JPH05219326A - Picture processor - Google Patents

Abstract

PURPOSE:To reduce deterioration in picture quality of a read picture caused by intermittent operation without increasing the unit cost by adjusting the line density of an original picture corresponding to the occupancy rate of picture information in a buffer memory. CONSTITUTION:A scanner 1 is made up of a picture input section 1a comprising a photoelectric conversion element such as a CCD and a drive system scanning the element or the like, and a picture processing section 1b processing an analog picture from the picture input section 1a into a white/black binary signal. When the reading is started, the presence of an idle area in a buffer memory 4 is checked to discriminate the occupancy rate of picture information to be stored thereby selecting the line density of picture reading. A plotter 2 prints out the picture and a coding/decoding section 3 compresses the picture information and decodes the data into received picture information. A MODEM 5 sends/ receives various protocol signals for controlling picture information and transmission, a network controller 6 is connected to a telephone line to apply prescribed line control through an operation display section 7 in the case of outgoing/ incoming call processing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus for concurrently performing an operation of sequentially reading a document image line by line and storing it in a buffer memory and an operation of sequentially reading and processing stored image information. ..

[0002]

2. Description of the Related Art Normally, a facsimile machine reads a document image and transmits it at the same time. In this case, the facsimile device has an operation of storing image information obtained by sequentially reading a document image line by line in a buffer memory, and an operation of sequentially reading the stored image information and encoding, that is, data compressing and transmitting. Are running in parallel.

The speed at which image information is read line by line is constant. On the other hand, the speed at which image information is encoded and transmitted line by line changes depending on the amount of change points of black and white pixels and the data transmission speed of the modem.

If the speed at which the image information is encoded and transmitted is slower than the speed at which the image is read, the buffer memory becomes full. In this case, pause the image reading operation,
When a certain amount of free space is available in the buffer memory, the reading operation is restarted.

At the time of stopping or resuming such image reading, a driving device for conveying an original for sub-scanning is intermittently operated.

[0006]

In such an intermittent operation, the document is pulled back or excessively advanced in reverse due to the inertia of the entire driving device and the delay in the rising operation of the motor. Therefore, when the buffer memory is full and an intermittent operation occurs, there is a problem that the image reading line position is displaced and the image quality of the read image deteriorates.

In order to prevent such deterioration of image quality,
It is conceivable to increase the memory capacity so that the buffer memory does not become full. However, in that case, another problem arises that the cost of the apparatus increases.

An object of the present invention is to solve the above problems and to provide an image processing apparatus capable of reducing the deterioration of the image quality of a read image without increasing the apparatus cost.

[0009]

To this end, the present invention determines the occupancy rate of image information in the buffer memory during execution of image reading, and if the occupancy rate is below a certain level, a certain line rate is determined. If the occupancy exceeds a certain level while reading the original image at a high density, the original image is read at a higher linear density, and the image information of each line obtained is read for each line of the above-mentioned constant linear density. It is characterized in that it is stored in a buffer memory after being converted into image information.

[0010]

When the occupancy rate of the image information in the buffer memory is high, the image is read with a higher linear density, so that the reading speed is reduced and the buffer memory is less frequently filled. As a result, the frequency of temporarily stopping the reading operation is also reduced, and the deterioration of image quality due to the intermittent operation of the driving device that conveys the original document is reduced. Further, since it is not necessary to increase the memory capacity of the buffer memory, the device cost will not be increased.

[0011]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a block diagram of a facsimile apparatus according to an embodiment of the present invention. In the figure, a scanner 1 reads an original image, and in the present embodiment, 8 × 3.85 (dots / mm) and 8 × 7.7.
(Dot / mm) and 8 × 15.4 (dot / mm)
It has a function of reading an image with the three types of linear densities. The scanner 1 includes an image input unit (1a) including a photoelectric conversion element such as a CCD and a driving system for scanning the photoelectric conversion element, and an image processing unit (binary processing of analog image information from the image input unit). b) etc.

The plotter 2 records and outputs an image. The encoding / decoding unit 3 compresses image information to be transmitted by a certain encoding method, and decodes the received image information to restore the original image information. The buffer memory 4 temporarily stores image information.

The modem 5 sends and receives image information and various procedure signals for transmission control. The network controller 6
A telephone line is connected, and predetermined line control is performed when making or receiving a call. The operation display unit 7 is for displaying various information such as the operating state of the device as the operator performs various operations. The system control unit 8 is a microcomputer that controls the above-mentioned units, and the system bus 9 is a signal line through which the above-mentioned units exchange various control signals and data with each other.

With the above-described structure, when transmitting a document with the facsimile apparatus of this embodiment, the operator sets the document to be transmitted on the scanner 1 and performs a predetermined transmission operation on the operation display unit 7. At the time of this transmission operation, a desired linear density of the transmission image is set.

As a result, the facsimile apparatus calls the other party and transmits the document image according to a known transmission control procedure. At the time of this image transmission, as shown in FIG. 2, the document image is sequentially read by the scanner 1, and the obtained image information is sequentially stored in the buffer memory 4. Further, in parallel with the operation, the image information stored in the buffer memory 4 is sequentially read and encoded by the encoding / decoding unit 3. Then, the encoded image information is modulated by the modem 5 and transmitted via the network control device 6. In this case, the image information will be transmitted at the data transmission rate set in the transmission control procedure.

Now, the linear density of the transmitted image is 8 × 3.85.
(Dot / mm) is set. Figure 3
Shows the image reading operation of the scanner 1 in this case. That is, when the scanner 1 starts the reading operation,
First, it is checked whether or not there is an empty area in the buffer memory 4 (process 101). If the buffer memory 4 has a free space (N in process 101), the occupation ratio of the stored image information is determined (process 102).

Immediately after the scanner 1 is started up, since the image information is not yet stored in the buffer memory 4, the occupation rate is zero. In this way, when the occupation rate is less than 50% (Processing 1
02 "less than 50%"), by the sub-scanning control means 1b,
As shown in FIG. 4A, the document is sub-scanned at a pitch of 1 / 3.85 mm to read one line of the document image (process 103). Then, the obtained image information is stored in the buffer memory 4 (process 104).

Thereafter, it is checked whether or not the reading of the original image is completed (process 105). If the reading is not completed (N in process 105), the process returns to the buffer empty check (process 101). This gives 8 × 3.85 (dots /
The image information of the linear density (mm) is sequentially stored in the buffer memory 4 line by line. The stored image information is encoded by the encoding / decoding unit 3 and sequentially transmitted by the modem 5.

By the way, the time required for the encoding / decoding unit 3 to encode one line of image information becomes longer as the number of black and white pixel change points in the image information increases. In that case, the amount of data after encoding increases, and the time required for the modem 5 to transmit the image information of one line also increases. Also, the modem 5
The transmission time of the image information also changes depending on the data transmission rate set in the transmission control procedure.

Now, if the speed at which the image information is stored in the buffer memory 4 becomes faster than the speed at which the image information is transmitted due to these causes, the occupancy rate of the image information in the buffer memory 4 gradually increases.

In this way, when the occupancy rate of the image information in the buffer memory 4 becomes 50% or more and 80% or less ("50% -80%" of the process 102), as shown in FIG. , The document is sub-scanned at a pitch of 1 / 7.7 mm to read the document image for two lines (process 106). The two-line section of the original image corresponds to one-line section having a 1 / 3.85 mm pitch.

In this case, the same pixels of the image information of the two lines are OR-processed to obtain 8 × 3.85 (dots / mm).
Is converted into image information for one line (process 107). Then, the obtained one-line image information is stored in the buffer memory 4 (process 104) and the same process is repeated (process 1).
01).

After that, when the occupancy rate of the image information in the buffer memory 4 further rises and exceeds 80%, (Processing 10
2 "80% excess"), as shown in FIG. 4C, the document is sub-scanned at a pitch of 1 / 15.4 mm to read the document image for four lines (process 108). This 4 of the manuscript image
The line section corresponds to one line section with a pitch of 1 / 3.85 mm.

In this case, the same pixels of the image information of the four lines are respectively OR-processed and converted into image information of one line of 8 × 3.85 (dots / mm) (Process 10).
7). Then, the obtained one-line image information is stored in the buffer memory 4 (process 104) and the same process is repeated (process 101).

By the way, as described above, the sub-scanning is 1/7.
If the pitch is switched to 7 mm or 1 / 15.4 mm, it will take time to obtain image information for one line of 8 × 3.85 (dots / mm).

Therefore, the speed at which the image information is stored in the buffer memory 4 is likely to be slower than the speed at which it is transmitted.
When the storage speed of the image information becomes slow as described above, the occupation rate of the image information in the buffer memory 4 decreases. In that case, the sub-scanning pitch is sequentially switched to the larger one as described above according to the occupation ratio. This allows the buffer memory 4
The occupancy rate will be adjusted to some extent.

On the other hand, when the transmission speed becomes extremely slow with respect to the image information storage speed, the buffer memory 4 becomes full. In this case, the document reading is stopped, and the process waits until a certain amount of empty area is secured (Y loop of processing 101).

Then, when a certain amount of free area is secured in the buffer memory 4 (N in process 101), the above reading process is restarted (to process 102). Then, when the reading of the original image is completed (N of processing 105), the above operation is completed.

As described above, in this embodiment, 8 × 3.8.
When transmitting an image with a linear density of 5 (dots / mm), the image reading is first started at the sub-scanning pitch of 1 / 3.85 mm, but if the occupancy of the buffer memory 4 increases, 1
/7.7 mm or 1 / 15.4 mm,
An image is read by narrowing the sub-scanning pitch, and the obtained image information of a plurality of lines is converted into 8 × 3.85 (dots / mm).

Since the reading speed is reduced by narrowing the sub-scanning pitch in this way, the buffer memory 4 becomes full, and the frequency of temporarily stopping the document conveying operation is also reduced. As a result, it is possible to reduce the deterioration of the image quality of the read image due to the intermittent operation of the driving device that conveys the document.

Further, in the present embodiment, when the number of black and white change points in one line is large, it takes a long time for the encoding process and the occupancy rate of the image information in the buffer memory 4 increases, so that the image reading is performed at a higher linear density. Is executed. An image having a large number of black and white change points is usually a small character or figure. Therefore, in the present embodiment, the image reading of the fine characters and figures in the original image of one page is executed with a higher linear density, so that the image quality of the read image is further improved.

In the present embodiment, the buffer memory 4
Since it is not necessary to increase the memory capacity, the device cost does not increase.

Next, another embodiment of the present invention will be described.

In the above embodiment, as shown in FIG.
For any of the three sub-scanning pitches, the occupancy rate of the image information in the buffer memory 4 is determined every time the original image is read in the 1 / 3.85 mm section, and the sub-scanning pitch is set under a predetermined condition. In this embodiment, the occupancy rate is determined every time one line is read regardless of the sub-scanning pitch, and the sub-scanning pitch is similarly switched under a constant condition.

By reading the original image in this manner, as shown in FIG.
The 3.85 mm section can be read as 1 line at a pitch of 1 / 7.7 mm and 2 lines at a pitch of 1 / 15.4 mm. In this case, the three lines are OR-processed to obtain image information of one line of 8 × 3.85 (dots / mm).

As a result, as compared with the case of the above-described embodiment, the sub-scanning pitch can be switched more promptly according to the change of the occupation rate of the buffer memory 4.

Next, another embodiment of the present invention will be described.

In each of the above-described embodiments, the sub-scanning pitch set for the occupation ratio of the image information in the buffer memory 4 is fixed in advance. However, in this embodiment, after the image reading operation is started,
The setting condition of the sub-scanning pitch is changed according to the operating condition.

In this embodiment, as shown in FIGS. 6A and 6B, two types of setting conditions for the sub-scanning pitch to be set for the occupancy ratio are prepared. That is, FIG.
The normal setting conditions are the same as those described above and the respective embodiments, and FIG. 6B shows the setting conditions in which the standard of the occupation ratio for narrowing the sub-scanning pitch is lowered.

First, as shown in FIG. 7, the sub-scanning pitch setting condition is set to the normal setting condition shown in FIG. 6A (process 201), and as described with reference to FIG. The reading operation of the original image is started (process 202).

Thereafter, the occurrence of the intermittent operation in which the buffer memory 4 is full and the reading is temporarily stopped is monitored (process 203). Here, if the intermittent operation is equal to or lower than a preset fixed frequency, the monitoring is continued as it is (Process 2
03 N loop).

Then, if the intermittent operation becomes more frequent than a certain frequency (Y in processing 203), the setting condition of the sub-scanning pitch is changed to the other setting condition shown in FIG. 6B (processing). 204).

Under the setting conditions shown in FIG. 9B, when the image information occupation ratio of the buffer memory 4 is 20% or more, the sub-scanning pitch is 1 / 7.7 mm, and when it exceeds 60%, it is 1 / 0.7 mm.
The image is read by switching to 15.4 mm.

In this way, at a lower occupation rate than usual,
By switching to a high image reading line density, the reading speed of image information is reduced, and the frequency with which the buffer memory 4 is filled is reduced, so the frequency of intermittent operation is also reduced.
As a result, the deterioration of the image quality of the read image is further reduced.

In each of the above-described embodiments, the original image is 8
The case of transmitting at a linear density of × 3.85 (dots / mm) has been described, but for example, when transmitting an image at 8 × 7.7 (dots / mm), the sub-scanning pitch is 1 / 7.7 mm. And switching to 2 stages of 1 / 15.4 mm,
It goes without saying that the sub-scanning pitch may be switched to a higher one than the pitch corresponding to the linear density of the transmitted image by a similar method.

Also, the facsimile apparatus for transmitting while reading the original image has been described as an example.
It is needless to say that the present invention can be similarly applied to not only a facsimile apparatus but also various image processing apparatuses that sequentially read image information and store it in a buffer and simultaneously read the image information and execute some processing.

[0048]

As described above, according to the present invention, the occupancy rate of image information in the buffer memory is determined during image reading, and if the occupancy rate exceeds a certain level, it is higher. The original image is read with linear density, and the image information of each line obtained is converted into image information with a predetermined linear density and stored in the buffer memory, so the buffer memory becomes full and the reading operation is temporarily stopped. Because it stops less often,
The deterioration of the image quality of the read image is reduced. Further, since it is not necessary to increase the memory capacity of the buffer memory, the device cost will not be increased.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a facsimile apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a flow of image information between respective units during image transmission.

FIG. 3 is a flowchart of an image reading operation.

FIG. 4 is an explanatory diagram of an image reading operation at various sub-scanning pitches.

FIG. 5 is an explanatory diagram of an image reading operation at various sub-scanning pitches according to another embodiment of the present invention.

FIG. 6 is an explanatory diagram of setting conditions of a sub-scanning pitch in still another embodiment of the present invention.

FIG. 7 is an operation flowchart showing an operation of changing a setting condition of a sub-scanning pitch in the embodiment.

[Explanation of symbols]

 1 Scanner 1a Image Input Unit 1b Image Processing Unit 2 Plotter 3 Encoding / Decoding Unit 4 Buffer Memory 5 Modem 6 Network Control Device 7 Operation Display Unit 8 System Control Unit

Claims (4)

[Claims] 1. A buffer memory for temporarily storing image information, an image reading means for sequentially reading an original image line by line and storing image information of a constant linear density in the buffer memory, and in parallel with the storing operation. Image processing means for sequentially reading and processing the stored image information, and image reading stopping means for temporarily stopping the reading of the image information until a certain empty area is formed when the buffer memory is full In the image processing apparatus, the memory occupancy rate determining means for determining the occupancy rate of the image information in the buffer memory, and when the occupancy rate is less than a certain level, the document image is normally read at the certain linear density. A reading means, a high linear density reading means for reading the original image at a linear density higher than the constant linear density when the occupation ratio exceeds a certain level, and a high linear density reading means for reading the original image. Image information converting means for converting the image information of each line obtained by the linear density reading means into the image information of each line of the above-mentioned constant linear density, and each line obtained by the image information converting means or the normal reading means. And an image information storage means for storing the image information of 1. in the buffer memory. 2. The original image is determined based on the occupancy rate of the image information in the buffer memory at a time interval for storing the image information of the constant linear density line by line in the buffer memory. The image processing apparatus according to claim 1, further comprising means for changing the read line density of the image. 3. The reading linear density of the original image is determined based on the occupancy rate of the image information in the buffer memory at a time interval for reading the original image line by line regardless of the linear density. The image processing apparatus according to claim 1, further comprising a changing unit. 4. Means for determining the frequency of occurrence of the image information reading stop state by the image reading stop means, and if the occurrence frequency is high, when the occupancy exceeds a specific level lower than the certain level. The image processing apparatus according to claim 1, further comprising: a unit that reads the original image with a linear density higher than the predetermined linear density.