JPH08163374A - Picture signal encoding device - Google Patents

Abstract

PURPOSE: To obtain a high compression encoding rate independently of the number of picture elements of one line of a picture signal to be encoded. CONSTITUTION: A picture memory 3 where picture signal data from an external device is stored, a picture signal selector 7 which reads out picture signal data from the picture memory 3 and outputs it to an encoding circuit 8 with a fixed length as the unit, and the encoding circuit 8 which compresses this picture signal data with the fixed length as the unit are provided. Further, the picture signal selector 7 is provided with the means which couples n blocks, each of which consists of m dots in the main scanning direction of picture signal data, in the subscanning direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a picture signal coding apparatus, and more particularly to a picture signal coding apparatus suitable for compressing image data.

[0002]

2. Description of the Related Art A conventional picture signal coding apparatus is a picture signal
When the number of pixels in a line is encoded for each predetermined fixed length (block) and the number of pixels in one line is less than the fixed length, Japanese Patent Laid-Open No. 56-1548
As disclosed in Japanese Patent Laid-Open No. 74, the fixed level pixels are added to make the fixed length and the encoding process is performed.

[0003]

However, in the above-mentioned conventional example, when the number of pixels of one line of the image signal to be encoded does not reach the predetermined fixed length, the fixed level pixels are added to fix the fixed length. Therefore, when the number of pixels in one line of the image signal to be encoded is less than the fixed length or when it is not an integral multiple of the fixed length, it is necessary to add the pixels and the data compression effect can be obtained. There was an inconvenience that it was not possible.

[0004]

SUMMARY OF THE INVENTION The object of the present invention is to improve the disadvantages of the conventional example, and particularly to reduce the number of picture signals to be encoded.
An object of the present invention is to provide a picture signal coding device capable of obtaining a high compression coding rate regardless of the number of pixels in a row.

[0005]

Therefore, according to the present invention, an image memory for accumulating image signal data from an external device and an image memory for reading out the image signal data from the image memory and outputting the image signal data in fixed length units to an encoding circuit. The image signal selector includes a signal selector and an encoding circuit that compresses the image signal data for each fixed length, and the image signal selector uses m dots in the main scanning direction of the image signal data as one block and n blocks in the sub scanning direction. It employs a structure such as a means for connecting. This aims to achieve the above-mentioned object.

[0006]

The image signal data from the external device is first stored in the image memory. Next, the image signal selector reads the image signal data from the image memory and outputs it to the encoding circuit in fixed length units. At this time, the image signal selector first blocks the image signal data by setting m dots as one block in the main scanning direction of the image signal data, and then connects n consecutive blocks in the sub scanning direction. The encoding circuit
This connected image signal data is compressed into a fixed length.
At this time, dummy data is added when the length is less than the fixed length, but the number of blocks to be added is smaller than when the image signal data is not converted, and thus the number of dummy data to be added is reduced.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a picture signal encoding apparatus according to this embodiment. The image signal encoding device is
Image memory 3 for storing image signal data from an external device
And an image signal selector 7 that reads out image signal data from the image memory 3 and outputs the image signal data to the encoding circuit in fixed length units,
An encoding circuit 8 for compressing the image signal data for each fixed length is provided. Moreover, the image signal selector 7 is provided with means for connecting one block of m dots in the main scanning direction of the image signal data to n blocks in the sub scanning direction.

FIG. 2A shows image signal data stored in the image memory 3.
It is explanatory drawing which shows the concept expanded to FIG. The image signal data is
Blocks are formed in units of m dots in the main scanning direction. Here, one row is divided into eight blocks in the main scanning direction.
The unit m of block formation is determined according to the fixed length of the encoding circuit 8. FIG. 2B is a diagram showing an example of fixed length data connected by the image signal selector 7. The image signal selector 7 has a number of n continuous in the sub-scanning direction as shown in the figure.
The blocks A1, B1, C1, D1 are connected. Thereby, compression can be performed in consideration of the main scanning direction and the sub scanning direction. Moreover, by setting the number of dots m (the number of bytes) and the number n to be continuous in the sub-scanning direction, it is possible to match the fixed length required for the encoding circuit 8.

FIG. 3 is a block diagram showing a configuration in which image signals are divided into blocks and the blocks are connected using a plurality of image memories. The embodiment shown in FIG. 3 is a buffer memory 1 for temporarily storing image signal data from an external device.
And a first image signal selector 2 for outputting m dots in the main scanning direction of the image signal data as one block, and the first image signal selector 2.
Image memory 3, 4, 5, 6 for storing the image signal data for each block from the image signal selector 2 for each n rows of the image signal data in the sub-scanning direction, and the image signal for the block. A second image signal selector 7 for connecting and outputting n blocks in the sub-scanning direction of image signal data by sequentially reading out data from n image memories, and n blocks for one block of m dots And an encoding circuit 8 for compressing the fixed-length image signal data.

Here, the buffer memory 1 includes an input speed of image signal data from an external device and a first image signal selector 2.
To the picture signal memories 3, 4, 5 and 6 from the picture data memory.

Next, the operation of this embodiment will be described.

(1). When image signal data is input from an external device, it is stored in the buffer memory 1.

(2). The first image signal selector 2 sequentially reads out the image signal data accumulated in the buffer memory 1 and divides the image signal data into blocks of m dots, and the image memories 3, 3.
Output to 4, 5, and 6. Here, since n = 4 and four image memories are provided, the first row in the sub-scanning direction is the first image signal memory 3, and the second row in the sub-scanning direction is the second image signal memory 4.
The third line is stored in the third image signal memory 5, and the fourth line is stored in the fourth image signal memory 6. The fifth line is stored in the first image signal memory.

(3). When all the data accumulated in the buffer memory 1 has been written in the respective image signal memories 3, 4, 5, and 6, the second image signal selector 7 causes the image signal memories 3,
The blocks are read from 4, 5, and 6 one by one, connected, and output to the encoding circuit 8. That is, as shown in FIG. 4, a first block of the image signal data a, a first block of the image signal data b, a first block of the image signal data c, and a first block of the image signal data d. The data are concatenated and output to the encoding circuit 8.

(4). When the encoding circuit 8 receives the data of the first line from the first image signal memory 3 to the fourth image signal memory 6, the encoding circuit 8 collectively performs encoding for each predetermined fixed length, and the code The converted data is written in a predetermined area of the buffer memory 1.

If the fixed length is not reached, dummy data of white pixels is added to the fixed length for encoding.

(5). The encoding circuit 8 similarly performs encoding on the second and third lines, and when the encoding of the image signal data of each image signal memory 3, 4, 5, 6 is completed, the buffer memory 1 The encoded data stored in is output to an external device.

In the present embodiment, the case where the number of image signal memories is four has been described, but the number of image signal memories is the minimum of the image signals to which the number of pixels of one line of fixed length for encoding is input. It can be set up to an integer value divided by the number of pixels.

Further, instead of equipping a plurality of image signal memories, one image signal memory is divided into a plurality of areas, and as shown in FIG. When writing data, a write address is designated according to a predetermined expansion method, so that a single image signal memory can perform the same processing as when a plurality of image signal memories are provided.

That is, according to the present invention, since the image signals of a plurality of blocks are encoded as one image signal, the compression efficiency is extremely higher than that of the conventional technique especially when compressing an image signal with a small amount of data in the main scanning direction. Become higher.

[0021]

Since the present invention is constructed and functions as described above, according to this, the image signal selector divides the image signal data into blocks by setting m dots as one block in the main scanning direction of the image signal data. , N consecutive blocks in the sub-scanning direction are connected, so that the encoding circuit can compress the connected image signal data as a fixed length.
At this time, dummy data is added when the length is less than the fixed length, but the number of blocks to be added is smaller than when the image signal data is not converted, and thus the number of dummy data to be added is reduced. As described above, it is possible to reduce the number of dummy data to be added even in the encoding processing of the image signal having a small amount of data in the main scanning direction, which is related to the number of pixels of one line of the image signal to be encoded. It is possible to provide an unprecedented excellent picture signal coding apparatus that can realize a high compression coding rate without a problem.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of the image memory shown in FIG.

FIG. 3 is a block diagram showing a configuration when a plurality of image memories are provided.

FIG. 4 is an explanatory diagram showing an example of connection of blocks according to the configuration shown in FIG.

[Explanation of symbols]

 1 buffer memory 2 1st picture signal selector 3 1st picture signal memory (picture memory) 4 2nd picture signal memory 5 3rd picture signal memory 6 4th picture signal memory 7 2nd picture signal selector ( Picture signal selector) 8 Encoding circuit

Claims (3)

[Claims] 1. An image memory that stores image signal data from an external device, an image signal selector that reads image signal data from the image memory and outputs the image signal data to a coding circuit in fixed length units, and the image signal data is fixed. An encoding circuit for compressing each length, and the image signal selector includes means for connecting m blocks in the main scanning direction of the image signal data to one block and n blocks in the sub scanning direction. An image signal encoding device characterized by: 2. A buffer memory for temporarily storing image signal data from an external device, a first image signal selector for outputting m dots in the main scanning direction of the image signal data as one block, and the first image signal selector. The image signal data for each block from the image signal selector is stored in each of n rows in the sub-scanning direction of the image signal data, and the blocked image signal data is stored in the n image memories. A second image signal selector that sequentially reads out and connects n blocks in the sub-scanning direction of the image signal data, and outputs the second image signal selector.
An image signal encoding device, comprising: an encoding circuit for compressing fixed-length image signal data in which one block of m dots is connected n times. 3. The second picture signal selector comprises means for adding dummy data when the fixed length in the encoding circuit does not reach in the n blocks. 2. The image signal encoding device according to 2.