JPH0758954A - Facsimile equipment - Google Patents

Abstract

PURPOSE:To evade the deterioration of a print-outputted image generated by combination by performing halftone image processing by selecting one of plural kinds of dither patterns, and performing document transmission. CONSTITUTION:When an operator desires the document transmission by a binary mode, an NCU 4 performs a dial calling operation by selecting the binary mode and issuing a dial instruction by an operating part 22, and G3 procedure is started by closing a DC loop by a reception side(callee side). After that. the selection of the binary mode is recognized, and a document image read by a read sensor 8 is correctively controlled by a read control part 10, and is simply binarized by a binarization circuit 11, and image data is modulated by a modem 6 via a CPU 14, and a modulation signal is sent out from the NCU 4 to a central office line 2. When all the image data are sent out, transmission is completed by the procedure of transmission completion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facsimile apparatus which performs a halftone reading process by a dither method when reading an original image in a halftone mode.

[0002]

2. Description of the Related Art Conventionally, according to the G3 facsimile standard, the scanning density of reading and recording is 8 pels (8 pixels / mm) in the main scanning direction and 3.85 line / in the sub scanning direction. mm (standard) or 7.7 line / mm (fine).

Therefore, in a conventional facsimile apparatus, a CCD sensor or a contact image sensor equivalent to 8 pels is used as a reading element, and a recording element is similarly 8 pels in terms of ease of control and reduction of space. In many cases, a thermal recording method is used in which recording is performed on a thermal recording paper by using a corresponding thermal head.

Therefore, the received data sent in accordance with the procedure of G3 is transferred to the thermal head as it is as image data of 8 pels after demodulation and decoding, and the recording and printing of 8 pels are performed.

[0005]

However, in the case of the above-described method of recording and printing on the thermal recording paper by the thermal head, since the thermal recording paper cannot be saved due to retirement and cannot be added to the recording paper. Today, plain paper is increasingly used as recording paper.

At this time, as a plain paper recording system, LBP is used.
(Laser beam printer) method and BJ (bubble jet) method are used, but usually LBP recording device and BJ
The recording device has a resolution of about 400 dpi, which is very high compared to the G3 standard of 8 pels and 3.85 line / mm.
In order to print and record with the J recording device, the resolution of the image data must be converted according to the recording device and transferred to the recording device.

Specifically, 8 pel, 3.85 line
In order to record image data of 400 mm / mm at 400 dpi, data is added to the original image data at regular intervals, interpolation is performed between pixels, and printing is equivalently performed.
Pel, 3.85 line / mm and the same size image recording are performed.

On the other hand, conventionally, as a reading process for facsimile transmission of an original having light and shade such as a photographic original, one having a halftone mode is generally used.

At this time, as a method of halftone reading,
Change the slice level periodically for each read pixel,
A dither method that expresses light and shade as a pixel block is often used.

Therefore, when the original image data transmitted from the facsimile apparatus for performing the halftone reading of such a dither system is received and recorded by the facsimile apparatus having the recording device for converting the resolution, the slice level of the dither pattern is changed. Since a cycle occurs during the period and a cycle of data interpolation for resolution conversion, a beat may occur in the printed and printed image depending on the dither pattern method.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a facsimile apparatus capable of avoiding image deterioration of a print output image caused by a combination of resolution conversion and halftone processing by a dither method.

[0012]

The present invention has a plurality of dither patterns in the halftone reading mode and, for example, NSF in the G3 procedure signal sent from the partner receiver side when the halftone original is transmitted. When the partner receiver has a means for retrieving signal data and recognizes that the resolution conversion is performed for the G3 standard resolution and recording and printing is performed by the recording device, one of the plurality of types of dither patterns is selected. Is selected, halftone image processing is performed, and the original is transmitted.

[0013]

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

In this apparatus, the reading resolution is 8 pels, 3.
85 line / mm, 16 in half-tone reading mode
It is a gradation dither method and the recording device is 360 dp.
It is assumed that the BJ recording device of i is used and the resolution conversion is performed for this purpose.

In FIG. 1, an office line 2 is a telephone line to which the present facsimile machine is connected. In addition, NCU4
A line control unit for controlling the connected office line 2,
The modem 6 modulates and demodulates data during communication.

The reading sensor 8 is for reading a document. In this embodiment, a contact sensor (CS) is used, and the reading resolution is 8 pel.

The reading control unit 10 is for correcting and controlling the output of the reading sensor 8, and the binarization circuit 11 has
It is a circuit that performs simple binarization in the value mode. The dither slice selection / control unit 12 is a circuit that controls the slice level of 16 gradations according to the dither pattern and performs binarization in the halftone reading mode. In the present embodiment, the dither pattern is a so-called spiral type. And Bayer type can be selected.

The CPU 14 is a central control unit for controlling each section of the apparatus, and the resolution conversion section 16 performs resolution conversion in order to print the image data demodulated during reception recording on the BJ recording apparatus 18. belongs to. Also,
The resolution of the BJ recording device 18 is 360 dpi.

The image memory 20 is for storing the image data demodulated by the modem 6 via the CPU 14 at the time of reception recording. The operation unit 22 has a keyboard and a display unit for the operator to operate, and the ROM 24 stores the control procedure program of this apparatus and other fixed data.

Next, FIG. 2 is a sequence chart showing the most general G3 control procedure. N on the receiving side
The SF signal is a signal having a data area that can be arbitrarily assigned. In the present embodiment, a data bit indicating that the facsimile machine "prints and records after resolution conversion" is assigned in this data area, and the NSF is used. This shall be declared by the signal.

FIG. 3 shows a dither pattern of this embodiment. In this embodiment, the dither slice selection /
The following control is performed by the control unit 12.

That is, the principle of the dither method in this embodiment is that 4 dots × 4 dots are set as one block, and this block is binarized at a slice level of 16 gradations to express this 1 block in 16 gradations. To do.

There are various methods depending on the arrangement of slice levels of 16 gradations in one block at this time. In this embodiment, the spiral type shown in FIG. 3A and the baye shown in FIG. 3B are used.
It is assumed to have r type.

In general, the spiral type of (1) is excellent in black and white contrast because black is solidified when the density is high, whereas the Bayer type of (2) has black dispersed. Therefore, there is a feature that black and white changes smoothly.

Therefore, the usual 8 pel, 3.85 lin
For an e / mm recording system, image data that has undergone halftone reading processing with a spiral dither pattern provides a printed image with excellent contrast.

However, like the apparatus of this embodiment, 8 pels,
When the resolution of 3.85 line / mm image data is converted and printed by a recording device of 360 dpi, the spiral type is excellent in contrast, and therefore the stripe pattern due to the beat of the cycle of the dither pattern and the cycle of resolution conversion is generated. It will be noticeable.

Therefore, in this case, by selecting the Bayer type, since the black dots are dispersed, the stripe pattern can be made inconspicuous.

Next, the operation of this embodiment will be described.

First, in the case of the copy operation, the operator sets a document and selects the copy operation using the operation unit 22. When the operator selects the binary mode, the document image is read by the reading sensor unit 8 (S1) and is corrected and controlled by the reading control unit 10 (S2), as shown in the flowchart of FIG. By recognizing the selection of the mode (S3), the binarization circuit 11 performs simple binarization (S4),
This binarized image data is sent to the CPU 14.

The CPU 14 uses this 8 pel, 3.85 l
The image data of ine / mm is periodically interpolated by the resolution conversion unit 16 (S5), transferred to the BJ recording unit 18, and recorded at 360 dpi (S6). As a result, 8 pels, 3. A print image of the same size as 85 line / mm can be obtained.

On the other hand, when the operator selects the halftone mode (S3), the signal interpolated by the reading control unit 10 in the above operation is the dither slice selection / control unit 1.
2, the Bayer type dither pattern is selected, and image processing is performed (S7). After that, the image data is printed and recorded by the CPU 14 as described above.

Next, the receiving operation in this embodiment will be described with reference to the flowchart of FIG.

First, after receiving a call (S11), the NCU 4 closes the DC loop (S12), and the modem 6 sends out a procedure signal as shown in FIG.

In the NSF signal among them, as described above, it is declared that this device is a device for performing recording after resolution conversion, and thereafter, it shifts to the reception of the image signal.

Next, the image signal coming from the line is demodulated by the modem 6 and reproduced as image data (S1
3), the CPU 14 stores the image data in the image memory 20.
(S14). After that, when all the image signals have been received and stored in the image memory 20, a procedure for ending communication is performed, and the reception ends (S15).

Here, the CPU 14 extracts the image data stored in the image memory 20 and transfers the image data to the resolution conversion unit 16, and thereafter, the resolution conversion is performed in the same manner as in the previous copy operation, and the BJ recording unit 18 performs 360 dpi. By 8pe
1, a printed image of the same size as 3.85 line / mm can be obtained.

Next, the transmission operation in this embodiment will be described with reference to the flowchart of FIG.

First, when the operator desires to send an original in the binary mode, the original is set and the operation unit 22 is used to set the original.
When selecting the value mode and dialing, the NCU4
The dial call operation is performed (S21), and the receiving side (called side)
When the DC loop is closed, enters the G3 procedure.

Thereafter, the selection of the binary mode is recognized in S22, and the original image read by the reading sensor 8 in S23 is
Correction control is performed by the reading control unit 10 (S24), simple binarization is performed by the binarization circuit 11 (S25), and this image data is
Modulated by the modem 6 via the CPU 14 (S2
6), this modulated signal is sent from the NCU 4 to the office line 2 (S27). And when all the image data is sent out,
The transmission is ended by the procedure of ending the communication.

When the operator desires to transmit the original in the halftone mode (S22), the modem 6 demodulates the NSF signal sent from the receiver side in the procedure after the dial call, and then the CPU 14 Searches for data (S2
8).

If the CPU 14 does not detect the data indicating that the recording device on the receiver side "prints and prints after resolution conversion" in the data in the NSF signal (S29). The image signal read by the reading sensor 8 in S30 is corrected and controlled in the reading control unit 10 in S31 and sent to the dither slice selection / control unit 12. At this time, the spiral type image is processed during the halftone image processing. Is selected (S32).

Thereafter, the image data is sent to the modem 6 via the CPU 14 and modulated (S26), and sent from the NCU 4 to the office line 2 (S27).

On the other hand, when the CPU 14 detects in the data in the NSF signal that the recording device on the receiver side "prints and prints after resolution conversion" (S29), S33 is executed. The image signal read by the reading sensor 8 is correction-controlled by the reading control unit 10 in S34 and sent to the dither slice selection / control unit 12. At this time, a Bayer type image is processed during halftone image processing. A dither pattern is selected (S35).

After this, the image data is C
It is sent to the modem 6 via the PU 14 and modulated (S2
6), it is sent from the NCU 4 to the office line 2 (S27).

After the above, when all the image data has been sent out, the procedure for ending the communication is performed and the sending operation is ended.

[0046]

As described above, according to the present invention,
In addition to having a plurality of types of dither patterns in the halftone reading mode, the other receiver side has means for searching for predetermined identification data in the G3 procedure signal sent from the other receiver side when transmitting the halftone original. When the resolution is converted to the resolution of the G3 standard and the recording apparatus recognizes that the recording and printing are to be performed, one of the plurality of types of dither patterns is selected, halftone image processing is performed, and the original is transmitted. As a result, it is possible to reduce image disturbance such as a striped pattern that occurs in the print output image on the receiver side.

Further, when the self-apparatus is provided with the print recording section for performing resolution conversion as in the above-described embodiment, the dither pattern is selected and the halftone image processing is similarly performed during the copying operation. As a result, it is possible to reduce image disturbance such as a striped pattern that occurs in the print output image even during copy printing.

[Brief description of drawings]

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

FIG. 2 is a sequence chart showing a general G3 control procedure.

FIG. 3 is an explanatory diagram showing a dither pattern used in the above embodiment.

FIG. 4 is a flowchart showing a copy operation of the above embodiment.

FIG. 5 is a flowchart showing a receiving operation of the above embodiment.

FIG. 6 is a flowchart showing a transmission operation of the above embodiment.

[Explanation of symbols]

 2 ... Station line, 4 ... NCU, 6 ... Modem, 8 ... Read sensor, 10 ... Read control unit, 11 ... Binarization circuit, 12 ... Dither slice selection / control unit, 14 ... CPU, 16 ... Resolution conversion unit, 18 ... BJ recording device, 20 ... Image memory, 22 ... Operation part, 24 ... ROM.

Claims (1)

[Claims] 1. A plurality of types of dither patterns in the halftone reading mode are provided, and a means for searching for predetermined identification data in a G3 procedure signal sent from the partner receiver side when a halftone original is transmitted is provided. When the partner receiver recognizes that the resolution is converted to the G3 standard resolution and the recording device prints and prints, one of the plurality of types of dither patterns is selected and halftone image processing is performed. , A facsimile machine characterized by transmitting originals.