JPS6284657A - Image processor - Google Patents

Abstract

PURPOSE:To eliminate the need to make a troublesome density adjustment according to original density by adding a means which performs quantization based on reference values which are higher and lower than a determined value respectively to a means which performs quantization based on the determined value. CONSTITUTION:A circuit which performs binary coding operation on the basis of an N% threshold value leads a level 11 corresponding to N% which is obtained through the division of a variable resistance 19(R1) for density variation to the minus input of a comparator 28, and the result is outputted to an AND gate 29. Another binary coding circuit performs binary coding operation based on an N+alpha% threshold value. Further, a binary coding circuit which codes an image signal X into a binary signal based on an N-beta% threshold level is provided. When a lustrous slip is used as an original, the binary-coding result based upon the shifted up N+alpha% threshold value is outputted to an OR gate 34. When a diazo-copied original is used as an original, the binary-coding result based upon the N-beta% threshold value is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an image processing apparatus, and more particularly to an image processing apparatus that quantizes and outputs an image signal read by an image reading means.

[Prior Art] Devices such as those described above are widely used for digitally processing images, such as facsimiles and image file devices.

FIG. 3 shows the configuration of an image reading device used in a facsimile machine or the like. As shown in the figure, a document 1 to be read is conveyed in the direction of the arrow by a conveying means (not shown), and is read by a reading sensor 2 . The reading position by the reading sensor 2 is illuminated by a light source 4 such as an LED array, and the reflected light is irradiated onto the reading sensor 2 through the lens 3.

The reading sensor 2 is composed of a CCD reading sensor or the like, and has light receiving elements sl to Sn arranged at a density of, for example, about 8 pixels/■, as shown in FIG. lens 3
is an array-like lens such as a SELFOC lens (trade name), and provides optical information on each scanning line of each of these light-receiving elements.

The analog image signal read by the reading sensor 2 is subjected to predetermined quantization, but in many cases it is converted into black and white binary information by comparing it with a predetermined slice level using a circuit such as a comparator.

[Problems to be Solved by the Invention] However, because the difference in density between the image information of the original and the background color used in this type of device varies, there are cases where the two character images of the original are not accurately quantized. .

For example, slips for carbon copying and the like may have glossy surfaces, and with such high-reflectance originals, unless the slice level for quantization is set to a high level, the text and other characters may be lost. Image information cannot be output as black information.

Furthermore, since the background portion of a document copied by a diazo copying machine has a mottled pattern with relatively high density, a low slice level must be set in order to output the background color as white information.

Normally, the above-mentioned slice level adjustment is performed by operating a density adjustment knob or the like, and the operator is required to perform this complicated operation one by one depending on the document.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides an image processing device that quantizes and outputs an image signal read by an image reading means. A first means for performing quantization, and second and third means for performing quantization using a reference value higher and lower than the determined value, respectively, are provided, and a predetermined level range in which the level of the image signal is relatively high is provided. If the peak level of the image signal is smaller than a relatively low predetermined value, the third quantization means is used; otherwise, the first quantization means is used. We adopted a configuration that quantizes the image signal.

[Function] According to the above configuration, originals with relatively high background density and image information density, such as glossy slips, are quantized using a high level reference value, and background and image information are quantized, such as in diazo copies. For documents with relatively low density, quantization is performed using a low-level reference value, so protonization output can be performed without missing image information.

[Embodiments] Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 is a circuit diagram showing an example of the configuration of an image processing device according to the present invention, in which the image signal outputted by the image reading device is
2 peak hold circuits 17°18 and comparator 2
0, 25, 27, 28 and 32.

The reading device consists of a line sensor completely similar to that shown in FIGS. 3 and 4, and is arranged with respect to the original 1 as shown in FIG. That is, reading sensor 2. Lens 3.
The light source 4 is configured to scan an area slightly wider than the width of the original 1, and a white reference plate 5 is placed at a reading position that extends beyond the original 1, and the density information of this reference plate is read and input by the sensor 2. It is possible to do so.

The output from the sensor 2 is performed as shown in FIG. 5, as in a normal CCD line sensor. FIG. 5 shows the output of the reading sensor 2 for one scanning line. As shown in the figure, the light receiving elements S l -S n of the sensor 2 are made to correspond to the original 1 and the white reference plate 5, and the density information of each element 81 to Sn is outputted using an output clock.
An image signal X having a scanning waveform as shown in 6 is obtained. Here, for simplicity, the original l is illustrated as having a uniform density of black or gray, and the waveform 6 is at a low level, but at the position of the white reference plate 5, the waveform 6 corresponds to that density. It is at a high level.

The reflectance of the white reference plate 5 is set to, for example, a reflectance comparable to that of plain paper copy paper for a copying machine, and a value equivalent to or higher than that of glossy slip paper.

The reading output of the white reference plate 5 is set as the maximum value (ioo%) of the image signal, as indicated by reference numeral 7 in FIG. Further, the binarization slice level is set to N% as indicated by reference numeral 11 according to the peak of the image signal. Here, the symbols A-D
are the scanning output level width of the background part of a document such as a glossy slip, the output level width of the 9-character ruled line part of the same document, the level width of the background part of a document such as a diazo copy, and the level width of the image information of the same document. It shows.

Now, in FIG. 1, the scanning output of the white reference plate 5 is input to the peak hold circuit 17 in response to a peak detection command (formed in response to a pulse corresponding to the reference plate position of the scanning control clock) on the signal line 17a. and this level (6th
7) is held in the peak hold circuit 17. Further, the peak value of the document portion is held in the peak hold circuit 18.

The peak level of the white reference plate held by the peak hold circuit 17 is input to a voltage dividing circuit 23 composed of resistors R2, R3, and R4. These three resistors form levels 10 and 17' (values between level widths B and C) in FIG. 6, respectively.

The comparator 20 is a level X of the image signal obtained by scanning the original.
is smaller than the signal level 10. On the other hand, the signal level IO is guided to the series connection of resistors R5 and R6 via a voltage follower 21 composed of an operational amplifier, and the level 12 in FIG. 6 is formed by the voltage division of these resistors.

Comparator 25 determines whether the image signal of this document is higher than signal level 12.

Therefore, the levels of the image signal X of the original are levels 10 and 12.
If it is between, comparator 20.25 is high L/
Since it outputs hell, latch 3 is applied via AND gate 24.
7 is set as a high level roll.

On the other hand, the signal level 17' formed by the resistor circuit 23 is led to the comparator 3o, and the comparator 30 detects that the peak value of the image signal X of the document held in the peak bold circuit 18 is the signal level 17'. If the level of the 0 image signal X is smaller than the level 17', the comparator 3o outputs a high level.

The second latch 37 and comparator 30 control the three AND gates 35, 29, and 33 directly or via the inverter 26, 36, select the outputs of the three binarization circuits described below, and select the output of the OR gate 34. Output via .

First, a circuit that performs binarization using an 8% threshold is provided. That is, the peak value of the original image signal I am guided by my own power. The comparator 28 indicates that the image signal X is at level 11.
(N%) and outputs the result to the AND gate 29.

The other binarization circuit binarizes the image signal X using a threshold of N+0%. The level 11 formed by the resistor 19 is amplified with the same polarity by a non-inverting amplifier 22 composed of an operational amplifier, and is output to a comparator 27 as a threshold level of N+0% (sign 9 in FIG. 6, that is, set between the level width AγB). guided by his single power. The comparator 27 performs binarization by determining whether the image signal X is greater than the threshold level 9 of N+0%.

The result is input to AND gate 35.

Furthermore, the image signal
A value converting circuit is provided.

A dark value level 11 of N% formed by a resistor 19 is applied to both ends of the series connection of resistors R9 and RIO via a voltage follower 31, and a threshold level 15 of N-β% is formed by the voltage division of these resistors. and is guided by the power of the comparator 32. The comparator 32 performs binarization by comparing the image signal X with this threshold level. The binarized output is input to an AND gate 33.

In the above configuration, when the above-mentioned glossy slip or the like is used as a document, the signal level of the image signal enters the part B in FIG. Output and gate 24
Latch 37 is set via. At this time, since the peak value of the original is clearly higher than the level l7', the comparator 30 outputs a low level. As a result, AND gate 35 is turned ON, AND gates 29 and 33 are turned OFF, and the result of z-value conversion performed using the N+0% shifted up threshold by 2 comparator 27 is applied to OR gate 3.
4.

Next, when a diazo copy original is used as an original, the peak value thereof is at least lower than level 12, so the comparator 25 outputs a low level and the latch 37 is not set.

On the other hand, the comparator 30 calculates the peak value of the image signal
Since it is lower than level 17 in the figure, it outputs level 1. As a result, the AND gate 33 is turned ON, and the AND gates 29 and 35 are turned OFF via the inverter 36, so that the N-
The binarization result performed using the β% threshold is output.

Furthermore, if the original is not one of the above two types but a normal handwritten original, the latch 37 will not turn on, and the comparator 30 will output a low level because the latch 37 is higher than the peak value level l7'.

Therefore, the AND gate 29 is turned ON and the AND gates 33 and 35 are turned OFF via the inverters 26 and 36, and a signal binarized at the dark value level of N% by the comparator 28 is output.

According to the embodiments described above, when using an original with a relatively high level of both background density and image information, or an original with relatively low background and image information, it is not necessary to manually adjust the density level one by one as in the past. Since an appropriate binarization slice level is automatically selected and quantization processing is performed without the need for change, it is possible to provide an excellent image processing device that can significantly improve operability and reduce operational errors.

[Effects] As is clear from the above description, according to the present invention, in an image processing device that quantizes and outputs an image signal read by an image reading means, the image signal is quantized using the determined reference value. When the first means and the second and third means respectively perform quantization using a reference value higher and a lower reference value than the determined value, and the level of the image signal is within a relatively high predetermined level range. The second quantization means is used, and if the peak level of the image signal is smaller than a relatively low predetermined value, the third quantization means is used, and in other cases, the first quantization means is used to convert the image signal. Since a configuration that performs quantization is adopted, there is no need to perform troublesome density adjustment according to the original density, and an excellent image processing device that can automatically and accurately set the density can be provided.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an example of the configuration of an image processing device according to the present invention, FIG. 2 is a perspective view showing the arrangement of the image reading device, and FIG. 3 is an explanatory diagram showing the configuration of the image reading device. Fig. 4 is an explanatory diagram showing the configuration of the reading sensor; Fig. 5 is an explanatory diagram showing the operation of the reading device shown in Figs. 2 to 4; Fig. 6 is an image of the device shown in Fig. 1. FIG. 3 is a diagram showing signal levels. 17.18... Peak hold circuit 20, 25.27.28.30.32... Comparator 21, 31... Voltage follower 28, 38
...Inverter 29, 33, 35...And gate 34...Or gate 37...Latch patent applicant Canon Co., Ltd. ;, 1 agent Patent attorney Takashi Kato −j

Claims (1)

[Claims] In an image processing device that quantizes and outputs an image signal read by an image reading means, a first means quantizes the image signal using a determined reference value, and a reference value higher and lower than the determined value. Second and third means for quantizing each value are provided, and when the level of the image signal is within a relatively high predetermined level range, the second quantization means is used, and the peak level of the image signal is relatively low. An image processing apparatus characterized in that when the image signal is smaller than a predetermined value, the third quantizing means is used, and in other cases, the first quantizing means is used to quantize the image signal.