JP2892361B2 - Encoding method, information transmission method, and information transmission device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to an encoding method, an information transmission method, and an information transmission used when compressing image data of an electronic still camera or the like. Related to the device.

(Prior Art) Conventionally, a variable-length coding table used for compressing data such as image data is composed of input data and variable-length code data (table 15) as shown in FIG.
0) and code length data (code length table 160). Even if the maximum code length is not so long, the code length table becomes considerably large as the types of input data increase. Further, since the variable-length code data itself has a maximum code length bit number as one word, the variable-length coding table is also very large. Further, at the time of decoding, the decoding table shown in FIG. 13 also has as input addresses the number of bits of the maximum code length, so that if the maximum code length is increased by one bit, it will be enormously large such that it will double. It was.

If such a device is used for data compression of, for example, an electronic still camera, the size of the device itself becomes large, which is extremely problematic as the device becomes more compact.

(Problems to be Solved by the Invention) That is, since the conventional variable-length coded data has been used as it is as a table, and the variable-length coded data has been directly input to the address of the decoding table, The encoding and decoding tables were very large.

Accordingly, the present invention has been made to solve such a problem, and an object of the present invention is to provide an encoding apparatus, an information transmission method, and an information transmission method capable of performing encoding and decoding with a very small table. An apparatus is provided.

[Constitution of the Invention] (Means for Solving the Problems) In the present invention, a first variable length code corresponding to input data and a second variable length code corresponding to the data length of the first variable length code are provided. A first variable-length code corresponding to input data is output by using a code conversion table configured by combining a code and a code so as to fit within a predetermined data length as a whole. .

On the encoding side, the first variable-length code corresponding to the input data and the second variable-length code corresponding to the data length of the first variable-length code as a whole fall within a predetermined data length. A code conversion table that outputs a first variable-length code corresponding to input data using a code conversion table configured in combination with the code conversion table and holds data corresponding to the first variable-length code on the decoding side. And outputting data corresponding to the first variable-length code output from the encoding side using the information transmission method.

(Operation) (1) When the length of the variable length code data is shortened by 1 bit,
By extending the length of the code length data by 1 bit, all code lengths can be represented. Therefore, the bit length of one word of the coding table is also increased only by one bit from the maximum code length.

(2) Change the variable-length code data from the first bit data by 1
By dividing the data into a continuous number of data (or 0) and subsequent data, the maximum bit length of one word is shortened, that is, the coding table is reduced. When encoding, this continuous number of data is
By converting the data into (or 0) continuous data and connecting subsequent data, variable-length code data can be generated.

(3) The variable-length code data is changed from the first bit data by 1
By separating the data into a continuous number of data and subsequent data, the maximum bit length of the code data is shortened, so that the number of bits of the address of the decoding table can be reduced, and the decoding table becomes smaller. It is.

Hereinafter, an embodiment of an electronic camera will be described with reference to the drawings.

An electronic camera system includes an electronic camera and a playback device. The former, that is, the electronic camera, is a device that captures and records an object using a semiconductor memory card as a recording medium, and the latter, that is, the player, reads out image information recorded on the memory card from the memory card,
This is an apparatus for displaying an image on a receiver or the like.

FIG. 1 is a perspective view of an electronic camera as viewed obliquely from behind, and a description of parts having the same functions as a normal (using a photographic film) still camera will be omitted. The electronic camera 10 is provided with a release 11 and an imaging number display unit 13. The electronic camera 10 also includes a semiconductor memory card
An insertion port 12 for inserting and removing the 15 from the right side is provided. Further, the electronic camera 10 is provided with a shutter speed selection dial 18.

FIG. 2 shows a schematic basic configuration of the electronic camera 10. At the time of imaging, the lens system is
Focusing is performed by the operation of 21, and the shutter speed is selected and set by the operation of the shutter speed selection dial 18. The aperture is adjusted by controlling the aperture 22 by the control circuit 24. In the electronic camera 10, adjustment of a shutter speed by a so-called electronic shutter is used. In the electronic shutter, the image sensor CC
The shutter speed is adjusted by controlling the charge storage time of the D array 26. An image of a subject is formed on the CCD array 26 via the lens system 21.

When the imaging operation is started and the release 11 is half-pressed (a state in which the release button is half pressed down) by an operator or a user's operation, the power supply voltage from the power source 23 using a battery is supplied to each electronic circuit. Supplied to the department. The amount of incident light is measured by the exposure sensor 19, and the control circuit 24 controls the diaphragm 22 according to the amount of incident light. The external color temperature is measured by the white balance sensor 17, and the control circuit 24 generates a white balance control signal according to the measured color temperature.

When the release 11 is further depressed and changes from a half-pressed state to a fully-pressed state (a state in which the release button is sufficiently depressed), the control circuit 24 generates a shutter pulse. The drive circuit 25 responds to the shutter pulse and
6. Signal processing circuit and A / D conversion circuit 27 and DPCM (Differ
ential PCM) 28, which provides the encoder 14 with control signals. In response to this control signal, the CCD array 26, the signal processing circuit A / D conversion circuit 27 and the DPCM 28, and the encoder 31 operate. An image information signal composed of an analog signal output from the CCD array 26 is converted into a digital signal by the A / D conversion circuit via a signal processing circuit A / D conversion circuit 27. The digitized image information signal is further quantized by a DPCM 28 in a prediction error, and is variable-length coded by an encoder 14. Encoder 14
Is supplied to the semiconductor memory card 15. In this way, the image information signal of the captured still image is stored in the semiconductor memory card 15 as a digital signal. It should be noted that the present invention
14 has features.

The encoder 14 described above will be described in detail. The encoder is configured as shown in FIG. The signal from the DPCM 28 shown in FIG. 2 is input to the variable length code and code length table 30, the variable length code data is input to the selector 34 via the latch 32, and the code length data is input to the adder 41 via the latch 33. Lower bit data that is added to the remaining bit number data of the output of the latch 36 and becomes the next remaining bit number data is input to the latch 36. The output of the latch 36 is also input to the selector 34. Upper bit data serving as the generated byte number data of the output of the adder 41 is input to the latch 38 and the selector 35, and the output of the latch 38 is input to the memory controller 40. The output of the selector 35 is input to the selector 34 via the latch 31.

One of the outputs of the selector 34 is input to the selector 35, and the output of the selector 39 is selected by the output of the memory controller 40 in accordance with the output data of the latch 38 via the latch 37 in units of a byte. It is stored in the memory card 15. This operation will be described after the description of the variable length code and code length table 30.

Hereinafter, one embodiment of the code and code length table will be described in detail with reference to FIG.

First, FIG. 4 is a diagram for describing encoding which is one embodiment of the present invention. When DPCM data is input from the input terminal 110, one-word data (variable-length code data and code-length data) corresponding to the input value is selected in the encoding table 100 as shown in a later stage, and one of the selected data is The part is input to the code length detection circuit 200 and a part is input to the output terminal 120. Then, the code length detection circuit 200 converts the code length data of the data output from the encoding table 100 into binary data and outputs the binary data to the output terminal 220.

The encoding table forms output data corresponding to the input values as shown in, for example, Table 1 (a). This table 1 (a)
Indicates the case where the input value is 0 to 7 and the code length is 2 to 5.

When code length data is stored on the LSB side as shown in Table 1 (a), the code length detection circuit is configured as shown in FIG.
When bit data is input to the input terminals 221-215, the code length is output to the output terminals 221-223 as natural binary data.

For example, in the code table, the output data is “100100” for the input value “2” (actually a 3-bit signal), and the LSB
Is input to terminals 211 to 215, code length data 3 (011) is output from terminals 221 to 223.

In the conventional encoding table, as a code length table,
In the case of this example, one word requires three bits, so that the entire encoding table has eight bits per word. Here, two bits are reduced per word.

Table 1 (b) shows the code data and code length data in MSB, LS
This is replaced by B, and a code length detection circuit and the like can be easily configured.

An encoder having the encoded data and the code length table configured as described above will be described with reference to FIG. As described above, the code data A from the encoding and code length table 30 is input to the selector 34 via the latch 32, and the code length data L to be output via the code length detection circuit is supplied to the adder 41 via the latch 33. Is entered. Adder 41
In, the output R (remainder number of bits; this Noyo case 8) of the latch 36 and the code length data L and is added (S), only the lower bit data S ₂ as the following number of remainder bit latch
Latched by 36. In the selector 34, the output C is determined by the number R of bits (for example, the power of 8).
Table 2 at this time is shown in Table 2. However, the code length is 1 to 24
This is the case.

Also the selector 35 selects and outputs from the most significant bit data number S ₁ indicating the number of generation of bytes of output S of the adder 41 the output C from the output C. Table 3 at this time is shown in Table 3. However, when the output byte number is 0 to 3 (0 bits, 8 bits, 16 bits, 24 bits). Selector 35
Becomes the input B of the selector 34 via the latch 31 when the next code data is input. Note that the upper bit data S ₁
Is 0 when S is 0-7, 1 when S is 8-15, 2,2 when S is 16-23
4 to 31 correspond to 3.

For example, as an example, the output B of the latch 31 is now “00” (corresponding to the input value 0), and the output A of the latch 32 is “10”.
0100 ”(corresponding to the input value 2), the number R of remaining bits is 2, and the selector 34 outputs the 2-bit data“ 00 ”of B
And “00100100” to which “100100” of A is connected is output C
Becomes The output C is input to the selector 39 as output D via the latch 37, although the memory controller 40 by the output W via the latch 38 receives the S ₁ controls the selector 39 and a memory card, S ₁ unless these last data When = 0, the selector 39 does not output D. When the output S = 1, 8 bits, when S ₁ = 2, 16 bits, and when S ₁ = 3, 24 bits are selected by the selector 39 in 8-bit units and stored in the memory card. Becomes Therefore,
S ₁ is, so that means the number of output bytes.

Next, an embodiment for further reducing the above-mentioned encoding table will be described with reference to FIG. As shown in Table 4 (a), the encoding table 300 stores one word data as one word.
, And the data following it is stored. The encoding table 300 outputs one continuous number of data to the signal line 320 and the subsequent data to the signal line 330 according to the data input from the input terminal 310. The continuous data generation circuit 400 is, for example, as shown in FIG.
It is converted into the continuous data created in (b) and output to the signal line 420. The selector 500 bit-shifts the subsequent data according to the continuous number of 1s, and outputs
The composite data of (b) is created and output to the output terminal 520. The data at this output terminal 520 is the same as the data in Table 1 (a). The code length data is converted to natural binary data by the code length detection circuit 200 and output to the output terminal 530.

FIG. 7 shows another embodiment, in which a code length of a variable-length code is obtained from a continuous number of data of 1 and code length data of data following the data. In this case, "0" data is input to the input terminals 211 to 213 of the code length detection circuit 200, and the data of the signal line 320 is input to the input terminals 214 to 215 by the LSB.
, The bit length of the connection code data is obtained. Here, the limiter 600 prevents the value from becoming 3 or more, and the offset data generator 701 always outputs a value of 1.

The encoding table 300 used in FIG. 6 and FIG.
One bit per word is smaller than the encoding table 100 used in FIG.

FIG. 9 shows an embodiment of the decoding device of the present invention. 1
The continuous number detection circuit 800 converts the number of consecutive 1's from the MSB of the data input from the input terminal 810 into a natural binary number and outputs it to the signal line 820. An example of this is shown in FIG. Show. Here, the selector 500 bit-shifts the data following the one continuous data according to the number of continuous ones, and outputs the data to the decoding table 900. Decryption table 9
00 indicates that the decoded data is output to the output terminal 930 in accordance with the continuous number of data of 1 and the data following it as shown in Table 5.
And outputs the bit length of the subsequent data to the signal line 920. From the bit length of the subsequent data and the data of the continuous number of 1, the input variable length code length is obtained by the limiter 600 and the adder 700 and output to the output terminal 940.

FIG. 10 shows another embodiment of the decoding apparatus. The decoding table 950 has a table of the code length of the input variable-length code instead of the table of the bit length of the subsequent data. The decoding table used in FIGS. 9 to 10 has a smaller number of words in this example than the conventional decoding table. become.

According to the present invention, in the encoding table, the number of bits required for one word can be reduced, and in the decoding table, the number of words required for decoding can be reduced. Table size can be reduced.

[Brief description of the drawings]

1 is a perspective view of an electronic camera, FIG. 2 is a configuration diagram of an electronic camera, FIG. 3 is a configuration diagram of an encoder according to the present invention, and FIG. 4 is a view for explaining an embodiment of the present invention. FIG. 5, FIG. 5 is a circuit configuration diagram of the code length detection circuit of FIG. 4, FIGS. 6 to 7 are diagrams for explaining another embodiment of the present invention, FIG. 9 to 10 are diagrams for explaining another embodiment of the present invention relating to decoding, FIG. 11 is a circuit configuration diagram, and FIGS. 12 to 13 are configuration diagrams of conventional encoding and decoding. It is. 100, 150, 300: encoding table, 160: code length table, 900, 950, 960: decoding table, 200: code length detection circuit, 400: continuous data generation circuit, 500: selector, 800 ...
1 consecutive number detection circuit

Claims (3)

(57) [Claims] 1. A combination of a first variable length code corresponding to input data and a second variable length code corresponding to the data length of the first variable length code so as to fall within a predetermined data length as a whole. A first variable-length code corresponding to input data, using a code conversion table configured as described above. 2. An encoding system comprising: a first variable length code corresponding to input data and a second variable length code corresponding to a data length of the first variable length code as a predetermined data; A first variable length code corresponding to the input data is output using a code conversion table configured to be combined to fit within the length, and the decoding side holds data corresponding to the first variable length code. An information transmission method comprising: outputting data corresponding to a first variable-length code output from an encoding side using a code conversion table to be transmitted. 3. A combination of a first variable length code corresponding to input data and a second variable length code corresponding to the data length of the first variable length code so as to fit within a predetermined data length as a whole. An encoding unit that outputs a first variable-length code corresponding to input data, using a code conversion table configured as described above, and a code conversion table that holds data corresponding to the first variable-length code, The first output from the encoding unit
And a decoding unit that outputs data corresponding to the variable length code.