JPH0345077A - Facsimile equipment - Google Patents

Abstract

PURPOSE:To send an original picture with a prescribed density correctly regardless of the recording system at a receiver side by extracting picture information with a darker density than an actual original density when a recording characteristic of a receiver side device has a characteristic with a large white picture element level and extracting the picture information with lighter density when the recording characteristic of the receiver side device has a characteristic with a large black picture element level and sending the result. CONSTITUTION:A picture read section 1 reading an original picture and extracting picture information is provided with a line image sensor 1a reading an original picture one by one line and a binarizing circuit 1b or the like converting an analog picture signal outputted from the line image sensor 1a into a binary picture element data. Then the recording characteristic of the receiver is discriminated before the transmission of picture information and an original picture is read, then picture information with darker density than the actual original density is extracted when the recording characteristic of the receiver has a characteristic with a larger white picture element level. On the other hand, picture information with lighter density than the actual original density is extracted when the recording characteristic of the receiver has a characteristic with a larger black picture element level. Thus the respective picture information is sent. Then the original picture is sent correctly with prescribed density.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a facsimile device.

[Prior Art] As an image recording method for facsimile machines, a thermal recording method that records an image on thermal paper using a thermal head, or a laser method that records an image on plain paper using a laser beam using an electrophotographic recording method is often used. It has been adopted.

By the way, in general, a thermal head has heating elements arranged at intervals corresponding to the resolution in the main scanning direction, but the width of each heating element in the sub-scanning direction is slightly wider than the width in the main scanning direction. It is formed.

Therefore, when a thermal recording type facsimile receives an image in which there is one black pixel in a white image, for example, as shown in FIG. 10(a), the recorded image is
As shown in FIG. 1(a), black pixels were recorded as being elongated in the sub-scanning direction. Furthermore, as shown in Figure 10(b), when an image in which there is one white pixel in a black image is received, as shown in Figure 11(b), the black pixel before and after the White pixels were recorded as small. Therefore, the original image was recorded with a higher density than the actual image.

On the other hand, in the laser method, a charged photoconductor is irradiated with laser light to remove the charge, and toner is attached to the photoconductor to form an image.

In this case, there are two methods, the so-called positive-positive method and the negative-positive method, based on the correspondence between the laser beam and the toner.

When a negative/positive type facsimile machine of this laser type receives an image as shown in Fig. 10(a), the image shown in Fig. 12(a) and Fig. 10(
In the case of the received image shown in b), the black pixels were recorded slightly larger, as shown in FIG. 12(b). For this reason, as in the case of the thermal recording method described above, the original image was recorded with a higher density than the actual one.6 On the other hand, with the positive-positive method facsimile machine, the When an image is received, as shown in FIG. 13(a), and when the received image is as shown in FIG. 10(b), as shown in FIG. 13(b), large white pixels are recorded. Ta. Therefore, contrary to the above, the original image was recorded with a lower density than the actual image.

[Problems to be Solved by the Invention] As described above, conventionally, there has been a problem in that the density of the m-stripe image transmitted by the transmitting side changes due to the difference in the recording method of the receiving side.

SUMMARY OF THE INVENTION An object of the present invention is to provide a facsimile apparatus that solves the above problems and allows a sending side to correctly transmit an original image at a constant density regardless of the recording method used on the receiving side.

[Means for Solving the Problems] To this end, the present invention determines the recording characteristics of a receiving device before transmitting image information, and when reading an original image, the recording characteristics of the receiving device determines whether white pixels are large or not. In the case of a characteristic where the black pixels become large, image information with a density higher than the actual original density is extracted, while in the case of a characteristic where the black pixels become large, image information with a lighter density is extracted and each image information is transmitted. It is characterized by what it did.

[Operation] This allows the transmitting side to correctly transmit a document image with a constant density, regardless of the recording method on the receiving side.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a block diagram of a facsimile machine according to an embodiment of the present invention. In the figure, an image reading section 1 reads a document image and extracts image information. The image reading section 1 includes a line image sensor la that reads a document image line by line, and converts an analog image signal output from the line image sensor la into binary pixel data. A binarization circuit 1b and the like are provided.

As shown in FIG. 2, this binarization circuit 1b has a function of converting the above-mentioned image signal into binary pixel data by switching the threshold value into three stages: standard value Ss, low value SL, and high value SH. It is equipped with

The image recording section 2 records one image on recording paper.

The encoding/decoding unit 3 encodes image information to be transmitted and decodes received image information. The network control device 4 performs predetermined calling/receiving operations by acquiring a line, sending out a selection signal which is an originating optical telephone number, detecting an incoming call, and the like. The modem 5 modulates and demodulates one-picture information and transmits the same, and also transmits various procedure signals in transmission control procedures. The communication control section 6 controls the network control device 4 and the modem 5 to execute facsimile transmission according to a predetermined transmission control procedure.

The operation display section 7 includes a display and operation keys, and displays the operating status of the facsimile machine and allows the operator to perform various operations.

The system control section 8 is composed of a microcomputer system and controls each of the above sections.

With the above configuration, the transmission operation of this facsimile apparatus will now be explained.

When performing transmission processing, as shown in FIG.

The operator sets a document on the image reading section 1 (process 101) and performs a predetermined transmission operation on the operation display section 7 (process 102).

As a result, the facsimile machine makes a call to the other party (process 103), and when the other party's facsimile machine responds (Y in process 104), a predetermined transmission control procedure is executed.

By the way, in this embodiment, in this transmission control procedure,
The receiving side sends an NSF signal to the transmitting side, and uses this NSF signal to notify the resolution and image recording method of the image recording section of the receiving side device.

At this time, the difference between the thermal recording method and the laser method is notified, and in the case of the laser method, the difference between the positive-positive method and the negative-positive method is also notified.

The facsimile machine on the sending side thereby determines the function on the receiving side (process 105).For example, if the resolution of the facsimile machine itself is 8 dots/m+a x 7.7/am,
The resolution on the receiving side is 16 dots/ma+ x 15.4/
If the receiving side has a higher resolution, such as mra (Y in process 106), the standard value Ss is selected as the threshold value of the binarization circuit 1b (process 107).

On the other hand, if the resolution of the own device is the same as that of the receiving side or lower than that of the receiving side (N in process 106), as shown in FIG.
The above threshold value is selected depending on the recording method on the receiving side. That is, the threshold value is selected to be a low value SL in the case of the negative/positive method of the thermal recording method and the laser method, and a high value H is selected in the case of the positive/positive method of the laser method (processing 108).

Next, the image information obtained by reading the original image using the threshold value selected in this way is transmitted according to a predetermined procedure (process 109).
).

For example, assume that the resolution of the receiving side is the same as or lower than that of the own device, and that the receiving side uses a negative/positive method such as a thermal recording method or a laser method. In this case, the binarization circuit 1b reads the original image using the low value SL as a threshold, so the transmitted image becomes lighter than when reading using the standard value Ss. However, in Fig. 11(a),
As explained in FIGS. 12(b) and 12(a) and 12(b), the above two methods have the characteristic of recording the received image at a higher density than the original density. This allows the receiving side to correctly record the original image with the original image density.

Furthermore, if the receiving side uses the positive-positive method, the binarization circuit 1b reads the original image using the high value H as a threshold, so the transmitted image will be darker than when it is read using the standard value Ss. However, Fig. 13(a)
, (b), in this method, contrary to the above, there is a characteristic that the density of the recorded image becomes thinner. This allows the receiving side to correctly record the original image with the original image density.

On the other hand, if the receiving side has high resolution, the changes in the size of recording pixels as explained in FIGS. 11 to 13 will be
It is considered that it is virtually unnoticeable.

Therefore, when the receiving side has a higher resolution than the sending side, the binarization circuit 1b reads the original image using the standard value Ss as a threshold and transmits it at normal density, so the receiving side receives the image at the appropriate density. You will be able to record.

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

The facsimile apparatus of this embodiment has the same configuration as that in FIG. 1 except for the image reading section 1.
As shown in the figure, line image sensor 1a and A/D
An (analog/digital) conversion circuit 1c and a dither processing circuit 1d are provided.

As shown in FIG. 6, the A/D conversion circuit 1c converts the analog image signal output from the line image sensor 1a into
This is converted into pixel data that indicates brightness levels in 16 gradations. In addition, in the A/D conversion circuit 1c, the quantization characteristics during this analog/digital conversion are as shown in the figure, a linear standard characteristic Qs and an arcuate characteristic Q)I and QL.
One of the three types is selected.

The dither processing circuit 1d converts the multi-value pixel data obtained by the A/D conversion circuit 1c into binary pixel data by known dither processing using, for example, dither matrix data as shown in FIG. It is something that converts.

With this configuration, when transmitting a document, the function of the destination facsimile device is determined before transmitting the image information, as in the above-described embodiment.

As shown in FIG. 8, when the resolution of the receiving side is higher than that of the own device, the quantization characteristics of the A/D conversion circuit IC are as follows.
Select standard characteristic Qs. Furthermore, if the resolution on the receiving side is the same as or lower than that of the own device, the recording method on the receiving side is determined. Then, in the case of a negative/positive thermal recording method or laser recording method, the quantization characteristic of the characteristic QH is selected, while in the case of the positive/positive method, the quantization characteristic of the characteristic QL is selected.

The image signal is converted from analog to digital using the quantization characteristics selected in this manner, and the resulting pixel data is dithered and transmitted to the other party.

By the way, when analog/digital conversion is performed in the A/D conversion circuit 1c, when the characteristic QH is used, the image density of the obtained pixel data becomes thin, and when the characteristic OL is used, contrary to the above, the image density of the obtained pixel data becomes dark.

Therefore, by selecting the quantization characteristic according to the recording method on the receiving side as described above, the receiving side can always record the received image at an appropriate density, as in the above-described embodiment.

Next, yet another embodiment will be described.

The facsimile apparatus of this embodiment has the same configuration as the above embodiment, and the quantization characteristic in the A/DC (analog/digital) conversion circuit 1c is fixed at the standard characteristic Qs.

By the way, considering the case of reading a document image with a density like this, when one Madrisk size read image is dithered, the number of white pixels of the resulting pixel data is:
As shown in FIG. 9, the brightness changes from 0 to 15 depending on the brightness level.

In this embodiment, the dither processing circuit 1d selects one of the three characteristics Ds, DH, and DL shown in the figure to perform dither processing. In this case, when the characteristic Ds is used, the obtained pixel data becomes lighter, and when the characteristic DH is used, the obtained pixel data becomes darker.

Therefore, similarly to the above embodiment, depending on the function of the receiving side,
By changing the density of the transmitted image on the transmitting side and transmitting it in this way, similar effects can be obtained.

By the way, when performing dither processing, dither matrix data is known to be of a concentrated type as well as a distributed type as shown in FIG.
This is more likely to occur in a decentralized case than in a centralized case.
The effects of the present invention are also high.

In each of the above embodiments, when the resolution on the receiving side is high, the original image is read and transmitted at a constant density, but even in that case, the reading density may be adjusted depending on the recording method on the receiving side. It may be changed.

For example, even in the case of the same thermal recording method, the degree of density change in the recorded image differs depending on the type of thermal head. It is conceivable to change the reading density of the image.

[Effects of the Invention] As described above, according to the present invention, the recording characteristics of the receiving device are determined before image information is transmitted, and when reading a document image, the recording characteristics of the receiving device are In the case of characteristics such that black pixels become large, image information with a density higher than the actual original density is extracted, and in the case of characteristics with large black pixels, image information with a lighter density is extracted and transmitted. Regardless of the method, the transmitting side can correctly transmit the original image with a constant density.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a facsimile machine according to an embodiment of the present invention, FIG. 2 is a graph showing binarization of image signals, FIG. 3 is an operational flowchart of transmission processing, and FIG. 4 is a diagram of various types of recording. An explanatory diagram showing the correspondence between the method and the threshold value during binarization, FIG. 5 is a schematic configuration diagram of an image reading section in another embodiment of the present invention, and FIG. 6 is an analog/digital conversion of the image signal. FIG. 7 is an explanatory diagram showing an example of dither matrix data; FIG. 8 is an explanatory diagram showing the correspondence between various recording methods and quantization characteristics in the above embodiment; FIG. The figure is a graph showing the characteristics of dither processing in another embodiment, Figures 10 (a) and (b) are explanatory diagrams showing an example of a received image, and Figures 11 (a) and (b) are thermosensitive recordings. Explanatory diagram showing the recording characteristics of the method, FIGS. 12(a) and (b)
FIG. 13(a) is an explanatory diagram showing the recording characteristics of the negative/positive recording method of the laser recording method. (b) is an explanatory diagram showing the recording characteristics of the positive-positive recording method of the laser recording method. 1... Image reading unit, 1a... Line image sensor, lb... Binarization circuit, lc... A/D (analog/digital) conversion circuit, 1d... Dither processing circuit,
2... Image recording section. 3... Encoding/decoding unit, 4... Network control device, 5...
・Modem, 6... Communication control section, 7... Operation display section,
8...System control unit. Figure Figure ty +yMbj Hundred Bow- Figure Figure Figure 8 Figure Brightness Level-

Claims (1)

[Claims] In a facsimile device that transmits an image to a facsimile device that has a recording characteristic in which white pixels or black pixels are larger than the pixel size corresponding to the resolution when recording an image, the above-mentioned recording characteristic of the receiving device is determined before image information is transmitted. If the recording characteristic of the receiving device is such that white pixels become large when reading a document image, image information with a density higher than the actual document density is extracted, while A facsimile apparatus comprising: an image information density variable means for extracting image information with a lower density when the characteristic increases, and a transmitting means for transmitting the extracted image information.