JPH09238350A - Dynamic image coder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the coding efficiency by utilizing correlation of frames as to each band component signal of an image signal divided into plural frequency bands. SOLUTION: A band split filter 10 divides an input image signal 100 into four band component signals. A 1st coding circuit 20 detects a motion vector from a band component signal 11 at a lowest frequency band and applies motion compensation prediction coding to the signal. A 2nd coding circuit 104 receives a motion vector as a result of the motion compensation and applies inter-frame coding or in-frame coding to band component signals 12, 13 including other high frequency bands in response to the motion vector 14. A 3rd coding circuit 30 applies in-frame coding to the band component signal 14 at the highest frequency band. Since the inter-frame coding is applied to the band component signals 12, 13 including the high frequency band, the correlation between frames is utilized, the generated code information quantity is small and the image quality of the decoded image is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a moving picture coding apparatus which divides an image signal into a plurality of frequency bands and performs subband coding.

[0002]

2. Description of the Related Art In recent years, subband coding has been known as one of compression methods for image signals. In this subband coding, an image signal is divided into band component signals (subband signals) in a plurality of frequency bands by a horizontal and vertical band division filter, and an optimum code is given to each of the divided band component signals. This is a process for converting the data.

FIG. 6 shows an explanatory diagram in the case of dividing an input image signal into four, as an example of sub-band division. A quadrature mirror filter (QMF) is known as a band division filter for removing aliasing distortion. In the figure, reference numerals 600, 608 and 612 are band pass filters having a high pass (HP) characteristic, 602, 610 and 614 are band pass filters having a low pass (LP) characteristic, and 604 and 606 are horizontal down-sampling circuits (decimation circuits). , 61
Reference numerals 6, 618, 620 and 622 are vertical down-sampling circuits (thinning-out circuits).

The input image signal 100 is horizontally filtered by band division filters 600 and 602, divided into two frequency bands, and then downsampled horizontally by downsampling circuits 604 and 606. Further, the down sampling circuit 60
4 is vertically filtered by band division filters 608 and 610, and the output of the down sampling circuit 606 is band division filters 612 and 614.
Vertically filtered by the image signal 10
0 is divided into four band components. Then, down-sampling circuits 616, 618, 620, and 622 down-sample the band components in the vertical direction. As a result, the input image signal 100 has a low-frequency band component signal 11 in the horizontal and vertical directions, a low-frequency band component signal 12 in the horizontal direction and a high frequency in the vertical direction, and a high-frequency band component signal in the horizontal direction and a low frequency in the vertical direction. Frequency band component signal 13 and high frequency band component signal 14 in both the horizontal and vertical directions
Is divided into four band components. The number of pixels of each band component is half the value of the input image signal 100 in both the horizontal and vertical directions.

Further, as another example of the above-mentioned sub-band division, FIG. 7 is an explanatory diagram in the case of dividing the input image signal 100 into seven. In FIG. 7, 700, 708, 7
12, 724, 732, and 736 are bandpass filters having high-pass characteristics, and 702, 710, 714, 726, and 73.
4, 738 are band-pass filters having low-pass characteristics, and 70
4, 706, 728, 730 are horizontal down-sampling circuits (decimation circuits), 716, 718, 720,
Reference numerals 722, 740, 742, 744, and 746 are vertical down-sampling circuits (decimation circuits).

In FIG. 7, as in FIG. 6, the input image signal 10
After dividing 0 into four, the lowest frequency band component signal (LL
Only 1) is further subjected to repeated horizontal and vertical filtering and down-sampling to obtain seven band component signals (HH1, HL1, LH).
1, HH2, HL2, LH2, LL2: where the numerical value is 1,
2 represents the number of layers). The number of pixels of each band component (HH2, HL2, LH2, LL2) in the second layer is 1/4 of the input image signal in both the horizontal and vertical directions.

As a moving picture coding apparatus using the above-mentioned sub-band division, for example, Kishimoto, Okumura, and Irie "HDTV transmission distribution system in ATM network" (PC
There is a moving picture coding apparatus shown in SJ'90).
This moving picture coding apparatus applies the transmitting unit to subband coding. FIG. 8 is a configuration diagram of band division subband encoding in a conventional moving image encoding apparatus. In the figure, 100 is a digitized input image signal,
Reference numeral 10 is a band division filter having the configuration shown in FIG. 6 or 7, and divides the input image signal 100 into band component signals of four frequency bands. Reference numeral 20 denotes a low-frequency coding circuit that performs motion compensation predictive coding on the component signal 11 in the lowest frequency band of the divided band component signals, and outputs coded data 112 and motion vector information 114. Reference numerals 30, 40, and 50 denote high-frequency encoding circuits having the same configuration as each other, and band component signals 12, 1 including a high-frequency region.
A quantizer 16 for quantizing 3 and 14 and a variable-length coding circuit 18 for variable-length coding the signal quantized by the quantizer 16 are built-in.
To output encoded data 116, 118, and 120, respectively. Reference numeral 60 denotes a multiplexing circuit, which is the low band encoding circuit 2
Coded data 112 from 0 and motion vector information 11
The coded data 116, 118 and 120 from the four and three high band coding circuits 30, 40 and 50 are multiplexed, and the multiplexed coded sequence 70 is output.

Here, the high frequency encoding circuits 30, 40 and 50.
The coding in 1 is a coding closed in the current frame (intra-frame coding). On the other hand, the coding in the low-band coding circuit 20 is a coding for the band component signal of the lowest frequency, and since the correlation between pixels is strong, the coding using frequency conversion by orthogonal transformation is performed, for example. This coding is interframe coding.

[0009]

However, the above configuration has the following problems. That is, when the motion of the input image is small, although the correlation between frames is generally strong, the coding of the band component signal including the high frequency range is always the intra-frame coding. This causes an increase in the code information amount. Further, since the coding of each band component signal is closed in that frequency band, the correlation existing between each band component cannot be used, which causes deterioration in image quality at the time of coding and an increase in the amount of generated code information.

The present invention has been made in view of the above problems of the prior art.
It is therefore an object of the present invention to provide a moving picture coding apparatus that positively uses the correlation between frames in band component signals, and a moving picture coding apparatus that does not increase the amount of generated code information at the time of coding.

[0011]

In order to achieve the above object, the present invention adopts a structure capable of performing inter-frame coding on a band component signal including a high frequency component, and also in a part of a high frequency band. Then adopts a configuration in which the image signal is not divided.

That is, the moving picture coding apparatus according to the first aspect of the invention is a band dividing means for dividing an image signal into band component signals of a plurality of frequency bands, and a lowest frequency band divided by the band dividing means. Motion detecting means for detecting a motion vector of the band component signal of the above, and a motion compensating means for obtaining a prediction error signal which is a difference between the band component signal of which the motion vector is detected by the motion detecting means and the prediction signal, and performing motion compensation. A low-band coding means for coding the prediction error signal motion-compensated by the motion compensating means, and a band component of a predetermined partial frequency band other than the frequency band of the band component signal in which the motion vector is detected. It is characterized by comprising high-band coding means for inter-frame coding the signal and other high-band coding means for intra-frame coding the band component signal of the remaining frequency band. To.

According to a second aspect of the present invention, there is provided a moving picture coding apparatus in which a band dividing means for dividing an image signal into band component signals of a plurality of frequency bands and a band of the lowest frequency band divided by the band dividing means. Motion detecting means for detecting a motion vector for a component signal; motion compensating means for obtaining a prediction error signal which is a difference between a band component signal in which the motion vector is detected by the motion detecting means and a prediction signal, and performing motion compensation; One of low-frequency coding means for coding the prediction error signal motion-compensated by the motion compensating means, and either inter-frame coding or intra-frame coding based on the motion vector information detected by the motion detecting means. And selecting a band component signal of a predetermined partial frequency band other than the frequency band of the band component signal in which the motion vector is detected according to the selection. A high band encoding means for reduction, characterized in that a further higher-band coding means for intraframe coding band component signals of the remaining frequency band.

According to a third aspect of the present invention, in the moving picture coding apparatus according to the first or second aspect, the low band coding means includes an orthogonal transformation circuit for orthogonally transforming the prediction error signal,
A quantizer for quantizing the prediction error signal converted by the orthogonal transform circuit; and a variable length coding circuit for variable length coding the prediction error signal quantized by the quantizer. To do.

According to a fourth aspect of the present invention, in the moving image encoding apparatus according to the first aspect, the high frequency encoding means includes a frame memory for storing decoded image data in band component units, and decoding of the frame signal. An image data and a subtracter for inputting a band component signal of a frequency band other than the frequency band of the band component signal in which the motion vector is detected, and subtracting the decoded image data from the band component signal to obtain a difference signal,
A quantizer for quantizing the difference signal of the subtractor, a variable length coding circuit for variable length coding the output of the quantizer, and an inverse quantizer for dequantizing the output of the quantizer. , An output of the dequantizer and the decoded image data of the frame memory are input, and an adder for adding both to obtain new decoded image data, the decoded image data of the adder being the frame memory. Is stored in.

According to a fifth aspect of the present invention, in the moving image encoding apparatus according to the second aspect, the high frequency encoding means performs intra-frame encoding or frame based on the motion vector information detected by the motion detecting means. A switching instruction circuit that instructs inter-coding, a frame memory that stores decoded image data in band component units, decoded image data of the frame signal, and a frequency band other than the frequency band of the band component signal in which the motion vector is detected. , A subtracter for subtracting the decoded image data from the band component signal to obtain a difference signal, and a frequency band of the band component signal in which the motion vector is detected according to the instruction of the switching instruction circuit. A first selector for selecting one of a band component signal of a frequency band other than the above and a difference signal of the good multiplier, and an output of the first selector. And variable-length coding circuit for variable-length coding and the quantizer, the output of the quantizer for quantizing,
An inverse quantizer that inversely quantizes the output of the quantizer; a second selector that selects the decoded image data of the frame memory or stops the selection according to an instruction of the switching instruction circuit; An output of the inverse quantizer and an output of the second selector are input, and an adder for adding both to obtain new decoded image data is provided, and the decoded image data of the adder is stored in the frame memory. It is characterized by being stored.

According to a sixth aspect of the present invention, in the moving picture encoding apparatus according to the fifth aspect, the first selector selects the output of the subtractor when the switching instruction circuit instructs interframe encoding. On the other hand, when the intra-frame coding is instructed, the band component signal in the frequency band other than the frequency band of the band component signal in which the motion vector is detected is selected, and the second
The selector is characterized in that when the switching instruction circuit instructs inter-frame coding, it selects the decoded image data in the frame memory, and when instructing intra-frame coding, the selection of the decoded image data is stopped.

According to a seventh aspect of the present invention, in the moving picture coding apparatus according to the fifth aspect, the switching instruction circuit inputs the motion vector information detected by the motion detecting means, and the number of motion vectors that are not zero values. When is greater than or equal to a set value, intraframe coding is instructed, and when the number of non-zero motion vectors is less than the set value, interframe coding is instructed.

According to an eighth aspect of the present invention, in the moving image encoding apparatus according to the first or second aspect, the other high band encoding means is a quantizer for quantizing the input band component signal. , And a variable length encoder for variable length encoding the output of the quantizer.

According to a ninth aspect of the present invention, there is provided a moving picture coding apparatus in which a band dividing means for dividing an image signal into band component signals of a plurality of frequency bands and a band of the lowest frequency band divided by the band dividing means. Motion detecting means for detecting a motion vector for a component signal; motion compensating means for obtaining a prediction error signal which is a difference between a band component signal in which the motion vector is detected by the motion detecting means and a prediction signal, and performing motion compensation; A low-band encoding unit that encodes a prediction error signal that has been motion-compensated by the motion compensation unit, and a high-band unit that encodes a band component signal in a frequency band other than the frequency band of the band component signal in which the motion vector is detected. Encoding means, and the plurality of frequency bands in the band dividing means are frequency bands excluding a predetermined frequency band.

According to a tenth aspect of the present invention, in the moving picture coding apparatus according to the ninth aspect, the predetermined frequency band is a frequency band having a high frequency in the horizontal and vertical directions. .

With the above arrangement, in the inventions according to claims 1 to 8, since the inter-frame coding is adopted in the high band coding means, the correlation between frames can be utilized and the image quality at the time of coding can be improved. The amount of generated code information can be improved and the amount of generated code information can be relatively small.

In particular, according to the second aspect of the invention, intra-frame coding or inter-frame coding is selected based on the motion vector detected for the low-frequency band component signal, and the high-frequency band component signal is selected. Since the coding is performed, the correlation existing between the band component signals can be used, and the deterioration of the image quality at the time of coding can be suppressed to a small level.

According to the ninth and tenth aspects of the present invention, since the image signal is not divided in a part of the high frequency band, the division processing speed of the image signal is increased and the amount of generated code information is increased. To be prevented. In particular, when the high frequency band that is not divided is limited to a band having a high frequency in the horizontal direction and the vertical direction, the band component signal has low power in this band, so that the image quality of the decoded image is kept good. It

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a moving picture coding apparatus according to the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
2 shows a moving picture coding apparatus according to the embodiment. In FIG. 1, 100 is a digitized input image signal, and 10 is a band division filter (band division means), which divides the input image signal 100 into band component signals of four frequency bands by the configuration of FIG. . That is, a signal 11 in the low frequency band in both the horizontal and vertical directions, a signal 12 in the low frequency range in the horizontal direction and a high frequency range in the vertical direction, a signal 13 in the high frequency range in the horizontal direction and a low frequency range in the vertical direction, and The signal 14 is divided into a high frequency signal 14 in both the vertical and vertical directions.

Reference numeral 20 is a first coding circuit for performing motion compensation predictive coding of the component signal 11 of the lowest frequency band among the divided band component signals, and outputs coded data 112 and motion vector information 114. To do. Reference numeral 104 denotes a second encoding circuit (high frequency encoding means) having a characteristic configuration of the present invention, which inputs a part of the band component signals 12 and 13 including the high frequency component and outputs the band component. Signals 12, 13
Is encoded between frames, and each encoded data 116,
118 is output. Reference numeral 30 denotes a third encoding circuit (another high frequency encoding means), which is the remaining high frequency band component signal 1
4 is input, the band component signal 14 is intra-frame encoded, and encoded data 120 is output. Reference numeral 60 denotes a multiplexing circuit, which is coded data 112 and motion vector information 114 from the first coding circuit 20 and coded data 1 from the second and third coding circuits 104 and 30.
16, 118, and 120 are multiplexed, and the multiplexed coded sequence 70 is output.

The third encoding circuit 30 has the same structure as the high frequency encoding circuit 30 of FIG. 8 showing the conventional example. That is, similar to the configuration of FIG. 8, a quantizer 16 for quantizing the band component signal 14 and a variable length coding circuit 18 for variable length coding the quantized signal are provided, and the coding is performed. Coded data 120 is output from the circuit 18.

The internal structure of the first encoding circuit 20 is shown in FIG. The encoding circuit 20 of FIG. 9 includes a motion detection circuit (motion detection means) 199 and a motion compensation circuit (motion compensation means).
200 and a low frequency encoding circuit (low frequency encoding means) 201.

The motion detection circuit 199 reads out a block 28 located around the block to be coded from the frame memory 198 described later, inputs the low frequency band signal 11, and finds the block which is the closest from both of them. The motion vector is selected, the motion vector is detected from the position of this block, and the detected motion vector information 114 is output to the multiplexing circuit 60.

The motion compensation circuit 200 has a frame memory 198 and a subtractor 191. The frame memory 198 stores a signal obtained by locally decoding the encoded data of the previous frame as described later, and the motion detection circuit 1
The block closest to the block based on the motion vector information 114 detected at 99 is output as the prediction signal 27. Further, the subtractor 191 subtracts the prediction signal 27 from the frame memory 198 from the low frequency band signal 11,
The prediction error signal 21 that is the result of the subtraction is output to the low-band encoding circuit 201.

The low frequency encoding circuit 201 orthogonally transforms the prediction error signal 21 from the subtractor 191 and outputs a transform coefficient signal 22 which is the result of the transformation.
92 and a quantizer 19 for quantizing the transform coefficient signal 22 of the orthogonal transform circuit 192 and outputting the quantized signal 23.
3 and the quantized signal 23 of the quantizer 193 are variable length coded and compressed, and the resulting coded data 112 is output to the multiplexing circuit 60.

The motion compensation circuit 200 further includes the quantized signal 23 of the quantizer 193 of the low band encoding circuit 201.
And an inverse quantizer 195 for dequantizing
95 inversely quantized signal 24 is inversely orthogonally transformed and locally decoded,
An inverse orthogonal transform circuit 196 that outputs the resulting decoded difference signal 25, and an adder 197 that adds the decoded difference signal 25 from the inverse orthogonal transform circuit 196 and the prediction signal 27 from the frame memory 198. , The adder 1
The current frame signal, which is the addition result of 97, is stored in the frame memory 198.

FIG. 3 shows the internal structure of the second encoding circuit 104. The encoding circuit 104 in the figure includes an encoding circuit 104a for inter-frame encoding the high band component signal 12, and
The other high band component signal 13 is composed of an encoding circuit 104b for inter-frame encoding.
b has the same configuration. The internal configuration of the encoding circuit 104a will be described below. The encoding circuit 104a in the figure includes a frame memory 306 that stores decoded image data obtained by locally decoding the encoded data of the previous frame in units of band components.
From the input band component signal 12 to the frame memory 30
Decoded image data (prediction signal) 31 of the previous frame from 6
7, a subtracter 301 for subtracting 7, a quantizer 302 for quantizing the difference signal 312 from the subtractor 301, and a variable length coding circuit for variable length coding the quantized signal 313 from the quantizer 302. And a dequantizer 304 that dequantizes and decodes the quantized signal 313 from the quantizer 302 to obtain a decoded differential signal 315, and a decoded differential signal 315 of the dequantizer 304. An adder 305 for adding the prediction signal 317 from the frame memory 306 to obtain locally decoded image data 316, and the locally decoded image data 316 of the adder 305 is stored in the frame memory 306 and stored in the next frame. Used for encoding.

Therefore, in the present embodiment, inter-frame coding using the difference between the locally decoded image signal of the previous frame and the coding of the two band component signals 12 and 13 which are high frequency band components is performed. Adopted. Therefore, when the motion of the input image is relatively small, there is a correlation between the frames, so that the coding efficiency can be increased and the generated code information amount can be suppressed to be small.

(Second Embodiment) FIG. 2 shows a second embodiment of the present invention.
2 shows a moving picture coding apparatus according to the embodiment. 2 is different from FIG. 1 in the internal configuration of the second encoding circuit 105. The motion vector information 114 detected by the first coding circuit 20 is input to the second coding circuit 105.

FIG. 4 shows the internal structure of the second encoding circuit 105. The coding circuit 105 in the figure comprises a coding circuit 105a for coding the high band component signal 12 and a coding circuit 105b for coding another high band component signal 13, and both circuits 105a and 105b are It has the same configuration. The internal configuration of the encoding circuit 105a will be described below.
The coding circuit 105a in the figure is obtained by adding the following configuration to the coding circuit 104a of the first embodiment.
Hereinafter, only the added configuration will be described, the same reference numerals will be given to the same configuration portions, and the description thereof will be omitted. In the encoding circuit 105a in the figure, an inter-frame / intra-frame encoding switching instruction circuit 402, a first selector 408,
And a second selector 409.

The inter-frame / intra-frame coding switching instruction circuit 402 inputs the motion vector information 114 from the motion detection circuit 199, compares the total number of non-zero motion vectors with the threshold value TH, and sets the result to zero. When the sum of non-valued motion vectors is greater than or equal to the threshold value TH, the instruction signal 421 is output so as to select intraframe coding, while when the sum of non-zero motion vectors is less than the threshold value TH, the interframe code is selected. The instruction signal 421 is output so as to select the conversion. The first selector 408 receives the instruction signal 421 and selects the input band component signal 12 when the selection of the intraframe coding is instructed, while the selection signal 421 is instructed when the selection of the interframe coding is instructed. , The difference signal from the subtractor 301 is selected, and the selected signal is output to the quantizer 302. The second selector 409 outputs the instruction signal 421.
When the selection of inter-frame coding is instructed, the prediction signal 317 of the frame memory 306 is selected, and this prediction signal 317 is output as the selection signal 429 to the adder 305, while the intra-frame coding is selected. When the selection is instructed, the selection of the prediction signal 317 is stopped.

Therefore, in the present embodiment, either intra-frame coding or inter-frame coding is selected and coded based on the motion vector information obtained from the low-frequency band component signal 11, and the input image is selected. When there is little motion, the inter-frame coding is performed using the correlation between frames, while when there is a lot of motion in the input image such as a scene change, intra-frame coding is performed, so the generated code information amount is It can be suppressed to a small level, and the deterioration of image quality at the time of encoding can be suppressed to a small level.

(Third Embodiment) FIG. 5 shows a moving picture coding apparatus according to the third embodiment. In the present embodiment, the entire configuration of the moving picture coding apparatus is shown in FIG. 8 showing a conventional example, or FIG. 1 showing the first or second embodiment of the present invention.
The configuration is the same as that of FIG. 2, and only the internal configuration of the band division filter 10 is different.

FIG. 5 shows the band division filter 9 of this embodiment.
2 shows the internal configuration of FIG. In the figure, reference numerals 600 and 602 denote band-pass filters having high-pass characteristics and low-pass characteristics, respectively, which are orthogonal mirror filters that divide the input image signal 100 into two frequency bands in the horizontal direction, and 604 and 606 denote the band-dividing filters 600 and 602. Is a down-sampling circuit for down-sampling each of the output signals of. Further, 610 is the down sampling circuit 6
04 is a band-pass filter having a low-pass characteristic for vertically filtering the output of 04, 612 and 614 are band-pass filters having a high-pass characteristic and a low-pass characteristic for vertically filtering the output of the down-sampling circuit 604, and 618, 620 and 622, respectively. Vertical down-sampling circuits for down-sampling the outputs of the vertical band-splitting filters 610, 612, 614, respectively. The down-sampling circuits 618, 620, 6
22 denotes a band component signal 13 having a high frequency in the horizontal direction and a low frequency in the vertical direction, a band component signal 12 having a low frequency in the horizontal direction and a high frequency in the vertical direction, and a low frequency band in both the horizontal and vertical directions. The component signal 11 is output.

Therefore, in the present embodiment, the high frequency band component signal is not divided in both the horizontal and vertical directions. This band component signal has a smaller signal power than the other three band component signals. Therefore, the image quality of the decoded image is not significantly affected, the division processing speed into band components is increased by the amount not divided, and the amount of code information generated at the time of encoding can be suppressed.

The present invention is not limited to the above embodiment. For example, in the first and second embodiments, the band division filter 10 performs the band division shown in FIG. 6, but the band division is performed by the band division of FIG. 7 or the band component LL2 in the band division of FIG. Is further repeatedly filtered in the horizontal and vertical directions and further down-sampled to divide into 10 band components, or other band dividing method may be used. Further, in the first and second embodiments, the second coding circuits 104 and 105 perform interframe coding on the band component signals 12 and 13, but interframe code other band component signals. May be.
Similarly, although the third encoding circuit 30 performs the intra-frame encoding on the band component signal 14, it may also intra-frame encode another band component signal. Further, in the second embodiment, the coding method is determined by comparing the total number of non-zero-valued motion vectors with the threshold value. However, even if the instruction signal is output by another determination method based on the motion vector information. Good. In addition, in the above embodiment, the orthogonal transformation circuit after motion compensation,
Quantization and variable length coding were performed, but PCM coding or D
PCM encoding may be performed. Moreover, the orthogonal transform, the quantization, and the variable length coding are not limited to these, and other methods may be used.

[0044]

As described above, according to the moving picture coding apparatus of the invention described in claims 1 to 8, the inter-frame coding is adopted for coding the band component signal in the high frequency range. Therefore, the correlation between frames can be used, the quality of a decoded image can be improved, and the amount of generated code information can be effectively reduced.

In particular, according to the moving picture coding apparatus of the second aspect of the invention, intraframe coding or interframe coding is selected based on the motion vector detected for the low-frequency band component signal, Since the band component signals in the high frequency band are coded, it is possible to suppress the deterioration of the image quality at the time of coding by utilizing the correlation existing between the band component signals.

According to the ninth and tenth aspects of the present invention, since the image signal is not divided in a part of the high frequency band, the image signal division processing speed can be improved. It is possible to prevent the increase of the generated code information amount. In particular, when the high frequency band that is not divided is limited to a band having a high frequency in the horizontal direction and the vertical direction, the image quality of the decoded image can be kept good.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a moving picture coding apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an overall configuration of a moving picture coding device according to a second embodiment of the present invention.

FIG. 3 is a diagram showing an internal configuration of a second coding circuit in the moving picture coding apparatus according to the first embodiment of the present invention.

FIG. 4 is a diagram showing an internal configuration of a second coding circuit in the moving picture coding apparatus according to the second embodiment of the present invention.

FIG. 5 is a diagram showing an internal configuration of a band division filter in a moving picture coding device according to a third embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a method of band division.

FIG. 7 is an explanatory diagram showing another method of band division.

FIG. 8 is a diagram showing an overall configuration of a conventional moving image encoding device.

FIG. 9 is a diagram showing an internal configuration of an encoding circuit in a conventional moving image encoding apparatus.

[Explanation of symbols]

10 band division filter 16 quantizer 18 variable length coding circuit 30 third coding circuit (other high frequency coding circuit) 104, 105 second coding circuit (high frequency coding circuit) 114 motion vector information 192 Orthogonal transformation circuit 193 Quantizer 194 Variable length coding circuit 199 Motion detection circuit (motion detection means) 200 Motion compensation circuit (motion compensation means) 201 Low band coding circuit (low band coding means) 301 Subtractor 302 Quantum Decoder 303 Variable length coding circuit 304 Dequantization circuit 305 Adder 306 Frame memory 402 Switching instruction circuit 408 First selector 409 Second selector

Claims (10)

[Claims] 1. A band division unit for dividing an image signal into band component signals of a plurality of frequency bands, and a motion detection unit for detecting a motion vector for the band component signal of the lowest frequency band divided by the band division unit. A motion compensation unit that obtains a prediction error signal that is a difference between a band component signal whose motion vector is detected by the motion detection unit and a prediction signal, and performs motion compensation; and a prediction error signal that is motion compensated by the motion compensation unit. A low-band coding means for coding, a high-band coding means for inter-frame coding a band component signal of a predetermined partial frequency band other than the frequency band of the band component signal in which the motion vector is detected, A moving picture coding apparatus, comprising: another high band coding means for intra-frame coding the band component signals of the remaining frequency bands. 2. Band division means for dividing an image signal into band component signals of a plurality of frequency bands, and motion detection means for detecting a motion vector for the band component signal of the lowest frequency band divided by the band division means. A motion compensation unit that obtains a prediction error signal that is a difference between a band component signal whose motion vector is detected by the motion detection unit and a prediction signal, and performs motion compensation; and a prediction error signal that is motion compensated by the motion compensation unit. A low-band encoding means for encoding, selecting either one of inter-frame encoding and intra-frame encoding based on the motion vector information detected by the motion detecting means, and the band in which the motion vector is detected. High-band encoding means for encoding a band component signal in a predetermined partial frequency band other than the frequency band of the component signal according to the selection, and the remaining frequency Band video encoding apparatus characterized by comprising a and another higher-band coding means for encoding the frame band component signals. 3. The low band encoding means comprises an orthogonal transform circuit for orthogonal transforming a prediction error signal, a quantizer for quantizing the prediction error signal transformed by the orthogonal transform circuit, and a quantizer for quantizing the quantizer. 3. The moving picture coding apparatus according to claim 1, further comprising a variable length coding circuit that performs variable length coding on the converted prediction error signal. 4. The high frequency encoding means includes a frame memory for storing decoded image data in band component units, decoded image data of the frame signal, and frequencies other than the frequency band of the band component signal in which the motion vector is detected. A band component signal of a band is input, a subtractor that subtracts the decoded image data from the band component signal to obtain a difference signal, a quantizer that quantizes the difference signal of the subtractor, and a quantizer of the quantizer. A variable length coding circuit for variable length coding the output, an inverse quantizer for dequantizing the output of the quantizer, an output of the dequantizer and the decoded image data of the frame memory are input, The moving image encoding apparatus according to claim 1, further comprising an adder that adds both of them to obtain new decoded image data, and the decoded image data of the adder is stored in the frame memory. 5. The high-band encoding means includes a switching instruction circuit for instructing intra-frame encoding or inter-frame encoding based on the motion vector information detected by the motion detecting means, and decoded image data in band component units. A frame memory that stores the decoded image data of the frame signal and a band component signal in a frequency band other than the frequency band of the band component signal in which the motion vector is detected are input, and the decoded image data is subtracted from the band component signal. A subtractor for obtaining a difference signal, and, in accordance with an instruction of the switching instruction circuit, one of a band component signal in a frequency band other than the frequency band of the band component signal in which the motion vector is detected, and the difference signal of the subtractor. A first selector for selecting one, a quantizer for quantizing the output of the first selector, and a variable length coding for the output of the quantizer A variable-length coding circuit, an inverse quantizer that inversely quantizes the output of the quantizer, and a decoding image data in the frame memory is selected according to an instruction from the switching instruction circuit, or the selection is stopped. 2 selectors, and an adder that inputs the output of the dequantizer and the output of the second selector and adds both of them to obtain new decoded image data. The moving picture coding apparatus according to claim 2, wherein the image data is stored in the frame memory. 6. The band selector signal, wherein the first selector selects the output of the subtractor when the switching instruction circuit instructs inter-frame coding, and the motion vector is detected when instructing intra-frame encoding. The second selector selects the decoded image data in the frame memory when the switching instruction circuit instructs the inter-frame encoding, and instructs the intra-frame encoding. 6. When performing, the selection of the decoded image data is stopped.
The moving picture encoding device according to the above. 7. The switching instruction circuit inputs the motion vector information detected by the motion detecting means, instructs the intra-frame coding when the number of non-zero motion vectors is equal to or more than a set value, and does not indicate the zero value. The moving picture coding apparatus according to claim 5, wherein when the number of motion vectors is less than a set value, interframe coding is instructed. 8. Another high-band encoding means comprises a quantizer for quantizing an input band component signal, and a variable-length encoder for variable-length encoding the output of the quantizer. The moving picture coding device according to claim 1 or 2. 9. A band division unit for dividing an image signal into band component signals of a plurality of frequency bands, and a motion detection unit for detecting a motion vector for the band component signal of the lowest frequency band divided by the band division unit. A motion compensation unit that obtains a prediction error signal that is a difference between a band component signal whose motion vector is detected by the motion detection unit and a prediction signal, and performs motion compensation; and a prediction error signal that is motion compensated by the motion compensation unit. A low-band coding means for coding, and a high-band coding means for coding a band component signal in a frequency band other than the frequency band of the band component signal in which the motion vector is detected, A plurality of frequency bands are frequency bands excluding a predetermined frequency band, and a moving picture encoding device. 10. The moving picture coding apparatus according to claim 9, wherein the predetermined frequency band is a frequency band having a high frequency in the horizontal and vertical directions.