JP3220217B2 - Facsimile machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facsimile apparatus for performing a predetermined scaling process when transmitting data to a memory.

[0002]

2. Description of the Related Art Conventionally, in a device for processing binarized image information such as a facsimile machine, a scaling process or a pixel density conversion process is performed on a binary image. For example, in a communication method called memory communication in facsimile, binarized image data is temporarily stored in a memory, and communication is started after a predetermined time has elapsed. After the start of communication, the specification of the other party is known. For example, if the size of the other party's printer is smaller than the size of the document to be transmitted, reduction / magnification processing is performed on the binary data stored in the memory.

In an actual facsimile machine, 400
When transmitting from a dpi system to a 200 dpi system (including 8 × 7.7 lines / mm), for example, if reduction of A3 size to A4 size is necessary depending on the relationship between the size of the transmission original and the size of the receiving printer, 36% magnification Becomes FIG. 9 shows a list of fixed-size reduction / magnification in facsimile.

[0004]

As such a binary image scaling method, various methods have already been proposed (for example, see Japanese Patent Publication No. 58-53781). The magnification processing means is switched based on information on whether or not a pseudo halftone is included in the image and the magnification, and the most suitable magnification processing method is selected for the type and magnification of the image, thereby achieving high quality. A binary image scaling method capable of scaling processing has already been proposed (Japanese Patent Application No. 3-355875). That is, for example, as the method of selecting the scaling means, the scaling process shown in FIG. 10 is selected.

[0005] In the above-mentioned proposed method, the multi-valued scaling process (for low magnification) is performed on the binary original image at all scaling factors less than 90%. With this method, 100% ~
The image quality is good at a magnification of about 70%,
At a large reduction ratio such as% or less, the image quality deteriorates greatly. That is, the lines of characters are cut, the texture of the picture is disturbed, and moire occurs in the picture. When the scaling process shown in FIG. 11 is selected as a method of selecting the scaling unit, if the logical sum method is used at all magnifications for a text-only document, character collapse will occur especially at 50% or less. It is too large to read. As described above, when a large reduction of 50% or less is performed on a binary image, there is a problem that image quality is significantly deteriorated.

On the other hand, some recent facsimile machines have high functions. For example, by omitting the pre-procedure of the control signal section (short protocol), the transmission time can be shortened and the communication cost can be reduced. There is a reduced AI-first control scheme. In other words, in this method, the functions (paper size, linear density, encoding method) of the partner device are stored, and if the facsimile of the partner device has not been updated, these information exchanges that are usually performed before image transmission are performed. Are omitted to reduce the transmission time.

[0007] An object of the present invention is to perform a predetermined scaling process on multi-valued data when the partner function is known by the AI first control method, and to reduce the adaptively processed binary image to 50% or less. An object of the present invention is to provide a facsimile apparatus which avoids deterioration of image quality caused by performing large zooming.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, a multi-tone digital signal is scaled at a predetermined magnification, and then binarized. in the facsimile apparatus having the function of transmitting after storing the image in memory, means for storing <br/> linear density of a plurality of destination of the printer communicate, by referring to the storage means when the memory transmission, the printer Means for performing multi-level magnification at a magnification corresponding to the linear density.

According to a second aspect of the present invention, a facsimile apparatus has a function of transmitting a digital signal after converting the multi-tone digital signal at a predetermined magnification, binarizing the digital signal, storing the binarized image in a memory, and transmitting the binarized image. in, multiple recipients of flops communicate
Means for storing the line density and paper size of the printer of the printer, by referring to the storage means when the memory transmission, the pre
Means for multi-level magnification at a magnification corresponding to the linear density of the printer and the paper size of the printer .

[0010]

In the partner information search unit, the number of the partner who has already communicated, the printer linear density, and the paper size are stored. The scanner refers to the partner information search unit at the time of memory transmission, selects a scaling ratio based on the stored printer linear density information and paper size information, and performs multi-value scaling processing.
The multi-value scaled image is binarized by the adaptive processing unit and transmitted.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a block diagram of a facsimile apparatus of the present invention. More specifically, FIG. 1 shows an example in which memory transmission is performed in a facsimile apparatus. This is an example of a case where communication is performed.

In FIG. 1, a partner information retrieval unit 1 stores a facsimile number of a partner who has already communicated and its printer linear density, and outputs the printer linear density in response to input of the partner number. A table is provided.
FIG. 2 is a diagram illustrating an example of a table storing correspondence between destination numbers and printer linear densities. The contents of this table are
When the function of the other party is changed, it is rewritten.

The scanner 2 has a photoelectric conversion element such as a CCD camera, reads an original, converts it into a 400 dpi, 6-bit digital signal (64 gradations), and outputs it. In general, in a scanner, magnification in the main scanning direction for multi-valued data is performed by signal processing called convolution. In the sub-scanning direction, the exposure time of the CCD image sensor is kept constant, and the CCD image is enlarged. This is performed by changing the moving speed of the sensor or the image information. That is, the moving speed in the sub-scanning direction is reduced to increase the speed, and the speed is reduced to increase the moving speed.

FIG. 3 is a diagram for explaining scaling in the main scanning direction. A pixel value P at a conversion pixel position indicated by a black circle is P = α × A
+ Β × B + γ × C + δ × D. Where α, β,
The values of γ and δ are coefficients that differ depending on the position between the BCs of the converted pixels.

In the apparatus of this embodiment, the scanner 2 selects a scaling factor as shown in FIG. 4 based on the information from the partner information search unit 1 and the scaled multivalued image data is subjected to adaptive processing. Sent to unit 3. For example, if the printer linear density of the other party is 200 dpi, the multi-value magnification is 50%.

FIG. 5 is a block diagram of the adaptive processing unit 3. That is, the selection circuit 34 selects the character processing unit 32 or the pattern processing unit 33 according to the character / design determination signal from the image area separation circuit 31. The character processing unit 32 performs, for example, an MTF correction filter and then performs a binarization process using a fixed threshold. The picture processing unit 33 performs a binarization process using an error diffusion method. As the image area separation processing, for example, the “separation method of mixed text / dot / photo image” described in IE90-32 IEICE Technical Report.

The storage unit 4 stores an adaptively processed binary image. Here, the binary image is encoded (MH encoding, M
R encoding) enables data compression.
In this case, the encoded binary image data is stored in the storage unit 4.
, And need to be decoded before performing a binary image scaling process described later.

In the binary image scaling section 5, scaling processing is performed on the binary image. This is because the function of the partner is not registered in the partner information search section 1 or the function of the partner is changed. In order to cope with the case, the binary image scaling unit 5 is provided. Further, in the present embodiment, it is assumed that the paper size of the other party is unknown. Therefore, if the paper size is smaller than the original, it is necessary to reduce the paper size.
A value image scaling unit 5 is provided.

The binary image scaling performed by the binary image scaling unit 5 is as follows.
Since it is reduction / magnification, when enlarging, for example, when the partner changes the function from 200 dpi to 400 dpi,
Since there is a 200 dpi binary image in the memory on the transmitting side in this embodiment, this is transmitted at the linear density, and the other side performs an appropriate process (for example, double-strike) to enlarge the image. .

FIG. 6 is a diagram showing the configuration of the binary image scaling unit 5. The binary image is converted into a multi-value, then multi-valued, and the scaled image is binarized and scaled. Output a binary image. That is, the binary-to-multilevel conversion is performed by performing multi-level conversion by low-pass filter processing. FIG. The product-sum operation using the filter weights is performed on 3 × 3 pixels centered on the target pixel position, and 0 to 15
(4 bits). Next, in multi-value scaling, sub-sampling according to the scaling factor is performed. For example, 75%
In the case of zooming, pixels are thinned out at a ratio of one pixel to four pixels in both the main scanning and the sub-scanning. The multi-value scaled image is binarized by an error diffusion method. Note that the scaling process of the binary image is not limited to the method described above, and another known method may be used.

According to the present embodiment, since the memory communication is performed, the magnification for performing the binary image scaling is at most 72% (the original is A3 size, and the paper size of the destination is A4), so that no significant image quality degradation occurs. In other words, the sender is 400 dpi,
The line density of the partner stored in the partner information search unit 1 is 2
In the case of 00 dpi, the multi-value scaling is performed at a scaling ratio of 50% in the scanner 2, the adaptive processing is performed, and the result is stored in the storage unit 4. If the document size on the transmitting side is A3 and the paper size of the destination is A4, the binary image scaling unit 5
A reduction process of 72% is performed on the 50% binary image, thereby preventing the image quality from deteriorating.

However, the function of the partner is the partner information search unit 1
If the function of the other party has not been registered or the function of the other party has been changed, there is a possibility that a scaling process of 50% or more is performed on the binary image, in which case the image quality deteriorates. .

Further, as another embodiment for transmitting data by the AI first control method, as shown in FIG. 8, a destination information number, a printer linear density, and a paper size are stored in the destination information search unit 1 as shown in FIG. The scanner 2 may perform scaling processing on the multi-valued data accordingly.

For example, when an image is read at 400 dpi, if the original size on the transmitting side is A3, the linear density of the partner printer is 200 dpi, and the partner paper size is A4, the multi-level magnification is set to the main scanning and sub-scanning. Both are 36%, the document size on the sending side is B4, and the linear density of the partner printer is 200
When the partner paper size is A4 at dpi, the multi-value magnification is 41% for both main scanning and sub-scanning, the document size on the transmitting side is A3, and the linear density of the partner printer is 8 × 7.7 lines / mm.
When the size of the partner paper is A4, the multi-value magnification is 37% for main scanning, 35% for sub-scanning, and the document size on the transmitting side is B4.
When the linear density of the partner printer is 8 × 7.7 lines / mm and the partner paper size is A4, the multi-value magnification is set to 4
2% and sub-scanning 40%. In this case, it is not necessary to perform the scaling process on the binary image due to the difference between the original size and the paper size of the destination. Note that the scaling ratio described above is
Magnification determined from the image resolution and the line density of the destination printer
1, the size of the document on the sending side and the size of the
Multiplication of magnification 1 and magnification 2 based on magnification 2 determined from the
Is calculated as an overall magnification. Also mentioned above
The magnification is calculated independently for the main and sub directions, for example,
A read at 400 dpi resolution (both main and sub)
For a document of 3 sizes, the resolution on the receiving side is 8 lines / mm in main scanning,
Transmit to A4 size printer at 7.7 sub-scans / mm
(The case in the bottom row of FIG. 9), the magnification is
Is calculated. Main: 297 mm (horizontal length) → 210 mm ≒ about 72% 400 dpi (≒) 16 lines / mm → 8 lines / mm ≒ 51%, so 72 × 51/100 → 37% Secondary; 420 mm (vertical length) → 297 mm ≒ 72% 400 dpi (≒) 16 lines / mm → 7.7 lines / mm ≒ 49% , 72 × 49/100 → 35%

As described above, according to the present embodiment, when the function of the other party is known using the AI first control method, the scaling process according to that is performed on the multi-value data. The probability that a large reduction in magnification will be performed on the binary image is reduced, and therefore, deterioration of the image quality is prevented.

[0026]

As described above, according to the first aspect of the present invention, at the time of memory transmission, the scaling of multi-value data is performed using the linear density information of the transmission partner obtained at the time of the previous communication. Since the processing is performed, deterioration in image quality can be suppressed as compared with the conventional scaling of a binary image.

According to the second aspect of the present invention, at the time of memory transmission, scaling processing is performed on multi-value data using the linear density information and the paper size information of the transmission partner obtained during the previous communication. Therefore, it is possible to suppress the deterioration of the image quality as compared with the conventional scaling of the binary image.

[Brief description of the drawings]

FIG. 1 is a block diagram of a facsimile apparatus of the present invention.

FIG. 2 is a diagram illustrating an example of a table storing correspondence between destination numbers and printer linear densities.

FIG. 3 is a diagram for explaining scaling in the main scanning direction.

FIG. 4 is a diagram illustrating a multi-value scaling ratio selected according to a linear density of a partner printer.

FIG. 5 is a block diagram of an adaptive processing unit.

FIG. 6 is a diagram illustrating a configuration of a binary image scaling unit.

FIG. 7 is a diagram illustrating an example of a low-pass filter.

FIG. 8 is a diagram showing an example of a table storing correspondences between destination numbers, printer linear densities, and paper sizes.

FIG. 9 is a diagram showing a list of fixed-size reduction / magnification in a facsimile.

FIG. 10 is a diagram showing a method of selecting a scaling unit that has already been proposed by the present applicant.

FIG. 11 is a diagram showing another method of selecting the scaling means already proposed by the present applicant.

[Explanation of symbols]

 1 partner information search unit 2 scanner 3 adaptive processing unit 4 storage unit 5 binary image scaling unit

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-98370 (JP, A) JP-A-63-54865 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 1/38-1/393 G06T 3/40

Claims (2)

(57) [Claims] A facsimile apparatus having a function of transmitting a multi-level digital signal after changing its scale at a predetermined magnification, binarizing the digital signal, storing the binarized image in a memory, and transmitting the binarized image. means for storing the linear density of the destination printer, by referring to the storage means when the memory transmission, before
A facsimile apparatus comprising: means for performing multi-level magnification at a magnification corresponding to the linear density of the printer . 2. A facsimile apparatus having a function of scaling a multi-tone digital signal at a predetermined magnification, binarizing the digital signal, storing the binarized image in a memory, and transmitting the image after the binarized image is stored in a memory. The line density and printing of the destination printer
Means for storing the sheet size of the data, with reference to the Symbol <br/>憶means during memory transmission, multilevel zooming magnification corresponding to <br/> paper size linear density and the printer of the printer And a facsimile apparatus.