JPH06178280A - Picture information coder and picture information decoder - Google Patents

Abstract

PURPOSE:To reduce code quantity by terminating coding at a termination code when non-significant information obtained from output information of a scanning means or re-quantization of the output information continues to the end. CONSTITUTION:An entropy coder 4 discriminates data and counts the number of consecutive 0s as a run length and allies 2-dimension Huffman coding by combining data not being zero and the run length of 0 data so far and stops scanning at an EOB code representing an end of a block when 0 data continues to its end. Then a coding signal bb obtained through a transmission line 5 and a demodulation means is decoded by an entropy decoder 6 in complementary relation to the entropy coder 4 and its output signal is fed to an inverse quantization device 8 via an inverse scanning means 7 implementing inverse scanning to the scanning means 3, in which inverse quantization is applied and the resulting output signal is synthesized by a synthesis filter bank 9 in complementary relation to a division filter bank 1 as an output picture digital signal cc and it is fed to the transmission line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image information encoding device and an image information decoding device.

[0002]

2. Description of the Related Art FIG. 7 is a block diagram for explaining a conventional divided filter bank, and FIG. 8 is a conceptual diagram for explaining respective bands of a plurality of signals obtained by the conventional divided filter bank. 9 is a conceptual diagram for explaining a conventional scanning method.

In recent years, a sub-band coding system has been proposed as a digital image information compression / decompression system. Among them, a method of performing band division as shown in FIG. 8 by performing analysis with a filter bank having a tree structure as shown in FIG. 7 is known as a method with high coding gain (Reference 1,
Fujii and Nomura: “About Wavelet conversion (5)”,
IEICE Technical Report, IE92-11 (1992).
Here, FIGS. 7 and 8 are FIG. 1, Fi
g. It is quoted from 2. ). In FIG. 8, the horizontal high band and the vertical low band obtained by performing two-dimensional sub-band division on the image signal are HL1, the horizontal high band is the vertical high band, HH1, and the horizontal low band. The band of the high frequency band in the vertical direction is represented by LH1, and the band obtained by performing two-dimensional sub-band division on the band of the low frequency band in the vertical direction in the horizontal direction is similarly defined as bands HL2, HH2, and LH2. Further, bands obtained by dividing the horizontal low band into the vertical low band are represented by HL3, HH3, LH3, and LL3 (lowest band in both horizontal and vertical directions).

For example, if the input image is horizontal 720 pixels ×
When it consists of 480 pixels in the vertical direction, the number of data in each band is H
L1, HH1, and LH1 are each 360 in the horizontal direction × 240 in the vertical direction, HL2, HH2, and LH2 are each 180 in the horizontal direction × 120 in the vertical direction, HL3, HH3,
LH3 and LL3 are each 90 in the horizontal direction x 6 in the vertical direction
It is 0. Band division as shown in FIG. 8 is also known as wavelet transform, but it is not always necessary to use a filter bank for wavelet transformation as a filter bank for band division and synthesis. Document 1 that can be used
Are described in.

The band-divided digital image signal as shown in FIG. 8 is requantized and further entropy coded. At the time of entropy coding, it is necessary to read out the requantized data in order and code them. This reading is generally called scanning. When entropy-encoded data is recorded on a digital VTR, it is often divided into a predetermined number of bits and error-correction encoded. Since the error generated in the recording / reproducing system is not necessarily corrected, the scanning method must take this into consideration. Even if the error could not be corrected by performing scanning as in Reference 2 (Ota: "Study of Image Coding by Wavelet Transform (2)", IEICE Spring National Convention, D-336, 1999). It can be seen that the effect is limited to a part of the image. Reference 2
This method is said to be a scanning method that can effectively use the locality of the image signal. The method of Document 2 will be briefly described below with reference to FIG. Note that FIG. 9 is a reference of FIG. Document 2 also cites the case of dividing into 10 bands as shown in FIG. L in FIG.
The layer 1 is for the layer 1 and the layer 2 is for the layer 2
3, HH3, LH3, Layer3 is band HL2, H
H2, LH2, and Layer4 have bands HL1, HH1,
LH1 is shown respectively. In FIG. 9, black circles are represented as data having a non-zero value, white circles are represented as data having a value of 0, and broken-line arrows indicate the scanning order. Therefore,
One data item in Layer 1 or band LL3 is scanned, and then Layer 2 or band HL3, HH3, L
The H3 data is scanned one by one. Layer3
That is, data in bands HL2, HH2, LH2 are scanned one by one, and Layer4, that is, bands HL1, HH1,
The data of LH1 is scanned one by one, and then the bandwidth HL1,
The data located immediately to the right of the previous data of HH1 and LH1, the data located immediately below, and the data located at the lower right are also scanned in the same manner. Further, the bands HL2, HH2, L
This is a method of scanning the data located to the right of the previous data of H2. Further, as shown in the figure, scanning of each subtree of the quadtree structure is performed after the last non-zero data by EOS (E
nd of Subtree) code is set to terminate.

The resolution of Layer 2 is twice as high as that of Layer 1 in both horizontal and vertical resolutions.
er3 is for Layer2, Layer4 is for Layer
Since the resolution is twice as high as that of er3 in both horizontal and vertical directions, it means that the scanning of FIG. 9 scans signals in all bands corresponding to image signals of horizontal 8 pixels × vertical 8 pixels at a certain position of the image. .

As described above, according to the conventional technique, the data extracted from each of the plurality of sub-band-divided bands are sequentially scanned from the data in the low band, and this scanning is repeated to make one block. It was scanning.

[0008]

However, since the scanning method as shown in FIG. 9 repeats scanning from the low range to the high range,
There is a drawback in that high frequency data having a high probability of “0” (non-significant information) is evenly allocated during the scanning period, and the code amount after entropy coding becomes relatively large.

Therefore, the present invention provides an image information coding apparatus capable of reducing the code amount of such an image information signal after entropy coding, and an image image information decoding apparatus corresponding thereto. The purpose is to do.

[0010]

The present invention provides the following configurations in order to solve the above problems.

A division filter bank for sub-band dividing the input image information into information relating to a plurality of bands, and information relating to the plurality of bands or information obtained by requantizing the information of a predetermined number for each of the plurality of bands. In an image information coding apparatus having a blocking unit that collects information and virtually blocks it, a scanning unit that scans the output information of the blocking unit in order from the information on the low band and for each band. An image information coding apparatus, comprising: an output information of the scanning means or an encoding means for stopping the encoding with an end code when the non-significant information of the information obtained by requantizing the output information continues to the end. .

In an image information decoding apparatus for decoding encoded image information, when insignificant information continues to the end, decoding means for decoding encoded information which is terminated by an end code, and the decoding means. Output information or information obtained by inversely quantizing the output information, and the inverse scanning means for performing inverse scanning for each band in order from the information related to the low band, and the output information of the inverse scanning means or the inverse quantization for the output information. An image information decoding apparatus, comprising: a synthesis filter bank that performs sub-band synthesis based on the obtained information.

A division filter bank for dividing input image information into sub-band information into a plurality of bands, and a predetermined number of pieces of information about the plurality of bands or information obtained by requantizing the information for each of the plurality of bands. In an image information coding apparatus having a blocking means for collecting information and virtually dividing it into blocks, output information of the blocking means based on information relating to a relatively low band of output information of the blocking means. Scanning means for scanning the information in the relatively high frequency band by changing the scanning order and scanning the information in the relatively low frequency band, and the output information of the scanning means or the output information of the scanning means. An image information encoding apparatus, comprising: an encoding unit that terminates encoding with an end code when insignificant information of quantized information continues to the end.

In the image information decoding device for decoding the encoded image information, when the non-significant information continues to the end, the decoding means for decoding the encoded information which is terminated by the end code, and the decoding means. Of the output information or the information obtained by dequantizing the output information is inversely scanned, and the information about the relatively high frequency band is based on the information about the relatively low frequency band. Image information decoding having inverse scanning means for varying the scanning order of the inverse scanning means and inverse scanning, and a synthesis filter bank for performing subband synthesis based on output information of the inverse scanning means or information obtained by inversely quantizing the output information apparatus.

A division filter bank for dividing the input image information into a plurality of bands by sub-band division, and output information of the division filter bank or information obtained by requantizing the output information is collected as predetermined information for each of the plurality of bands. In an image information encoding device having a block forming means for virtually forming a block, a relatively small portion of the output information of the block forming means is output based on information relating to a relatively low band of the output information of the block forming means. An image information coding apparatus having a DPCM coding means for selectively DPCM coding information relating to a high frequency band.

In an image information decoding apparatus for decoding encoded image information, the decoded information relating to a relatively low frequency band and the decoded information relating to a relatively high frequency band are supplied. And DPCM decoding means for selectively DPCM decoding the decoded information on the relatively high frequency band based on the decoded information on the relatively low frequency band. Image information decoding device.

[0017]

1 is a block diagram of a first embodiment of an image coding / decoding apparatus according to the present invention, FIG. 2 is a conceptual diagram for explaining a virtual data block, and FIG. 4 is a conceptual diagram for explaining an example, FIG. 4 is a block diagram of a second embodiment of an image encoding / decoding device according to the present invention, FIG. 5 is a block diagram of a third embodiment of an image encoding device according to the present invention, FIG. 6 is a block diagram of a third embodiment of the image decoding apparatus according to the present invention. Embodiments will be described below with reference to the drawings.

[First Embodiment] The outline of the first embodiment is that the high-frequency components of an image are visually less important than the low-frequency components.
Focusing on the high probability that the data value related to the high frequency band is 0 because coarse requantization is performed, scanning is performed in order from the signal related to the low frequency band of the virtual block and for each band. It was decided to.

(Image Coding Device) The image coding device will be described with reference to FIG. An input digital image signal aa supplied from a transmission line (not shown) is subjected to two-dimensional sub-band division by a tree-structured division filter bank 1 as shown in FIG. 7, and divided into 10 bands as shown in FIG. It Further, the quantizer 2 requantizes the signals in each band.
The name of each band signal is HL as shown in FIG.
1, HH1, LH1, HL2, HH2, LH2, HL
3, HH3, LH3, LL3.

Then, data is collected from the data of each band and grouped in the same manner as in the conventional example, and is virtually regarded as a block. That is, one from LL3, HL3, HH3, and LH3, and two from HL2, HH2, and LH2 in the horizontal direction.
HL1, HH1, LH, 4 pieces in total x 2 pieces in the vertical direction
A total of 16 pieces of data from 1 to 4 in the horizontal direction × 4 in the vertical direction are collected and regarded as a total of 64 virtual data blocks. By collecting the data in this way, it means that the signals of all bands corresponding to the image signal of horizontal 8 pixels × vertical 8 pixels at a certain position of the input image are collected. FIG. 2 shows one of such data blocks. In the figure, one section divided by a solid line or a broken line represents one piece of data, and each piece of data is represented by (i, j) (i and j are 0 <i <7 and 0, respectively). <J <7 is an integer, i indicates the i-th row and j indicates the j-th column data.) As shown, for example, (0, 0), (0,
1), (1, 1), (1, 0) are in the band LL3,
Data from HL3, HH3, LH3, (0,
2), (0, 3), (1, 2), (1, 3) are bands HL
2 is data from (0, 4) to (0, 7),
(1,4) to (1,7), (2,4) to (2,7),
(3, 4) to (3, 7) are data from the band HL1. The other data are also data from the illustrated bands.

Then, the scanning means 3 scans the virtual data blocks of FIG. 2 as follows and rearranges them one-dimensionally. First, (0,0), (0,1), (1,0),
(1,1), (0,2), (0,3), (1,2),
(1,3), (2,0), (2,1), (3,0),
(3,1), (2,2), (2,3), (3,2),
Scanning is performed in the order of (3, 3) (referred to as scanning A).

Next, the data from the band LH1,
(4,0) to (4,3), (5,0) to (5,3),
(6, 0) to (6, 3) and (7, 0) to (7, 3) are scanned in this order (referred to as scan B).

And, the data from the band HL1,
(0,4) to (3,4), (0,5) to (3,5),
(0, 6) to (3, 6) and (0, 7) to (3, 7) are scanned in this order (referred to as scan C).

Finally, the data from the band HH1
(4,4) to (4,7), (5,4) to (5,7),
(6, 4) to (6, 7) and (7, 4) to (7, 7) are scanned in this order (referred to as scan D). In this way, the signals obtained by performing the scans A to D are supplied to the entropy encoder 4.

The entropy encoder 4 determines whether the value of each data is 0, and the number of consecutive 0-value data is counted as a run length. On the other hand, when there is non-zero data, two-dimensional Huffman coding is performed by combining the value and the run length of the zero data up to that point. When 0 data continues to the end, EOB (E
The scan is terminated with the nd of Block) code. The coded signal bb thus obtained is supplied to the transmission line 5 via the modulation means (not shown).

(Image Decoding Device) In FIG. 1, the entropy decoder in which the coded signal bb obtained through the transmission line 5 and the demodulation means (not shown) has a complementary relationship with the entropy encoder 4 described above. Decrypted at 6. Then, the output signal is supplied to the inverse quantizer 8 via the inverse scanning means 7 which performs the scanning reverse to that of the above-mentioned scanning means 3, where the same quantization step as that of the above-mentioned quantizer 2 is used. Inverse quantization is applied. Then, the output image digital signal cc obtained by synthesizing the output signal of the inverse quantizer 8 by the synthesizing filter bank having a complementary relationship with the above-mentioned division filter bank 1
Is supplied to a transmission line (not shown).

It should be noted that FIG. 2 shows the arrangement of virtual blocks, and it goes without saying that it is not necessary to arrange data on an actual storage device. In the above example, the image signals are HL1, HH1, LH1, HL2, HH2, LH2, H.
It is divided into 10 bands of L3, HH3, LH3, and LL3.
It is natural that the entropy coding can be performed in the same manner even when the data is divided into L4, HH4, LH4, and LL4, and the total of 13 bands are divided. Further, in the present embodiment, the two-dimensional Huffman coding is performed by combining the 0 run length and the value of the non-zero data following the 0 run length, but these may be coded separately.
Further, the data (0, 0) may be processed differently from other data. Further, in this embodiment, the data from the band LH1 is scanned next to the data from the bands HL1 and HH1, but the data from the band HL1 is scanned and then the band L
The data from H1 and HH1 may be scanned. The scanning order of the data in the scan A does not have to be as described above. This is the same for scans B, C and D. The scanning order of these may be determined in advance by the encoder and the decoder.

Further, for example, as shown in FIG. 3, the band LH1
Is further divided into two bands LHL1 and LHH1, the method of the present invention can be applied, and the data (4,0) to (7,0) and (4,1) to FIG.
From the band LHL1 as (7, 1), (4, 2)-
Band LH as (7, 2) and (4, 3) to (7, 3)
The data from H1 may be used.

[Second Embodiment] In this embodiment, the bands LH1 and HL of the virtual data blocks (FIG. 2) of the first embodiment are used.
1, the method of scanning the data from HH1,
The scanning method of the signal relating to the relatively high frequency band is changed based on the signal relating to the relatively low frequency band.

(Encoding Device) A second embodiment will be described with reference to FIG. The same components as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

From the quantizer 2, the signal 2a relating to the first relatively low frequency band and the signal 2 relating to the first relatively high frequency band
b and are output. Here, the signal 2a related to the first relatively low frequency band is a signal corresponding to the above-described scan A, and is (0, 0 to 3) in the data block of FIG.
It has data of (1, 0-3), (2, 0-3), (3, 0-3), while the signal 2b relating to the first relatively high band is the other data. Is a signal related to.

Signal 2 relating to the first relatively low frequency band
a is supplied to the first scanning unit 31 and the discriminating unit 33. The first scanning means 31 performs the above-described scan A on the signal 2a relating to the first relatively low frequency band and supplies the signal 2a to the entropy encoder 4.

Further, the discriminating means 33 has a predetermined threshold value T1 (T
1 is a positive integer) and the absolute values of the data (0, 2), (0, 3), (1, 2), (1, 3), which are the data from the band HL2, are compared, and the absolute value of T1 or more is compared. The number of data having a value is counted, and the result is set as the number N1. Similarly, data (2, which is data from the threshold T1 and the band LH2)
0), (2,1), (3,0), and (3,1) are compared with each other, and the number of data having an absolute value of T1 or more is counted, and the result is set as the number N2. To do. And N
It is determined whether or not 2> N1, and the result is supplied to the second scanning means 32.

If N2> N1, then the second
Scanning means 32 of data from band LH1 (4,
0) to (4, 3), (5, 0) to (5, 3), (6,
0) to (6, 3) and (7, 0) to (7, 3) are scanned,
Next, data (0, 4) from the band HL1
(3,4), (0,5) to (3,5), (0,6) to
(3, 6), (0, 7) to (3, 7) are scanned, and finally, (4, 4) to (4, 4) to (4, 4) which are data from the band HH1.
7), (5,4) to (5,7), (6,4) to (6,
7), and the signals obtained by scanning (7, 4) to (7, 7) are supplied to the entropy encoder 4.

On the contrary, when N1 ≧ N2, the data from the band HL1 is (0, 4) to (3, 4), (0, 5).
~ (3, 5), (0, 6) ~ (3, 6), (0, 7) ~
Scan (3, 7) and then the data from band LH1 are (4, 0) to (4, 3), (5, 0) to (5, 3),
(6,0) to (6,3), (7,0) to (7,3) are scanned, and finally, data from the band HH1 is (4,
4) to (4, 7), (5, 4) to (5, 7), (6,
The signals obtained by scanning 4) to (6, 7) and (7, 4) to (7, 7) are supplied to the entropy encoder 4.

Then, the entropy encoder 4 encodes the output signal of the second scanning means 32 subsequent to the output signal of the first scanning means 31.

(Decoding Device) The signals decoded by the entropy decoder 6 are divided into a signal 6a relating to the second relatively low frequency band and a signal 6b relating to the second relatively high frequency band. Separate output. Here, the signal 6a relating to the second relatively low frequency band is a signal having data corresponding to the scan A and is supplied to the discriminating means 33 and the first reverse scanning means 71. On the other hand, the signal 6b relating to the second relatively high frequency band is supplied to the second reverse scanning means 72.

The discriminating means 33 is similar to the encoder side in that the threshold value T1 and the data (0, 2), (0, 3), (1, 2),
The absolute values of (1, 3) are compared with each other, the number of data having an absolute value of T1 or more is counted, and the result is counted by the number N1.
And Similarly, the threshold T1 and the data (2, 0), (2,
1), (3,0), (3,1) are compared with each other, and the number of data having an absolute value of T1 or more is counted, and the result is set as the number N2, and N2> N1. Then, the result is supplied to the second reverse scanning means 72.

The second reverse scanning means 72 has N2> N1.
If it is, it is considered that the code corresponding to the scan A is followed by the code corresponding to the data from the band LH1, and the reverse scanning is performed. Conversely, if N1 ≧ N2, the code corresponding to the scan A is selected. Subsequently, the code corresponding to the data from the band HL1 is considered to be input, and the signal obtained by performing the inverse scanning is supplied to the inverse quantizer 8. Therefore, it is not necessary to send the information indicating which of the data from the band LH1 and the data from the band HL1 was scanned first.

The first inverse scanning means 71 supplies the inverse quantizer 8 with a signal obtained by inversely scanning the signal 6a relating to the second relatively low frequency band. The inverse quantizer 8 has a first
Similar to the embodiment, the output signal of the first scanning means 71 is inversely quantized, and then the output signal of the second scanning means 72 is inversely quantized.

Generally, since the diagonal high-frequency components of the image are not visually significant, coarse re-quantization may be performed for the band HH1, and therefore the data from HH1 is likely to have a value of 0. . Further, the correlation between bands when divided into subbands does not completely disappear, but the band H
There is a correlation between L1 and HL2 and between LH1 and LH2. Therefore, in the data block of FIG. 2, if the power of the data from LH2 is lower than that of the data from HL2, the data from LH1 is more likely to have lower power than the data from HL1, and the probability that the value is 0 is lower. high. Therefore, by scanning adaptively as described above, scanning within a block is
The probability of being terminated by OB becomes high, and the code amount as a result of entropy coding can be made small.
Further, even in the case where scanning is forcibly aborted midway for controlling the code amount, more important data can be encoded first, so the influence of scanning abort is small.

In the above embodiment, N1 is obtained from the data from the band HL2 and N2 is obtained from the data from the band LH2.
(T1 ′ is a positive integer) and the data from the band HL3 are compared, and if the absolute value of the data from HL3 is larger, then N
It is also possible to add 1 to 1 and compare T1 ′ with the data from the band LH3 to add 1 to N2 if the absolute value of the data from LH3 is larger.

Further, when one frame of a TV signal is regarded as one image for encoding, the information amount of LH1 is often relatively large due to the interlaced structure.
In such a case, N1 plus an appropriate value and N1
By comparing with, the probability that the data from LH1 is scanned first may be increased.

Alternatively, instead of N1 and N2, HL2
It is also possible to compare the sum of absolute values of data from (and HL3) and the sum of absolute values of data from LH2 (and LH3), and change the scanning order depending on the result. Alternatively, the maximum value of the absolute values of the four data from HL2 and LH
The scanning order may be changed by comparing the maximum value of the absolute values of the four pieces of data from 2 to each other and the result thereof.

[Embodiment 3] This embodiment relates to encoding of data from the band LH1 or HL1 of the virtual data block (shown in FIG. 2) of the first embodiment.
The DPCM coding is selectively performed based on a signal related to a relatively low frequency band. Second using FIGS. 5 and 6
An encoding device according to the embodiment will be described. The same components as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

(Encoding Device) In FIG. 5, the quantizer 2
As a result, the signal 2a related to the first relatively low band and the signals 2c and 2d related to the relatively high band are output.
Here, the signal 2a is a signal corresponding to the scan A, and has the bands LL3, HL3, LH3, HH3, HL2, LH2.
It is a signal from HH2. Further, the signal 2c has a band HL1.
And the signal 2d is data from LH1 and HH1.

Then, the signal 2a relating to the first relatively low frequency band is supplied to the discrimination means 10. This discrimination means 10
Is DP in 2c and 2d which are signals related to a relatively high frequency band
It plays a role of determining whether or not the CM is adaptively applied. Here, the case where the DPCM is applied only to the signal 2c will be described, but it goes without saying that the DPCM may also be applied to the signal 2d.

First, the data from the band HL2 in the signal 2a relating to the first relatively low band (0, 2),
The absolute values of (0, 3), (1, 2), and (1, 3) are compared with a predetermined threshold value T2 (T2 is a positive integer). Then, the number of data having an absolute value of T2 or more is counted, and the result is set to the number N3. Similarly, the data from the band LH2 is (2,0), (2,1), (3,0), (3,
The absolute value of 1) is compared with the threshold value T2, the number of data having an absolute value of T2 or more is counted, and the result is set as the number N4. Furthermore, the threshold T2 and the data (2, 2),
The absolute values of (2, 3), (3, 2), and (3, 3) are compared, the number of data having an absolute value of T2 or more is counted, and the result is set to the number N5. The numbers N3 to N5 thus obtained and the numbers NT1, NT2 (N
T1 and NT2 are positive integers including 0), and N3> N
It is determined whether or not T1 and N4 + N5 <NT2, and the result is supplied to the selection means 12.

The DPCM encoding means 11 is the data of the signal 2c from the band HL1 (0, 4) to (3, 4),
(0,5) to (3,5), (0,6) to (3,6),
(0, 7) to (3, 7) are DPCM encoded as follows. That is, the data (3, 4) is converted into (3, 4)-(2,
4), (2,4) into (2,4)-(1,4),
(1,4) is set to (1,4)-(0,4). Similarly,
The data (k, 5) is converted into (k, 5)-(k-1, 5),
(K, 6) becomes (k, 6)-(k-1, 6), and (k,
7) is set to (k, 7)-(k-1, 7) (k = 3,
2, 1). As a result, the difference data is obtained following the data (0, 4) to (0, 7). And DPCM
The output signal of the encoding means 11 is supplied to the other input of the selection means 12 whose one input is supplied with the signal 2c.

The first selecting means 13 has N3> NT1.
If N4 + N5 <NT2, the output signal of the DPCM encoding means 11 is selected, and if not, the signal 2c is selected and the obtained signal is supplied to the scanning means 3.

The scanning means 3 first scans the signal 2a relating to the first relatively low frequency band, and then the selecting means 12
Scan the output signal of, then the band LH1 in signal 2d
Scan the data from, and finally the band HH1 in signal 2d
The signal obtained by scanning the data from is supplied to the entropy encoder 4, and the same encoding as in the first embodiment is performed.

(Decoding device) In FIG. 6, the output signal of the entropy decoder 6 is supplied to the reverse scanning means 7 to perform scanning in the reverse order of the scanning performed by the scanning means 3 to obtain the signal 2
signal 7a relating to the second relatively low frequency band corresponding to a
Then, a signal 7c corresponding to the signal 2c and a signal 7d corresponding to the signal 2d are obtained. Then, the signal 7a is supplied to the discrimination means 10 and the dequantizer 8, and the signal 7c is supplied to the DP.
The signal is supplied to the CM decoding means 21 and the selection means 12, and further, the signal 7d is supplied to the inverse quantizer 8.

Then, the discrimination means 10 makes a discrimination similar to that of the encoding device. That is, N3> NT1 and N4 + N5 <N
It is determined whether or not it corresponds to T2, and it is determined whether or not the signal 7c related to the band HL1 has been DPCM encoded by the encoding device. Then, the selecting means 12 selects the output signal of the DPCM decoding means 21 if it is DPCM-encoded, while selecting the signal 7c if it is not DPCM-encoded and dequantizes the result. Supply to the container 8. Therefore, it is not necessary to send the information indicating whether the data from the band HL1 has been DPCM encoded.

Here, the DPCM decoding means 21 is (0, 4) to which is the decoding result data of the Huffman code.
(3,4), (0,5) to (3,5), (0,6) to
DP of (3,6) and (0,7) to (3,7) as follows
Decode CM. That is, the data (1, 4) is converted into (1,
4) + (0,4), (2,4) into (2,4) + (1,
In (4), (3,4) becomes (3,4) + (2,4).
Similarly, the data (m, 5) is converted to (m, 5) + (m-1,
5), (m, 6) to (m, 6) + (m-1, 6),
(M, 7) is changed to (m, 7)-(m-1, 7) (m =
1, 2, 3). Then, the inverse quantizer 8 outputs the signal 7a,
The output signal of the selection means 12 and the signal obtained by performing the inverse quantization in the order of the signal 7d are supplied to the synthesis filter bank 9.

The above N3> NT1 and N4 + N5 <NT2
In the case of, the probability that the image signal portion of 8 pixels × 8 pixels of the corresponding input image is a vertical edge is high, and the band HL1
Often, there is a vertical correlation between the signals from. Therefore, by DPCM coding, a smaller value is entropy coded, and as a result, the code amount can be reduced. On the other hand, if the signal from the band HL1 is unconditionally DPCM-encoded, a signal having no correlation in the vertical direction has a larger value, and the code amount cannot be reduced so much even when viewed on the entire screen.

In the present embodiment, the discriminating means, DPCM
Encoding means, DPCM decoding means, and selection means are added to determine the case of N5> NT1 and N3 + N4 <NT2, and adaptive processing is performed on the signal from the band LH1 as well as the signal from the band HL1. May be. In such a case, the probability of a horizontal edge is high, and the signal from the band LH1 often has a horizontal correlation. Therefore,
By performing DPCM encoding, a smaller value is entropy encoded, and as a result, the code amount can be reduced.

[0057]

As described above, according to the configuration of the present invention,
The scanning unit scans the output information of the blocking unit in order from the low band information and for each band, and the non-significant information of the output information of the scanning unit or the information obtained by requantizing the output information until the end. In the case of continuing, since it has an encoding means for stopping the encoding by the end code, it is possible to scan the high frequency information having a high probability of becoming non-significant information (0 data) at the end, and as a result, the encoding means There is an effect that the code amount of the output can be reduced. Furthermore, the image information decoding device has the effect of being able to decode the coded information.

Further, as described above, according to the configuration of the present invention, based on the information relating to the relatively low frequency band of the output information of the blocking means, the relatively high frequency band of the output information of the blocking means is determined. Scanning means that scans information relating to the relatively low frequency band by varying the scanning order of the information relating to the bandwidth, and insignificance of the output information of the scanning means or the information obtained by requantizing the output information. When the information continues to the end, since it has an encoding means that terminates the encoding with an end code, there is a high probability that information related to a relatively low band will be non-significant information from information related to a relatively low band. There is an effect that the band can be predicted and the band can be scanned later, and as a result, the code amount of the output of the encoding means can be reduced. Further, since the decoding device has a reverse scanning means for changing the scanning order of the information in the relatively high frequency band based on the signal in the relatively low frequency band and performing reverse scanning, There is an effect that information related to a relatively high frequency band can be decoded even if is not transmitted.

Further, as described above, according to the configuration of the present invention, based on the information relating to the relatively low frequency band of the output information of the blocking means, the relatively high frequency band of the output information of the blocking means is used. Since the coding means for selectively DPCM-encoding the band-related information is provided, the DPCM coding is performed by predicting the correlation property of the signal in the relatively high band from the signal in the relatively low band. Therefore, there is an effect that the code amount of the output of the encoding unit can be reduced without deteriorating the image quality. Further, in the image information decoding device, the information related to the decoded relatively high frequency band is transmitted based on the decoded information related to the relatively low frequency band.
Since there is a decoding means for performing CM decoding, there is an effect that decoding can be performed without transmitting information regarding whether or not DPCM coding has been performed.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment of an image encoding / decoding device according to the present invention.

FIG. 2 is a conceptual diagram for explaining a virtual data block.

FIG. 3 is a conceptual diagram for explaining another example of band division.

FIG. 4 is a block diagram of a second embodiment of an image encoding / decoding device according to the present invention.

FIG. 5 is a block diagram of a third embodiment of an image encoding device according to the present invention.

FIG. 6 is a block diagram of a third embodiment of an image decoding apparatus according to the present invention.

FIG. 7 is a block diagram for explaining a conventional divided filter bank.

FIG. 8 is a conceptual diagram for explaining respective bands of a plurality of signals obtained by a conventional divided filter bank.

FIG. 9 is a conceptual diagram for explaining a conventional scanning method.

[Explanation of symbols]

aa input image signal (input image information) 1 division filter bank 2 quantizer (blocking means) 3 scanning means 31 first scanning means (scanning means) 32 second scanning means (scanning means) 2a first comparison Signal related to relatively low band (information related to relatively low band) 2b Signal related to first relatively high band (information related to relatively high band) 4 Entropy encoder (code Encoding means 6 Entropy decoder (decoding means) 9 Synthesis filter bank 11 DPCM encoding means 21 DPCM decoding means

Claims (6)

[Claims] 1. A division filter bank for sub-band dividing input image information into information relating to a plurality of bands, and information relating to the plurality of bands or information obtained by requantizing the information is predetermined for each of the plurality of bands. In an image information coding apparatus having a blocking means for collecting a number of pieces of information and virtually dividing the information into blocks, a scan for scanning the output information of the blocking means in order from the information on the low band and for each band. Image information code, characterized by comprising: means and output means of the scanning means or encoding means for stopping the encoding with an end code when the non-significant information of the information obtained by requantizing the output information continues to the end. Device. 2. An image information decoding apparatus for decoding encoded image information, comprising: decoding means for decoding encoded information which is terminated by an end code when insignificant information continues to the end; and the decoding means. Reverse scanning means for reversely scanning the output information of the converting means or the information obtained by dequantizing the output information in order from the information on the low frequency band and for each band, and the output information of the reverse scanning means or the reverse output of the output information. An image information decoding apparatus, comprising: a synthesis filter bank that performs sub-band synthesis based on quantized information. 3. A division filter bank that divides input image information into sub-bands into information relating to a plurality of bands, and information relating to the plurality of bands or information obtained by requantizing the information is predetermined for each of the plurality of bands. In an image information coding apparatus having a block forming means for collecting a number of pieces of information and virtually forming a block, the block forming means of the block forming means is output based on information relating to a relatively low band of output information of the block forming means. Of the output information, scanning is performed by changing the scanning order of information related to a relatively high frequency band,
Scanning means for scanning the information relating to the relatively low frequency band, and when the non-significant information of the output information of the scanning means or the information obtained by requantizing the output information continues to the end, the encoding is terminated by the end code. An image information encoding device comprising: an encoding unit. 4. An image information decoding apparatus for decoding encoded image information, comprising: decoding means for decoding encoded information which is terminated by an end code when insignificant information continues to the end; and the decoding means. The output information of the conversion means or the information obtained by dequantizing the output information is inversely scanned in the information in the relatively low frequency band, and the information in the relatively low frequency band is converted into the relatively high frequency band based on the information in the relatively low frequency band. Image information having an inverse scanning means for varying the scanning order of such information and performing inverse scanning, and a synthesis filter bank for performing subband synthesis based on output information of the inverse scanning means or information obtained by inversely quantizing the output information. Decoding device. 5. A division filter bank for dividing input image information into a plurality of bands into sub-bands, and output information of the division filter bank or information obtained by requantizing the output information is given predetermined information for each of the plurality of bands. In an image information encoding device having a block forming unit that collects and virtually forms a block, among the output information of the block forming unit based on information relating to a relatively low band of the output information of the block forming unit. An image information coding apparatus comprising a DPCM coding means for selectively DPCM coding information relating to a relatively high band. 6. An image information decoding apparatus for decoding encoded image information, comprising: decoded information relating to a relatively low frequency band and decoded information relating to a relatively high frequency band. Is supplied, and the information related to the decoded relatively high band is selectively DPCM based on the information related to the decoded relatively low band.
An image information decoding apparatus having a DPCM decoding means for decoding.