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BACKGROUND OF THE INVENTION
The present invention relates to an image reading apparatus suitable for
use in facsimile terminal equipment, and more particularly to an
improvement in picture quality of image information obtained by scanning
an original matter.
Conventional facsimile terminal equipment is provided with two kinds of
binarization units for carrying out binarization and pseudo gray scale
processing, and a user selects one of two kinds of processing in
accordance with an original to be read (refer to the instruction manual of
Hitachi high-speed facsimile HIFAX 130M). The reason for this is as
follows. In a case where the binarization processing is carried out, the
tone of a halftone region on a photograph or the like cannot be expressed.
On the other hand, in a case where the pseudo gray scale processing is
carried out, it is impossible to reproduce a character or line in a
satisfactory manner. Further, as to processing for improving the picture
quality of image information, in order to prevent a character, a line, or
the like from being destroyed or becoming light, contour enhancement
processing is carried out for image information obtained by scanning an
original. When the contour enhancement processing is carried out for a dot
region, however, a Moire pattern is often generated in a binary output. A
method of preventing the generation of a Moire pattern is proposed in a
Japanese Patent Application Un-examined Publication JP-A-2-292,956. In
this method, a dot region is detected to carry out smoothing processing
for the dot region, and contour enhancement processing is carried out for
regions other than the dot region. Thus, the generation of a Moire pattern
in the dot region is prevented, and the sharpness of characters is
improved in a character region. Further, another method of preventing the
generation of a Moire pattern is proposed in a Japanese Patent Application
Un-examined Publication JP-A-2-168,771. In this method, the smoothing
processing is first carried out for image information, and then the
contour enhancement processing is carried out. Thus, the generation of a
Moire pattern in a dot region is prevented, and the sharpness of a
character is improved.
As mentioned above, in the conventional facsimile terminal equipment, one
of two kinds of binarization processing is selected in accordance with the
original used. Now, consider a case where an original, on which a dot
region and a character region coexist, such as a newspaper is used. When
the binarization processing is selected, the halftone of the dot region
cannot be expressed, and moreover a Moire pattern is generated in the dot
region by the contour enhancement processing. On the other hand, when the
pseudo gray scale processing is selected, each of a character and a thin
line is output in a discontinuous form. In either binarization processing,
a large number of black or white discrete pixels are generated which do
not exist in the original. Thus, when a coding method for reducing the
amount of information by paying attention to the continuity of pixels, for
example, Modified Huffmann (MH) coding method or Modified Relative Element
Address Designate (MR) coding method is used, there arise problems that
the amount of code is increased and a transmission time is also increased.
Further, when the method of preventing the generation of a Moire pattern by
detecting a dot region is used to improve the picture quality of an output
image, there arises a problem that an unclear image region such as a dot
region including character information is misjudged, and thus an output
image is deteriorated. In order to solve this problem, a large-scale,
dot-region discriminating circuit is required. When the method of
preventing the generation of a Moire pattern is carried out, there arise
the following problems. In the smoothing processing, the density values of
pixels adjacent to a target pixel in horizontal, vertical and oblique
directions are averaged. Accordingly, even when the contour enhancement
processing is carried out for a thin line whose width is nearly equal to
the width of one scanning line, the thin line cannot be restored. Further,
in a case where a region including n pixels in a traverse direction is
required for smoothing processing and a region including m pixels in a
traverse direction is required for contour enhancement processing, a
memory is necessary which can store image data corresponding to at least
(m+n-1) lines.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an image information
processor which can improve the picture quality of an output image by
emphasizing the contour portions of a character, a photograph and the
like, and by preventing a Moire pattern from generating in a dot region,
can prevent an increase in amount of code, and makes it unnecessary to set
desired binarization processing for each original.
In order to attain the above object, according to the present invention,
there is provided an image information processor which comprises means for
scanning an original matter to convert each pixel data into an electric
signal, means for controlling the start of image processing, a filter for
carrying out enhancement processing among a plurality of adjacent pixels
arranged in oblique directions, after smoothing processing has been
carried out among a plurality of continuous pixels arranged in scanning
and traverse directions (hereinafter referred to as "dot filter"), and
means for carrying out binarization such as simple binarization and pseudo
gray scale processing.
More specifically, according to the above image information processor, when
an original matter is set at a predetermined position and the image
processing is started, image information read out by the scanning means is
applied to the dot filter. When the image information passes through the
dot filter, a dot pattern, that is, a pattern, in which high-density
pixels are arranged in a direction oblique with respect to a scanning
direction, is subjected to smoothing processing, and a character, a line,
or the like, that is, a pattern, in which high-density pixels are
continuously arranged in a horizontal or vertical direction, is subjected
to contour enhancement processing. The output of the dot filter is
subjected to binarization processing or pseudo gray scale processing. As
mentioned above, a dot region is subjected to the smoothing processing by
the dot filter. Accordingly, no Moire pattern is generated in the dot
region. Further, the contour portions of a character, a line and the like
are subjected to contour enhancement processing, and thus the character,
the line and the like do not become light, are not destroyed, and do not
get blurred. That is, a binary output capable of producing a high-quality
image is obtained.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram showing an embodiment of an image information processor
according to the present invention.
FIG. 2 is a diagram showing an example of calculation made by a filter.
FIGS. 3A to 3C are diagrams for explaining a first example of a dot filter
according to the present invention.
FIGS. 4A to 4C are diagrams for explaining a second example of a dot filter
according to the present invention.
FIG. 5 is a circuit diagram showing the hardware of the second example of
FIG. 4A.
FIG. 6 is a block diagram showing a system which is provided with an image
information processor according to the present invention.
FIG. 7 is a block diagram showing a first embodiment of the combination of
an operation panel and image improving, binarization unit which are shown
in FIG. 6.
FIG. 8 is a block diagram showing a second embodiment of the combination of
an operation panel and image improving, binarization unit.
FIG. 9 is a block diagram showing a third embodiment of the combination of
an operation panel and image improving, binarization unit.
FIG. 10 is a block diagram showing a fourth embodiment of combination of an
operation panel and image improving, binarization unit.
FIG. 11 is a diagram showing a filter group corresponding to the dot filter
of FIG. 3A.
FIG. 12 is a diagram showing a filter group corresponding to the dot filter
of FIG. 4A.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will be explained below in detail, with reference to
the drawings.
FIG. 1 shows filter characteristics according to the present invention.
Referring to FIG. 1, when image information is applied to a dot filter 205,
a region where high-density pixels are distributed discretely and
regularly, for example, a dot region is subjected to smoothing processing,
and a region where high-density pixels are continuously distributed, for
example, a character or line is subjected to contour enhancement
processing. As a result, not only is the generation of a Moire pattern due
to binarization unit 200 prevented, but also the character or line is
prevented from becoming light, being destroyed, or getting blurred on the
basis of the processing of the binarization unit 200.
FIG. 2 shows an example of calculation made by a filter. Let us suppose
that in a pixel region including three pixels in each of scanning
direction and traverse direction, P.sub.22 is a target pixel data which is
to be processed by the filter. It is to be noted that the positions of
pixels in a scanning direction are given by j=1 to 3 and the positions of
pixels in a vertical scanning direction are given by i=1 to 3. Each pixel
data P.sub.ij is multiplied by a corresponding filter coefficient
A.sub.ij, and the products thus obtained are summed up to obtain the
filter output for the target pixel data P.sub.22. As is well known, this
processing is the convolutional operation in a digital filter.
FIGS. 3A to 3C are diagrams for explaining a first example of a dot filter
according to the present invention, and FIG. 11 is a diagram for
explaining the operation of a filter group corresponding to the first
example.
In more detail, FIG. 3A shows coefficients of a dot filter 205 (that is,
the first example), and FIGS. 3B and 3C show the procedure for obtaining
the coefficients of FIG. 3A.
Referring to FIG. 3B, in a region including five pixels in a scarming
direction and three pixels in a traverse direction, the mean density of a
5-pixel region is calculated. That is, the mean density A(b)=(a+b+c+g+l)/5
of a pixel region which contains a b-pixel as a center pixel, the mean
density A(d)=(c+d+e+i+n)/5 of a 5-pixel region which contains a d-pixel as
a center pixel, the mean density A(h)=(c+g+h+i+m)/5 of a 5-pixel region
which contains an h-pixel as a center pixel, the mean density
A(l)=(a+g+k+l+m)/5 of a 5-pixel region which contains an l-pixel as a
center pixel, and the mean density A(n)=(d+i+m+n+o)/5 of a 5-pixel region
which contains an n-pixel as a center pixel, are calculated. For a dot
image, these mean density values A(b), A(d), A(h), A(l) and A(n) are
nearly equal to one another. Next, as shown in FIG. 3C, an edge
enhancement value E(h) with respect to the h-pixel in the region which
includes five pixels in a scanning direction and three pixels in a
traverse scanning direction, is calculated. This calculation is carried
out among the b-pixel, the d-pixel, the h-pixel, the l-pixel and the
n-pixel. At this timel the above-mentioned mean density values A(b), A(d),
A(h), A(l) and A(n) are used for calculating the edge enhancement value
E(h), which is given by the following equation:
E(h)=5A(h)-A(b)-A(d)-A(l)-A(n).
Results of such calculation processing are used as the coefficients of the
dot filter 205 of FIG. 3A. Thus, this filter 205 has both the smoothing
characteristic and the edge enhancement characteristic.
FIG. 11 shows a circuit structure which uses two kinds of filters for
smoothing and enhancement and has a same characteristic as that of the
filter shown in FIG. 3.
A filter group 305 shown in FIG. 11 is applied with an image signal which
is given from the N-th scanning line parallel to a scanning direction, an
image signal which is given from the (N-1)th scanning line and has passed
through one 1-line delay unit 300, and an image signal which is given from
the (N-2)th scanning line and has passed through two 1-line delay unit
300, to deliver the result of calculation for a target pixel on the
(N-1)th scanning line. The smoothed output of each pixel on the N-th
scanning line is obtained by a filter 301. That is, the density of each of
three contiguous pixels on the N-th scanning line is multiplied by 1/5,
the density of a pixel which exists on the (N-1)th scanning line and
corresponds to the center pixel of the three contiguous pixels, is
multiplied by 1/5, and the density of a pixel which exists on the (N-2)th
scanning line and corresponds to the above center pixel, is multiplied by
1/5. Five products thus obtained are summed up, to obtain the smoothed
output. Similarly, the smoothed output of each pixel on the (N-1)th
scanning line is obtained by a filter 302. That is, the density of each of
three contiguous pixels on the (N-1)th scanning line, the density of a
pixel which exists on the N-th scanning line and corresponds to the center
pixel of the three contiguous pixels on the (N-1)th scanning line, and the
density of a pixel which exists on the (N-2)th scanning line and
corresponds to the above center pixel, are used for smoothing calculation.
The smoothed output of each pixel on the (N-2)th scanning line is obtained
by a filter 303. That is, the density of each of three contiguous pixels
on the (N-2)th scanning line, the density of a pixel which exists on the
N-th scanning line and corresponds to the center pixel of the three
contiguous pixels on the (N-2)th scanning line, and the density of a pixel
which exists on the (N-1)th scanning fine and corresponds to the above
center pixel, are used for smoothing calculation. As mentioned above, the
smoothing calculation is carriedtout among contiguous pixels arranged in
each of scanaing and traverse directions. Accordingly, in a region where
high-density pixels are arranged at regular intervals in oblique
directions, such as a dot region, the smoothed output of a pixel is given
by the mean density of a pixel group which includes the above pixel as a
center pixel. On the other hand, a character or line has a plurality of
contiguous high-density pixels arranged in scanning and traverse
directions. Accordingly, the density of a pixel in the contour portion of
the character or line is relatively well maintained, in spite of smoothing
processing.
Next, smoothed pixel data on each scanning line are applied to a filter
304, to perform enhancement calculation for the target pixel on the
(N-1)th scanning line. That is, the data of the target pixel is multiplied
by 5, data of pixels which exist on the N-th scanning line and are
adjacent to the target pixel in oblique directions, are multiplied by -1,
and data of pixels which exist on the (N-2)th scanning line and are
adjacent to the target pixel in oblique directions, are multiplied by -1.
The products thus obtained are summed up to obtain the enhancement value
of the target pixel. As can be seen from the above, contour enhancement
calculation is carried out among pixels arranged in oblique directions.
Accordingly, in a region where pixel having the same density are arranged
at regular intervals in oblique directions, such as a dot pattern, the
above-mentioned products cancel one another, and thus the density of the
target pixel is scarcely enhanced. On the other hand, in a character or
line, pixels having the same density are contiguously arranged in scanning
and traverse directions. Accordingly, the density of a pixel in the
contour portion of the character or line is greatly enhanced by the
enhancement processing.
The filter group 305 of FIG. 11 includes two kinds of filters, that is, the
smoothing filters 301, 302 and 303 and the enhancement filter 304. On the
other hand, according to the present invention, as shown in FIGS. 3A to
3C, both the smoothing processing and the enhancement processing are
carried out at the same time by the dot filter 205 which includes five
pixels in a scanning direction and three pixels in a traverse direction.
By making smoothing filter coefficients on each scanning line different
from each other, even the dot filter 205 including three pixels in a
vertical scanning direction can carry out both the smoothing processing
and the enhancement processing. That is, according to the present
invention, it is not required to increase the number of line memories for
1-line delay.
FIGS. 4A to 4C are diagrams for explaining a second example of a dot filter
according to the present invention, and FIG. 12 is a diagram for
explaining the operation of a filter group corresponding to the second
example. More specifically, FIG. 4A shows coefficients of a dot filter 205
(that is, the second example), and FIGS. 4B and 4C show the procedure for
obtaining the coefficients of FIG. 4A.
Referring to FIG. 4B, in a region including five pixels in a scanning
direction and two pixels in a traverse direction, the mean density of a
4-pixel region is calculated. That is, the mean density A(g)=(b+f+g+h)/4
of a 4-pixel region which contains a g-pixel as a center line, the mean
density A(c)=(b+c+d+h)/4 of a 4-pixel region which contains a C-pixel as a
center pixel, and the mean density A(i)=(d+h+i+j)/4 of a 4-pixel region
which contains an i-pixel as a center pixel, are calculated. For a dot
image, these means density values A(c), A(g) and A(i) are nearly equal to
one another. Next, as shown in FIG. 4C, an edge enhancement value E(c)
with respect to the c-pixel in the region which includes five pixels in a
scanning direction and two pixels in a traverse direction, is calculated.
This calculation is carried out among the c-pixel, the g-pixel, and the
i-pixel. At this time, the above-mentioned mean density values A(c), A(g)
and A(i) are used for calculating the edge enhancement value E(c), which
is given by the following equation:
E(c)=5A(c)-2A(g)-2A(i)
Results of such calculation processing are used as the coefficients of the
dot filter 205 of FIG. 4A. Thus, this filter 205 has both the smoothing
characteristic and the contour enhancement characteristic.
FIG. 12 shows a circuit structure which uses two kinds of filters for
smoothing and enhancement and has the same characteristics as that of the
filter shown in FIG. 4.
A filter group 404 shown in FIG. 12 is applied with an image signal which
is given from the N-th scanning line parallel to a scanning direction, and
an image signal which is given from the (N-1)th scanning line and has
passed 1-line delay unit 300, to deliver the result of calculation for a
target pixel on the N-th scanning line. The smoothed output of each pixel
on the N-th scanning line is obtained by a filter 401. That is, the
density of each of three contiguous pixels on the N-th scanning line is
multiplied by 1/4, and the density of a pixel which exists on the (N-1)th
scanning line and is contiguous to the center pixel of the three
contiguous pixels, is multipliedby 1/4. Four products thus obtained are
summed up, to obtain the smoothed output. Similarly, the smoothed output
of each pixel on the (N-1)th scanning line is obtained by a filter 402.
That is, the density of each of three contiguous pixels on the (N-1)th
scanning line and the density of a pixel which exists on the N-th scanning
line and is contiguous to the center pixel of the three contiguous pixels,
are used for smoothing calculation. As mentioned above, the smoothing
calculation is carried out among contiguous pixels arranged in each of
scanning and traverse directions. Accordingly, in a region where
high-density pixels are arranged at regular intervals in oblique
directions, such as a dot region, the smoothed output of a pixel is given
by the mean density of a pixel group which includes the pixel as a center
pixel. On the other hand, a character or line has contiguous pixels in
scanning and traverse directions. Accordingly, the density of a pixel in
the contour portion of the character or line is relatively well
maintained, in spite of smoothing processing.
Next, smoothed pixel data on each scanning line are applied to a contour
enhancement filter 403, to perform enhancement processing for the target
pixel on the N-th scanning line. That is, the data of the target pixel is
multiplied by 5, and the data of each of two pixels which exist on the
(N-1)th scanning line and are adjacent to the target pixel in oblique
directions, is multipliedby -2. Three products thus obtained are summed
up, to obtain the enhancement value of the target pixel. As can be seen
from above, contour enhancement calculation is carried out among pixels
arranged in oblique directions. Accordingly, in a region where pixels
having the same density are arranged at regular intervals in oblique
directions, such as a dot pattern, the above-mentioned products cancel one
another, and thus the density of the target pixel is scarcely enhanced. On
the other hand, in a character or line, pixels having the same density are
contiguously arranged in scanning and traverse directions. Accordingly,
the density of a pixel in the contour portion of the character or line is
greatly enhanced by enhancement processing. Further, the filter group 404
includes two kinds of filters, that is, the smoothing filters 401 and 402
and the enhancement filter 403. On the other hand, according to the
present invention, both the smoothing processing and the enhancement
processing are carried out at the same time by the dot filter 205 which
includes five pixels in a scanning direction and two pixels in a traverse
direction. By making smoothing filter coefficients on each scanning line
different from each other, even the dot filter 205 including two pixels in
a traverse direction can carry out both the smoothing processing and the
enhancement processing. That is, according to the present invention, it is
not required to increase the number of line memories for 1-line delay.
FIG. 5 is a block diagram showing the hardware of the dot filter 205 of
FIG. 4A.
Referring to FIG. 5, a delay element 601 is used for delaying an image
signal by one pixel in a scanning direction, and can be formed of a
flip-flop circuit. A multiplier 602 is used for multiplying image data by
a filter coefficient, and can be realized by the combination of an adder
and a shift register. An adder 603 is used for sunnning up the outputs of
multipliers 602. A 1-line delay device 604 is used for storing data on a
scanning line which precedes a scanning line having a target pixel, and
can be formed of a semiconductor memory. The circuit of FIG. 5 can be
formed of digital circuit elements, and can be incorporated in a large
scale integration circuit.
FIG. 6 is a block diagram showing the whole construction of an embodiment
of facsimile terminal equipment according to the present invention.
Referring to FIG. 6, control unit 101 sends and receives a control signal
through a system bus, to control all of the equipment and to carry out the
transmission and reception of an image signal and a copying operation. The
control unit 101 is formed of, for example, a microprocessor. An operation
panel 102 is an interface, by which a user requires the equipment to carry
out desired processing, and includes, for example, push buttons for
inputting the telephone number of a destination. Reading device 103
generates an image signal by scanning an original matter. The reading
device 103 includes, for example, a CCD line sensor as a photoelectric
conversion element, and includes a pulse motor for scanning the original.
Distortion correcting unit 104 is used to correct the inhomoginity in the
output of the reading device 103 and gamma-characteristics, thereby
normalizing the image signal. Image improving, binarization unit 105
carries out processing for producing a high-quality output image such as
edge enhancement processing and the prevention of a Moire in a dot region,
and further carries out binarization processing. For example, a Laplacian
filter may be used for enhancing edges, and a smoothing filter may be used
for preventing the generation of a Moire pattern in the dot region. As to
binarization, a binarization method using a single threshold value, and a
pseudo gray scale processing method for expressing the tone of an output
image (for example, a dithering method or error diffusion method), are
known. Coding unit 106 compresses the amount of binary image information,
and coding methods such as MH method and MR method are used in the coding
unit 106. A code memory 107 serves as means for storing a coded image
signal, and can be formed of a semiconductor memory. Communication device
108 sends the codes to a transmission line and for receiving codes from
the transmission line. When the transmission line is a telephone line, a
modem is used as the communication device 108. Decoding unit 109 decodes
the codes which are sent from the code memory 107 through the system bus,
to the binary image signal. Recording unit 110 prints out the binary image
on a paper, and may include a laser printer. The operation of the present
embodiment will be explained below.
(1) Transmission of Document
When an operator sets an original in the reading device 103, sets the
telephone number of a destination and desired processing on the panel 102,
and then presses a processing start button, the control unit 101 starts
image processing. Thus, an image signal from the reading device 103 is
normalized by the distortion correcting unit 104, and then converted into
binary data by the image improving, binarization unit 105. The binary data
is converted by the coding unit 106 into codes, which are stored in the
code memory 107. The codes in the code memory 107 are sent to the
destination through the communication device 108 and the telephone line.
(2) Reception of Document
Coded data which is sent from the telephone line through the communication
device 108, is once stored in the code memory 107. The coded data in the
code memory 107 is decoded by the decoding unit 109 to the binary signal,
which is printed on recording paper by the recording unit 110.
(3) Copying
When a user sets an original in the reading device 103, sets the telephone
number of a destination and desired processing on the panel 102, and then
presses the processing start button, the control unit 101 starts image
processing. Thus, an image signal from the reading device 103 is
normalized by the distortion correcting unit 104, and then converted into
binary data by the image improving, binarization unit 105. The binary data
is printed on a paper by the recording unit 110.
FIG. 7 is a block diagram showing a first embodiment of the combination of
the operation panel and the image improving, binarization unit which are
used in the facsimile terminal equipment of FIG. 6. Referring to FIG. 7,
an operation panel 102 includes destination setting unit 201 and a
processing start button 202 for starting or stopping processing. Image
improving, binarization unit 105 is made up of a dot filter 205 and pseudo
gray scale processing unit 207. The dot filter 205 has the characteristics
of FIG. 1, and the pseudo gray scale processing unit 207 is binarization
unit capable of realizing pseudo tone expression by using, for example,
the dithering method or error diffusion method.
Next, the operation of the first embodiment will be explained.
When image information is transmitted, an original is set in the reading
device, the telephone number of a destination is input by the destination
setting unit 201 of the operation panel 102, and then the processing start
button 202 is pressed. In a case where image information is copied, the
original is set in the reading device, and then the processing start
button 202 is pressed. Thus, an image signal passes through the dot filter
205, and then binarization capable of realizing pseudo tone expression is
carried out for the output of the dot filter 205 by the pseudo gray scale
processing unit 207. Thus, the contour portion of a character or figure on
the original is emphasized, and a dot-region is smoothed. Accordingly, a
high-quality binary output is obtained which is excellent in
reproducibility of a character or thin line and can prevent the generation
of a Moire pattern in the dot region. That is, an operator is not required
to select one of binarization and pseudo gray scale processing in
accordance with a pattern on an original. Thus, there will not arise the
following problems of the prior art. That is, when the binarization is
selected, the pseudo tone expression for a halftone region becomes
impossible. On the other hand, when the pseudo gray scale processing is
selected, a character becomes light or blurred, and thus cannot be read.
According to the first embodiment, the operation panel is not required to
include a device for selecting one of binarization and pseudo gray scale
processing in accordance with a pattern on an original, and moreover the
start or stop of transmission can be indicated only by the button 202.
Thus, the operation of a user can be simplified.
Next, a second embodiment of the combination of the operation panel and the
image improving, binarization unit will be explained, with reference to
FIG. 8.
Referring to FIG. 8, like the first embodiment of FIG. 7, the operation
panel 102 includes the destination setting unit 201 and the processing
start/stop button 202 for starting or stopping processing. The second
embodiment, however, is different from the first embodiment of FIG. 7 in
that image improving, binarization unit 105 includes a white pixel
detecting unit 204 for detecting a white image in the neighborhood of a
target pixel, the dot filter 205, a contour enhancement filter 206
connected in parallel with the dot filter 205 for carrying out contour
enhancement no matter whether image information indicates a dot region or
a character/figure region, the pseudo gray scale processing unit 207, and
a changeover switch 209 for connecting one of the outputs of the filters
205 and 206 to the pseudo gray scale processing unit 207 in accordance
with the output of the white pixel detecting unit 204. The white pixel
detecting unit 204 may be realized by eight equalizer detectors each
formed by a logic circuit. Each of the equalizer detectors has two inputs
and one output. The image data of eight peripheral pixels adjacent to a
target pixel are input to every input of the eight equalizer detectors. An
image data representing a white is input to every other input of the
equalizer detectors. The logical sum of the outputs of eight equalizer
detectors is the output from the white pixel detecting unit 204.
Next, the operation of the second embodiment will be explained. In a case
where image information is transmitted, an original matter is set in the
reading device, the telephone number of a destination is input by the
destination setting unit 201 of the operation panel, and then the
processing start button 202 is pressed. When image information is copied,
the original is set in the reading device and then the processing start
button 202 is pressed. Accordingly, it is not required to use conventional
apparatus for selecting one of binarization and pseudo gray scale
processing in accordance of the image information of the original. An
image signal passes through the dot filter 205 and the contour enhancement
filter 206, and is then applied to the switch 209. When the white pixel
detecting unit 204 detects a white image in the neighborhood of a target
pixel, it is determined that the target pixel does not exist in a dot
region, and thus the output of the | | |
