JP3089892B2 - Image data processing 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 data processing apparatus for processing image data based on a dither matrix.

[0002]

2. Description of the Related Art Conventionally, facsimile machines, copiers,
2. Description of the Related Art In a videophone or the like, processing of image data of an image displayed on a document, a still screen, or the like is performed based on a dither matrix. As an example, Japanese Patent Publication No. 63-3
There is an image data processing device described in Japanese Patent No. 3349. In the image data processing apparatus, the image data representing the density level of the image is a dither matrix (hereinafter referred to as mx) representing a threshold level corresponding to m × kn pixels.
kn, which is referred to as a dither matrix of kn, thereby obtaining binarized data of m columns and kn rows of m × kn pixels (hereinafter referred to as m × kn binarized data). Is created.

[0003]

However, the above-mentioned m × kn
The binarized data of m × n obtained by extracting the binarized data of (i) every k−1 rows has a problem that bias of the gradation characteristic occurs.

For example, when an image data processing apparatus is provided in a transmission unit of a facsimile apparatus, the resolution of the receiving facsimile apparatus may be lower than that of the transmitting facsimile apparatus during facsimile communication. In this case, the binarized data processed at a high resolution in the transmitting facsimile machine is transmitted every predetermined row, but the gradation characteristic of the transmitted (received) binarized data is Due to the bias, the original image may not be reproduced well in the receiving facsimile machine.

The gradation characteristics of m × n binarized data are the same as the gradation characteristics of m × n binarized data when image data is processed based on an m × n dither matrix. It is desirable, but not so. When the image data representing the density of the region consisting of 4 × 8 pixels is processed based on the 4 × 8 dither matrix 200 shown in FIG. 12, the 4 × 8 pixels of each gradation shown in FIG. Binary data is created. When these 4 × 8 binarized data are extracted every other row, 4 × 4
Is obtained. However, the 4 × 4 binarized data composed of 1, 3, 5 and 7 rows of the 4 × 8 binarized data has gradations of (0) to (8) of the 4 × 8 binarized data. )
During (17) through (31) (not shown), the gray level of the 4 × 8 binarized data is changed from (9) through
If it is between (16), there is no change in the gradation characteristics, such that it does not change.

SUMMARY OF THE INVENTION An object of the present invention is to provide m × n binary data obtained by extracting m × kn binarized data generated by processing by an image data processing apparatus every k−1 rows. An object of the present invention is to avoid occurrence of bias in gradation characteristics in quantified data.

[0007]

The gist of the present invention is to provide a method for processing image data as a halftone image.
× kn (where m, n, and k are integers of 2 or more)
Dither matrix that defines the threshold value
Comparing each threshold value of the image data with the value of the image data
Create binary data by creating binary data
In the image data processing device includes means, said 2 Nekade
Data to extract data every k-1 rows from data
Providing extraction means and the dither matrix
From (i, k × (j−1) +1) to (i, k × j)
(Where, i is 1 to m an integer, j is an integer 1 or n) as the threshold value of the pixels of the changes one by one stage
I did it.

[0008]

[Action] In the image data processing apparatus of the present invention, a binary
Binarized data from image data by digitized data creation means
Created by the data extraction means from the binarized data
When data is extracted every k−1 rows, the threshold value of the pixel whose image data is (i, k × (j−1) +1) to (i, k × j) changes by one stage. The processing is performed based on a dither matrix of × kn. Therefore, m × n binarized data obtained by extracting m × kn binarized data created by processing by the image data processing device of the present invention every k−1 rows is:
The gradation of the density of the image of m × kn stages is k × (j−1) or
It is the same as long as it is between k × j−1 , and changes when the gradation of the image density becomes k × j. That is, the gradation characteristics of the m × n binarized data are the gradation characteristics of the m × n binarized data created by processing the same image data based on the m × n dither matrix. Will be the same as

[0009]

As described above, the binarized data of m × kn created by the image data processing apparatus of the present invention is k-
The m × n binarized data obtained by extracting every other row does not have a bias in gradation characteristics. Therefore, when the image data processing apparatus of the present invention is provided in a facsimile apparatus, for example, even if m × kn binary data is transmitted every k−1 rows, the receiving facsimile apparatus can improve the original image. Can be reproduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A facsimile apparatus provided with an image data processing apparatus according to one embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a diagram showing the appearance of the facsimile machine. As shown in FIG. 6, the main body 10 of the facsimile apparatus includes a container-shaped lower cover 12, an upper cover 14 that covers the lower cover 12, and a frame (not shown) disposed inside the lower cover 12. I have.

A receiver 16 is attached to the lower cover 12, as shown in FIG. In the lower cover 12, as shown in FIG. 6, a recording paper cassette 20 capable of accommodating a large number of recording papers 18 as recording media is set. The recording paper 18 is sent out one by one from a recording paper cassette 20 by a paper feed roller 22, and then sent to a recording device 30 by a recording paper feeding device 28 including a paper guide 24, a pair of feeding rollers 26, and the like. letter,
Images such as figures are recorded. The feed roller 26 includes a driving device (not shown), and is rotated by driving the driving device. Reference numeral 32 denotes a recording paper leading edge sensor, which detects the leading end of the recording paper 18 sent out from the recording paper cassette 20, and determines the recording start timing of the recording device 30 based on the detection.

The recording device 30 is provided in the upper cover 14. The recording device 30 includes a recording head 34 controlled by a recording head control device 33 (see FIG. 8), a platen 36 rotatably provided at a position facing the recording head 34, and an ink ribbon device 38. I have. The recording head 34 is of a thermal type, and has a large number of heating elements arranged in a line in a direction perpendicular to the direction in which the recording paper 18 is fed. As will be described later in detail, the heating element at a position determined based on a signal supplied to the recording head controller 33 is heated. The platen 36 is rotated around a center line by a driving device (not shown) to
Is to be sent. The ink ribbon device 38 has a thermal ink ribbon 40 having a width corresponding to the recording range of the recording head 34 and an ink ribbon feeding device 42 for feeding the thermal ink ribbon 40. The thermal ink ribbon 40 is sent in synchronization with the recording paper 18, and the recording paper 1 is fed by feeding the thermal ink ribbon 40 and the recording paper 18 and pressing the thermal ink ribbon 40 against the recording paper 18 by the recording head 34.
8 is recorded. Recording paper 18 on which an image is recorded
Is guided to a paper guide 52, sent to a paper discharge tray 54, and discharged out of the apparatus. Reference numeral 56 denotes a recording paper discharge sensor. When recording is continuously performed on a plurality of sheets, after the recording paper discharge sensor 56 detects that the recording paper 18 on which the image has been recorded is completely discharged, the next recording is performed. Feeding of the paper 18 from the recording paper cassette 20 is started to avoid paper jam.

An image reading device 62 for reading an image recorded on a document 60 is provided in the upper cover 14. The original 60 is placed on an original receiver 64 which is detachably attached to the upper cover 14.
Is set between a pair of document guides 66 shown in FIG. The leading end of the set document 60 is detected by a document sensor 68 provided in the upper cover 14, and the document 60 is
The document is fed to the image reading device 62 by a document feeder 74 including a paper guide 72, a feed roller 73, and the like.

The feed rollers 70 and 73 are each composed of a pair of rollers, and are respectively driven by motors 78 and 80 (FIG. 8).
). The motors 78 and 80 are respectively connected to drive circuits 84 and
86. The rotation speeds of the motors 78 and 80 are controlled so as to be always the same.

The image reader 62 includes a light source 88 as a light emitter, lenses 89, mirrors 90 and 92, and a plurality of charge coupled devices as light receivers.
(Hereinafter, abbreviated as a CCD) 94 and the like.
After the reflected light from the mirror 9 is collected by the lens 89, the mirror 9
CCDs reflected by 0,92 and arranged in a line
The image is read one line at a time by receiving light at 94 and displaying the image on the document 60.

A pixel is a minimum unit constituting an image.
This is an area (area) on the document 60 that is read by one CCD 94. The size of one pixel is determined by various factors such as the size of the CCD 94, the positions and angles of the mirrors 90 and 92, the position and the focal point of the lens 89, but in the present facsimile apparatus, the size in the main scanning direction is 0.1 mm. The size in the sub-scanning direction is determined by the feed amount (feed speed) of the document 60 while the image reading device 62 reads one line.

In this facsimile apparatus, the original 60
Is selectable between 0.26 mm, 0.13 mm, and 0.065 mm, and the size (area) of one pixel when each of these feed amounts is selected is 0.13 mm.
× 0.26mm, 0.13mm × 0.13mm, 0.13mm ×
0.065 mm. As the feed amount decreases, the area of one pixel decreases, and the resolution increases.

The CCD 94 is a photoelectric conversion element that outputs a voltage corresponding to the intensity of the received reflected light. The relationship between the intensity of the received light and the magnitude of the output voltage is shown in FIG. As is clear from the figure, the stronger the reflected light, the higher the output voltage. That is, the output voltage of one CCD 94 has a magnitude based on the density of one pixel constituting an image, and a signal (hereinafter, referred to as image data) representing the magnitude of the output voltage is supplied to the system control device 82. Thus, binarized data is created.

Reference numeral 96 denotes a document leading edge sensor for detecting the leading edge of the document 60.
Reading is started based on the detection of the leading edge of zero. After reading, the document 60 is discharged out of the opening 98.

An operation panel 99 is provided on the upper cover 14 as shown in FIG. A liquid crystal display 100 and a resolution (RESOLUTION) key 102 are provided above the operation panel 99 in the figure, and a fine (FINE) lamp 104,
A semi-fine (S.FINE) lamp 105 is provided. Also, a keyboard 106 is provided below,
A numeric keypad 108 is on the left side of the keyboard 106, a copy (COPY) key 110 and a start (START) key 114 are on the right side, and a memory (MEMORY) key 116, a function (FUNCTION) key 118, and a set ( Various keys such as a SET key 120 and cursor keys 122 and 124 are provided.

A copy key 110 is a key for instructing copying of a document and for instructing a start of copying, and a start key 114 is a key for instructing a start of processing. A function key 118 is a key for instructing display of various functions that can be executed in the facsimile apparatus.
2, 124. Set key 120
Is a key for instructing the selection, and the memory key 116
Is a key for instructing selection of memory transmission.

The resolution key 102 is a key for designating a resolution. As described above, the feed speed of the document 60, that is, the number of rotations (the number of steps) of the motors 78 and 80 is controlled in accordance with the resolution. Further, the feeding speed of the recording paper 18 and the thermal ink ribbon 40 is also controlled according to the resolution. The resolution can be selected from normal, fine, semi-super fine (hereinafter abbreviated as S. fine) and photo. Normal, Fine, and S. Fine are selected when a normal image such as a character is read, and Photo is selected when a halftone image such as a photo is read. When the photo is selected, 16 gradations (corresponding to fine) and 32 gradations (corresponding to S. fine) can be selected. If Normal is selected, the feed amount of the document 60 is set to 0.26 mm, if Fine is selected, the feed amount is set to 0.13 mm, and if S. Fine is selected, the feed amount is set to 0.065 mm. You.

When the resolution key 102 is not pressed, normal is selected. In this case, neither the fine lamp 104 nor the S. fine lamp 105 is turned on. When the resolution key 102 is pressed once, fine is selected, and the fine lamp 104 is turned on. When the button is pressed twice, S. fine is selected, the fine lamp 104 is turned off, and the S. fine lamp 105 is turned on. Among these Normal, Fine and S. Fine, the feed rate is the fastest when Normal is selected, but the resolution is the highest when S. Fine is selected.

When the resolution key 102 is pressed three times, a photo is selected, and the fine lamp 104 is turned on. Both the fine lamp 104 and the S. fine lamp 105 are turned on. If a photo is selected,
As will be described later in detail, 16 gradations and 3 gradations are operated by operating the function keys 118 and the cursor keys 122 and 124.
One of two gradations is selected.

The facsimile apparatus is controlled by a system controller 82 shown in FIG. System control unit 8
2 is a CPU, two kinds of dither matrices 130, 1
32, a ROM for storing a control program,
A system control unit 142 including a RAM having a quantified data memory is provided. The system control unit 142 is provided with a binarization circuit 146 and a threshold circuit 14 by a bus 144.
8, a parallel / serial conversion circuit 150, an encoding / decoding control circuit 152, a transmission / reception control circuit 154, and the like. The system control device 82 includes the image reading device 62, the recording head control device 33, and the operation panel 9.
9, a line 156, drive circuits 84 and 86, etc. are connected. Further, although not shown, various devices necessary for the operation of the facsimile apparatus, such as the recording paper leading edge sensor 32, the recording paper discharging sensor 56, the document sensor 68, and the document leading edge sensor 96, are connected.

The binarizing circuit 146 includes the image reading device 62
Is converted into binary data. The binarizing circuit 146 includes the image reading device 6
2, while the image data read is provided by
Threshold data is supplied from the threshold circuit 148, and the image data is compared with the threshold data to generate binary data. When the image data is larger than the threshold data, it is set to 0 (white), and when it is smaller, it is set to 1 (black), so that the binary data is created. When the binary data for one row is created, it is stored in a binary data memory (not shown) of the RAM.

The threshold circuit 148 stores the threshold data a0 to a31 shown in FIG. 9 and supplies it to the binarization circuit 146 based on a command. When Normal, Fine, or S. Fine is selected, uniform threshold data of a predetermined size is supplied. When Photo is selected, each threshold of the dither matrices 130 and 132 is supplied. The threshold data having a size corresponding to the value level is supplied. When Normal, Fine, or S. Fine is selected, the size of the threshold data is changed in accordance with an operation of a key (not shown) by an operator. Also,
When the threshold level of the 32-gradation dither matrix 130 is 4, the threshold data a4 is supplied, and
When the threshold level of the gradation dither matrix 132 is 2
In this case, the threshold data a4 (= b2) is also supplied.

The gradation represents the density of the halftone image at discrete levels. When 32 tones are selected, the shade of the halftone image is divided into 32 levels from white to black, and when 16 tones are selected, it is divided into 16 levels. The amount of change in the threshold data corresponding to one step of the threshold level in 32 gradations is １ ／ of that in 16 gradations.

The numbers described in the dither matrix 130 in FIG. 1 represent the threshold level of each pixel. As shown in FIG. 9, as the threshold level increases, the corresponding threshold level increases. Data becomes smaller. However, in FIG. 9, for simplicity, the interval between adjacent threshold levels and the interval between adjacent threshold data values are uniform, but in fact, they vary logarithmically. It is usually done as follows.

The numbers can also be considered to represent the gradation of a region composed of 4 × 8 pixels. In that case, the image data is detected as a unit including an area composed of 4 × 8 pixels. When the image data becomes smaller (the halftone image in the area composed of 4 × 8 pixels becomes darker), black (1) is sequentially assigned to the pixels with the smaller numbers.
To be. Therefore, if the image data detected using a region composed of 4 × 8 pixels as one unit is processed based on the dither matrix 130, binary data of each gradation as shown in FIG. 2 can be created.

The dither matrix 132 in FIG. 3 is the same as the dither matrix 130 except that an area composed of 4 × 4 pixels is one unit. Since the feed amount of the document at 16 gradations is twice as large as that at 32 gradations, an area composed of 4 × 4 pixels at 16 gradations and an area composed of 4 × 8 pixels at 32 gradations. Are the same, and as shown in FIG.
Is the same as the gradation h in the 16 gradations. Also, 4x
By processing image data detected using a region consisting of four pixels as one unit based on the dither matrix 132, binary data of each gradation shown in FIG. 4 can be created.

The parallel / serial conversion circuit 150 converts a parallel signal into a serial signal. The signals processed in parallel by the system control unit 142 are converted into serial signals and supplied to the printhead control device 33.

The encoding / decoding control circuit 152 encodes the binary data, decodes an encoded signal inputted from the outside, and supplies it to the RAM.

When the transmission / reception control circuit 154 is connected to the line 156 between the facsimile machine on the transmitting side (own apparatus) and the facsimile apparatus on the receiving side (hereinafter, referred to as a partner apparatus) 160, It communicates with the device 160, and converts the binarized data processed in its own device into:
When transmitting at a reduced resolution, control is performed such that the binarized data stored in the RAM is transmitted for each predetermined row.

The operation of the facsimile apparatus according to the present embodiment configured as described above will be described. First, when copying the original 60, the original 60 is set on the original platen 64, the resolution is selected, and then the copy key 110 is pressed. If the resolution key 102 is not pressed , normal is selected. When the image is
During reading for the number of lines, the motors 78 and 80 are driven in four steps, and the document 60 is fed by 0.26 mm in the sub-scanning direction. The image data read by the image reading device 62 is supplied to the binarization circuit 146, and is compared with predetermined threshold data to generate binarized data.

In the binarization circuit 146, when the image data is smaller than the threshold data, the pixel is 1 (black).
If it is large, it is set to 0 (white).
The created binarized data is supplied to the binarized data memory of the RAM one row at a time. The binarized data stored in the RAM is supplied to the printhead controller 33 via the parallel / serial conversion circuit 150, and a predetermined heating element of the printhead 34 is heated. The feed speed of the recording paper 18 and the feed amount of the thermal ink ribbon 40 are controlled to a size corresponding to the feed amount (resolution) when reading the document 60. The read image is recorded on the recording paper 18 and discharged to the paper discharge tray 54.

By pressing the resolution key 102 once,
Fine is selected. While the image is read by the image reading device 62 for one line, the motors 78 and 80 are driven in two steps, and the original 60 is fed by 0.13 mm.
Similarly, if the resolution key 102 is pressed twice, S. Fine is selected, and the feed amount of the document 60 becomes 0.065 mm. In that case, the motors 78 and 80 are driven one step at a time.

When the resolution key 102 is pressed three times,
Photo is selected. Next, function key 11
When the numeric keys 108 of "8" and "5" are sequentially pressed, "5. USER OPTIONS" is displayed on the liquid crystal display 100. After confirmation, press the set key 120 and press “4”.
Is pressed, "4. GRAY SCAL
E "is displayed. After that, when the set key 120 is pressed,
"GRAY SCALE: 32" or "GRAY S
CALE: 16 "is displayed. The gradation selected last time is displayed. "GRAY SCALE: 32"
Is displayed, the set key 120 is depressed in order to determine 32 gradations. To select 16 gradations, one of the cursor keys 122 and 124 is pressed, and after the display changes to "GRAY SCALE: 16," the set key 120 is pressed.

When 32 gradations are selected, the original 60 is fed by 0.065 mm while the image is read by the image reading device 62 for one line. While the image data is supplied to the binarization circuit 146, the threshold data corresponding to each threshold level of the dither matrix 130 shown in FIG. The binarization circuit 146 compares the image data with the threshold data to generate binarized data.

More specifically, as shown in FIGS. 9 and 10, when the image data output from one CCD 94 is ax and the threshold data is a0, the image data ax is changed to the threshold data a0. Smaller than 2 at that pixel
The quantified data is set to 1 (black). Threshold data is a16
In this case, the image data ax is set to 0 (white) because it is larger than the threshold data. The binarized data is created based on the following equation. S (o, p)> T (q, r) s (o, p) = 0 S (o, p) <T (q, r) s (o, p) = 1 where S (o, p) Is the size of image data of (o, p) pixels on the document 60 output by one CCD 94, and T (q, r) is the threshold level of (q, r) pixels of the dither matrix 130. S (o, p) is the binarized data of the (o, p) pixel.

However, the binarized data created as described above is not always the same as the binarized data as shown in FIG. In this embodiment, the image data of one pixel output from one CCD 94 is compared with the threshold data of the dither matrix 130 corresponding to the threshold level of the pixel.
If the density (density) of the area composed of 4 × 8 pixels is not uniform, the binary data will not be the same as in FIG.
However, in an area composed of 4 × 8 pixels, the amount of change in image data is small, and the number of pixels that become black (1) increases as the image data decreases. Looking at the created image as a whole, a smooth halftone image can be obtained.

When 16 gradations are selected, the original 60 is fed by 0.13 mm while the image reading device 62 reads one line. While the image data is supplied to the binarization circuit 146, each threshold data corresponding to the threshold level of the dither matrix 132 shown in FIG. 3 is supplied. Hereinafter, binarized data is created by performing the same processing as when 32 gradations are selected.

Next, a case where a document is transmitted will be described. When the original 60 is transmitted, there are direct transmission and memory transmission, and in any case, before the transmission is started, communication between the receiving partner apparatus 160 and the transmitting apparatus (own apparatus) is performed. Is performed. The communication is performed before the reading of the original is started when the direct transmission is selected, and is performed after the reading of the original is completed when the memory transmission is selected.

First, the case where direct transmission is performed will be described. The original 60 is set, and the resolution key 1
02 or the function key 118 is operated to select a resolution. After that, the facsimile number of the partner device 160 is input by the ten keys 108. When the start key 114 is pressed, the partner device 160 is called, the line 156 is connected, and communication starts. The feed amount is 0.
4 × 8 2 read at 065 mm (S. Fine)
When the digitized data is transmitted to a facsimile apparatus having a receiving record sending amount of 0.13 mm (fine), there is a problem that the image data is doubled in the receiving facsimile apparatus. To avoid this,
The resolution in both devices must be the same.

When the partner device 160 is connected to the line 156, signals representing all the resolutions of the partner device 160 are transmitted from the partner device 160 to the own device. In the own device, a signal representing a resolution lower than the resolution selected by the operator among all the resolutions provided by the own device,
Signals that match each other are searched for with the transmitted signal. Then, a signal representing the highest resolution is selected from the searched signals, the resolution in the own device is determined to be the resolution represented by the selected signal, and the signal representing the resolution is transmitted to the partner device 160. .

More specifically, when the resolution key 102 is pressed twice in the own apparatus, the S.P.
If the signal indicating S. fine, fine, and normal is transmitted from the partner device 160 when fine is selected, the resolution in the own device is determined to be S. fine, and S. fine is determined.
A signal indicating fine is transmitted to the partner device 160.

If the signal transmitted from the partner device 160 indicates fine or normal, the resolution is determined to be fine regardless of whether S. fine has been selected by the operator. When the signal transmitted from the partner device 160 is only normal, the resolution is determined to be normal. Conversely, when the fine is selected in the own apparatus, the fine is selected even if a signal indicating S. fine is transmitted from the partner apparatus 160.

When the resolution key 102 is pressed three times,
When the photo is selected, 32 or 16 gradations are further selected. Thereafter, communication with the partner device 160 is performed before image reading is started. In the own device, 32 gradations are selected, and the other device 1
When a signal indicating S. fine, fine, and normal is transmitted from 60, the resolution of the own device is determined to be 32 gradations, and the image data processed in 32 gradations is transmitted to the partner device 16.
Sent to 0. When a signal indicating fine or normal is transmitted from the partner device 160, the resolution is set to 16 gradations. Further, when 16 gradations are selected in the own device, even if a signal or the like indicating S. Fine is transmitted from the partner device 160, the 16 gradations remain. This is because, as described above, the feed amount at 32 gradations of the photo is 0.065 mm, which is the same as that of S. Fine, and
This is because the feed amount in gradation is 0.13 mm, which is the same as that in fine.

After the resolution is determined and transmitted, the image reading device 62 starts reading an image in the own device. While the image is read for one line, the original 60 is fed by a feed amount corresponding to the determined resolution, and the read image data is supplied to the binarization circuit 146 and compared with threshold data. Binary data is created and transmitted to the partner device.

Next, the case where the memory transmission is performed will be described. After the original 60 is set and the resolution is selected, the memory key 116 is pressed, and the facsimile number of the partner device 160 is input by the ten keys 108. When the start key 114 is pressed, reading of an image is started at a feed speed of the document 60 according to the selected resolution. The image data read by the image reading device 62 is supplied to a binarization circuit 146, and is compared with threshold data to create and encode binary data. The data is sequentially stored in the memory one row at a time.

After the reading is completed, the resolution is determined and transmitted as in the case of direct transmission. Then, the coded binary data stored in the RAM is transmitted to the partner device 160 via the transmission / reception control circuit 154 according to the determined resolution.

When S. fine is selected in the own apparatus and a signal or the like representing S. fine is transmitted from the partner apparatus 160, a signal representing S. fine is transmitted to the other apparatus 160 and stored in the RAM. The encoded binary data passes through the transmission / reception control circuit 154 as it is,
60. When a signal indicating fine or normal is transmitted from the partner device 160,
The encoded binary data stored in the RAM is transmitted at a reduced resolution, that is, every other row or every third row.

In the own apparatus, after reading an image by selecting a photo and selecting 32 gradations, communication with the partner apparatus 160 is performed, and S. Fine, Fine. When a signal indicating normal is transmitted, the partner device 160
A signal representing S. fine is transmitted to the destination device 160 via the transmission / reception control circuit 154 as the encoded binary data in the RAM. Fine. When a signal indicating normal is transmitted, a signal indicating fine is transmitted to the partner device 160,
The binarized data in the RAM is transmitted every other line (at a reduced resolution). In this embodiment, the odd rows (1, 3,
5, 7 ...) are transmitted.

It is assumed that the density of the area composed of 4 × 8 pixels is uniform, and that the binarized data shown in FIG. 2 is actually created as a result of processing the image data based on the dither matrix 130. The gradation of the 4 × 4 binarized data composed of 1, 3, 5, and 7 rows of the 4 × 8 binarized data shown in FIG. (0), (1)
The same applies to the case of (2), which changes when (2) is reached, and the same when the gradation of 4 × 8 binary data is (2), (3), and changes when (4) is reached. The above 4 × 4 binarized data and 4 × 4 of FIG.
Comparing with the binarized data, it can be seen that the gradation characteristics provided by these binarized data are the same. That is, 1, 3, 5, 7 of the 4 × 8 binary data shown in FIG.
In the 4 × 4 binarized data composed of rows, no bias in gradation characteristics occurs.

Actually, since the density of the area composed of 4 × 8 pixels is not uniform, the same binary data as the binary data of each gradation shown in FIG. 2 is not always created. Absent. However, in an area composed of 4 × 8 pixels, the amount of change in the image data is small, and the (i, k × (j−1) +1) pixel to (i, k × j) pixel of the dither matrix 130 Since the threshold levels are sequentially changed one by one, 4 × 4 binarization obtained by extracting every other row of 4 × 8 binarization data actually created in this embodiment. Also in the data, it is possible to prevent the gradation characteristics from being biased. Therefore, even if the own device transmits 4 × 8 binarized data every other row, the tone characteristics of the 4 × 4 binarized data received by the partner device 160 are not biased.

When 16 gradations are selected in the own device and a signal indicating fine is transmitted from the partner device 160, and 16 gradations are selected in the own device,
When a signal representing S. Fine or the like is transmitted from the partner device 160, the encoded binary data stored in the RAM is transmitted as it is.

As described above, in the 4 × 4 binarized data obtained by extracting every other row of the 4 × 8 binarized data created by the image data processing apparatus of this embodiment, No bias in gradation characteristics occurs. Therefore, even if the transmission-side facsimile apparatus including the image data processing apparatus of the present embodiment transmits 4 × 8 binarized data every other line, the reception-side facsimile apparatus can reproduce the original image well. You. In this embodiment, the binarization circuit 146 performs the binarization processing.
Of the transmission / reception control circuit 154
The encoded binary data stored in the AM is stored in a predetermined row.
The part that controls the data extraction is sent every time
Make up.

In the above embodiment, the image data processing apparatus is provided in the facsimile apparatus capable of selecting between 16 gradations and 32 gradations.
It is also possible to provide a facsimile apparatus capable of selecting 48 gradations. When 48 gradations are selected, the image data is processed based on the dither matrix 180 shown in FIG. When the memory transmission is selected, 48 gradations are selected, and when only signals indicating fine and normal are transmitted from the partner device 160, the encoded binary data stored in the RAM is converted into three. Every other line (1,
4, 7,...).

The threshold level represented by the dither matrix is not limited to the dither matrices 130 and 132.
(I, k × (i−1) +1) pixels to (i, k × i)
Other modes may be used as long as the threshold level differences of the pixels change sequentially by one stage. For example, the threshold level is changed from (i, k × (i−1) +1) pixels to (i, k).
Xi) It may be possible to decrease by one stage for pixels. Furthermore, when extracting every k-1 rows, 2
It may be extracted from the row (or the k-th row). Even in that case, the bias of the gradation characteristics is avoided.

Further, in the above embodiment, one C
Image data output by CD94 and dither matrix 1
By comparing the threshold value data corresponding to the threshold level of each of the 30 pixels with the threshold value data, 4 × 8 binarized data is created.
As in the case of outputting image data representing the average density of an area composed of eight pixels, a threshold corresponding to image data common to an area composed of 4 × 8 pixels and a threshold level of the dither matrix 130. Binary data may be created by comparing with value data. By doing so, it is possible to create an image in which the density of image data read by an image reading device having a low resolution changes smoothly.

Further, in the above embodiment, the size of the image data output from the image reading device 62 is compared with the threshold data corresponding to the threshold level represented by the dither matrix. The image data may be processed in the processing circuit, and the processed data may be compared with threshold data. For example,
The image data can be converted into data representing a density value. In this case, the threshold value circuit 148 stores threshold value data of the density value. Further, the image data may be converted into level data directly comparable to the threshold levels of the dither matrices 130 and 132.

Further, in the above-described embodiment, the image data is processed based on the dither matrices 130 and 132 both when reading an image when copying is performed and when reading when transmitting an image. However, at the time of reading when copying is performed, a different dither matrix, for example, dither matrix 2
00 may be processed.

Although not specifically exemplified, the present invention can be carried out in various modified and improved forms based on the knowledge of those skilled in the art without departing from the scope of the claims.

[Brief description of the drawings]

FIG. 1 is a diagram showing a dither matrix stored in a ROM of a system control device of a facsimile apparatus including an image data processing device according to an embodiment of the present invention.

FIG. 2 is a diagram showing binarized data created based on the dither matrix.

FIG. 3 is a diagram showing another dither matrix stored in a ROM of the system control device.

FIG. 4 is a diagram showing binarized data created based on the dither matrix.

FIG. 5 is a perspective view showing the facsimile apparatus.

FIG. 6 is a sectional view of the facsimile machine.

FIG. 7 is a plan view showing an operation panel of the facsimile apparatus.

FIG. 8 is a block diagram showing the image data processing device.

FIG. 9 is a diagram showing a relationship between image data of an image reading apparatus of the facsimile apparatus and threshold data.

FIG. 10 is a diagram showing processing of image data in the image data processing device.

FIG. 11 is a diagram showing a dither matrix in another mode different from the above dither matrix.

FIG. 12 is a diagram showing a dither matrix stored in a ROM of a system control device of a conventional facsimile machine.

FIG. 13 is a diagram showing binarized data created based on the dither matrix.

[Explanation of symbols]

 62 image reader 78, 80 motor 82 system controller 94 CCD 130, 132, 150 dither matrix 146 binarization circuit 148 threshold circuit 154 transmission / reception control circuit 170, 171, 172, 173 pixels

Claims (1)

(57) [Claims] 1. A method for processing image data as a halftone image.
For example, m × kn (where m, n, and k are integers of 2 or more)
Dither that defines the threshold value corresponding to the pixels in the
Each threshold value of the matrix and the value of the image data are
By comparing, the binarized data for creating the binarized data
In the image data processing apparatus including the data creating means , data is extracted every k-1 rows from the binary data.
And a data extraction means for extracting the dither matrix from (i, k × (j−1) +1) to (i, k × j) (where i is an integer of 1 or more and m or less, and j is 1 or more. An image data processing device, wherein the threshold value of a pixel (an integer equal to or less than n) sequentially changes by one stage.