JPS6153896B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a system for transmitting a variable code length code obtained by encoding an image signal of a facsimile device.

Generally, when transmitting this type of variable code length code, it is necessary to specify the effective code length, so conventionally, for example, encoding was performed using a code with regularity such that the code length increased by an integral multiple. This regularity specifies the effective code length. However, as encoding becomes more complex, there are many cases where it does not match the regularity, and the transmission method in such cases is becoming more complex. On the other hand, in order to suppress the redundancy of a signal to be transmitted, a method of referring to an encoding table has been used, but a method of referring to an encoding table including the code length is not yet known.

The present invention has been made in view of the above-mentioned points, and is a facsimile machine with a simple structure and high transmission efficiency, in which an effective code length can be specified for variable code lengths that have no regularity by having codes and code lengths in the same table. This provides a variable code length transmission method for the device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A variable code length transmission method for a facsimile apparatus according to an embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is an image signal processing section, 2 is an encoding table, 3 is a code length counter, and 4 is a code register. The image signal processing unit 1 performs necessary processing on the input image signal 1a, such as black and white determination, extraction of a specific pattern, and calculation of black and white run length, and then inputs table reference signals Ao~ to the encoding table 2.
Ak is sent, and at the same time, an encoding designation signal 1b is sent to the code length counter 3 and code register 4. At this time, the code length data Bo to B _M from the encoding table 2 referenced by the values of the table reference signals Ao to Ak
is sent to the code length counter 3, and the code data Co~C _N
is led to the code register 4 and temporarily stored.
Next, a transmission clock 1c matching the transmission speed is sent from the image signal processing section 1 to the code length counter 3 and code register 4.

The code register 4 is composed of a register having a parallel-to-serial conversion function, and is shifted bit by bit by the transmission clock 1c, and sequentially sends out a serial transmission signal 4a. The code length counter 3 is composed of a down counter with a preset function, and is counted down by 1 by the transmission clock 1c. When the counted value reaches 0, it sends a transmission end signal 3a to the image signal processing unit 1. This completes the previous code transmission and prepares for the next encoding.
In this way, sequential variable code length transmission is efficiently performed.

FIG. 2 shows an example of the structure of the encoding table, and shows a case where the maximum code length is "16". The possible range of bits B ₀ to B ₃ indicating the code length is 0 to 15, and when transmitting code data in 2 bits, for example, B ₀ to _{B 3} are 0001. At this time, bits C ₁₅ and C ₁₄ of the code data are transmitted sequentially.

As described above, according to the present invention, variable code length transmission can be performed efficiently with a simple configuration, and since the encoding method is based on a table reference method, the table contents can be encoded even when the code is changed. ,
This has the advantage that it can be handled by changing both the code length. Therefore, there is a degree of freedom in selecting the optimal encoding method even when performing complex and irregular encoding.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention;
FIG. 2 is a configuration diagram showing an example of an encoding table. 1... Image signal processing unit, 2... Encoding table,
3... Code length counter, 4... Code register.

Claims (1)

[Claims] 1. In the variable code length transmission method of a facsimile device, which encodes and transmits an image signal using a redundancy suppression method, the input image signal is subjected to predetermined processing necessary for encoding, and then, according to the processing result, an image signal processing unit that outputs a coding reference signal and generates a coding designation signal; code data that inputs the coding reference signal as an address and is stored in advance in an area designated by this address; and this code data. An encoding table that outputs code length data representing the length of each of A code register that sends out one bit at a time and the code length data output from the encoding table are input, and the number of bits specified by this code length data is counted. 1. A variable code length transmission method for a facsimile apparatus, comprising a code length counter that outputs a transmission end signal and thereby stops generation of an encoding designation signal to end one code transmission operation.