JPH09200538A - Image reading device - Google Patents

Abstract

(57) Abstract: The processing time required for encoding is determined by counting the number of black and white reversals of one line when reading a document and determining whether to compress the image data based on this number. (EN) Provided is an image reading device which can be shortened and which can speed up encoding. An image reading unit 113 that scans an original to read an image line by line, a black and white inversion number counting unit that counts the number of black and white inversions of the read image of each line, and reads the read image as image data. Data accumulating means 104 to be stored in the buffer, compression selecting means for judging whether or not to compress the accumulated image data based on the black and white inversion number counted by the black and white inversion number counting means,
An encoding unit 107 that encodes only the image data determined to be compressed among the image data based on the determination by the compression selecting unit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device capable of accumulating image data read from a document in a memory.

[0002]

2. Description of the Related Art When a manuscript is read by a facsimile machine and the data is encoded, in the conventional facsimile machine, the amount of compressed data after encoding is larger than the amount of read data before compression in the case of complicated image data. In some cases, the data compression process cannot be effectively performed.

Therefore, in the past, in order to efficiently use the image memory in the facsimile apparatus, a threshold value is set for the data amount after the compression process, and when the encoded data amount exceeds the threshold value, A method of decompressing is used during the encoding of one line currently being scanned.

[0004]

However, in such a method, since it is necessary to encode all lines until the threshold value is exceeded, it takes a considerable amount of time for encoding. .

In order to solve such a problem, it is an object of the present invention to provide an image reading apparatus capable of shortening the processing time required for encoding and increasing the encoding speed.

It is another object of the present invention to provide an image reading apparatus capable of reducing the overhead of the entire system and efficiently using the image memory by speeding up the encoding process. And

[0007]

In order to solve the above-mentioned problems, an image reading apparatus according to a first aspect of the present invention comprises an image reading means for scanning an original and reading the image line by line, and an image for each line read. Of the black and white inversion number, a data accumulating means for storing the read image as image data in a reading buffer, and a black and white inversion number counted by the black and white inversion number counting means. A compression selecting unit that determines whether to compress the image data, and an encoding unit that encodes only the image data that is determined to be compressed among the image data based on the determination of the compression selecting unit.

An image reading apparatus according to a second aspect is the image reading apparatus according to the first aspect.
The image reading apparatus described above is characterized in that a threshold of the number of black and white inversions, which indicates whether or not to compress the stored image data, is set based on the number of main scan pixels.

An image reading apparatus according to a third aspect of the present invention is the image reading apparatus according to the first aspect.
The image reading apparatus described above is characterized in that a threshold value of the number of black and white inversions indicating whether or not to compress the accumulated scan data is set based on the main scan resolution.

An image reading device according to a fourth aspect is the image reading device according to the first aspect.
In the image reading apparatus described above, the threshold value of the number of black and white reversals that determines whether or not to compress the accumulated scan data is set based on the document width set on the reading document table.

An image reading apparatus according to a fifth aspect is the image reading apparatus according to the first aspect.
In the image reading apparatus described above, the threshold value of the number of black and white reversals for whether or not to compress the accumulated scan data is set based on the main scan resolution and the document width set on the reading document table. And

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Image reading apparatuses according to some embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
3 is a system block diagram of a facsimile embodying the image reading apparatus A according to the embodiment of FIG.

As shown in FIG. 1, in this embodiment, the image reading apparatus A includes a CPU 101, a ROM 102, and an R.
AM 103 and image memory 104 as image storage means
A registration unit 105, encoding / decoding processing units 106 and 107 as encoding means, an operation unit 108, and a MODEM.
109, an NCU (network control unit) 110, an image processing unit 112, and a scanner 113 as an image reading unit.

Here, the CPU 101 constitutes a system control section for controlling the entire image reading apparatus A.

The ROM 102 stores a control program executed by the CPU 101.
By executing this control program, the black and white inversion number counting means for counting the number of black and white inversions of the read image of each line and the black and white inversion number counted by the black and white inversion number counting means are stored in the image memory 104. A compression selecting unit for determining whether or not to compress the image data is configured.

The RAM 103 is used as a work area as needed.

The image memory 104 is used to store image data as described above, and is a DRAM.
Etc.

The registration unit 105 is composed of an SRAM or the like, and is for storing and reading set values for performing operation control.

In the present embodiment, the coding / decoding processing units 106 and 107 are the communication coding / decoding processing unit 106,
The reading / recording encoding / decoding processing unit 107 is for performing dedicated encoding / decoding processing.

The operation unit 108 is composed of a keyboard or the like and is used by the operator to perform various input operations.

A MODEM (modulator / demodulator) 109 is for modulating / demodulating a transmission / reception signal of a facsimile.

The NCU (network control unit) 110 has a function of transmitting a selection signal (dial pulse or tone dialer) to the communication line 111, and is used to perform an automatic incoming call operation and line control operation by detecting a ringing tone. It is a thing.

The scanner 113 is a CS image sensor,
It is composed of a document transport mechanism and the like, and scans a document, optically reads it, and converts it into electrical image data.
This image data is corrected by the image processing unit 112 and output as high-definition image data.

Next, the operation of the image reading apparatus A having the above configuration will be specifically described with reference to the flowchart shown in FIG.

When the operator operates the operation unit 108 to perform a reading operation, the image reading apparatus A confirms that there is an original document at a predetermined position, for example, the original reading table. A read operation is accepted (step S201).

Depending on the contents set in the registration unit 105 by the operator's reading operation or the state displayed on the display lamp (consisting of an LED or the like) on the operation unit 108, the image reading apparatus A determines the reading density, resolution and error diffusion. The image processing method such as the above and the document size are set in the image processing unit 112 (step S202), and then the threshold of the number of black and white inversion is set according to Table 1 based on the resolution in the main scanning direction (step S203). .

[0028]

[Table 1] Further, a read buffer for storing read data and a variable for storing the number of black and white inversions are secured in the RAM 103 in advance.

Next, the motor speed for driving the original feeding system of the scanner 113 is set (step S20).
4).

The following reading process (step S205)
Repeated for each line until one page is reached (step S206), the reading process for one page is completed,
Then, the above reading process is repeated for each page until all the originals are exhausted (step S207).

That is, the reading process for each line is performed as follows.

First, the reading buffer for one line is acquired (step S211), and the buffer address and the number of main scanning pixels of the image are set in the DMA controller (step S2).
212).

A reading trigger is issued to the image processing section 112 (step S213), and the image sensor output of the scanner 113 is image-processed. The data output from the image processing unit 112 is transferred to the reading buffer according to the previous DMA setting (step S214).

When the processing for one line is completed, the black / white inversion number counted by the image processing unit 112 is read out from the register of the image processing unit 112 and set in the black / white inversion number storage variable (step S215).

The previously determined threshold of the number of black and white inversions is compared with the number of black and white inversions of each line (step S216). If the number of black and white inversions of each line is larger than the threshold, the line is uncompressed. If it is smaller, the line is compressed. In the case of non-compression, a non-compression code indicating non-compression is added to the beginning of each line (step S21).
7) The read data is transferred to the image memory 104 (step S219). On the other hand, in the case of compression, MH encoding processing is performed (step S218), and MH data is transferred to the image memory 104 (step S219).

As described above, in the present embodiment, the encoding process is not performed for the non-compressed line, so that the encoding process as a whole can be speeded up and the image memory 104 can be used efficiently.

Further, in the present embodiment, the image reading apparatus A is
The image density, resolution, image processing method such as error diffusion, and document size are set in the image processing unit 112 (step S20).
2) Then, based on the number of main scan pixels in the main scanning direction, the threshold value of the number of black and white inversion can be set according to Table 1.

(Second Embodiment) In the image reading apparatus A according to the first embodiment, the threshold of the number of black and white inversion is set based on the resolution or the number of main scan pixels shown in Table 1. In the image reading device A according to the present embodiment,
The threshold value of the number of black and white reversals is set according to the document width as shown in Table 2.

That is, the image reading apparatus A according to the present embodiment
Sets the threshold of the white / black reversal number from Table 2 below according to the document width set on the reading platen, compares this threshold value with the black / white reversal number of the read image data, and sets the threshold value. When the read / write image data has a large black / white inversion number, it is not compressed, and when it is small, it is compressed.

[0040]

[Table 2] As described above, also in the image reading apparatus A according to the present embodiment, the encoding process is not performed for the non-compressed line, so that the encoding process as a whole can be speeded up and the image memory can be used efficiently. it can.

Further, the threshold value may be set from Table 3 according to the combination of both the resolution and the document width.

(Third Embodiment) The image reading apparatus A according to the present embodiment sets the threshold value of the white / black reversal number from Table 3 below according to the resolution and the document width set on the reading document table. The threshold value is set, and this threshold value is compared with the white / black inversion number of the read image data. If the white / white inversion number of the read image data is larger than the threshold value, it is not compressed, and if it is smaller, it is compressed. To do.

[0043]

[Table 3] As described above, also in the present embodiment, the image reading device A
Does not perform encoding processing on non-compressed lines, the encoding processing as a whole can be speeded up, and the image memory can be used efficiently.

[0044]

As described above, in the present invention, when the document is read by the image reading means, the black-and-white inversion number counting means obtains the inversion number of the black and white pixels of one line, and the accumulating means obtains the read image data. After storing in the reading buffer, the compression selection means compares the previous white / black inversion number with a predetermined threshold of the white / white inversion number to determine whether or not to compress. If it is large, it is not compressed. As described above, according to the present invention, since the encoding process is not performed on the non-compressed line, the encoding process as a whole can be speeded up and the image memory can be efficiently used.

[Brief description of drawings]

FIG. 1 is a system block diagram of a facsimile apparatus embodying an image reading apparatus according to the present invention.

FIG. 2 is a flowchart showing a reading operation of the image reading apparatus according to the first embodiment of the present invention.

[Explanation of symbols]

 A image reading apparatus 101 CPU 102 ROM 103 RAM 104 image memory 105 registration unit 106 communication encoding / decoding processing unit 107 reading / recording encoding / decoding processing unit 108 operation unit 109 MODEM 110 NCU 112 image processing unit 113 scanner

Claims (5)

[Claims] 1. An image reading unit that scans a document to read an image line by line, a black and white inversion number counting unit that counts the number of black and white inversions of the read image of each line, and reads the read image as image data. Data storage means for storing in a buffer, compression selection means for determining whether or not to compress the stored image data based on the black and white inversion number counted by the black and white inversion number counting means, and determination of the compression selection means An image reading apparatus including an encoding unit that encodes only image data determined to be compressed based on the above. 2. The image reading apparatus according to claim 1, wherein a threshold for the number of black and white inversions, which indicates whether or not to compress the stored image data, is set based on the number of main scan pixels. 3. The image reading apparatus according to claim 1, wherein a threshold for the number of black and white inversions, which indicates whether or not to compress the accumulated scan data, is set based on a main scan resolution. 4. The threshold value of the number of black and white reversals for compressing the accumulated scan data is set based on the document width set on the reading document table. Image reading device. 5. A threshold value for the number of black and white reversals that determines whether or not to compress the accumulated scan data is set based on the main scan resolution and the document width set on the reading document table. The image reading apparatus according to claim 1.