frame coding) mode, and the selected mode is output as the mode signal 46m. Further, in the present embodiment, there are two inputs of the activity 12b and the activity 15b, but three inputs may be used as in the later-described embodiment, and the number of inputs is not limited (see the fifteenth embodiment which will be described later). ).

FIG. 30 shows an embodiment of the processing flow of the control signal generator 46c. The operation of the control signal generator 46c is to output the selection signal 150 and the control signal 42 according to the mode selected by the input mode signal 46m. The control signal generator 46c receives the input image signal 1
2, prediction error signal 15, weighted activities 12b and 15b, mode signal 4
Enter 6m. The control signal generator 46c checks the mode signal 46m, and outputs INTER (interframe coding).
In the mode, the prediction error signal 15 is output as the selection signal 150. The control signal generator 46c controls the activity 15
According to the size of b, the quantization step size (QUANT) and the DC are stored in the memory table shown in FIG.
Read the T output coefficient. The control signal generator 46c
Checks the mode signal 46m and outputs the input image signal 12 as the selection signal 150 in the case of the INTRA (intra-frame coding) mode. The control signal generator 46c determines the quantization step size (QUAN) from the memory table shown in FIG. 31B according to the size of the activity 12b.
T) and the DCT output coefficient are read. Read out quantization step size and DCT output coefficient and mode signal 4
6m are multiplexed and output as a control signal 42. In the present embodiment, the inputs are the activities 12b and 15b after weighting, but the activities 12a of the signal input image signal and the activity 15a of the prediction error signal before weighting may be input. However, in this case, it is necessary to change the contents of the memory table or the threshold. Also, the number of thresholds shown in FIG.
It may be more or less depending on the assignment of T and DCT output coefficients. The values of the QUANT and DCT output coefficients to be assigned may be changed according to the purpose of giving priority to image quality or encoding efficiency.

By performing weighting in this manner, it is possible to intentionally select a signal to be output as the selection signal 150. That is, the advantage of performing the weighting is that the occurrence probability of the input signal (the probability that the input signal is output as a selection signal) can be controlled according to the requirements of the encoding processing device and the image to be processed.

Embodiment 13 FIG. In Example 10 above,
The coding control unit 41 obtained the coding control signal 42 from the activities of the input image signal 12 and the prediction error signal 15, but the adaptive filter 22 did not perform the filtering and the activity of the prediction error signal 15 that was subjected to the filtering process. The encoding control signal 42 may be derived based on the activity of the signal having the smallest activity by comparing the activity of the prediction error signal 15 in that case.

FIG. 32 is a diagram showing an example of this embodiment. In the figure, reference numeral 24a denotes a prediction signal that has been subjected to filter processing by the adaptive filter 22. 24b is an adaptive filter 2
2 is a prediction signal that has not been subjected to the filtering process.
These prediction signals 24a and 24b are subtracted by subtracters 3a and 3
b, and a difference from the input image signal 12 is obtained, and prediction error signals 15x and 15y are output. The prediction error signals 15x and 15y are input to the encoding control unit 41, and the encoding control signal 42 is obtained by the operation described above.

Embodiment 14 FIG. In Example 13 above,
The coding control unit 41 derives the coding control signal 42 based on the activity of the prediction error signal 15 subjected to the filtering process by the adaptive filter 22 and the activity of the prediction error signal 15 when the filtering process is not performed. In this case, the activity of at least one of the activity of the prediction error signal 15 that has been subjected to the filter processing by the adaptive filter 22 and the activity of the prediction error signal 15 that has not been subjected to the filter processing may be weighted.

Embodiment 15 FIG. In Example 13 above,
The coding control unit 41 derives the coding control signal 42 based on the activity of the prediction error signal 15 that has been subjected to the filtering process by the adaptive filter 22 and the activity of the prediction error signal 15 when the filtering process has not been performed. Prediction error signal 15 filtered by filter 22
And the activity of the prediction error signal 15 when the filtering process is not performed, and the activity of the input image signal 12 based on the intra-frame prediction, and a code is determined based on the activity of the signal having the smallest activity. The conversion control signal 42 may be derived.

FIG. 33 is a diagram showing an example of this embodiment. 33 differs from FIG. 32 in that the input image signal 1
2 is input to the encoding control unit 41. The encoding control unit 41 outputs the filtered prediction error signal 15x
And the prediction error signal 15y and the input image signal 12 which have not been subjected to the filtering process, and the coding control signal 42 is derived by selecting a signal having the smallest activity, for example.

FIG. 34 is a diagram showing the configuration of the encoding control unit 41 in this embodiment. The above-described encoding control unit 4
The difference from 1 is that the filtered prediction error signal 15x
And three signals, that is, the prediction error signal 15y not subjected to the filtering process and the input image signal 12.
The activity calculation unit 45 calculates the activity of the three input signals and outputs the calculated activity to the activity comparison and selection unit 46. FIG. 35 is a diagram showing the configuration of the activity comparison and selection unit 46. The activity comparison and selection unit inputs the activities 12a, 15a, and 15c of the three signals calculated by the activity calculation unit 45 to the weighting circuit 46a. It is assumed that the weighting circuit 46a stores W1, W2, and W3 as weighting coefficients in advance.
The weighting circuit multiplies the activity 12a by W1, the activity 15a by W2,
c is multiplied by W3 and weighted, and the weighted activities 12b, 15b and 15d are output to the comparator 46b. The comparator 46b compares the three weighted signals, and generates a mode signal 46m from the magnitude relation. The control signal generator 46c receives the input image signal 12, the filtered prediction error signal 15x, and the unfiltered prediction error signal 15y, and
m, and selects one of the signals based on
Is output. The control signal generator 46c outputs the selection signal 1
When the signal selected as 50 is the input image signal 12, the quantization step size and DCT output coefficient stored in the memory table in advance are read according to the size of the activity 12b of the input image signal 12. Alternatively, when the signal selected as the selection signal 150 is the filtered prediction error signal 15x, the quantization step stored in the memory table in advance according to the size of the activity 15b of the filtered prediction error signal 15x. Read the size and DCT output coefficient. Alternatively, when the signal selected as the selection signal 150 is the unfiltered prediction error signal 15y, it is stored in the memory table in advance according to the magnitude of the activity 15d of the unfiltered prediction error signal 15y. The quantized step size and DCT output coefficient are read. The read quantization step size, DCT output coefficient and mode signal 46m are multiplexed and output as a control signal 42.

Embodiment 16 FIG. In Example 15 above,
The encoding control unit 41 compares the activity of the prediction error signal 15 filtered by the adaptive filter 22 with the activity of the prediction error signal 15 when the filtering process is not performed, and the activity of the input image signal 12 by intra-frame prediction. Then, the coding control signal 42 is derived based on the activity of the signal having any of the smallest activities. However, at the time of derivation, the activity of the prediction error signal 15 subjected to the filtering process by the adaptive filter 22 and the filtering process are not performed. Of the prediction error signal 15 in the case and the input image signal 12 by the intra-frame prediction
At least one of the activities may be weighted.

Embodiment 17 FIG. In Example 15 above,
The encoding control unit 41 compares the activity of the prediction error signal 15 filtered by the adaptive filter 22 with the activity of the prediction error signal 15 when the filtering process is not performed, and the activity of the input image signal 12 by intra-frame prediction. Then, the coding control signal 42 is derived based on the activity of the signal having the smallest activity, but the activity of the prediction error signal which has been subjected to the filtering process control from the filter control unit in advance and the input image by the intra-frame prediction. The coding control signal 42 may be derived based on the activity of the signal having the smallest activity by comparing the activity with the signal.

Embodiment 18 FIG. In Example 17 above,
The activity of the prediction error signal, which has been subjected to the filtering process control from the filter control unit in advance, is compared with the activity of the input image signal by intra-frame prediction, and the coding control signal is determined based on the activity of the signal having the smallest activity. 42, but when comparing the activity of the prediction error signal, which has been subjected to the filtering process control from the filter control unit in advance, with the activity of the input image signal by intra-frame prediction, at least one of the activities is weighted. May go.

FIG. 36 is a diagram showing an example of this embodiment. The feature of FIG. 36 is that the filter control unit 21
Filter control signal 23 output from encoding control section 4
This is the point input to 1. This filter control signal 2
When 3 is input to the encoding control unit 41, it is input to the weighting circuit 46a shown in FIG. Weighting circuit 46a
By analyzing the filter control signal 23, it can be determined that the adaptive filter 22 is on or off. Therefore, for example, the adaptive filter 22
When the prediction error signal 15 based on the prediction signal 24 in which is turned on is input to the encoding control unit 41, weighting is performed, and the prediction error signal 15 based on the prediction signal 24 in which the adaptive filter 22 is turned off is encoded. When input to the control unit 41, it is possible to perform control not to perform weighting. Note that the weighting control is not limited to ON and OFF, and it is also possible to dynamically change the weighting value according to the value of the filter control signal 23.

Embodiment 19 FIG. In Example 10 above,
The input signal 12 and the frame memory 1 are stored in the filter control unit 21.
The filter control signal 23 is determined by normalizing the information corresponding to the difference from the input image signal 12 with the input image signal 12. However, the filter control signal 23 is determined based on the magnitude of the information itself corresponding to the difference without normalization. May be output.

Embodiment 20 FIG. In Example 10 above,
The input signal 12 and the frame memory 1 are stored in the filter control unit 21.
The filter control signal 23 is determined by normalizing the information corresponding to the difference between the input signal 12 and the signal from the frame memory 1 by the input signal 12. The filter control unit 21 corresponds to the difference between the input signal 12 and the signal from the frame memory 1. Filter control signal 23 according to information
May be determined.

Embodiment 21 FIG. In Example 10 above,
Information corresponding to the difference between the input image signal 12 and the signal from the frame memory 1 is input by the filter control unit 21 to the input image signal 1.
Although the filter control signal 23 is determined by normalizing by 2, the filter control signal 23 may be output to the adaptive filter 22 based on the result of normalizing the information corresponding to the difference with the signal from the image memory 1.

Embodiment 22 FIG. In the tenth embodiment, the adaptive filter unit 22 is arranged after the frame memory 1, but the adaptive filter 22 may be arranged after the adder 6 as shown in FIG. In this case, the filtered local image signal or the unfiltered local image signal is written into the frame memory 1 and the subtractor 3
And the prediction signal 24 output from the frame memory 1 to generate a prediction error signal 15 to perform coding control.

Embodiment 23 FIG. Further, the frame memory 1 is not limited to the image frame unit but may be the field unit, and the same processing can be performed when a plurality of frames are provided.

Embodiment 24 FIG. Further, the filter control unit and the coding control unit may be integrated to perform overall control as a new coding control unit. FIG. 38 is a diagram showing an example of this embodiment. The feature of this figure is that an encoding control / filter control unit 50 is provided. This encoding control / filter control unit is obtained by integrating the filter control unit 21 and the encoding control unit 41 of the above-described embodiment.
As described above, the filter control unit 21 and the encoding control unit 4
Since both 1 operate using the activity of the input signal, a small device can be obtained by sharing the portion for calculating these activities. In addition, since the calculation of the activity is performed collectively at one place, the control of the entire apparatus can be easily performed.

Embodiment 25 FIG. In the tenth embodiment, the motion vector detection unit 2 is provided. However, the same processing can be performed even when the motion vector detection unit 2 is not provided, for example, by always setting the motion amount to zero by simplifying the apparatus. is there.

Embodiment 26 FIG. In the ninth to twenty-fifth embodiments, the coding control unit 41 or the coding control / filter control unit 50 is combined with the feedback control based on the coded data output from the coding unit 4 to perform the coding control. May be performed. FIG. 39 is a diagram illustrating a case where feedback control is performed on the encoding control unit 41 illustrated in the ninth embodiment. In the figure, reference numeral 100 denotes a transmission buffer for storing encoded data output from the encoding unit 4;
Reference numeral 60 denotes a transmission signal output from the transmission buffer 100, 1
01 is a feedback signal fed back from the transmission buffer 100. The encoding control unit 41 controls the encoding control signal 42 based on the feedback signal 101. For example, assuming that the feedback signal 101 indicates the data occupancy of the transmission buffer, when the data occupancy is high, the encoding control signal 42 is output so that the encoding amount of the encoding unit 4 is reduced. Conversely, when the data occupancy is low, the encoding control signal 42 is output so that the encoding amount of the encoding unit 4 is increased.

Embodiment 27 FIG. Further, in the above embodiment, the case where the difference between the maximum value and the minimum value of the signal or the sum of absolute differences or the sum of squares of the differences from the signal average value is used as the characteristic based on the signal as the signal activity has been described. An activity is an example of a feature obtained based on a signal. As a feature based on the signal as described above, a difference between a maximum value and a minimum value of a signal or a sum of absolute differences or a sum of squares of differences from a signal average value is used. A similar effect can be obtained by using not only the case of using the difference signal but also the other difference signal or dispersion.

Embodiment 28 FIG. In the first to twenty-seventh embodiments, a case has been described in which image data of 8 × 8 pixels is used as a processing unit. However, when other processing units such as 16 × 16 pixels, 32 × 32 pixels, or 8 × 16 pixels are used. It does not matter.

Embodiment 29 FIG. In the first to twenty-seventh embodiments, images are handled as signals and data. However, signals and data such as radar and audio may be handled, and the present invention is not limited to image data.

[0127]

Since the first to seventeenth aspects of the present invention are configured as described above, the following effects can be obtained.

By using the difference information between the input signal and the signal from the frame memory in the filter control unit to change the filter strength for cutting the high frequency component, the high frequency component does not remain in the signal to be encoded and the coding efficiency is reduced. Is improved.

Further, since the filtering process is performed irrespective of the motion, the visual resolution is not reduced even in the moving area. Also, by removing high-frequency components that are hard to be visually perceived even in a static region, a visually good encoded image can be obtained.

Further, even when an image used for prediction contains a large number of quantization errors, high frequency components are removed by the filtering process, and the coding efficiency is improved.

Further, by using a plurality of high-frequency component removal filters having different filter intensities, it is possible to always perform prediction such that the encoding loop gain is small, and the encoding efficiency is improved.

By controlling the coding error based on the error information per pixel, a decoded image with a small coding error is always generated, and prediction over the next frame and thereafter can be performed efficiently.

Since the eighteenth to twenty-seventh aspects are configured as described above, the following advantages can be obtained.

By deriving the coding control signal based on the activities of the input signal and the prediction error signal in the coding control section, the coding efficiency can be improved.

By weighting the activities handled by the encoding control unit, the probability of occurrence of the selected signal can be controlled in accordance with the requirements of the encoding processing device and the image to be processed.

Since the filtering process and the derivation of the coding control signal are performed irrespective of the motion, the high-frequency component which is hardly perceived even in the static region is removed without lowering the visual resolution even in the moving region. Thus, a visually good encoded image can be obtained.

Even when an image used for prediction contains a large amount of quantization error, high-frequency components are removed by filter processing, and the coding control unit performs a coding control signal based on a signal having the least activity. Is derived, the coding efficiency is improved.

The encoding control unit derives the encoding control signal based on the signal of the mode having the minimum activity from the activities of the signals of the plurality of modes, so that the encoding control unit always predicts that the encoding loop gain is small. And the coding efficiency is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of an inter-frame encoding processing method according to an embodiment of the present invention.

FIG. 2 is a block diagram of a filter control unit according to one embodiment of the present invention.

FIG. 3 is a diagram illustrating a method for calculating difference information according to an embodiment of the present invention.

FIG. 4 is a diagram for explaining signal activity in one embodiment of the present invention.

FIG. 5 is a diagram for explaining signal activity in one embodiment of the present invention.

FIG. 6 illustrates a filter control unit on /
It is an off determination flowchart.

FIG. 7 shows a filter control unit on /
It is an off determination flowchart.

FIG. 8 shows a filter control unit on /
It is an off determination flowchart.

FIG. 9 is a diagram for explaining one-dimensional, two-dimensional, and three-dimensional filter processing in one embodiment of the present invention.

FIG. 10 is a diagram for describing filtering processing across processing units according to an embodiment of the present invention.

FIG. 11 is a diagram for explaining the operation of the adaptive filter in one embodiment of the present invention.

FIG. 12 is a diagram for describing an output example of an adaptive filter according to one embodiment of the present invention.

FIG. 13 is a block diagram of an inter-frame encoding method according to a second embodiment of the present invention.

FIG. 14 is a block diagram of an inter-frame encoding processing method according to a third embodiment of the present invention.

FIG. 15 is a block diagram of an inter-frame encoding processing method according to a fourth embodiment of the present invention.

FIG. 16 is a block diagram of an inter-frame encoding processing method according to a fifth embodiment of the present invention.

FIG. 17 is a block diagram of a filter control unit according to Embodiment 5 of the present invention.

FIG. 18 is a diagram for explaining an operation of an encoding unit according to the fifth embodiment of the present invention.

FIG. 19 is a block diagram of an inter-frame encoding processing method according to a sixth embodiment of the present invention.

FIG. 20 is a block diagram of a control unit according to a sixth embodiment of the present invention.

FIG. 21 is a diagram for explaining a relationship between a frame and a field according to a seventh embodiment of the present invention.

FIG. 22 is a block diagram of an inter-frame encoding processing method according to a ninth embodiment of the present invention.

FIG. 23 is a block diagram of an encoding control unit according to Embodiment 9 of the present invention.

FIG. 24 is a block diagram of an activity comparison and selection unit according to Embodiment 9 of the present invention.

FIG. 25 is a block diagram of an inter-frame encoding processing method according to a tenth embodiment of the present invention.

FIG. 26 is a diagram for explaining the operation of the weighting circuit according to the tenth embodiment of the present invention.

FIG. 27 is a processing flowchart of a weighting circuit according to an embodiment of the present invention.

FIG. 28 is a processing flowchart of a weighting circuit in Embodiment 12 of the present invention.

FIG. 29 is a processing flowchart of a comparator according to an embodiment of the present invention.

FIG. 30 is a processing flowchart of a control signal generator according to one embodiment of the present invention.

FIG. 31 is a diagram showing a memory table of a control signal generator according to one embodiment of the present invention.

FIG. 32 is a block diagram of an inter-frame encoding processing method according to Embodiment 13 of the present invention.

FIG. 33 is a block diagram of an inter-frame encoding processing method according to Embodiment 15 of the present invention.

FIG. 34 is a block diagram of an encoding control unit according to Embodiment 15 of the present invention.

FIG. 35 is a block diagram of an activity comparison and selection unit according to Embodiment 15 of the present invention.

FIG. 36 is a block diagram of an interframe encoding processing method according to Embodiment 18 of the present invention.

FIG. 37 is a block diagram of an inter-frame encoding processing method according to Embodiment 22 of the present invention.

FIG. 38 is a block diagram of an inter-frame encoding processing method according to Embodiment 24 of the present invention.

FIG. 39 is a block diagram of an inter-frame encoding processing method according to Embodiment 26 of the present invention.

FIG. 40 is a block diagram of a conventional interframe coding processing method.

FIG. 41 is a diagram for explaining an operation when a filter is turned on / off in a conventional interframe coding processing method.

FIG. 42 is a diagram for explaining an operation of a filter of a conventional example of an interframe encoding processing method.

FIG. 43 is a diagram for explaining an operation of a filter of a conventional example of an inter-frame encoding processing method.

[Explanation of symbols]

1 frame memory, 2 motion vector detector, 3 subtractor, 4 encoder, 5 local decoder, 6 adder,
7 filter, 8 filter control section, 11 image signal of one frame before, 12 input signal, 13 motion vector,
14 motion compensation prediction signal, 15 prediction error signal, 16
Encoded error signal, 17 local decoding error signal, 18
Local decoded signal, 19 Smoothed local decoded signal, 2
0 control signal, 21 filter control unit, 22 adaptive filter unit, 23 filter control signal, 24 prediction signal, 2
5 Difference information per pixel, 30 Difference information calculation unit, 31
Determination unit, 32 difference information, 33 difference information calculation unit per pixel, 41 coding control unit, 42 coding control signal, 45
Activity calculation unit, 46 activity comparison and selection unit, 150 selection signal.

Claims (8)

[Claims] 1. An encoding control method comprising: an encoding unit that encodes an inter-frame signal generated from an input signal and a signal read from a frame memory or encodes an intra-frame signal. Encoding based on the comparison result and the characteristic determined based on the intra-frame signal, and controlling the selection of intra-frame encoding or inter-frame encoding in the encoding unit based on the comparison result. Providing an encoding control unit that outputs a control signal, the encoding control unit, when comparing the characteristics obtained based on the inter-frame signal and the characteristics obtained based on the intra-frame signal, A coding control method, wherein weighting is performed on at least one of them and comparison is performed. 2. An encoding control method comprising: an encoding unit that encodes an inter-frame signal or an intra-frame signal generated from an input signal and a signal read from a frame memory. An encoding control unit that outputs an encoding control signal that controls encoding of the encoding unit using characteristics obtained based on a signal read from a frame memory, a filter that performs a filter process, the input signal, An encoding control method comprising: a filter control unit that receives a signal from a frame memory as an input and outputs a control signal of the filter. 3. The encoding control unit according to claim 1, wherein the encoding control unit determines at least a characteristic obtained based on the filtered prediction error signal and a characteristic obtained based on the prediction error signal when the filtering is not performed. 3. The encoding control according to claim 2, wherein at least any two of the characteristics obtained based on the intra-frame signal are compared, and an encoding control signal is set based on the comparison result. method. 4. The encoding control unit includes: a feature obtained based on the prediction error signal that has been subjected to the filtering process; and a feature obtained based on the prediction error signal when the filtering process has not been performed. 4. The coding control according to claim 3, wherein when comparing at least two of the features obtained based on the input signal by prediction, at least one of the comparisons is weighted. method. 5. An encoding control signal from the encoding control unit is obtained based on a characteristic obtained based on a prediction error signal which has been subjected to a filtering process under control of the filter control unit in advance and an intra-frame signal. 3. The encoding control method according to claim 2, wherein the signal is compared with the obtained characteristic, and the signal is set and controlled based on the comparison result. 6. A comparison between a feature obtained based on a prediction error signal which has been subjected to filter processing control by the filter control unit in advance and a feature obtained based on an intra-frame signal. 6. The encoding control method according to claim 5, wherein a comparison is performed by weighting one of the two. 7. A patent comprising an encoding control unit for outputting an encoding control signal to an encoding unit in order to perform feedback control based on encoded data output from the encoding unit. Claims 1, 2, and 3
Item 7. The encoding control method according to Item 4, Item 5, or Item 6. 8. The encoding control unit uses a difference between a maximum value and a minimum value of a signal or a sum of absolute differences or a sum of squares of differences from a signal average value as a feature obtained based on the signal. Claims 1 and 2
Item 8. The encoding control method according to item 3, item 3, item 4, item 5, item 6, or item 7.