JP3244549B2 - Image input device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image input apparatus, such as a facsimile apparatus or a scanner, for temporarily stopping conveyance of a document and interrupting reading when a buffer for storing compressed image data becomes full.

[0002]

2. Description of the Related Art Generally, at the time of transmission in a facsimile apparatus, if the transmission rate is low, the I / O rate of the other party is low, or if the amount of image information is large and the compression time is long, image compression is performed. When the buffer for storing data becomes full, reading is interrupted, and when a certain amount of free space is generated in the buffer, reading is resumed.

Conventionally, in this type of image input apparatus, when the compression processing is delayed as shown in, for example, Japanese Patent Laid-Open No. 2-161871, the reading speed is reduced to 1 / n and the reading is performed. In the conventional image input device, encoding is performed according to the data occupation amount of a buffer memory as disclosed in, for example, Japanese Patent Application Laid-Open No. 2-1070065. It is configured to change the amount.

[0004]

However, in the conventional image input apparatus disclosed in Japanese Patent Application Laid-Open No. HEI 2-161871, the feed amount fluctuates when the document is stopped, as shown in FIG. However, there is a problem that the image quality is degraded due to lack of a thin line. In addition, Japanese Unexamined Patent Application Publication No.
Similarly, the method disclosed in Japanese Patent No. 107065 has a problem that the image quality is deteriorated when the coding amount is reduced.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described conventional problems, and has as its object to provide an image input apparatus capable of minimizing deterioration of image quality when document conveyance is temporarily stopped and reading is interrupted. I do.

[0006]

In order to achieve the above object, a first means is to read and output an image of a document.
Input means and a signal output from the image input means.
Processing means for generating binarized image data based on the
Image compression means for compressing the binarized image data
Stage and storage means for storing the compressed image data
And the compressed image data of the read original image
Once stored in the storage means, and then transmitted sequentially
Then, the usage amount of the storage means is determined, and the usage amount is determined in advance.
When the amount is less than the set amount, the image compression means
The compression of the image data is continued and the used amount is set in advance.
When the amount exceeds the specified amount, the storage means is full
And if it is full, the image input means
Scanning of the original by the
For example, monitor the binary data of one line of the original before compression
Then, as a monitor result, the number of black pixels is equal to or less than a preset number.
If the reading of the original by the image input means is interrupted ,
And control means for causing

[0007] The second means is the first means, all pixels said control means as said monitoring result, wherein the benzalkonium to interrupt reading of the document when the white pixel.

[0008] The third means is the first or the second means.
The control means has a line detection circuit and a CPU.
The monitor is performed by a line detection circuit, and the line
It characterized the Turkey to interrupt the reading of the <br/> document by the CPU based on the detection signal in the detection circuit.

[0009] The fourth means is the third means, wherein:
The multi-value data before the binarization is input to the line detection circuit.
The multi-value data is binarized by the line detection circuit.
The monitoring is performed by using

A fifth means is the first means, wherein
Control means for occupying the compressed data in the storage means;
The prevailing rate is monitored and the image input means in the sub-scanning direction.
The above occupation ratio which differs according to the read line density is stored as the threshold value.
Characterized the this <br/> usage means determines whether or amount set in advance.

[0011]

In the first means, the amount of use of the storage means is set in advance.
Before the compression for one line of the original
Of the number of black pixels as a result of monitoring
Is less than a preset number, the image input means
Since the reading of the original is interrupted, it is possible to prevent the image quality from deteriorating due to the lack of an image in an area with a small number of thin lines or character images when the conveyance of the original is temporarily stopped and the reading is interrupted.

In the second means, the reading of the document is interrupted when all the pixels are white as a result of the monitor. Therefore, when the transport of the document is temporarily stopped and the reading is interrupted, a thin line is missing or the image quality is reduced. Deterioration can be prevented.

In the third means, since the CPU controls the interruption of the reading of the original based on the detection signal of the monitor circuit, the load on the CPU can be reduced.

[0014] In the fourth means, the binary value is added to the line detection circuit.
The multi-value data before conversion is input, and the line detection circuit
Since the monitoring is performed by binarizing the value data, the load on the CPU can be reduced.

In a fifth means, the storage means of the compressed data is
The occupancy of the stage is monitored, and the
Different occupancy depending on the reading line density in the sub-scanning direction
And the remaining storage capacity is set in advance.
Since it is determined whether the amount is equal to or larger than the amount, it is possible to prevent the image quality from being degraded due to lack of a thin line.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a facsimile apparatus as an embodiment of the image input apparatus of the present invention, FIG. 2 is a block diagram showing an image processing section of FIG. 1 in detail, and FIG. 3 explains the operation of the facsimile apparatus of FIG. It is a flowchart for the.

The reading section 1 shown in FIG. 1 is roughly constituted by an image input section 1a and an image processing section 1b. The image input section 1a is composed of a light source, a reflection mirror, an image forming lens, a document conveying motor, etc. The reading sensor 10 is provided as shown in FIG.

In the image processing section 1b, as shown in FIG. 2, an analog video signal read by the sensor 10 is subjected to shading correction by the analog image processing section 11 and then quantized into multi-valued digital data. The image is transferred to the image processing unit 12.

The multi-value data is configured as a 3 × 3 matrix together with the previous two lines of multi-value data already stored in the image processing memory 13 by the digital image processing unit 12, and based on this data, the MTF is calculated. Amended,
Next, after being binarized into black and white data, the system bus 14
Is output to

Returning to FIG. 1, the system bus 14 has a CPU
(Central Processing Unit) 15, Memory 16, Operation Unit 17
, A recording unit 18, a communication control unit 19, and an image compression / decompression unit 2.
0 etc. are connected. The CPU 15 controls each unit 1, 10 to 14, and 16 to 20 of the facsimile machine,
In particular, reading control of a document as shown in FIG. 3 is performed.

A memory (buffer) 16 stores compressed data of a document read by the reading section 1 and stores received image data. An operation section 17 includes various keys and a display section necessary for a facsimile apparatus. ing. The recording unit 18 records the received image and the original image read by the reading unit 1 on recording paper, and the communication control unit 19 controls facsimile communication via a line.

The image compression / decompression section 20 compresses the original image read by the image input section 1a and stores it in the memory 16, and decompresses the code of the received image stored in the memory 16. As described above, when the transmission rate is low, when the I / O rate of the other party is low, or when the amount of image information is large and the compression time is long, the buffer 16 for storing the compressed data of the image is used. When the buffer 16 becomes full, the reading is interrupted, and when a certain amount of free space is generated in the buffer 16, the reading is started.

Next, the operation of the above embodiment will be described with reference to FIG. First, when a line is established and transmission is started (step S1), reading of a document is started by the image input unit 1a (step S2), and the digital image processing unit 1 is started.
The image data binarized by the image compression / decompression unit 20
And stores it in the buffer 16. The compressed data is sequentially transmitted to the other party according to the transmission rate and the like.

If the document compression process is not to be terminated, the process proceeds from step S4 to step S5, where the buffer 1
It is determined whether the area of No. 6 is used more than half,
If the determination is YES, the process proceeds to step S6. If the determination is NO, the process returns to step S3 to continue the compression process.

In step S6, it is determined whether or not the area of the buffer 16 is full. If YES, the process jumps to step S9, and if NO, the process proceeds to step S7. In this embodiment, the CPU 15 monitors the binary data of one line before compression in step S7. If all the pixels of one line are white, the CPU stops the motor for transporting the original and stops reading. If all the pixels in one line are not white, the process returns to step S3 to continue the compression process.

Next, while the reading is interrupted, the compressed data in the buffer 16 is monitored, and when the data is exhausted, the motor for transporting the original document is restarted to restart reading (step S11), and the process returns to step S3 to perform the compression process. Resume. This routine ends when the compression processing ends in step S4.

Therefore, according to the above embodiment, when the area of the buffer 16 is full, if all the pixels of one line before compression are white, the motor for conveying the original document is stopped and reading is interrupted. It is possible to prevent the image quality from deteriorating due to missing lines, and to minimize the image quality degradation when the document transport is temporarily stopped and reading is interrupted.

In the above embodiment, when all the pixels of one line before compression are white in step S8, the motor for conveying the original is stopped to stop reading. In the case where the number of black pixels is 1028, as shown in FIG. 4, when the number of black pixels in one line is equal to or less than a predetermined number such as 10 pixels (step S8a), the motor for transporting the original is stopped to stop reading. May be
In this case, even if the white line does not easily appear, it is possible to minimize the deterioration of the image quality on the line with few character images.

In the above embodiment, the CPU 15 determines the pixel. However, the determination of the pixel by hardware can reduce the load on the CPU 15. That is, as shown in detail in FIG. 5, the multi-value data from the analog processing unit 11 shown in FIG.
The image processing memory 1
3 is configured as a 3 × 3 matrix together with the multi-value data of the previous two lines already stored in M.3, the MTF is corrected by the MTF correction circuit 122 based on this data, and then the threshold value set by the threshold value setting circuit 124 Is converted into black and white data by the binarization circuit 123 based on the image data, and is output to the system bus 14 by the image information transfer circuit 125.

In this embodiment, the white line detection circuit 1
Reference numeral 26 monitors the binarized data. If all the pixels on one line are white (or the number of white pixels on one line is less than a predetermined number), a detection signal is sent to a CPU (central processing unit) 15 via a system bus 14. It is configured to output. The timing generation circuit 127 outputs necessary timing signals to the circuits 121 to 126 in the digital image processing unit 12.

Also, instead of the white line detection circuit 126 detecting whether or not all the pixels on one line are white based on the data from the binarization circuit, the white line detection circuit 126a is used as shown in FIG. The multi-level data from the processing unit 11 is divided into two based on the threshold set by the threshold setting circuit 124.
The data may be converted into a value to detect whether or not all the pixels on one line are white based on the data.

Further, in the above-described embodiment, it is determined in step S5 shown in FIG. 3 whether or not the area of the buffer 16 has been used by more than half. Instead, as shown in FIG. It may be configured to determine the density. That is, for example, when the linear density is 3.75 lp / mm (step S51), the occupancy of the buffer 16 is 80%.
In the above case (step S52), the process proceeds to step S6 shown in FIG. 4, and when it is not 80% or more, the process returns to step S3 to continue the compression process.

When the linear density is 7.7 lp / mm (step S53) and the occupancy of the buffer 16 is 50% or more (step S54), the process proceeds to step S6 shown in FIG. In this case, the process returns to step S3 to continue the compression process. When the linear density is not the above value, when the occupancy of the buffer 16 is 25% or more (step S55), the process proceeds to step S6 shown in FIG.
If not, the flow returns to step S3 to continue the compression process.

In this example, when the line density is high, the read amount of one line is large, so that the probability of detecting a white line can be increased, and therefore the image quality is degraded due to lack of a thin line. Can be prevented.

[0035]

As described above , according to the first aspect of the present invention , the amount of use of the storage means is more than a predetermined amount.
If it becomes, the binarized data before compression for one line of the original
Monitor the number of black pixels as a result of monitoring.
The number so with the following to that control means interrupting the reading of the document by the image input means when the image in the area thin lines and character images is small in the case of interrupting the reading stop conveyance of the document once It is possible to prevent the image quality from deteriorating due to chipping.

According to the second aspect of the present invention , the monitor result
As control is performed so that reading of the document is interrupted when all the pixels are white, it is necessary to temporarily stop the conveyance of the document and to prevent the image quality from deteriorating due to missing thin lines when reading is interrupted. Can be.

According to the third aspect of the present invention , line detection is performed.
Circuit and CPU, monitored by line detection circuit
And based on the detection signal of the line detection circuit,
Than you interrupt the reading of the document by the U, it is possible to reduce the burden of the CPU.

According to the fourth aspect of the invention , line detection is performed.
The circuit receives multi-valued data before binarization, and
Since the multi-value data is binarized and monitored by the application detection circuit, the load on the CPU can be reduced.

According to the fifth aspect of the present invention , the compressed data
Monitor the occupancy of the data in the storage means, and
Depending on the reading line density in the sub-scanning direction by the image input
The usage of the storage means is set in advance with the occupancy rate as a threshold
Since it is determined whether or not the amount is equal to or greater than the set amount, it is possible to prevent the image quality from deteriorating due to lack of a thin line.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a facsimile apparatus as one embodiment of an image input apparatus according to the present invention.

FIG. 2 is a block diagram illustrating an image processing unit of FIG. 1 in detail;

FIG. 3 is a flowchart for explaining the operation of the facsimile machine of FIG. 1;

FIG. 4 is a flowchart for explaining a main part of a modification of the operation shown in FIG. 3;

FIG. 5 is a block diagram showing a modification of the digital image processing unit shown in FIG. 2 in detail.

FIG. 6 is a block diagram showing another modification of the digital image processing unit shown in FIG. 2 in detail.

FIG. 7 is a flowchart for explaining a main part of another modification of the operation shown in FIG. 3;

FIG. 8 is an explanatory diagram illustrating a document feed amount when the conveyance of a document is temporarily stopped and reading is interrupted.

[Explanation of symbols]

 1a Image input unit 15 CPU (central processing unit) 16 Memory (buffer) 20 Image compression / decompression unit 126, 126a White line detection circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 1/04-1/207 G06T 1/00 G06T 1/60 H04N 1/41-1/419

Claims (5)

(57) [Claims] An image input for reading and outputting an image of a document.
Binarization based on a signal output from the input means and the image input means
Image processing means for generating compressed image data, and image compression means for compressing the binarized image data
When a storage means for storing image data which has been the compressed, the compressed image data of the read document image wherein
Once stored in the storage means, and then transmitted sequentially,
Determine the usage of the storage means, and set the usage in advance
If the amount is less than
Continue compressing the data and make sure that the
If the storage means is full
And if it is full, the image input means
Scanning of the original is interrupted.
Monitors one line of binary data before compression and monitors
If the number of black pixels is less than the preset number as a result,
The image processing apparatus characterized by and a control unit that causes interrupting reading of the document by the serial image input means. 2. The image processing apparatus according to claim 1, wherein the control unit interrupts reading of the document when all pixels are white pixels as the monitor result . 3. The control device according to claim 1, wherein the control unit includes a line detection circuit and a control unit.
U, and the monitor is performed by a line detection circuit.
To the CPU based on the detection signal of the line detection circuit.
Thus the image processing apparatus according to claim 1, wherein the benzalkonium to interrupt the reading of the document. 4. The apparatus according to claim 1, wherein the line detection circuit has a function of:
Multi-level data is input, and the multi-level data is input to the line detection circuit.
The image processing apparatus according to claim 3, wherein the monitoring is performed by binarizing the value data . 5. The control means according to claim 1 , wherein
Monitoring the occupancy in the storage means, and
Different occupancy depending on the reading line density in the sub-scanning direction
The usage amount of the storage means as a threshold is equal to or greater than a preset amount
The image processing apparatus according to claim 1, wherein it is determined whether or not the image processing is performed.